Effects of high-humidity hot air impingement blanching (HHAIB) pretreatment on the change of antioxidant capacity, the degradation kinetics of red pigment, ascorbic acid in dehydrated red peppers during storage

Quality changes and shelf-life prediction of far-infrared radiation heating assisted pulsed vacuum dried blueberries by SSA-ELM

The effects of storage conditions on the changes in quality attributes of blueberries dried by far-infrared radiation heating assisted pulsed vacuum drying (FIR-PVD) during accelerated storage for 72 days were investigated. The total phenolics (TP), total monomeric anthocyanins (TMA) contents, and antioxidant activities greatly decreased with the increase of storage time. The highest retention rates of TP and TMA of FIR-PVD blueberries were obtained under the dark-vacuum condition after accelerated storage, i.e. 43.71 % and 30.38 %, respectively. Compared to hot air drying (HAD) samples, FIR-PVD samples exhibited slightly higher degradation rates of TP and TMA during storage. Light-air condition markedly promoted the decrease of antioxidant activities of FIR-PVD and HAD blueberries. The L* and b* values of dried samples decreased, while a* values increased slowly with the increase of accelerated storage time. Additionally, salp swarm algorithm (SSA) and extreme learning machine (ELM) were applied to establish a shelf-life prediction model. The modeling results showed that ELM model optimized by SSA (SSA-ELM) can be an effective predictive tool for the shelf life of dried blueberries under different conditions.

Sea buckthorn Flavonols extract co-loaded Zein/gum Arabic nanoparticles: Evaluating cellular absorption in Caco-2 cells and antioxidant activity in HepG2 cells

Improving sea buckthorn flavonoids (SF) stability and bioacccessibility is of more practical significance for evaluating the total bioacccessibility of such foods. Therefore, we prepared nanoparticles using zein and gum Arabic (GA) by anti-solvent precipitation to encapsulate SF. Nanoparticles were characterized and assessed for their effect on the stability, release, bioaccessibility, absorption, and antioxidant properties of SF in the in vitro digestion and cell line. The uniform, regular nanoparticles achieved 77.19 % encapsulation efficiency. The SF retention rates during long-term storage (60.46 %) and in vitro digestion (53.76 %) demonstrated that nanoparticles exhibited good stability and bioaccessibility compared to free SF. Furthermore, cellular absorption, the free radical scavenging rate for ABTS (85.26 %) and DPPH (80.48 %), as well as inhibitory effects on intracellular ROS further demonstrated that bilayer nanoparticles could successfully protect and exert biological characteristics of SF. This study evaluated the overall bioaccessibility of sea buckthorn flavonoids using a nanoparticle delivery system, which holds even greater significance for guiding the development of this category of natural foods.

Changes in Carotenoids and Quality Parameters of Sweet Paprika (Capsicum annuum) After an Accelerated Heat Treatment

Paprika, obtained from dried red pepper (C. annuum), is valued for its characteristic colour and flavour. Its carotenoid content, which is important for both sensory and nutritional quality, varies depending on several factors (agronomic conditions and technological treatment with special attention to the drying methods) that influence the colour and antioxidant capacity of the samples. This study investigated the effect of an accelerated thermal treatment (80 °C for 8 h) applied to evaluate the oxidative stability of the carotenoids and the colour of ground paprika depending on its origin (Peru or China). Changes in quality parameters (ASTA index and CIELAB colour), carotenoid content and profile (HPLC-DAD) and lipophilic antioxidant capacity (FRAP and ABTS•+ methods) were evaluated. Untreated Chinese samples had 30% more total carotenoids than Peruvian samples, but this was not reflected in ASTA units, indicating that at least a 50% carotenoid variation is required for significant differences. Treatment resulted in a carotenoid loss of 70% in Peruvian and 30% in Chinese samples, with changes in total carotenoids correlating positively with antioxidant capacity. Both origins had similar carotenoid profiles, with β-carotene being the predominant carotenoid, while distinct contents were observed between the origins. The higher content of esterified carotenoids in Chinese peppers resulted in better thermal stability. The results highlight the necessity for tailored production processes to maintain nutritional integrity and antioxidant capacity.

Analysis of changes in nutritional compounds of dried yellow chili after different processing treatments

Dried yellow chili is highly appreciated by consumers due to its excellent quality and flavor. The quality of products is determined by the drying and storage methods. In this study, dried yellow chilis were processed by natural air drying and hot air drying methods and then stored under three conditions: ambient temperature, ambient temperature with light avoidance, and at 10 °C with light avoidance for 12 months. The changes in the bioactive compounds during this period were analyzed attempting to reveal correlations between the different treatments and these compounds, with the aim of providing references for maintaining the bioactive compounds of pepper products. The results showed that samples treated with hot air had higher levels of fatty acids, resulting in a more pronounced flavor. During storage, samples stored at 10 °C with light avoidance were more effective in preserving soluble solids, total protein content, total phenols, capsaicinoids and most fatty acids.

