Ougan juice debittering using ultrasound-aided enzymatic hydrolysis: Impacts on aroma and taste

N-Acetyl-O-methyl-tyrosine from Bipolaris bicolor: A novel fungicide for postharvest anthracnose and citrus preservation

The necessity for safe and effective alternatives to conventional chemical fungicides is underscored by postharvest citrus fruit losses due to anthracnose, caused by Colletotrichum gloeosporioides. In this context, the biocontrol fungus Bipolaris bicolor WZU-HOG4, isolated from Ougan pericarp, was identified as possessing antimicrobial activity. Through bioassay-guided fractionation and subsequent metabolite profiling, N-Acetyl-O-methyl-tyrosine was identified as the active antifungal compound using NMR and HRESIMS. This compound demonstrated significant inhibitory effects against C. gloeosporioides and other pathogens, exhibiting a relatively broad-spectrum antifungal activity. Molecular docking analysis indicated that N-acetyl-O-methyl-tyrosine binds to tyrosinase with greater affinity than Vitamin C, effectively inhibiting its activity. Furthermore, Ougan fruits treated with the compound exhibited increased activities of antioxidant enzymes SOD, POD, and CAT, reduced MDA content, and decreased oxidative stress during storage. Cytotoxicity assays conducted on HEK-293 cells confirmed the compound's safety at the tested concentrations. N-acetyl-O-methyl-tyrosine emerges as a promising natural antifungal and tyrosinase inhibitor for citrus postharvest preservation, providing a safe alternative to chemical preservatives for extending shelf life.

Multivariate analysis to evaluate the storage time of cocoa honey (Theobroma cacao L.) processed by pasteurization and high intensity ultrasound

This study investigated the effects of thermal pasteurization, thermal pasteurization with additives, and high-intensity ultrasound techniques on the storage of cocoa honey (Theobroma cacao L.) over a 28-day period. Physicochemical analyses revealed significant differences among the treatments, with thermal pasteurization maintaining stability for up to 14 days, pasteurization with additives for up to 28 days, and ultrasound treatment for up to 21 days. All conservation methods effectively inhibited microbial growth throughout the 28 days. The compounds detected in the highest relative contents were 2-heptyl acetate and palmitic acid, with esters representing the predominant chemical class. The application of multivariate analysis tools provided a more efficient exploration of the VOC data, demonstrating that pasteurization with additives produced a more consistent compound profile throughout the storage period. These findings indicate that pasteurization with additives and ultrasound technology were the most effective methods for extending the shelf life of cocoa honey.

Clarification of Sugarcane Juice Catalyzed by Magnetic Immobilized Laccase Intensified by Alternating Magnetic Field

In this study, Cu2+-chelated magnetic silicon dioxide nanoparticles were synthesized as carriers for laccase immobilization. The prepared magnetic immobilized laccase was applied in the clarification of sugarcane juice. The optimal conditions for the clarification of sugarcane juice with magnetic immobilized laccase in a shake flask were determined to be as follows: a temperature of 35 °C, pH of 5.5, rotation speed of 150 r/min, and immobilized laccase dosage of 1.0 mg/mL. The sucrose in the sugarcane juice inhibited both free and immobilized laccase. The inhibitory effect was characterized as mixed inhibition, wherein competitive inhibition played a dominant role. An alternating magnetic field was introduced into the catalysis process using magnetic immobilized laccase, and the catechin degradation rate was improved to 77.2% under a magnetic field intensity of 80 Gs and magnetic field frequency of 400 Hz. Under the optimal alternating magnetic field conditions, the treatment time of sugarcane juice was reduced to 20 min when catalyzed by the magnetic immobilized laccase, wherein a decolorization rate of 54.4%, reduction in turbidity of 89.7%, and total phenol degradation rate of 43.4% were achieved. Compared with the shaking condition, the assistance of alternating magnetic fields can shorten the clarifying time, increase the clarifying effect, and enhance the catalyst reusability. These results reveal useful information about the enzymatic treatment of high-sugar juice and provide a potential strategy for juice clarification with magnetic immobilized enzymes.

Effect of Drying Temperature on Sensory Quality, Flavor Components, and Bioactivity of Lichuan Black Tea Processed by Echa No. 10

Lichuan black tea (LBT) is a well-known congou black tea in China, but there is relatively little research on its processing technology. Echa No. 10 is the main tea tree variety for producing LBT. This study investigated the sensory quality, flavor components, and bioactivity of Echa No. 10 Lichuan black tea (LBT) at different drying temperatures (70, 80, 90, 100, 110, 120, and 130 °C). During 80-120 °C, increasing the drying temperature enabled a higher sweet aroma concentration and enhanced the sweetness in the taste, in contrast to reducing the floral, fruity, and sweet aromas, and increasing the bitterness and astringency, at >120 °C. Additionally, with an increasing drying temperature, the contents of tea polyphenols and total catechins significantly decreased, with the theaflavins decreasing first and then increasing, and the alcohols, aldehydes, esters, and hydrocarbons increasing first and then decreasing. Meanwhile, compounds (including linalool, (Z)-linalool oxide (furanoid), (E)-linalool oxide (furanoid), cis-β-Ocimene, and methyl salicylate) contribute more to the floral and fruity aromas at <110 °C. Furthermore, low-temperature drying favors the antioxidant and inhibitory effects of the α-amylase, α-glucosidase, and glucose absorption activity. Both the tea quality and bioactivity results revealed 80-110 °C as the optimal drying temperature range for LBT.

Manganese biofortification in grapevine by foliar spraying improves volatile profiles of Cabernet Sauvignon grapes and wine sensory traits

Manganese (Mn) is involved in plant metabolism as an enzyme cofactor. However, the role of Mn in the formation of volatile compounds in grapes has rarely been studied. To address this gap, this study explored the effect of foliar Mn application on the aroma traits of grapes and wine. Mn nutrient solutions at different concentrations (0 (CK), 300, 1200, and 2400 mg/L) were sprayed on grapevines in 2017 and 2018 and the volatile compounds, odor activity, and sensory features of grapes and wine were investigated. The results showed that Mn application significantly increased Mn content in grape leaves and fruits at harvest. Compared with CK, the total volatile content of grapes was significantly increased by Mn treatment in both years because of the promotion of the accumulation of alcohols and esters. Particularly, 1200 mg/L Mn treatment resulted in a higher sensory score than CK, especially in terms of intensity, duration, and harmony. Multivariate analysis and odor activity values jointly identified eight volatile compounds (ethyl acetate, phenylethyl acetate, and phenylethyl alcohol, etc.) as key odorants that contribute to the floral and fruity flavors of Mn-treated wine. Overall, this study indicated that a moderate concentration of Mn is beneficial for improving the fragrance characteristics of grapes and wines. The results have implications for micronutrient management of grapevines to improve wine flavor quality.

