Quality changes of pasteurised orange juice during storage: A kinetic study of specific parameters and their relation to colour instability

Lycopene extract as an antibrowning agent for edible coating of fresh cut apples

Edible coatings have been utilized for fresh fruit and vegetable preservation to ensure their safety and freshness. The present study reported the effect of edible coatings incorporated with Lycopene extract and Ascorbic Acid on fresh cut Apple slices (Red Delicious) during storage at refrigeration temperature for 12 days. The dipping treatments include Lycopene extract (LC-100 mg), Ascorbic acid (AAC-100 mg) and a combination of both LC + AAC (100 mg lycopene extract and 100 mg Ascorbic acid). Quality parameters (color, physicochemical and enzymatic activities) were studied up to 12 days at refrigeration temperature. Dipping treatments of LC and LC + AAC significantly showed lowest enzymatic activity than AAC treatment. However, color was not preserved in LC + AAC treatments due to high concentration of olive oil in these treatments. Furthermore, physicochemical quality was better preserved in LC + AAC treatments.

Investigating the impact of storage duration and temperature on vitamin C in various citrus genotypes: A meta-analysis method

The present work disseminates a solid scientific meta-analysis method to investigate the impact of storage duration and temperature on vitamin C of citrus. This work is initiated by designing of the PICO framework, collecting, and organizing the articles, creating selection criteria, sorting articles, identifying factors influencing moderation effects and sources of diversity, tabulating data, and employing analysis in the form of a linear mixed model. Using this method, we identified 54 distinct studies from a pool of 289 eligible peer-reviewed publications, focusing on variations of vitamin C in citrus. The method provides mean values in both quadratic and linear regression forms.•This method provides a detailed description starting from topic selection to statistical methodologies intended for performing meta-analysis.•All guidelines for conducting this method have been approved by all authors and adhere to the standard PRISMA-P guidelines.•Disseminating this method in a peer-reviewed publication aims to facilitate scholarly discussions and promote transparency, ultimately improving the standard for performing meta-analysis on vitamin C levels in citrus concerning various genotypes, storage temperatures, and durations.

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.

Vitamin C variation in citrus in response to genotypes, storage temperatures, and storage times: A systematic review and meta-analysis

Numerous published studies have highlighted discrepancies in the duration and storage temperature used for preserving vitamin C content on various citrus genotypes worldwide. The present study aimed to analyze the variation in vitamin C content as influenced by citrus genotype, duration, and storage temperature using meta-analysis approaches. Data searching, selection, and tabulation resulted in a comprehensive database constructed from 1412 data points gathered from 54 individual studies, following PRISMA-P guidelines. The vitamin C content varied widely, ranging from 0 to 76.2 mg/100 mL in whole data of citrus fruit. Meta-analysis findings revealed that the duration of storage significantly impacted the vitamin C content in citrus fruits. Specifically, for grapefruit, mandarin, and orange, the length of storage significantly influenced their vitamin C levels (P < 0.01), with a consistent decrease observed over time. The correlation coefficients (R2) were 0.63 for grapefruit, 0.9 for mandarin, and 0.69 for orange. In contrast, no significant difference was found in terms of vitamin C levels between hybrid and lime citrus concerning the impact of storage time. However, other results indicated a significant influence of storage temperature on the variation in vitamin C levels for both citrus and hybrid varieties (P < 0.001). Depending on the genotype, tangerine had significantly lower vitamin C content compared to other varieties, at 16.9 mg/100 mL, with vitamin C ranging from 13.2 to 20.9 mg/100 mL (P < 0.001). The highest vitamin C content was found in lemon and hybrid varieties, around 65.5 (range 59.3-76.2) and 48.3 (range 29.6-75.5), respectively, all in mg/100 mL (P < 0.001). Furthermore, there was a tendency for decreasing vitamin C concentration due to temperature (P = 0.078), while citrus variety experienced a decrease, although not significant. The ideal temperature (15 °C) and duration of storage (56 days) to minimize vitamin C loss in citrus fruits are at their optimum point. In conclusion, the deterioration of vitamin C in citrus fruits is influenced by both temperature and storage duration, and its content is also impacted by the variety of citrus.

Effects of juicing methods on the bioactive compounds and flavor quality of 'Black-seed' pomegranate from three producing areas

BACKGROUND

Color, nutrients and flavor are the key characteristics of pomegranate juice, but they are susceptible to processing methods and raw materials. In this study, the effects of aril juicing and whole fruit juicing methods on the composition of 'Black-seed' pomegranate juice from three producing areas were studied, including physicochemical parameters, color attributes, organic acids, sugars, phenolic compounds, and volatile compounds.

RESULTS

The whole fruit juicing method resulted in higher juice yields of pomegranate fruit with 69.01-72.59%, hue angle values were 5.95-6.45°, and the juice remained red. The highest level of citric acid (21.21 g L-1 ), total acids (24.78 g L-1 ), and total anthocyanin content (435.59 mg L-1 ) were found in whole fruit juice, and seven tannins were detected. The most abundant volatile compounds were (Z)-3-hexen-1-ol and 1-hexanol in all juice samples, with alcohol content increased and aldehydes content decreased by whole fruit juicing. Principal component analysis revealed that the 24 indexes (variable important in projection >1) clearly distinguished juice samples obtained by two juicing methods, with ellagic acid hexoside, (E)-2-heptenal, (+)-catechin, and octanoic acid having the best discriminatory potential.

CONCLUSION

Overall, the effects of juicing method on 'Black-seed' pomegranate juice were greater than those of raw-material-producing areas. These results confirmed the potential for using the whole 'Black-seed' pomegranate for processing, and also provided a theoretical basis for the healthy product development and utilization of dark-color pomegranate varieties. © 2023 Society of Chemical Industry.