Transcriptome analysis integrated with changes in cell wall polysaccharides of different fresh-cut chili pepper cultivars during storage reveals the softening mechanism

Cell wall disassembly and transcriptomic changes during storage of two fresh-cut chili pepper cultivars displaying contrasting softening rates were investigated. Results showed that Hangjiao No. 2 (HJ-2) softened more rapidly than Lafeng No. 3 (LF-3). Compared with LF-3, HJ-2 had a higher content of WSP, more side chains of RG-I in three pectin fractions, and higher activities of PME, PL, and β-Gal at day-0. During storage, HJ-2 showed more markable pectin solubilization, more severe degradation in CSP and NSP, and greater loss of side chains from RG-I in three pectin fractions, which were correlated with increased activities of PG and α-L-Af. Furthermore, the higher up-regulation of PG (LOC107870605, LOC107851416) and α-L-Af (LOC107848776, LOC107856612) were screened in HJ-2. In conclusion, the different softening rate between cultivars was not only due to the fundamental differences in pectin structure but also pectin degradation regulated by related enzymes and gene expression levels.

High-humidity hot-air impingement blanching conditions for the inhibition of potato-browning enzymes and for quality retention

BACKGROUND

Potato is an important non-cereal crop. It provides carbohydrates, a major source of energy in the human diet. Blanching during the processing of fresh fruits and vegetables is essential for their preservation. High-humidity hot-air impingement blanching (HHAIB) is a promising emerging technology for pretreating different food materials. This research aimed to identify the optimum HHAIB conditions for the inhibition of potato-browning enzymes, maintaining their nutritional and physical quality, and to compare this with conventional hot-water blanching (HWB).

RESULTS

Polyphenol oxidase (PPO) inactivation, total phenol content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, color, textural attributes, thermal properties, microstructure, and particles crystallinity were evaluated. The relative humidity (RH), temperature, and duration of HHAIB required for PPO inactivation (2.59%) were 50%, 105 °C, and 4 min, respectively, which resulted in a complete gelatigination of potato starches, based on the thermal properties and the microstrcture of the blanched potatoes. These conditions led to improvements in TPC to 312.54 μg GAE.g-1 FP, DPPH scavenging to 1.99 μmol TE.g-1 FP, as well as enhancements in color and crystallinity. When HHAIB was conducted at lower temperatures (85 and 95 °C) there were negative effects on the blanched potatoes' color and crystallinity, along with a non-safe level of PPO activity.

CONCLUSION

High-humidity hot-air impingement blanching was superior to HWB, inhibiting PPO, maintaining nutrients, and preserving physical properties, especially under the optimum conditions revealed by the principal component analysis. It provides an excellent technique for blanching and pretreating potatoes, preserving them, and maintaining their quality. © 2023 Society of Chemical Industry.

A High-Performance Liquid Chromatography with Electrochemical Detection Method Developed for the Sensitive Determination of Ascorbic Acid: Validation, Application, and Comparison with Titration, Spectrophotometric, and High-Performance Liquid Chromatography with Diode-Array Detection Methods

L-ascorbic acid (vitamin C, VC), an essential nutrient obtained from the diet to maintain various vital signs for the human body, is a crucial indicator of food quality and nutritional value. Herein, high-performance liquid chromatography with electrochemical detection (HPLC-ECD) was developed and validated with the advantages of higher sensitivity, simpler operation processes, and more rapid detection in measuring VC levels in honey samples when compared with the common methods (titration, spectrophotometric, and HPLC-DAD methods). The results of the HPLC-ECD methodological validation showed that the limit of detection (LOD) was 0.0043 µg mL-1; the relative standard deviations (RSDs) of the intra- and inter-day values were between 2.51% and 5.15%, and the regression coefficient was >0.999 in the linear range of 0.1 to 20 µg mL-1. The validated HPLC-ECD method was also successfully utilized to evaluate the VC levels in different varieties of honey samples with various storage durations as well as in fruit and biological samples. This study provided a perspective for the further accurate determination of VC content in food and biological samples.