Research advances in technologies and mechanisms to regulate vinegar flavor

New vinegar needs a long maturing time to improve its poor flavor before sale, which greatly increases its production cost. Therefore, it is urgent to explore regulation technologies to accelerate vinegar flavor maturation. Based on literature and our research, this review introduces the latest advances in flavor regulation technologies of vinegar including microbial fortification/multi starters fermentation, key production processes optimization and novel physical processing technologies. Microbial fortification or multi starters fermentation accelerates vinegar flavor maturation via enhancing total acids, esters and aroma precursors content in vinegar. Adjusting raw materials composition, fermentation temperature, and oxygen flow reasonably increase alcohols, organic acids, polyphenols and esters levels via generating more corresponding precursors in vinegar, thereby improving its flavor. Furthermore, novel processing technologies greatly promote conversion of alcohols into acids and esters in vinegar, shortening flavor maturation time for over six months. Meanwhile, the corresponding mechanisms are discussed and future research directions are addressed.

Revealing the synergistic antibacterial mechanisms of resveratrol (RES) and pulsed electric field (PEF) against Acetobacter sp

In the wine industry, Acetobacter sp. is a typical spoilage microorganism responsible for increased volatile acids and wine spoilage. This study investigated the impact of combined treatment using varying concentrations of resveratrol (RES) and pulsed electric field (PEF) on the bactericidal efficacy, intracellular enzyme activities, and cellular metabolism of Acetobacter sp. The results from the Weibull mathematical model revealed a notable enhancement in the bactericidal effectiveness of the RES and PEF treatments with increasing RES concentration. In addition, the synergies between RES and PEF might not only resulted in the deactivation of Alcohol dehydrogenase (ADH) and Aldehyde dehydrogenase (ALDH) of Acetobacter sp., but also induced modifications in the secondary and tertiary structures of intracellular enzymes as evidenced by fluorescence, ultraviolet, fourier transform infrared, and circular dichroism spectra. Furthermore, metabolomics results showed that 1,910 metabolites exhibited differential expression, with 1,118 metabolites being down-regulated and 792 metabolites being up-regulated. After the synergies between RES and PEF, 17 biochemical pathways were significantly changed, mainly involving amino acid metabolism, carbohydrate metabolism, cofactor and vitamin metabolism, nucleotide metabolism, etc. These findings demonstrated that the combined treatment of RES and PEF can effectively suppress the growth of Acetobacter sp. and the inactivation mechanism of Acetobacter sp. by PEF in conjunction with RES was revealed.

Homologous expression of Aspergillus niger α-L-rhamnosidase and its application in enzymatic debittering of Ougan juice

The α-L-rhamnosidase (rha1) gene was homologously expressed in Aspergillus niger strains CCTCC 206047 and CCTCC 206047ΔpyrG, using hygromycin B and auxotrophic as selection markers. The engineered A. niger strains RHA001-1 and RHA003-1 were screened, yielding α-L-rhamnosidase activities of 20.81 ± 0.56 U/mL and 15.35 ± 0.87 U/mL, respectively. The copy numbers of the rha1 gene in strains RHA001-1 and RHA003-1 were found to be 18 and 14, respectively. Correlation analysis between copy number and enzyme activity in the A. niger strains revealed that α-L-rhamnosidase activity increased with the copy number of the rha1 gene. Recombinant α-L-rhamnosidase was utilized for the enzymatic debittering of Ougan juice, and its process conditions were optimized. Furthermore, the primary bitter substance neohesperidin (2.22 g/L) in Ougan juice was converted into hesperetin 7-O-glucoside (1.47 g/L) and hesperidin (0.143 g/L). This study presents a novel approach for the production of food-grade α-L-rhamnosidase and establishes a technical foundation for its application in the beverage industry.

Purification and characterization of limonin D-ring lactone hydrolase from sweet orange (Citrus sinensis (L.) Osbeck) seeds

BACKGROUND

Citrus products often suffer from delayed bitterness, which is generated from the conversion of non-bitter precursors (limonoate A-ring lactone, LARL) to limonin under the catalysis of limonin D-ring lactone hydrolase (LDLH). In this study, LDLH was isolated and purified from sweet orange seeds, and a rapid and accurate high-performance liquid chromatography method to quantify LARL was developed and applied to analyze the activity and enzymatic properties of purified LDLH.

RESULTS

Purified LDLH (25.22 U mg-1) showed bands of 245 kDa and 17.5 kDa molecular weights in native polyacrylamide gel electrophoresis (PAGE) and sodium dodecyl sulfate PAGE analysis respectively. After a 24 h incubation under strongly acidic (pH 3) or strongly alkaline (pH 9) conditions, LDLH still retained approximately 100% activity. Moreover, LDLH activity was not impaired by thermal treatment at 50 °C for 120 min. Enzyme inhibition assays showed that LDLH was inactivated only after ethylenediaminetetraacetic acid treatment, and other enzyme inhibitors showed no significant effect on its activity. In addition, the LDLH activity of calcium ion (Ca2+) intervention was 108% of that in the blank group, and that of zinc ion (Zn2+) intervention was 71%.

CONCLUSION

LDLH purified in this study was a multimer containing 17.5 kDa monomer with a wide pH tolerance range (pH 3-9) and excellent thermal stability. Moreover, LDLH might be a metallopeptidase, and its activity was stimulated by Ca2+ and significantly inhibited by Zn2+. These findings improve our understanding of LDLH and provide some important implications for reducing the bitterness in citrus products in the future. © 2024 Society of Chemical Industry.

Optimization of sensory properties of ultrasound-treated strawberry vinegar

Vinegar is renowned for its benefits to human health due to the presence of antioxidants and bioactive components. Firstly, this study optimized the production conditions of ultrasound-treated strawberry vinegar (UT-SV), known for its high consumer appeal. The sensory properties of UT-SV were optimized by response surface methodology (RSM) to create the most appreciated strawberry vinegar. Secondly, various quality parameters of conventional strawberry vinegar (C-SV), UT-SV, and thermally pasteurized strawberry vinegar (P-SV) samples were compared. RSM was employed to craft the best strawberry vinegar based on consumers ratings of UT-SV. Sensory characteristics, bioactive values, phenolic contents, and organic acid contents of C-SV, UT-SV, and P-SV samples were assessed. Through optimization, the ultrasound parameters of the independent variables were determined as 5.3 min and 65.5 % amplitude. The RSM modeling levels exhibited high agreement with pungent sensation at 98.06 %, aromatic intensity at 98.98 %, gustatory impression at 99.17 %, and general appreciation at 99.26 %, respectively. Bioactive components in UT-SV samples increased after ultrasound treatment compared to C-SV and P-SV samples. Additionally, the amount of malic acid, lactic acid, and oxalic acid increased after ultrasound treatment compared to C-SV samples. Ultimately, UT-SV with high organoleptic properties was achieved. The ultrasound treatment positively impacted the bioactive values, phenolic and organic acid content, leading to the development of a new and healthy product.