Stability of vitamin C, carotenoids, phenols, and antioxidant capacity of pasteurised orange juice with resistant maltodextrin storage

Resistant maltodextrin (RMD) was added at increasing concentrations (0%, 2.5%, 5% and 7.5%) before pasteurisation to orange juice to analyse its potential protective effect on the health-related bioactive compounds of pasteurised orange juice throughout its storage time. Samples were characterised in terms of basic physico-chemical properties and bioactive compounds at the beginning of the storage. Higher concentrations of RMD proved to better preserve the bioactive compounds of orange juice, thus obtaining a higher antioxidant capacity (AC). Stability of all samples was determined by measuring the same parameters at days 0, 15, 45, 75, 105, 136 and 170 of storage. °Brix and pH were very stable in all samples along storage, while all bioactive compouds had negative variations. However, RMD addition slightly improved ascorbic acid, vitamin C, total phenols, and total carotenoids retention, improving then its AC. This effect was greater in the 5% RMD-added samples. All bioactive compounds showed a positive Pearson's correlation coefficient with AC. Colour variations were also measured at days 105 and 170. All samples had a positive variation of all colour parameters, being this clearer at day 170. This work enlights the potential functionality of RMD to better preserve the health-related compounds of pasteurised orange juice.

Sensory Evaluation, Physico-Chemical Properties, and Aromatic Profile of Pasteurised Orange Juice with Resistant Maltodextrin

The beneficial health effects of prebiotics have been demonstrated in numerous research papers. However, their incorporation into daily food remains unfamiliar to consumers. This work evaluates the effects of the addition of resistant maltodextrin (RMD) on the sensory attributes of pasteurised orange juice, together with the physico-chemical properties and the aromatic profile. RMD addition increased the sweetness and decreased the acidity and bitterness, resulting in a higher overall panellists' rating of orange juice. It also proportionally increased °Brix together with density and decreased acidity. Colour changes were registered with higher RMD concentrations. Orange pulp presence affected the volume particle size distribution analysis, while RMD addition did not have any effect. The aroma volatile compounds were also analysed. Pulp-added samples showed a higher quantity of alcohol and aldehydes, whereas pulp-free samples registered higher terpene and terpenoid values. Ketones and acids were also quantified. RMD had a moderate impact on volatile compound quantifications, with the orange pulp presence playing a much more decisive role. A correspondence analysis was also performed to relate instrumental and sensory determinations for all samples. This work proves that the addition of RMD to orange juice is technologically feasible while also achieving a good response at the sensory level.

Non-enzymatic browning of a composite puree of Choerospondias axillaris, snow pear, and apple: kinetic modeling and correlation analysis

Choerospondias axillaris, snow pear, and apple composite fruit puree can be affected by non-enzymatic browning during storage decreasing the market value of the product. This study aimed to explore, using kinetic methods, the effects of non-enzymatic precursors (polyphenols and ascorbic acid) and intermediates (5-hydroxymethylfurfural) on fruit puree stored at 4 °C for 35 days. The results showed that ascorbic acid fitted the first-order reaction model, while the 5-hydroxymethylfurfural was consistent with the complex reaction model. Furthermore, the 5-hydroxymethylfurfural content was 1.53 ± 0.18 mg/L, (corresponding to an increase of 565%), and the ascorbic acid content was 0.88 ± 0.22 mg/100 g, (corresponding to a decrease of 98.5%). The results also demonstrated a change in the titratable acid, soluble solids, and pH of the fruit puree. Finally, the correlation results revealed a significant correlation between non-enzymatic browning and 5-hydroxymethylfurfural, titratable acid, and pH (p < 0.05). Overall, the results suggest that the Maillard reaction could be responsible for the non-enzymatic browning of fruit purees during storage.

Comparison of high pressure and thermal pasteurization on the quality parameters of strawberry products: a review

Strawberry (Fragaria ananassa) is rich in bioactive compounds with high antioxidant activity. High pressure processing (HPP) is an efficient alternative to preserve these bioactive compounds in terms of microbial inactivation and shelf-life stability. This review compares the effects of pasteurization methods using high pressure or thermal pasteurization (TP) on the quality parameters of various strawberry-based products. To summarize, most of the high pressure-treated products are microbiologically stable and showed minimum degradation of thermolabile compounds than TP-treated ones. However, some studies reported that high pressure did not have an advantage over TP especially in the preservation of phenolic phytochemicals during storage. The insufficient enzyme inactivation and high residual activity of enzymes after high pressure treatment could cause anthocyanins degradation thus affecting the product quality. Overall, this review could be valuable to potential processors in evaluating the effective commercialization of high pressure-treated strawberry products.

Quality changes of HHP orange juice during storage: Metabolomic data integration analyses

High hydrostatic pressure (HHP) is a non-thermal method of sterilizing orange juice. However, knowledge of the quality variation during its storage is limited. This study aimed to comprehensively analyze metabolite variations during HHP orange juice storage using gas chromatography-mass spectrometer and liquid chromatography-mass spectrometry. Fifty-seven volatiles and 49 non-volatiles were identified. Partial least square analysis results showed that 21 days was a dividing point for metabolites highly varied. Results of relative odor activity value showed nonanal, methyl butanoate, and ethyl butanoate decreased after six days, which might reduce fruity flavor. After 21 days, over 60 % of metabolites such as linalool, α-pinene, and ascorbic acids decreased while α-terpineol and limonin increased, which would likely result in a change of coniferous, tarry, and bitter, as well as decreased organoleptic quality and antioxidative activities. This study provides a theoretical basis to optimize the shelf-life of HHP orange juice and advice for consumers' choices.