Antioxidant potential and factors influencing the content of antioxidant compounds of pepper: A review with current knowledge

The use of natural food items as antioxidants has gained increasing popularity and attention in recent times supported by scientific studies validating the antioxidant properties of natural food items. Peppers (Capsicum spp.) are also important sources of antioxidants and several studies published during the last few decades identified and quantified various groups of phytochemicals with antioxidant capacities as well as indicated the influence of several pre- and postharvest factors on the antioxidant capacity of pepper. Therefore, this review summarizes the research findings on the antioxidant activity of pepper published to date and discusses their potential health benefits as well as the factors influencing the antioxidant activity in pepper. The major antioxidant compounds in pepper include capsaicinoids, capsinoids, vitamins, carotenoids, phenols, and flavonoids, and these antioxidants potentially modulate oxidative stress related to aging and diseases by targeting reactive oxygen and nitrogen species, lipid peroxidation products, as well as genes for transcription factors that regulate antioxidant response elements genes. The review also provides a systematic understanding of the factors that maintain or improve the antioxidant capacity of peppers and the application of these strategies offers options to pepper growers and spices industries for maximizing the antioxidant activity of peppers and their health benefits to consumers. In addition, the efficacy of pepper antioxidants, safety aspects, and formulations of novel products with pepper antioxidants have also been covered with future perspectives on potential innovative uses of pepper antioxidants in the future.

Metabolomics provide a novel interpretation of the changes in flavonoids during sea buckthorn (Hippophae rhamnoides L.) drying

Flavonoids are major nutrients in sea buckthorn berries. However, the effects of drying methods on flavonoids in sea buckthorn berries are unclear. In this study, ultra-performance liquid chromatography and metabolomics were adopted to analyse the effects of hot air drying (HAD) and infrared drying (IRD) on flavonoid compounds and antioxidant capacity in sea buckthorn berries. In total, 97 metabolites belonging to 12 classes were identified, including 26 flavones, 23 flavonols, and 11 flavanones. Additionally, 32 differential metabolites were identified among groups. Isorhamnetin and quercetin contents increased in response to HAD and IRD, while (-)-epigallocatechin and (-)-gallocatechin contents decreased. Differential metabolism of flavonoid compounds occurred mainly via the flavonoid biosynthesis and secondary metabolite biosynthesis pathways. Flavonoid compound degradation might be associated with antioxidant activity during drying. This study elucidated the effect of drying on nutritional components of sea buckthorn berries and may guide the improvement of quality during food processing.

Effect of dielectric barrier discharge (DBD) cold plasma-activated water pre-treatment on the drying properties, kinetic parameters, and physicochemical and functional properties of Centella asiatica leaves

Centella asiatica L. (CA) is a medicinal plant that gained significant commercial and research interest because of its bioactive compounds, which have functional properties such as antioxidant activity. However, it must be dried before use to improve its shelf life and prepare it for food and pharmaceutical applications. Therefore, in this investigation CA leaves were pre-treated with blanching and cold plasma activated water (CPAW), followed by recirculatory hot air and vacuum drying at 40, 50, and 60 °C. Vacuum-drying took 150-720 min, while hot-air drying took 60-180 min to dry. Page and Logarithmic models best fit for leaf drying kinetics, according to AIC, with R² between 0.966 and 0.999 and RMSE between 0.001 and 0.069. CPAW pre-treatment increased leaf quality more than blanching in vacuum drying. Drying leaves at 40 °C boosted antioxidants (4021.462 μg TE (g dw)^-1 and 3.356 mg GAEAC (g dw)^-1), TPC (35.049 mg GAE (g dw)^-1), and TFC (311.274 mg QE (g dw)^-1) and is recommended. Vacuum-drying with CPAW pre-treatment preserved leaf microstructure better than hot-air drying. This study illuminates CA leaf drying behaviour and allow mass production without damaging bioactive components. These results could be used as a roadmap for future technological advances that will make it possible to use the bioactive components of CA in food formulation.

Major lipophilic pigments in Atlantic seaweeds as valuable food ingredients: Analysis and assessment of quantification methods

Current trends towards the use of ingredients from natural origin in food, cosmetic and pharmaceutical industry, place macroalgae as a good reservoir of novel compounds. Among them, lipophilic major pigments such as chlorophylls and fucoxanthin, are of great interest because of their multiple applications as bioactive compounds and dyes. In this work, a mid-polarity medium was used to extract pigments from twenty-four species from North coast of Spain, including brown (Phaeophyceae) and red macroalgae (Rhodophyta). The fucoxanthin and chlorophyll a content was assessed by means of two different methods, spectrophotometric and high-performance liquid chromatography coupled to diode array detection (HPLC-DAD). The effect of dried processing on the pigment content of selected species was also evaluated. A linear relationship between the extractability of fucoxanthin and chlorophyll a was observed, being the highest content recorded among members belonging to the order Fucales and Undaria pinnatifida. This work provides good insights about the content on pigments in Spanish North Atlantic macroalgae with future commercial value in different industrial fields, as well as a critical overview of the suitability of the quantification methods and challenges related to their effect in results evaluation.