Comprehensive quality evaluation of fermented-steaming Fructus Aurantii based on chemical composition, flavor characteristics, and intestinal microbial community

Fructus Aurantii (FA) is an edible and medicinal functional food used worldwide that enhances digestion. Since raw FA (RFA) possesses certain side effects for some patients, processed FA (PFA) is commonly used in clinical practice. This study aimed to establish an objective and comprehensive quality evaluation of the PFA that employed the technique of steaming and fermentation. Combined with the volatile and non-volatile components, as well as the regulation of gut microbiota, the differentiation between RFA and PFA was analyzed. The results showed that the PFA considerably reduced the contents of flavonoid glycosides while increasing hesperidin-7-O-glucoside and flavonoid aglycones. The electronic nose and GC-MS (Gas chromatography/mass spectrometry) effectively detected the variation in flavor between RFA and PFA. Correlation analysis revealed that eight volatile components (relative odor activity value [ROAV] ≥ 0.1) played a key role in inducing odor modifications. The original floral and woody notes were subdued due to decreased levels of linalool, sabinene, α-terpineol, and terpinen-4-ol. After processing, more delightful flavors such as lemon and fruity aromas were acquired. Furthermore, gut microbiota analysis indicated a significant increase in beneficial microbial taxa. Particularly, Lactobacillus, Akkermansia, and Blautia exhibited higher abundance following PFA treatment. Conversely, a lower presence of pathogenic bacteria, including Proteobacteria, Flexispira, and Clostridium. This strategy contributes to a comprehensive analysis technique for the quality assessment of FA, providing scientific justifications for processing FA into high-value products with enhanced health benefits. PRACTICAL APPLICATION: This study provided an efficient approach to Fructus Aurantii quality evaluation. The methods of fermentation and steaming showed improved quality and safety.

Bitter flavors and bitter compounds in foods: identification, perception, and reduction techniques

Bitterness is one of the five basic tastes generally considered undesirable. The widespread presence of bitter compounds can negatively affect the palatability of foods. The classification and sensory evaluation of bitter compounds have been the focus in recent research. However, the rigorous identification of bitter tastes and further studies to effectively mask or remove them have not been thoroughly evaluated. The present paper focuses on identification of bitter compounds in foods, structural-based activation of bitter receptors, and strategies to reduce bitter compounds in foods. It also discusses the roles of metabolomics and virtual screening analysis in bitter taste. The identification of bitter compounds has seen greater success through metabolomics with multivariate statistical analysis compared to conventional chromatography, HPLC, LC-MS, and NMR techniques. However, to avoid false positives, sensory recognition should be combined. Bitter perception involves the structural activation of bitter taste receptors (TAS2Rs). Only 25 human TAS2Rs have been identified as responsible for recognizing numerous bitter compounds, showcasing their high structural diversity to bitter agonists. Thus, reducing bitterness can be achieved through several methods. Traditionally, the removal or degradation of bitter substances has been used for debittering, while the masking of bitterness presents a new effective approach to improving food flavor. Future research in food bitterness should focus on identifying unknown bitter compounds in food, elucidating the mechanisms of activation of different receptors, and developing debittering techniques based on the entire food matrix.

Current situation, trend, and prospects of research on functional components from by-products of baijiu production: A review

In the present scenario marked by energy source shortages and escalating concerns regarding carbon dioxide emissions, there is a growing emphasis on the optimal utilization of biomass resources. Baijiu, as the Chinese national spirit, boasts remarkably high sales volumes annually. However, the production of baijiu yields various by-products, including solid residues (Jiuzao), liquid wastewater (Huangshui and waste alcohol), and gaseous waste. Recent years have witnessed dedicated research aimed at exploring the composition and potential applications of these by-products, seeking sustainable development and comprehensive resource utilization. This review systematically summarizes recent research, shedding light on both the baijiu brewing process and the bioactive compounds present baijiu production by-products (BPBPs). The primary focus lies in elucidating the potential extraction methods and applications of BPBPs, offering a practical approach to comprehensive utilization of by-products in functional food, medicine, cosmetic, and packaging fields. These applications not only contribute to enhancing production efficiency and mitigating environmental pollution, but also introduce innovative concepts for the sustainable advancement of associated industries. Future research avenues may include more in-depth compositional analysis, the development of utilization technologies, and the promotion of potential industrialization.

Fermentation-promoting effect of three salt-tolerant Staphylococcus and their co-fermentation flavor characteristics with Zygosaccharomyces rouxii in soy sauce brewing

Staphylococcus is the dominant genus in the fermentation process of soy sauce, but its effect on the flavor of soy sauce has not been clearly established. In order to investigate the role of this genus in soy sauce fermentation, individual fermentation with Staphylococcus spp. screened from the moromi and their co-fermentation with an ester-producing yeast of Zygosaccharomyces rouxii were designed. Through the analysis of physicochemical properties, organic acid composition, volatile flavor compounds (VFCs) and sensory characteristics during fermentation, Staphylococcus was confirmed as a contributor to the acidity, ester aroma and alcohol aroma of soy sauce. In their co-fermentation with yeast, the ester aroma of soy sauce was further enhanced. Moreover, pathway enrichment analysis and network construction of key VFCs also revealed potential metabolic networks for formation of characteristic flavor compounds in co-fermentation. This work will help optimize the fermentation functional microbiota to obtain better soy sauce flavor.

Partial substitution of wheat flour with soybean and gluten powder: impact on flavor characteristics of Pixian Douban-Meju and its quality

BACKGROUND

In this study, different proportions of soybean flour and gluten flour were used as partial replacements for wheat flour for the fermentation of Pixian Douban-Meju (PXDB). The aim was to study the effects of soybean flour/gluten flour on the quality improvement of PXDB.

RESULTS

In comparison with the control group (CT) (0% substitution of wheat flour), substitution of wheat flower with 12.5% soybean flour (the H2 group), 7.5% gluten flour (G2), and 10% gluten flour (G3) improved the amino acid nitrogen content by 3.8%, 5.6%, and 9.4% respectively. The mixtures of wheat flour and gluten flour (G2 or G3) increased the organic acid and free amino acid content. The results of two-dimensional gas chromatography mass spectrometry (GC × GC-MS) showed that the amount of key aroma substances increased about sixfold in comparison with the CT group (194.61 g.kg-1 ), achieving 1283.67, 1113.883, and 1160.19 g.kg-1 in the H2, G2, and G3 groups, respectively. There were also more aldehydes and pyrazines in all the substitution groups. Quantitative descriptive analysis indicated that the G3 sample presented the best organoleptic quality with a reddish-brown color and a more mellow aroma than the control sample.

CONCLUSION

In conclusion, the fermentation of G3 resulted in higher quality PXDB-meju, showing that partial substitution of wheat flour with gluten improved the quality of PXDB. © 2023 Society of Chemical Industry.

Sonication results in variable quality and enhanced sensory attributes of Adajamir (Citrus assamensis) juice: A study on an underutilized fruit

Citrus assamensis, commonly known as Adajamir, is an underutilized fruit with distinctive sensory and nutritional properties. The limited amount of research on this particular citrus type was recognized as one of the research gaps for this study. The objective of this study was to evaluate and compare the impacts of sonication, pasteurization, and thermosonication techniques on the quality and sensory attributes of Adajamir juice. A randomized experimental design was used in the study, wherein the juice underwent three different treatments. The results indicate that there were no significant changes in pH or titratable acidity following all treatments. Yet, notable differences in juice color were observed. The use of sonication and thermosonication resulted in an increase in β-carotenoid levels. Additionally, total phenolic content and antioxidant activities were observed to increase. All three treatments led to a reduction in ascorbic acid levels relative to the control. However, the complete elimination of microbial growth was observed during the thermal treatment. Compared to other approaches, sonication has been shown to be notably more efficacious in enhancing both the flavor and aroma. Sonication has been observed to improve the perceived bitterness to a certain degree. These findings support the potential of sonication as an alternative preservation method for Adajamir juice, offering enhanced quality and sensory acceptance.