A New Method to Determine Antioxidant Activities of Biofilms Using a pH Indicator (Resazurin) Model System

Biopolymeric films were prepared with gelatin, plasticizer, and three different types of antioxidants (ascorbic acid, phytic acid, and BHA) corresponding to different mechanisms in activity. The antioxidant activity of films was monitored for 14 storage days upon color changes using a pH indicator (resazurin). The instant antioxidant activity of films was measured by a DPPH free radical test. The system using resazurin was composed of an agar, an emulsifier, and soybean oil to simulate a highly oxidative oil-based food system (AES-R). Gelatin-based films (GBF) containing phytic acid showed higher tensile strength and energy to break than all other samples due to the increased intermolecular interactions between phytic acid and gelatin molecules. The oxygen barrier properties of GBF films containing ascorbic acid and phytic acid increased due to the increased polarity, while GBF films containing BHA showed increased oxygen permeability compared to the control. According to "a-value" (redness) of the AES-R system tested with films, films incorporating BHA showed the most retardation of lipid oxidation in the system. This retardation corresponds to 59.8% antioxidation activity at 14 days, compared with the control. Phytic acid-based films did not show antioxidant activity, whereas ascorbic acid-based GBFs accelerated the oxidation process due to its prooxidant activity. The comparison between the DPPH free radical test and the control showed that the ascorbic acid and BHA-based GBFs showed highly effective free radical scavenging behavior (71.7% and 41.7%, respectively). This novel method using a pH indicator system can potentially determine the antioxidation activity of biopolymer films and film-based samples in a food system.

The effect of supercritical carbon dioxide on the physiochemistry, endogenous enzymes, and nutritional composition of fruit and vegetables and its prospects for industrial application: a overview

Consumers have an increasing demand for fruit and vegetables with high nutritional value worldwide. However, most fruit and vegetables are vulnerable to quality loss and spoilage during processing, transportation, and storage. Among the recently introduced emerging technologies, supercritical carbon dioxide (SCCO2) has been extensively utilized to treat and maintain fruit and vegetables mainly due to its nontoxicity, safety, and environmentally friendly. SCCO2 technology generates low processing costs and mild processing conditions (temperature and pressure) that allow for the application of CO2 at a supercritical state. This review aimed to summarize the current knowledge on the influence of SCCO2 technology on the quality attributes of fruit and vegetable products, such as physicochemical properties (pH, color, cloud, particle size distribution, texture), sensory quality, and nutritional composition (ascorbic acid, phenolic compounds, anthocyanins, carotenoids, and betalains). In addition, the effects and mechanisms of the SCCO2 technique on endogenous enzyme inactivation (polyphenol oxidase, peroxidase, and pectin methylesterase) were also elucidated. Finally, the prospects of the SCCO2 technique for industrial application was discussed from the economic and regulatory aspect.

Characterization of Effects of Different Tea Harvesting Seasons on Quality Components, Color and Sensory Quality of "Yinghong 9" and "Huangyu" Large-Leaf-Variety Black Tea

Harvesting seasons are crucial for the physicochemical qualities of large-leaf-variety black tea. To investigate the effect of harvesting seasons on physicochemical qualities, the color and sensory characteristics of black tea produced from "Yinghong 9" (Yh) and its mutant "Huangyu" (Hy) leaves were analyzed. The results demonstrated that Hy had better chemical qualities and sensory characteristics, on average, such as a higher content of tea polyphenols, free amino acids, caffeine, galloylated catechins (GaCs) and non-galloylated catechins (NGaCs), while the hue of the tea brew (ΔE*ab and Δb*) increased, which meant that the tea brew was yellower and redder. Moreover, the data showed that the physicochemical qualities of SpHy (Hy processed in spring) were superior to those of SuHy (Hy processed in summer) and AuHy (Hy processed in autumn), and 92.6% of the total variance in PCA score plots effectively explained the separation of the physicochemical qualities of Yh and Hy processed in different harvesting seasons. In summary, Hy processed in spring was superior in its physicochemical qualities. The current results will provide scientific guidance for the production of high-quality large-leaf-variety black tea in South China.

Effect of a Multifunctional Biosurfactant Extract Obtained from Corn Steep Liquor on Orange and Apple Juices

Biosurfactant extracts are multifunctional ingredients composed of natural polymers that can be used in the food industry as stabilizing and antimicrobial agents, although their inclusion in food matrices has been scarcely explored. In this work, a biosurfactant extract, with antimicrobial properties, obtained from a fermented stream of the corn wet-milling industry was introduced into an apple and orange juice matrix to evaluate the changes produced in the sugar consumption, pH, and biomass formation at different temperatures (4-36 °C) and storage time (1-7 days). It was observed that the addition of biosurfactant extract reduced the hydrolysis rate of polymeric sugars, decreasing the concentration of soluble sugars from 85.4 g/L to 49.0 g/L in apple juice after 7 days at 20 °C in the absence and presence of biosurfactant extract, respectively. In general, soluble sugars increased in juices for 5-6 days and after those sugars decreased at different rates depending on the temperature of storage. Differences in sugar solubilization and degradation were more significant in apple juice than in orange juice at 20 °C and 7 days of storage, achieving for orange juice values of 101 and 102 g/L in the absence and presence of biosurfactant extract, respectively. Biomass growth was almost unaffected by the biosurfactant extract concentration and the optimal conditions for biomass production were detected at intermediated temperatures after 6-7 days of storage for both apple and orange juices, obtaining maximum concentrations of 1.68 g/L and 1.54 g/L for apple juice and orange juice, respectively, in the absence of biosurfactant extract. The pH during storage was kept in the range of 3.35-3.48 for apple juice and of 3.40-3.77 for orange juice.

Effects of aqueous ozone treatment on the nutritional attributes of mango (Mangifera indica L.) fruit juice

The global fruit juice market is expanding alongside the exponentially growing demand for a healthy lifestyle. Fruit juice is a preferred drink among all age groups as it contains numerous essential nutrients that benefit human health. The safety aspects of fruit juice are equally important as its healthy features. The conventional method of thermal pasteurisation has been known to produce fruit juice of inferior quality. Hence, ozone is being considered as an alternative, non-thermal form of pasteurisation. With its strong oxidation potential, ozone exhibits antimicrobial characteristics and produces no toxic by-products. However, for ozone to be successfully adopted by juice producers, the synergistic effects of the composition of fruit juice and ozone treatment must be adequately evaluated. Therefore, the present work subjected various concentrations of Chokanan mango juice (MJ), diluted with distilled water (DW) at 100MJ:0DW, 75MJ:25DW, and 50MJ:50DW to aqueous ozone treatment at different ozone doses. The effects of these treatments on the physicochemical and antioxidant properties of the MJ were evaluated. Ozone was found to be effective in decreasing the pectin methylesterase (PME) activity arising from the de-esterification of the pectin molecules, and increasing the DPPH activity, thereby increasing the juice quality. Significant effects on the total colour difference (ΔE) and total phenolic content (TPC) were observed in proportion to the increases in ozone dose. The colour of the treated MJ was found to be positively correlated with the TPC, while a kinetic study was performed to investigate the proportionality of the colour and TPC degradation. The first-order reaction model fitted well with the degradation patterns of L* and b*, as well as the ΔE of the MJ samples. A significant difference was observed between the degradation rate constant (k-value) for the MJ samples, which suggested that the k-value could have been affected by not only the ozone dose, but also the juice matrix. The present work demonstrated that the composition of fruit juice was an essential intrinsic parameter that must be assessed before adopting ozone as a form of non-thermal pasteurisation to produce fruit juice which is stable in quality, and safe for consumption.

Estimation of degradation kinetics of bioactive compounds in several lingonberry jams as affected by different sweeteners and storage conditions

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Kinetic parameters for degradation of bioactives during jam’s storage were determined.

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Protective effects of some sweeteners on bioactive compounds content were revealed.

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Natural sweetener stevia enhanced the storage stability of most bioactive compounds.

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Storage at low temperature reduces the degradation of bioactive compounds in jams.

Lingonberry fruits are considered to play an important role in nutrition, as they comprise a variety of health-promoting components. Because of lingonberries seasonal availability and also due to their rapid degradation, their stability during processing is a continuous challenge for the food industry. Lingonberries are ideal fruits in making jam due to their natural deep reddish color, but recently, increased demand for low-calorie jams with alternative sweeteners has gained special attention. In this line, the objective of this study was to monitor the changes in anthocyanins, vitamin C, total phenolics, total reducing sugars and antioxidant capacity of several lingonberry jams formulated with different sweeteners (sucrose, fructose, erythritol, brown sugar, coconut sugar, stevia, saccharin). Due to the fact that storage conditions are important factors for jam quality, the jams were stored for 180 days at 4 °C and 25 °C (both under light and dark conditions). The rate constants (k) and the half time values (t_1/2) of the degradation processes were determined and degradation kinetics was studied. For all analyzed conditions, first-order reaction kinetics was established for the degradation process of anthocyanins, whereas a second-order kinetic model described the degradation of the other compounds. Kinetic parameters showed that the stability of the studied compounds was highly influenced by the type of sweetener used in jam formulation. Total phenolics and antioxidants were best preserved in the presence of stevia, coconut sugar and fructose, whereas a destabilizing effect of erythritol on vitamin C and anthocyanins content during storage was observed. Among all the studied compounds, anthocyanins presented the fastest degradation, regardless storage conditions. The stability of studied compounds was higher at lower storage temperature (4 °C), while increasing the temperature at 25 °C and exposure to light determined higher rate of the degradation processes. The results provide useful information for understanding some bioactive compounds degradation in real foods, contributing to the development of new food products and providing information of commercial importance.

Inactivation of Escherichia coli in apple cider using atmospheric cold plasma

Atmospheric cold plasma (ACP) is a promising non-thermal technology that has the potential to inactivate microorganisms in foods. In this work, the inactivation of E. coli K12, acid-adapted E. coli K12, and E. coli O157:H7 in apple cider by ACP was investigated using feed gases as simulated air (SA) (80 % N₂ + 20 % O₂) and a mixture of 90 % N₂ + 10 % O₂ with various processing times (0 to 180 s). We obtained the reduced the populations of both acid-adapted and non-adapted E. coli K12 by 5 log CFU/mL within 120 s, and E. coli O157:H7 within 90 s. Additionally, no significant changes in the °Brix, pH, temperature, or titratable acidity (TA) of apple cider were observed after exposure to ACP. However, processing times longer than 120 s resulted in significant changes in the pH values. The highest concentration of ozone and hydrogen peroxide reached to 0.22 ± 0.1 mg/L for CG in 180 s and 0.07 ± 0.01 mg/L for SA in 150 s, respectively. Both acid-adapted and non-acid adapted E. coli K12 was found to be more resistant to ACP processing than E. coli O157:H7 after the 90 s, so it could serve as a surrogate for E. coli O157:H7. When we compared the effect of the gas type on inactivation, non-selective media, the results showed no significant differences between the gas types, while selective media demonstrated significant differences. In optical absorption spectroscopy measurements of plasma species, primarily ozone peaks were observed. Furthermore, the optical absorption spectroscopy also revealed that the inactivation of the bacteria could be attributed to some plasma species with wavelengths between 190 and 308 nm. The findings provided a perspective on the use of ACP as a method for decontaminating fruit juices as a non-thermal processing.