Identification of regionalmarkers based on the flavor molecular matrix analysis of sauce-aroma style baijiu

BACKGROUND

Baijiu is a very complex system and its flavor substances are endogenous, influenced by raw materials, starter, production process, production region and other factors. The production region directly affects the composition of flavor substances and quality of baijiu. However, identification of baijiu region is challenging because the corresponding relationship between the production region and baijiu quality is not clear, and the identification of regionalmarkers is indeterminate. In this study, the differences in volatile components of sauce-aroma style baijiu from four representative regions were investigated.

RESULTS

A total of 94 volatile compounds were identified in samples tested. Additionally, it was verified that 35 potential flavor substances had important contributions to the aroma of sauce-aroma style baijiu. Meanwhile, nine potential regionalmarkers were screened through multivariate analysis. Further, based on distribution of volatile compounds and the results of sensory evaluation combined with multivariate analysis, a molecular matrix and correlation network were established according to the results of addition experiments, which showed that six substances had a significant impact on the flavor of the tested samples.

CONCLUSION

Six key flavor substances (ethyl octanoate, ethyl 2-methylpropanoate, propyl acetate, ethyl heptanoate, 2-nonanone and butyl hexanoate) were considered as important regionalmarkers to effectively identify the production region of sauce-aroma style baijiu. © 2023 Society of Chemical Industry.

Unveiling innovation in aroma attribute evaluation of Niulanshan Baijiu: An advanced exploration of two different processing methods via food sensory omics and penalty analysis

Niulanshan Baijiu (NLS), a notable variety of Baijiu known for its light flavor and extensive historical legacy, was subjected to a comparative analysis using two different processes: Hunzheng Xucha (HX) and Qingzheng Qingcha (QQ). The study combined sensory-oriented flavor analysis and penalty analysis to assess the differences between the two processes. Aroma compounds in NLS were extracted using liquid-liquid extraction and headspace solid phase microextraction. Gas chromatography-olfactometry-mass spectrometry was employed to identify 46 aroma-active compounds, including the first-time discovery of ethyl isohexanoate and 2,4-nonadienal in NLS. Quantification of 35 compounds with odor activity value (OAV) ≥ 1 was achieved using internal standard curve methods. Sensory assessments by a cohort of 111 participants highlighted the preference for HX-NLS in terms of flavor, while QQ-NLS exhibited a sour-Chen aroma that required improvement. The study further revealed the significant impact of acetic acid, butyric acid, hexanoic acid, octanoic acid, and 3-methylbutanal on the sour-Chen aroma in liquor.

Impact of thermal pasteurization and thermosonication treatments on black grape juice (Vitis vinifera L): ICP-OES, GC-MS/MS and HPLC analyses

Grape juice is a widely consumed fruit due to its bioactive compounds, minerals, and aroma components. Our objective was to investigate ultrasound treatment of black grape juice affects its bioactive components due to using response surface methodology (RSM) and artificial neural network (ANN) optimization. At the same time, mineral components, sugar components, organic acids, and volatile aroma profiles were compared in black grape juice treated with thermal and ultrasound pasteurization. ANN showed superior predictive values (>99%) to RSM. Optimal combinations were obtained at 40 °C, 12 min, and 65% amplitude for thermosonication. Under these conditions, phenolic, flavonoid, antioxidant activity, and anthocyanin values were 822.80 mg GAE/L, 97.50 mg CE/L, 24.51 mmol Trolox/L, and 368, 81 mg of mv-3-glu/L, respectively. Thermosonicated grape juice (TT-BGJ) was tested against black grape juice (P-BGJ) produced with conventional thermal methods. This study investigated the effects of thermal pasteurization and thermosonication on black grape juice bioactive compounds and minerals, aroma profile, and sensory evaluation. Thermosonication affected the aroma profile less, 329.98 μg/kg (P-BGJ) and 495.31 μg/kg (TT-BGJ). TT-BGJ was detected to contain seven different mineral elements (Mn, K, Fe, Mg, Cu, Zn, and Na). Thermosonication caused an increase in Fe, Zn, Mn, and K minerals. Panelists generally liked the TT-BGJ sample. These results suggest that the thermosonication process may potentially replace the traditional black grape juice processing thermal process.

Characterization of the interaction between allicin and soy protein isolate and functional properties of the adducts

BACKGROUND

Soybean meal, a by-product of the soybean oil production industry, has a high protein content but the compact globular structure of the protein from soybean meal limits its wide application in food processing. Allicin has been found to have numerous functional properties. In this study, allicin was interacted with soy protein isolate (SPI). The functional properties of the adducts were investigated.

RESULTS

Binding with allicin significantly quenched the fluorescence intensity of SPI. Static quenching was the main quenching mechanism. The stability of adducts decreased with increasing temperature. The greatest extent of binding between allicin and sulfhydryl groups (SH) of SPI was obtained at an allicin/SH molar ratio of 1:2. The amino groups of SPI did not bind with allicin covalently. Soy protein isolate was modified by allicin through covalent and non-covalent interactions. Compared with SPI, the emulsifying activity index and foaming capacity of adducts with a ratio of 3:1 were improved by 39.91% and 64.29%, respectively. Soy protein isolate-allicin adducts also exhibited obvious antibacterial effects. The minimum inhibitory concentrations (MICs) of SPI-allicin adducts on Escherichia coli and Staphylococcus aureus were 200 and 160 μg mL^-1 , respectively.

CONCLUSION

The interaction of allicin with SPI is beneficial for the functional properties of SPI. These adducts can be used in different food formulations as emulsifiers, foamers, and transport carriers. © 2023 Society of Chemical Industry.

Aroma enhancement of blueberry wine by postharvest partial dehydration of blueberries

Blueberries with 20%, 30%, and 40% weight loss were used for winemaking, aiming to explore the feasibility of applying postharvest dehydration for improving blueberry wine aroma. Postharvest dehydration decreased the titratable acidity of blueberries and their resultant wines. Total anthocyanins and phenols in blueberries with 30% weight loss were increased by 25.9% and 16.1%, respectively, due to concentration effects, while further dehydration resulted in a decline. Similar trends were observed in blueberry wines. Moderate postharvest dehydration increased total terpenes, benzeneacetaldehyde and phenylethyl alcohol, ethyl butanoate, methyl salicylate, 1-hexanol, and γ-nonalactone content in blueberries and wines, which could enhance the floral, fruity, and sweet notes of blueberry wines. Wines made from blueberries under severe dehydration (40% weight loss) had the lowest overall aroma score, which was related to the higher content of 4-ethyl-phenol and 4-ethylguaiacol. In conclusion, moderate postharvest dehydration benefited the aroma enhancement of blueberry wine.