Chemical composition and technofunctional properties of carrot (Daucus carota L.) pomace and potato (Solanum tuberosum L.) pulp as affected by thermomechanical treatment

Fiber rich by-products derived from primary agri-food production such as carrot pomace and potato pulp are available in large quantities, but their functional properties do not necessarily meet the requirements for use in specific food applications. Thermomechanical treatment (extrusion) of carrot pomace and potato pulp changes both dietary fiber polysaccharide structures and technofunctionality of the materials. Solubility of dietary fiber constituents changes, resulting in higher levels of water- and ethanol-soluble poly-/oligosaccharides. On a structural level, particularly arabinans and galactans as neutral side chains of type I rhamnogalacturonan were degraded under thermomechanical stress. Galacturonic acid portions (preferably from homogalacturonan or rhamnogalacturonan I) and their degree of methylation were also negatively affected. On a functional level, water absorption of potato pulp increased up to three times following extrusion, whereas water absorption of carrot pomace decreased with extrusion processing. The observed, enhanced swelling behavior for extruded carrot pomace was accompanied by higher complex viscosity of the dispersions. Swelling of potato pulp particles increased largely (up to 25 times) following extrusion, resulting in highly viscous pastes. Phytochemicals were retained up to 50%, heat-induced contaminants were formed only to a small extent (up to 8.1 mg 5-hydroxymethylfurfural·kg− 1 dry matter for carrot pomace; up to 71 µg acrylamide·kg− 1 dry matter for potato pulp).

Graphical abstract

Fast and eco-friendly method using atmospheric solids analysis probe mass spectrometry to characterize orange varieties

Orange fruit is one of the most popular types of fruit in the world, and its juice is the main product of its processing. This study aimed to evaluate a simple, fast, and eco-friendly methodology, atmospheric solids analysis probe mass spectrometry (ASAP-MS), to assess the chemical profile of four oranges varieties (Valencia, Folha Murcha, Pera, and Iapar). The oranges' varieties were evaluated for the physicochemical composition (extraction yield, pH, total titratable acidity, total soluble solids [TSS], °Brix), ratio (TSS/TA), and bioactive compounds (ASAP-MS analysis). The characterization of oranges resulted in great values of oranges yield according to the varieties (44.00-48.10% [w/w], adequate and characteristic acidity [0.73-1.35%], soluble solids content (10.24-13.80°Brix), pH (3.30-3.96), and ratio (7.59-19.90) level for this fruit. This powerful method showed that all analysis procedures were simple, fast, and easy because there is no need to prepare the sample and the analysis time lasted 2 min. Besides, results obtained exhibited a vast array of chemical groups. Principal component analysis (PCA) defined and distinguished the varieties of the orange. Therefore, ASAP-MS and PCA showed that they are very attractive candidates for routine analysis to monitor the varieties of the orange with its pronounced advantages, besides being contributing to the environment because it does not use any quantities of organic solvents. This methodology was applied for the first time to this type of sample.

HPLC-DVD combined with chemometrics to analyze the correlation between the Q-marker content and color of Corni Fructus

Although Corni Fructus (CF) is a fruit with great economic value and development potential in medicine and food, too much reliance on personal experience for quality evaluation seriously limits the trading and circulation of CF. In the present study, through the research on the correlation between the chemical composition and the appearance color, a standard colorimetric card related to CF quality was established, which simplified the quality evaluation process and improved the accuracy of the visual evaluation of CF. Firstly, a total of 29 batches of CF from different places were collected. Then, "imread" in the MATLAB software was used to convert the color of all samples into RGB values, and HPLC-DVD was used to measure the content of the main chemical components in CF. Thereafter, the correlation between the content and color was studied by using MLR, BP-ANNs and SVM chemometric tools to screen the Q-marker of CF, which was further confirmed by in vivo and in vitro experiments. Finally, the Q-marker standard colorimetric card with the best fitting degree is established according to the prediction model. Thus, this study provides an auxiliary reference for the color evaluation of CF and a reference for the standardization and quantification of the macro characteristics of traditional Chinese medicine and food.

Formulation of Laurus nobilis Essential Oil Nanoemulsion System and Its Application in Fresh-Cut Muskmelons

The objective was to elucidate the influences of Laurus nobilis essential oil nanoemulsion on the quality properties of fresh-cut muskmelons (Cucumis melo L.) stored at 4 °C for 8 days. The L. nobilis oil nanoemulsion coating can inhibit changes in the browning index and titratable acidity level of muskmelon samples. The browning index in the slices treated with L. nobilis oil nanoemulsion was 0.095 ± 0.007, as compared with that of the control (0.314 ± 0.018). Meanwhile, L. nobilis oil nanoemulsion treatment maintained total phenolic content, with values ranging from 11.13 ± 0.74 mg GAE/g FW to 9.47 ± 0.75 mg GAE/g FW and inhibited the activities of related enzymes, such as polyphenol oxidase, peroxidase and antioxidant enzymes (catalase and peroxidase). Moreover, the application of L. nobilis oil nanoemulsion inhibited the proliferation of spoilage microorganisms. The population of the aerobic bacteria of the muskmelon samples subjected to L. nobilis oil nanoemulsion treatment was 5.14 ± 0.47 log CFU/g FW, whereas that of the control was 9.42 ± 0.88 log CFU/g FW after 8 days. Therefore, the tested L. nobilis oil nanoemulsion may contribute to the inhibition of surface browning and enhancement of the shelf life of fresh-cut muskmelons for eight days at refrigerator temperature.

Effect of Galangal Essential Oil Emulsion on Quality Attributes of Cloudy Pineapple Juice

Galangal essential oil is obtained from the rhizomes of galangal with proven anti-inflammatory, antioxidant, antiviral, and antimicrobial properties, which are valuable in the food industry. To explore the effect of galangal essential oil on the quality of pineapple juice, 0.05, 0.1, 0.2, and 0.4% galangal essential emulsion were added, and their influence on the physical stability, physicochemical properties, microbial quantity, and aroma profiles of cloudy pineapple juice were evaluated. The essential oil emulsion of galangal is a milky white liquid with a strong aroma of galangal. The pH values of emulsion increased from 4.35 to 5.05 with the increase in essential oil concentration, and there was no significant difference in the particle size of the pineapple juice. The results showed that the galangal essential oil emulsion was stable and the stability of the cloudy pineapple juice was significantly enhanced by the essential oil emulsion determined using LUMiSizer. The cloudy pineapple juice with a 0.2% essential oil emulsion showed the most stability during storage. The lightness of the cloudy pineapple juice increased instantly with the essential oil emulsion addition. In addition, the microbial quantity of the cloudy pineapple juice was decreased by the individual essential oil emulsion or combined with thermal treatment to hold a longer shelf life. The microbial counts in pineapple juice treated by 0.4% essential oil emulsion and thermal treatment only increased from 1.06 to 1.59 log CFU/ml after 4 days of storage at 25°C. Additionally, the pH and total soluble solids showed a slightly increasing trend; however, the value of titratable acidity, free radical scavenging capacity, and ascorbic acid content of the cloudy pineapple juice showed no significant change. Finally, the results of the electronic nose showed that the aroma components of the pineapple juice were changed by the essential oil emulsion and thermal treatment, and the difference was especially evident in the content of the sulfur, sulfur organic, and aromatics compounds. Consequently, the results indicated that galangal essential oil emulsion can be used as juice additives to improve the quality attributes and extend the shelf-life of cloudy pineapple juice.

Reaction pathways and factors influencing nonenzymatic browning in shelf-stable fruit juices during storage

The occurrence of nonenzymaticbrowning in fruit juices during storage is a major quality defect. It negatively affects consumer acceptance and consumption behavior and determines the shelf-life of these products. Although nonenzymatic browning of fruit juices has been the subject of research for a long time, the exact mechanism of the nonenzymatic browning reactions is not yet completely understood. This review paper aims to give an overview of the compounds and reactions playing a key role in nonenzymatic browning during the storage of fruit juices. The chemistry of the plausible reactions and their relative importance will be discussed. To better understand nonenzymatic browning, factors affecting these reactions will be reviewed and several strategies and methods to evaluate color changes and browning will be discussed. Nonenzymatic browning involves three main reactions: ascorbic acid degradation, acid-catalyzed sugar degradation, and Maillard-associated reactions. The most important NEB pathway depends on the matrix. Nonenzymatic browning is affected by many factors, such as the juice composition, the pH, the oxygen availability (packaging material), and the storage conditions. Nonenzymatic browning can thus be considered as a complex problem. To characterize color changes and browning and obtain insight into the browning mechanism of fruit juices, food scientists applied several approaches and strategies. These included the use of model systems with/without the addition of labeled compound and real systems as well as advanced analytical methods.

Evaluation of quality changes of differently formulated cloudy mixed juices during refrigerated storage after high pressure processing

Cloudy fruit and vegetable mixed juice (MJ) pasteurized by high pressure processing (HPP) showed an increasing market demand. However, browning, sedimentation, and flavor changes of HPP juice during storage have been a great challenge for the beverage industry. The aim of this work was to investigate quality changes of HPP MJs during storage and to explore the potential to create the shelf-stable MJs with fresh-like organoleptic quality through HPP. In the work, commercial MJ1 (orange, mango, and kiwifruit) and MJ2 (carrot and pineapple) were formulated and their quality changes during storage were investigated. The results indicated no visible color changes and sedimentation were observed in MJ1 and MJ2 during refrigerated storage (90 days). However, sucrose decreased as glucose and fructose increased; a large number of aldehydes and alcohols decreased but some terpenoids increased during storage. In general, blending proper fruit and vegetable to produce MJs combing with HPP could maintain high cloud and color stability, but sugars and volatiles clearly changed during storage.

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HPP mixed juice showed high color and cloud stability during chilled storage.

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Aldehydes and alcohols decreased but terpenoids increased during storage.

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Sucrose decreased with glucose and fructose increasing during storage.

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Carrot-pinapple mixed juice showed high quality stability during storgae.

Thermosonication Combined with Natural Antimicrobial Nisin: A Potential Technique Ensuring Microbiological Safety and Improving the Quality Parameters of Orange Juice

Currently, thermal pasteurisation (TP) remains the most widely applied technique for commercial orange juice preservation; however, a high temperature causes adverse effects on the quality attributes of orange juice. In order to explore a novel non-thermal sterilization method for orange juice, the impacts of thermosonication combined with nisin (TSN) and TP treatments on the quality attributes including microbial and enzyme inactivation and the physicochemical, nutritional, functional, and sensory qualities of orange juice were studied. Both TP and TSN treatments achieved desirable bactericidal and enzyme inactivation effects, and nisin had a significant synergistic lethal effect on aerobic bacteria in orange juice (p < 0.05). Additionally, TSN treatment significantly improved the color attributes of orange juice and well maintained its physicochemical properties and sensory quality. More importantly, TSN treatment significantly increased the total polyphenols content (TPC) and total carotenoids (TC) by 10.03% and 20.10%, increased the ORAC and DPPH by 51.10% and 10.58%, and the contents of total flavonoids and ascorbic acid were largely retained. Correlation analysis of antioxidant activity showed that the ORAC and scavenging ability of DPPH radicals of orange juice are mainly attributed to TC and TPC. These findings indicate that TSN shows great potential application value, which could guarantee the microbiological safety and improve the quality attributes of orange juice.

Kinetic studies of 5-(hydroxymethyl)-furfural formation and change of the absorption at 420 nm in fruit juices for the improvement of pasteurization plants

Preservation of juices is essential to obtain microbial safe products. There are various established methods as pasteurization. Heretofore, only the kinetic figures of microbial inactivation were considered but not those of reaction impairing the chemical quality. For a gentler processing, knowledge of the kinetics of relevant chemical conversion reactions is necessary. 5-(Hydroxymethyl)-furfural (HMF) formation and the color change of juices are important attributes. The non-isothermal Rhim method was used to determine the activation energy and pre-exponential factor for HMF formation in different juices and an isothermal method for the reaction order. Values for the activation energy from 133 to 303 kJ/mol were obtained with a zeroth reaction order. A correlation between HMF and the color change could be found. Based on the kinetic figures, lines with equal effects for the chemical changes and for the lethal effect on microorganisms were calculated. Time-temperature settings for the gentlest treatment could be found.