Sensory profile of pulse-based high moisture meat analogs: A study on the complex effect of germination and extrusion processing

Germination and extrusion are two processes that could affect beany flavors in pulse-based high-moisture meat analogs (HMMAs). This research studied the sensory profile of HMMAs made by protein-rich flours from germinated/ungerminated pea and lentil. Air-classified pulse protein-rich fractions were processed into HMMAs with twin screw extrusion cooking, optimized at 140 °C (zone 5 temperature) and 800 rpm screw speed. Overall, 30 volatile compounds were identified by Gas Chromatography-Mass Spectrometry/Olfactory. Chemometric analysis exhibited that the extrusion markedly (p < 0.05) reduced beany flavor. A synergistic effect of germination and extrusion process was observed, decreasing some beany flavors such as 1-octen-3-ol and 2,4-decadienal, and the overall beany taste. Pea-based HMMAs are suitable for lighter, softer poultry meat, while lentil-based HMMAs are suited for darker, harder livestock meat. Those findings offer novel insights into the regulation of beany flavors, odor notes, color, and taste to improve the sensory quality of HMMAs.

Ultrasound-assisted formation of chitosan-glucose Maillard reaction products to fabricate nanoparticles with enhanced antioxidant activity

The influence of ultrasonic processing parameters including reaction temperature (60, 70 and 80 °C), time (0, 15, 30, 45 and 60 min) and amplitude (70, 85 and 100%) on the formation and antioxidant activity of Maillard reaction products (MRPs) in a solution of chitosan and glucose (1.5 wt% at mass ratio of 1:1) was investigated. Selected chitosan-glucose MRPs were further studied to determine the effects of solution pH on the fabrication of antioxidative nanoparticles by ionic crosslinking with sodium tripolyphosphate. Results from FT-IR analysis, zeta-potential determination and color measurement indicated that chitosan-glucose MRPs with improved antioxidant activity were successfully produced using an ultrasound-assisted process. The highest antioxidant activity of MRPs was observed at the reaction temperature, time and amplitude of 80 °C, 60 min and 70%, respectively, with ∼ 34.5 and ∼20.2 μg Trolox mL^-1 for DPPH scavenging activity and reducing power, respectively. The pH of both MRPs and tripolyphosphate solutions significantly influenced the fabrication and characteristics of the nanoparticles. Using chitosan-glucose MRPs and tripolyphosphate solution at pH 4.0 generated nanoparticles with enhanced antioxidant activity (∼1.6 and ∼ 1.2 μg Trolox mg^-1 for reducing power and DPPH scavenging activity, respectively) with the highest percentage yield (∼59%), intermediate particle size (∼447 nm) and zeta-potential ∼ 19.6 mV. These results present innovative findings for the fabrication of chitosan-based nanoparticles with enhanced antioxidant activity by pre-conjugation with glucose via the Maillard reaction aided by ultrasonic processing.

Role of flavonoids in controlling obesity: molecular targets and mechanisms

Obesity presents a major health challenge that increases the risk of several non-communicable illnesses, such as but not limited to diabetes, hypertension, cardiovascular diseases, musculoskeletal and neurological disorders, sleep disorders, and cancers. Accounting for nearly 8% of global deaths (4.7 million) in 2017, obesity leads to diminishing quality of life and a higher premature mortality rate among affected individuals. Although essentially dubbed as a modifiable and preventable health concern, prevention, and treatment strategies against obesity, such as calorie intake restriction and increasing calorie burning, have gained little long-term success. In this manuscript, we detail the pathophysiology of obesity as a multifactorial, oxidative stress-dependent inflammatory disease. Current anti-obesity treatment strategies, and the effect of flavonoid-based therapeutic interventions on digestion and absorption, macronutrient metabolism, inflammation and oxidative stress and gut microbiota has been evaluated. The use of several naturally occurring flavonoids to prevent and treat obesity with a long-term efficacy, is also described.

α-L-rhamnosidase: production, properties, and applications

α-L-rhamnosidase [EC 3.2.1.40] belongs to glycoside hydrolase (GH) families (GH13, GH78, and GH106 families) in the carbohydrate-active enzymes (CAZy) database, which specifically hydrolyzes the non-reducing end of α-L-rhamnose. Αccording to the sites of catalytic hydrolysis, α-L-rhamnosidase can be divided into α-1, 2-rhamnosidase, α-1, 3-rhamnosidase, α-1, 4-rhamnosidase and α-1, 6-rhamnosidase. α-L-rhamnosidase is an important enzyme for various biotechnological applications, especially in food, beverage, and pharmaceutical industries. α-L-rhamnosidase has a wide range of sources and is commonly found in animals, plants, and microorganisms, and its microbial source includes a variety of bacteria, molds and yeasts (such as Lactobacillus sp., Aspergillus sp., Pichia angusta and Saccharomyces cerevisiae). In recent years, a series of advances have been achieved in various aspects of α-validates the above-described-rhamnosidase research. A number of α-L-rhamnosidases have been successfully recombinant expressed in prokaryotic systems as well as eukaryotic systems which involve Pichia pastoris, Saccharomyces cerevisiae and Aspergillus niger, and the catalytic properties of the recombinant enzymes have been improved by enzyme modification techniques. In this review, the sources and production methods, general and catalytic properties and biotechnological applications of α-L-rhamnosidase in different fields are summarized and discussed, concluding with the directions for further in-depth research on α-L-rhamnosidase.

A Strategy for Rapid Acquisition of the β-D-Fructofuranosidase Gene through Chemical Synthesis and New Function of Its Encoded Enzyme to Improve Gel Properties during Yogurt Processing

A chemical gene synthesis strategy was developed in order to obtain β-D-fructofuranosidase, and a novel gene, AlFFase3, was characterized from Aspergillus luchuensis and expressed in Escherichia coli. The recombinant protein was purified, showing a molecular mass of 68.0 kDa on SDS-PAGE, and displaying a specific activity towards sucrose of up to 771.2 U mg^-1, indicating its exceptional enzymatic capacity. AlFFase3 exhibited stability between pH 5.5 and 7.5, with maximal activity at pH 6.5 and 40 °C. Impressively, AlFFase3, as a soluble protein, was resistant to digestion by various common proteases, including Flavourzyme, acidic protease, pepsin, neutral protease, Proteinase K, alkaline proteinase, and trypsin. AlFFase3 also demonstrated significant transfructosylation activity, with a yield of various fructooligosaccharides up to 67%, higher than almost all other reports. Furthermore, we demonstrated that the addition of AlFFase3 enhanced the growth of probiotics in yogurt, thereby increasing its nutritional value. AlFFase3 also improved the formation of yogurt gel, reducing the gel formation time and lowering the elasticity while increasing its viscosity, thereby improving the palatability of yogurt and reducing production costs.