Effect of Oxidative Stress on Physicochemical Quality of Taiwanese Seagrape (Caulerpa lentillifera) with the Application of Alternating Current Electric Field (ACEF) during Post-Harvest Storage

This study aims to determine the physicochemical quality of seagrape (Caulerpa lentillifera) as a freshness label for products cultivated in different seasons. The applied post-harvest storage experiments compared between, within and without seawater that led to oxidative stress conditions. Water content, malondialdehyde (MDA) compound, total phenolic content (TPC), and chlorophyll content were observed at 0, 3, 6, and 9 days of storage. The storage without seawater showed sharper quality reductions by reaching 20–40% of water loss, 70–90% of MDA production, 15–25% of TPC reduction, and 40–60% of total chlorophyll degradation. The storage within seawater showed lower quality reductions due to the specific growth rates still reaching 5–10%. This study found that the greater the physicochemical quality, the slower the decomposition rates of the stored seagrape during storage. Therefore, the seagrapes’ obvious discoloration occurred earlier in winter, followed by summer and spring. Kinetics of chlorophyll degradation on seagrape in different seasons meet different order-reactions during storage. Furthermore, alternating current electric field (ACEF) treatment with 125 kV/m of intensity for 60 min can lower the spring seagrapes’ physicochemical quality by reaching 10–30% of inhibition, resulting in the shelf-life extension for up to 12 days of post-harvest storage.

Effect of Adding Resistant Maltodextrin to Pasteurized Orange Juice on Bioactive Compounds and Their Bioaccessibility

Resistant maltodextrin (RMD) is a water-soluble and fermentable functional fiber. RMD is a satiating prebiotic, reducer of glucose and triglycerides in the blood, and promoter of good gut health, and its addition to food is increasingly frequent. Therefore, it is necessary to study its potential effects on intrinsic bioactive compounds of food and their bioaccessibility. The aim of this study was to evaluate the effect of adding RMD on the bioactive compounds of pasteurized orange juice with and without pulp, and the bioaccessibility of such compounds. RMD was added at different concentrations: 0 (control sample), 2.5%, 5%, and 7.5%. Ascorbic acid (AA) and vitamin C were analyzed using HPLC, whereas total phenols, total carotenoids (TC), and antioxidant capacity were measured using spectrophotometry. After that, sample in vitro digestibility was assessed using the standardized static in vitro digestion method. The control orange juice with pulp presented significantly higher values of bioactive compounds and antioxidant capacity than the control orange juice without pulp (p < 0.05). RMD addition before the juice pasteurization process significantly protected all bioactive compounds, namely total phenols, TC, AA, and vitamin C, as well as the antioxidant capacity (AC) (p < 0.05). Moreover, this bioactive compound protective effect was higher when higher RMD concentrations were added. However, RMD addition improved phenols and vitamin C bioaccessibility but decreased TC and AA bioaccessibility. Therefore, the AC value of samples after gastrointestinal digestion was slightly decreased by RMD addition. Moreover, orange pulp presence decreased total phenols and TC bioaccessibility but increased AA and vitamin C bioaccessibility.

Effect of Cryoconcentration Assisted by Centrifugation-Filtration on Bioactive Compounds and Microbiological Quality of Aqueous Maqui (Aristotelia chilensis (Mol.) Stuntz) and Calafate (Berberis microphylla G. Forst) Extracts Pretreated with High-Pressure Homogenization

The objective of this study was to evaluate the effect of cryoconcentration assisted by centrifugation-filtration on the bioactive compounds and the microbiological quality of aqueous maqui (Aristotelia chilensis (Mol.) Stuntz) and calafate (Berberis microphylla G. Forst) extracts pretreated with high-pressure homogenization (HPH). Aqueous extracts were prepared from fresh fruits which were treated with HPH (predefined pressure and number of passes). The best pretreatment was determined by aerobic mesophilic, fungal, and yeast counts. Treated extracts were frozen at −30 °C in special tubes and centrifuged at 4000 rpm for 10 min to obtain the cryoconcentrated product. The optimal pretreatment conditions for HPH were 200 MPa and one pass in which the extracts exhibited no microorganism counts. Cryoconcentration by freezing and subsequent centrifugation-filtration in a single cycle showed high process efficiency (>95%) in both soluble solids and bioactive compounds (total polyphenols and anthocyanins) and antioxidant capacity of the fresh fruits and extracts. The HPH treatment and subsequent cryoconcentration assisted by centrifugation-filtration is an efficient technology to obtain concentrates with good microbiological quality and a high content of bioactive compounds.

Formation pathways and precursors of furfural during Zhenjiang aromatic vinegar production

As a flavor and quality parameter, furfural has potential undesirable effects. This study aimed to elucidate furfural formation, including generation, pathways, and possible precursors during the production of Zhenjiang aromatic vinegar. A cereal vinegar model, rich in saccharides, amino acids, and organic acids, was used to explore the potential precursors. Furfural and 5-hydroxymethylfurfural (HMF) mainly generated during the decoction process, but the HMF also increased during the aging process. Three pathways were found to coexist for the formation of furfural: (i) the Maillard reaction induced by saccharides and nitrogenous compounds, (ii) the direct cleavage of pentose, and (iii) indirect conversion from pentosan, which only made a minor contribution. Furfural was not formed from HMF or l-ascorbic acid in vinegar. Instead, ribose, xylose, arabinose, galacturonic acid, glucuronic acid, and pentosan were the main precursors. These insights may be useful for the risk/benefit balance and improve the flavor quality and safety.