Efficient Degradation for Raffinose and Stachyose of a β-D-Fructofuranosidase and Its New Function to Improve Gel Properties of Coagulated Fermented-Soymilk

A novel β-D-fructofuranosidase gene was identified via database mining from Leptothrix cholodnii. The gene was chemically synthesized and expressed in Escherichia coli, resulting in the production of a highly efficient enzyme known as LcFFase1s. The enzyme exhibited optimal activity at pH 6.5 and a temperature of 50 °C while maintaining stability at pH 5.5-8.0 and a temperature below 50 °C. Furthermore, LcFFase1s exhibited remarkable resistance to commercial proteases and various metal ions that could interfere with its activity. This study also revealed a new hydrolysis function of LcFFase1s, which could completely hydrolyze 2% raffinose and stachyose within 8 h and 24 h, respectively, effectively reducing the flatulence factor in legumes. This discovery expands the potential applications of LcFFase1s. Additionally, the incorporation of LcFFase1s significantly reduced the particle size of coagulated fermented-soymilk gel, resulting in a smoother texture while maintaining the gel hardness and viscosity formed during fermentation. This represents the first report of β-D-fructofuranosidase enhancing coagulated fermented-soymilk gel properties, highlighting promising possibilities for future applications of LcFFase1s. Overall, the exceptional enzymatic properties and unique functions of LcFFase1s render it a valuable tool for numerous applications.

Physiology, quorum sensing, and proteomics of lactic acid bacteria were affected by Saccharomyces cerevisiae YE4

The interaction mode between lactic acid bacteria (LAB) and yeast in a fermentation system directly determines the quality of the products, thus understanding their mode of interaction can improve product quality. The present study investigated the effects of Saccharomyces cerevisiae YE4 on LAB from the perspectives of physiology, quorum sensing (QS), and proteomics. The presence of S. cerevisiae YE4 slowed down the growth of Enterococcus faecium 8-3 but had no significant effect on acid production or biofilm formation. S. cerevisiae YE4 significantly reduced the activity of autoinducer-2 at 19 h in E. faecium 8-3 and at 7-13 h in Lactobacillus fermentum 2-1. Expression of the QS-related genes luxS and pfs was also inhibited at 7 h. Moreover, a total of 107 E. faecium 8-3 proteins differed significantly in coculture with S. cerevisiae YE4-these proteins are involved in metabolic pathways including biosynthesis of secondary metabolites; biosynthesis of amino acids; alanine, aspartate, and glutamate metabolism; fatty acid metabolism; and fatty acid biosynthesis. Among them, proteins involved in cell adhesion, cell wall formation, two-component systems, and ABC transporters were detected. Therefore, S. cerevisiae YE4 might affect the physiological metabolism of E. faecium 8-3 by affecting cell adhesion, cell wall formation, and cell-cell interactions.

Enhancing the foaming properties of brewer's spent grain protein by ultrasound treatment and glycation reaction

The denaturation state and relatively poor solubility of brewer's spent grain protein (BSGP) have limited its industrial application. Ultrasound treatment and glycation reaction were applied to improve the structural and foaming properties of BSGP. The results showed that all ultrasound, glycation, and ultrasound-assisted glycation treatments increased the solubility and surface hydrophobicity of BSGP while decreasing its zeta potential, surface tension and particle size. Meanwhile, all these treatments resulted in a more disordered and flexible conformation of BSGP, as observed by CD spectroscopy and SEM. After grafting, the result of FTIR spectroscopy confirmed the covalent binding of -OH between maltose and BSGP. Ultrasound-assisted glycation treatment further improved the free SH and S-S content, which might be due to -OH oxidation, indicating that ultrasound promoted the glycation reaction. Furthermore, all these treatments significantly increased the foaming capacity (FC) and foam stability (FS) of BSGP. Notably, BSGP treated with ultrasound showed the best foaming properties, increasing the FC from 82.22% to 165.10% and the FS from 10.60% to 131.20%, respectively. In particular, the foam collapse rate of BSGP treated with ultrasound-assisted glycation was lower than that of ultrasound or traditional wet-heating glycation treatment. The enhanced hydrogen bonding ability and hydrophobic interaction between protein molecules caused by ultrasound and glycation might be responsible for the improved foaming properties of BSGP. Thus, ultrasound and glycation reactions were efficient methods for producing BSGP-maltose conjugates with superior foaming properties.

Characterization of aroma compounds and effects of amino acids on the release of esters in Laimao baijiu

BACKGROUND

Laimao baijiu is a typical soy-sauce aroma-type baijiu in China. Amino acids are non-volatile compounds in baijiu and are beneficial to human health. Aroma is one of the important indicators that are used to evaluate the quality of baijiu. The interaction between aroma-active compounds and non-volatile compounds can also affect the release of aroma compounds. In this study, we identified the active-aroma compounds and amino acids in Laimao baijiu by stir bar sorptive extraction (SBSE), gas chromatography-olfactometry (GC-O), gas chromatography-mass spectrometry (GC-MS), and ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). The interaction between amino acids and key esters was investigated by sensory analysis and partition coefficients.

RESULTS

A total of 63 aroma compounds and 21 amino acids were identified. Twenty-one esters were identified from them as major aroma-active ester compounds with odor activity values ≥ 1. Finally, sensory analysis revealed that l-alanine had a significant effect on the strength of the aromas of esters, suggesting that low concentrations of amino acids were more likely to promote the release of esters and high concentrations were more likely to inhibit this. The partition coefficient can be a good explanation for this phenomenon.

CONCLUSION

l-Alanine can significantly affect the aroma intensity of key ester aroma compounds in Laimao baijiu, and the effects of different concentrations of amino acids are different. This work shows that amino acids, as non-volatile compounds, have a regulatory effect on the release of aroma compounds in alcoholic beverages, which may provide new technical support for the aroma modulation of alcoholic beverages. © 2022 Society of Chemical Industry.

Inoculation strategies affect the physicochemical properties and flavor of Zhenjiang aromatic vinegar

Inoculation strategy is a significant determinant of the flavor quality of Zhenjiang aromatic vinegar. Herein, the comparative analyses of the effects of various inoculation strategies on the physicochemical properties, microbial community structure, and flavoring characteristics of Zhenjiang aromatic vinegar were performed. The results showed that the contents of total acid (6.91 g/100 g), organic acid (2099.63 ± 4.13 mg/100 g) and amino acid (3666.18 ± 14.40 mg/100 g) in the direct inoculation strategy were higher than those in the traditional inoculation strategy (6.21 ± 0.02 g/100 g, 1939.66 ± 4.16 mg/100 g and 3301.46 ± 13.41 mg/100 g). At the same time, it can effectively promote the production of acetoin. The diversity of strains under the traditional inoculation strategy was higher than that under the direct inoculation strategy, and the relative abundance of major microbial genera in the fermentation process was lower than that under the direct inoculation strategy. In addition, for two different inoculation strategies, pH was proved to be an important environmental factor affecting the microbial community structure during acetic acid fermentation. The correlation between main microbial species, organic acids, non-volatile acids, and volatile flavor compounds is more consistent. Therefore, this study may help to develop direct injection composite microbial inoculants to replace traditional starter cultures in future research.

Sono-activation of food enzymes: From principles to practice

Over the last decade, sono-activation of enzymes as an emerging research area has received considerable attention from food researchers. This kind of relatively new application of ultrasound has demonstrated promising potential in facilitating the modern food industry by broadening the application of various food enzymes, improving relevant industrial unit operation and productivity, as well as increasing the yield of target products. This review aims to provide insight into the fundamental principles and possible industrialization strategies of the sono-activation of food enzymes to facilitate its commercialization. This review first provides an overview of ultrasound application in the activation of food protease, carbohydrase, and lipase. Then, the recent development on ultrasound activation of food enzymes is discussed on aspects including mechanisms, influencing factors, modification effects, and its applications in real food systems for free and immobilized enzymes. Despite the far fewer studies on sono-activation of immobilized enzymes compared with those on free enzymes, we endeavored to summarize the relevant aspects in three stages: ultrasound pretreatment of free enzyme/carrier, assistance in immobilization process, and modification of the already immobilized enzyme. Lastly, challenges for the scalability of ultrasound in these target areas are discussed and future research prospects are proposed.

Ultrasonic Treatment Enhances the Antioxidant and Immune-Stimulatory Properties of the Polysaccharide from Sinopodophyllum hexandrum Fruit

We aimed to assess the potential of ultrasonic treatment on the processing of polysaccharides as functional foods or food additives. The polysaccharide from Sinopodophyllum hexandrum fruit (SHP, 52.46 kDa, 1.91 nm) was isolated and purified. SHP was treated with various levels of ultrasound (250 W and 500 W), resulting in the formation of two polysaccharides, SHP1 (29.37 kD, 1.40 nm) and SHP2 (36.91 kDa, 0.987 nm). Ultrasonic treatment was found to reduce the surface roughness and molecular weight of the polysaccharides, leading to thinning and fracturing. The effect of ultrasonic treatment on polysaccharide activity was evaluated in vitro and in vivo. In vivo experiments showed that ultrasonic treatment improved the organ index. Simultaneously, it enhanced the activity of superoxide dismutase, total antioxidant capacity, and decreased the content of malondialdehyde in the liver. In vitro experiments demonstrated that ultrasonic treatment also promoted proliferation, nitric oxide secretion, phagocytic efficiency, costimulatory factors (CD80+, CD86+) expression, and cytokine(IL-6, IL-1β) production of RAW264.7 macrophages.

Variation of Aroma Components of Pasteurized Yogurt with Different Process Combination before and after Aging by DHS/GC-O-MS

Pasteurized yogurt is a healthy yogurt that can be stored in ambient temperature conditions. Dynamic headspace sampling (DHS) combined with gas chromatography-olfactory mass spectrometry (GC-O-MS), sensory evaluation, electronic nose (E-nose), and partial least squares discriminant analysis (PLS-DA) were used to analyze the flavor changes of pasteurized yogurt with different process combinations before and after aging. The results of odor profiles showed that the sensory descriptors of fermented, sweet, and sour were greatly affected by different process combinations. The results of odor-active compounds and relative odor activity value (r-OAV) showed that the combination of the production process affected the overall odor profile of pasteurized yogurt, which was consistent with the sensory evaluation results. A total of 15 odor-active compounds of 38 volatile compounds were detected in pasteurized yogurt samples. r-OAV results revealed that hexanal, (E)-2-octenal, 2-heptanone, and butanoic acid may be important odor-active compounds responsible for off-odor in aged, pasteurized yogurt samples. PLS-DA and variable importance of projection (VIP) results showed that butanoic acid, hexanal, acetoin, decanoic acid, 1-pentanol, 1-nonanal, and hexanoic acid were differential compounds that distinguish pasteurized yogurt before and after aging.

Synergy of physicochemical reactions occurred during aging for harmonizing and improving flavor

Numerous counterfeit vintage Baijiu are widely distributed in the market driven by economic interest which disturb the market economic rules and damage the reputation of particular Baijiu brand. Found on the situation, the Baijiu system variation during aging period, aging mechanisms and discrimination strategies for vintage Baijiu are systematically illuminated. The aging mechanisms of Baijiu cover volatilization, oxidation, association, esterification, hydrolysis, formation of colloid molecules and catalysis by metal elements or other raw materials dissolved from storage vessels. The discrimination of aged Baijiu has been performed by electrochemical method, colorimetric sensor array or component characterization coupled with multivariate analysis. Nevertheless, the characterization of non-volatile compounds in aged Baijiu is deficient. Further research on the aging principles, more easy-operation and low-cost discrimination strategies for aged Baijiu are imperative. The above information is favorable to better understand the aging process and mechanisms of Baijiu, and promote the development of artificial aging techniques.

Ultrasound-assisted production of alcoholic beverages: From fermentation and sterilization to extraction and aging

Ultrasound is sound waves above 20 kHz that can be used as a nonthermal ''green'' technology for agri-food processing. It has a cavitation effect, causing bubbles to form and collapse rapidly as they travel through the medium during ultrasonication. Therefore, it inactivates microorganisms and enzymes through cell membrane disruption with physicochemical and sterilization effects on foods or beverages. This emerging technology has been explored in wineries to improve wine color, taste, aroma, and phenolic profile. This paper aims to comprehensively review the research on ultrasound applications in the winery and alcoholic beverages industry, discuss the impacts of this process on the physicochemical properties of liquors, the benefits involved, and the research needed in this area. Studies have shown that ultrasonic technology enhances wine maturation, improves wine fermentation, accelerates wine aging, and deactivates microbes while enhancing quality, as observed with better critical aging markers such as phenolic compounds and color intensity. Besides, ultrasound enhances phytochemical, physicochemical, biological, and organoleptic properties of alcoholic beverages. For example, this technology increased anthocyanin in red wine by 50%. It also enhanced the production rate by decreasing the aging time by more than 90%. Ultrasound can be considered an economically viable technology that may contribute to wineries' waste valorization, resource efficiency improvement, and industry profit enhancement. Despite numerous publications and successful industrial applications discussed in this paper, ultrasound up-scaling and applications for other types of liquors need further efforts.

Citrus juice off-flavor during different processing and storage: Review of odorants, formation pathways, and analytical techniques

As the most widespread juice produced and consumed globally, citrus juice (mandarin juice, orange juice, and grapefruit juice) is appreciated for its attractive and distinct aroma. While the decrease of characteristic aroma-active compounds and the formation of off-flavor compounds are easy to occur in processing and storage conditions. This review provides a comprehensive literature of recent research and discovery on citrus juice off-flavor, primarily focusing on off-flavor compounds induced during processing and storage (i.e., thermal, storage, light, oxygen, package, fruit maturity, diseases, centrifugal pretreatment, and debittering process), formation pathways (i.e., terpene acid-catalyzed hydration, caramelization reaction, Maillard reaction, Strecker degradation, and other oxidative degradation) of the off-flavor compounds, effective inhibitor pathway to off-flavor (i.e., electrical treatments, high pressure processing, microwave processing, ultrasound processing, and chemical treatment), as well as odor assessment techniques based on molecular sensory science. The possible precursors (terpenes, sulfur-containing amino acids, carbohydrates, carotenoids, vitamins, and phenolic acids) of citrus juice off-flavor are listed and are also proposed. This review intends to unravel the regularities of aroma variations and even off-flavor formation of citrus juice during processing and storage. Future aroma analysis techniques will evolve toward a colorimetric sensor array for odor visualization to obtain a "marker" of off-flavor in citrus juice.