Potential of 1H NMR fingerprinting and a model system approach to study non-enzymatic browning in shelf-stable orange juice during storage

For the first time, a model system approach was combined with ¹H NMR fingerprinting in studying non-enzymatic browning (NEB) of pasteurized shelf-stable orange juice during storage. Various NEB precursors were used individually or in combinations to formulate simple or complex model systems, respectively, in citric acid buffer. Based on orange juice composition, ascorbic acid, sugars (sucrose, glucose and fructose) and amino acids (proline, arginine, asparagine, aspartic acid, serine and glutamic acid) were selected as the precursors for the model systems. After pasteurization and during subsequent accelerated storage (42 °C, 16 weeks) the model systems displayed a three-phase browning development. The initial browning phase was mainly the result of ascorbic acid degradation especially in the presence of amino acids and sugars. In the later phases, the contribution of reactions of sugars and amino acids to browning became apparent. The application of ¹H NMR fingerprinting on a simple model system containing ascorbic acid revealed that its degradation pathway to intermediates such as xylonic acid, acetic acid and erythrulose was responsible for the major changes during storage. When this model system was complexed by inclusion of sugars and amino acids, the hydrolysis of sucrose to glucose and fructose was identified as the main reaction leading to differences in the samples throughout storage. These three sugars dominated the NMR spectra of the samples, overshadowing several important compounds for NEB such as ascorbic acid and its degradation products. Other more advanced NMR experiments such as two-dimensional NMR analyses should be applied in future research to identify unknown compounds from NEB reactions.

Starch hydrolysis during mashing: A study of the activity and thermal inactivation kinetics of barley malt α-amylase and β-amylase

Hydrolysis of starch is key in several industrial processes, including brewing. Here, the activity and inactivation kinetics of amylases throughout barley malt mashing are investigated, as a prerequisite for rational optimisation of this process. Varietal differences were observed in the activity of α- and β-amylases as a function of temperature for six barley and malt varieties. These differences were not reflected in the resulting wort composition after mashing, using three isothermal phases of 30 min at 45 °C, 62 °C and 72 °C with intermediate heating by 1 °C/min. Thermal inactivation kinetics parameters determined for α- and β-amylases of an industrially relevant malt variety in a diluted system showed that enzymes were inactivated at lower temperatures than expected. The obtained kinetic parameters could predict α-amylase, but not β-amylase inactivation in real mashing conditions, suggesting that β-amylase stability is enhanced during mashing by components present or formed in the mash.

Insight into non-enzymatic browning of shelf-stable orange juice during storage: A fractionation and kinetic approach

BACKGROUND

Non-enzymatic browning (NEB) is the main quality defect in shelf-stable orange juice and other fruit juices during storage. Previous studies on NEB focused solely on the soluble fraction of orange juice, regardless of the fact that both soluble and insoluble fractions turn brown during extended storage. Clear evidence of the relative contribution of both fractions to NEB is currently lacking in the literature. This study investigated the contribution of the soluble and insoluble fractions of orange juice, which were obtained by centrifugation and ethanol precipitation, to NEB during storage. Changes in different NEB-related attributes, such as ascorbic acid (AA) degradation, and the browning index (BI), were quantified and kinetically modeled.

RESULTS

Evaluation of color during storage showed that the orange juice and the soluble compound-containing fractions turned brown whereas the insoluble fractions did not. The soluble compound-containing fractions showed exactly the same browning behavior with storage as the plain orange juice. Based on the kinetic parameters obtained, the degradation of AA, the hydrolysis of sucrose, the increase in the glucose and fructose content, and the formation of furfural and 5-hydroxymethylfurfural during storage were similar for the plain orange juice and the soluble compound-containing fractions.

CONCLUSION

This work provided evidence that the soluble fraction of orange juice plays the major role in NEB, unlike the insoluble fraction, which seems to make no contribution. Results from this work also demonstrate the potential use of the soluble fraction as an orange-juice-based model system of reduced complexity that can be used for the further investigation of NEB processes. © 2020 Society of Chemical Industry.

Kinetic modelling of vitamin C losses in fresh citrus juices under different storage conditions

The degradation kinetics of vitamin C in different citrus juice types (tangerine, grapefruit, orange and lime) were investigated during four hours storage at temperatures of 4 and 25°C under different storage conditions in terms of light and oxygen presence. The loss of vitamin C at each sample followed the first-order kinetic model. During storage, predicted half-life of vitamin C ranged from 137.586 to 467.486 min for tangerine; 105.444 to 203.100 min for grapefruit; 365.702 to 1044.668 min for orange and 540.076 to 722.016 min for lime juices. These results indicated that the highest and lowest retentions of vitamin C were observed in orange and grapefruit juices respectively during storage. Additionally, storage time, light penetration and oxygen presence were the most effective factors on vitamin C degradation while the storage temperature revealed no significant effect on the vitamin C content.

Storage effects on the quality quartet of orange juice submitted to moderate thermosonication: Predictive modeling and odor fingerprinting approach

The effects of moderate thermosonication (MTS) on the quality quartet: physico-chemical, microbial, nutritional and sensory qualities of orange juice (OJ) inoculated with Alicyclobacillus acidoterrestris (AAT) were studied during 24 days of storage at ambient and refrigerated temperatures. The bioactive compounds and antioxidant activity of OJ decreased with storage, while the pectin methyl esterase (PME) increased. Nonetheless, noticeable changes were observed from the 12th day of storage. There was no obvious (p > 0.05) variation in pH and total soluble solids. To determine the nutritional and microbial quality characteristics of OJ during storage, non-linear kinetic curves were successfully fitted with least square fitting polynomial and four-parameter log-logistic distribution models. The E-nose sensors succeeded in discriminating between the aroma of non-treated and treated OJ based on linear discriminant analysis (LDA). Furthermore, terpenes, alcohol and partially aromatic compounds were the main spoilage indicators of OJ during storage based on E-nose analysis and confirmed by HS-SPME-GC/MS analysis. Thus, MTS significantly extended the shelf life of the quality quartet of natural OJ at 4 °C. E-nose-GC/MS fusion offered odor fingerprints to AAT microorganisms that can be used as spoilage index without using traditional food analysis techniques. The proposed approach can be used as an alternative tool for rapid detection of spoilage microorganisms in OJ.