A Comparative Study on the Debittering of Kinnow (Citrus reticulate L.) Peels: Microbial, Chemical, and Ultrasound-Assisted Microbial Treatment

Kinnow mandarin (Citrus reticulate L.) peels are a storehouse of well-known bioactive compounds, viz., polyphenols, flavonoids, carotenoids, limonoids, and tocopherol, which exhibit an effective antioxidant capacity. However, naringin is the most predominant bitter flavanone compound found in Kinnow peels that causes their bitterness. It prohibits the effective utilization of peels in food-based products. In the present study, a novel approach for the debittering of Kinnow peels has been established to tackle this problem. A comparative evaluation of the different debittering methods (chemical, microbial, and ultrasound-assisted microbial treatments) used on Kinnow peel naringin and bioactive compounds was conducted. Among the chemical and microbial method; solid-state fermentation with A. niger led to greater extraction of naringin content (7.08 mg/g) from kinnow peels. Moreover, the numerical process optimization of ultrasound-assisted microbial debittering was performed by the Box–Behnken design (BBD) of a response surface methodology to maximize naringin hydrolysis. Among all three debittering methods, ultrasound-assisted microbial debittering led to a greater hydrolysis of naringin content and reduced processing time. The optimum conditions were ultrasound temperature (40 °C), time (30 min), and A. niger koji extract (1.45%) for the maximum extraction rate of naringin (11.91 mg/g). These debittered Kinnow peels can be utilized as raw material to develop therapeutic food products having a high phytochemical composition without any off-flavors or bitterness.

Effect of Six Lactic Acid Bacteria Strains on Physicochemical Characteristics, Antioxidant Activities and Sensory Properties of Fermented Orange Juices

Six lactic acid bacteria strains were used to study the effects on physicochemical characteristics, antioxidant activities and sensory properties of fermented orange juices. All strains exhibited good growth in orange juice. Of these fermentations, some bioactive compositions (e.g., vitamin C, shikimic acid) and aroma-active compounds (e.g., linalool, 3-carene, ethyl 3-hydroxyhexanoate, etc.) significantly increased in Lactiplantibacillus plantarum and Lactobacillus acidophilus samples. DPPH free radical scavenging rates in L. plantarum and Lacticaseibacillus paracasei samples increased to 80.25% and 77.83%, respectively. Forty-three volatile profiles were identified, including 28 aroma-active compounds. 7 key factors significantly influencing sensory flavors of the juices were revealed, including D-limonene, linalool, ethyl butyrate, ethanol, β-caryophyllene, organic acids and SSC/TA ratio. The orange juice fermented by L. paracasei, with more optimization aroma-active compounds such as D-limonene, β-caryophyllene, terpinolene and β-myrcene, exhibited more desirable aroma flavors such as orange-like, green, woody and lilac incense, and gained the highest sensory score. Generally, L. paracasei fermentation presented better aroma flavors and overall acceptability, meanwhile enhancing antioxidant activities.

Effect of pulsed electric field on soybean isoflavone glycosides hydrolysis by β-glucosidase: Investigation on enzyme characteristics and assisted reaction

This work aimed to investigate how pulsed electric field (PEF) technology as an alternative to enhance the enzymatic hydrolysis of soybean isoflavone glycosides (SIG). To achieve it, the effect of PEF treatment on the activity, kinetics, thermodynamics and structure of β-glucosidase (β-GLU) were evaluated. The parameters for PEF-assisted hydrolysis of soybean isoflavone glycosides were optimized by response surface methodology. The results showed that PEF treatment increased the relative activity and catalytic efficiency of β-GLU with moderate electric field intensity. Furthermore, PEF treatment induced the secondary and tertiary structural change of β-GLU, the α-helix content increased by 4.23% and the β-fold content decreased by 3.70%. The optimum conditions for PEF treatment were established as the highest yield of isoflavone aglycones achieved 94.58%. Therefore, these results indicated that PEF treatment could be used as an efficient process to improve the β-GLU properties, converting soybean isoflavone glycoside to their aglycones form.

Degradation Mechanism of Soybean Protein B3 Subunit Catalyzed by Prolyl Endopeptidase from Aspergillus niger during Soy Sauce Fermentation

Soy sauce secondary precipitate formed due to the B₃ subunit seriously affects soy sauce's appearance quality. In this study, a prolyl endopeptidase (APE) from Aspergillus niger, which could degrade approximately 50% of the B₃ subunit and increase proline content by 24% in soy sauce, was isolated and identified. The results showed that APE was an acidic salt-tolerant serine protease (62 kDa), which was optimally active at 40 °C and pH 4.0, and retained more than 69% activity in 3 M NaCl solution over 10 days. As a potential substrate of APE, the B₃ subunit contains 10 proline residues. High salinity could not damage the hydrogen bonds, salt bridges, and interior hydrophobicity of APE; thus, the spatial structures and activity of APE in 3 M NaCl solution were stable within 3 days and decreased thereafter. High salinity made the B₃ subunit more rigid and lowered the catalytic activity of APE on the B₃ subunit, hindering complete hydrolysis of the B₃ subunit. This was the first report about the APE capable of degrading the B₃ subunit and reducing the secondary precipitate of soy sauce, providing a new possibility to solve the secondary precipitate of soy sauce.

Recent Advances in the Application of Enzyme Processing Assisted by Ultrasound in Agri-Foods: A Review

The intensification of processes is essential for the sustainability of the biorefinery concept. Enzyme catalysis assisted by ultrasound (US) may offer interesting opportunities in the agri-food sector because the cavitation effect provided by this technology has been shown to improve the efficiency of the biocatalysts. This review presents the recent advances in this field, focused on three main applications: ultrasound-assisted enzymatic extractions (UAEE), US hydrolysis reactions, and synthesis reactions assisted by US for the manufacturing of agri-food produce and ingredients, enabling the upgrading of agro-industrial waste. Some theoretical and experimental aspects of US that must be considered are also reviewed. Ultrasonic intensity (UI) is the main parameter affecting the catalytic activity of enzymes, but a lack of standardization for its quantification makes it unsuitable to properly compare results. Applications of enzyme catalysis assisted by US in agri-foods have been mostly concentrated in UAEE of bioactive compounds. In second place, US hydrolysis reactions have been applied for juice and beverage manufacturing, with some interesting applications for producing bioactive peptides. In last place, a few efforts have been performed regarding synthesis reactions, mainly through trans and esterification to produce structured lipids and sugar esters, while incipient applications for the synthesis of oligosaccharides show promising results. In most cases, US has improved the reaction yield, but much information is lacking on how different sonication conditions affect kinetic parameters. Future research should be performed under a multidisciplinary approach for better comprehension of a very complex phenomenon that occurs in very short time periods.