Response Surface Optimization of Solar Drying Conditions and the Effect on the Quality Attributes and Drying Characteristics of Qula Casein

The objective of this study was to investigate the potential application of a mixed-mode solar dryer to Qula dehydration in the Qinghai-Tibet Plateau of China. A three-factor five-level central composite rotatable design (CCD) of the response surface methodology (RSM) was employed to evaluate the influences of drying process variables on quality attributes in terms of lipid oxidation [peroxide (POV) and thiobarbituric acid reactive substance (TBARS)] and Maillard reaction (5-hydroxymethylfurfural, 5-HMF). The impact of drying temperature (30−50 °C), material thickness (5−15 mm), and wind velocity (0.4−1.4 m/s) on the color, POV, TBARS, and 5-HMF of Qula were studied. Optimum operating conditions were found to be a temperature of 43.0 °C, material thickness of 11.0 mm, and wind velocity of 1.0 m/s based on the minimum of POV, TBARS, and 5-HMF. In this condition, the values of POV, TBARS, and 5-HMF were 0.65 meq/kg, 0.516 mg/kg, and 4.586 mg water/L, respectively, which are significantly lower than for drying of Qula by open sun-drying (p < 0.05). Compared with open sun-drying, the drying time of Qula by solar drying was shortened by 61.5%. The results indicate that the mixed-mode solar dryer is a feasibility drying technology for Qula and could effectively improve the quality of products.

Effect of High-Humidity Hot Air Impingement Steaming on Cistanche deserticola Slices: Drying Characteristics, Weight Loss, Microstructure, Color, and Active Components

Cistanche deserticola is one of the most precious herbal medicines and is widely used in the pharmaceutical and healthy food industries. Steaming is an important step prior to drying in the processing of C. deserticola. This research investigated the effects of high-humidity hot air impingement steaming (HHAIS) parameters such as temperature, time, and relative humidity (RH) on drying characteristics, weight loss, color, microstructure, and active components of C. deserticola slices. The results showed that the steaming process caused a weight loss in C. deserticola; however, increasing the RH reduced the weight loss. Starch gelatinization observed from the microstructure of the steamed samples explained their long drying time. The Page model can well fit the drying process with a high R² (>0.956) under the drying conditions of 60°C and 6 m/s. Steaming increased the content of phenylethanoid glycosides, and the highest content was obtained at 95°C and 60% RH for 20 min, 75°C and 70% RH for 20 min, and 75°C and 60% RH for 30 min. The steamed samples appeared in an oil black color. When the color difference (ΔE) values were in the range of 16.79–20.12, the contents of echinacoside and acteoside reached the maximum. Steaming at 95°C and 60% RH for 20 min, 75°C and 70% RH for 20 min, and 75°C and 60% RH for 30 min are the optimum process conditions. The results from this work provide innovative steaming technology and suitable processing parameters for producing C. deserticola decoction pieces with a high quality, which will broaden its potential application in the functional health food industry.

Green alternative methods for pretreatment of whole jujube before the drying process

BACKGROUND

Jujube contains a waxy cuticle that acts as a barrier against fungal pathogens, prevents nutrition damage and leakage due to mechanical damage, and maintains water content. Chemical treatment before drying is the most commonly used method for whole jujube. Although chemical pretreatment can effectively enhance drying kinetics, it can lead to the loss of soluble nutrients and cause food safety issues due to chemical residues. Therefore, this study aimed to explore the effect of various pretreatments (cold plasma, cold plasma activated water, ultrasonics, thermosonication, and blanching) on the drying process and quality properties of whole jujube so as to find effective green alternatives to chemical pretreatment.

RESULTS

The application of chemical, cold plasma, and thermosonication significantly altered the surface morphology of jujube by etching larger cracks and holes, which can facilitate the transfer of moisture, thereby improving the drying rate and the effective diffusivity. Chemical, cold plasma, and thermosonication pretreatment reduced drying time by 18%, 12%, and 7% respectively, thereby increasing the content of total phenolics by 13%, 12%, and 6% respectively, and enhancing antioxidant capacity (ferric reducing antioxidant power) by 13%, 11%, and 3% respectively. In addition, chemical and cold plasma pretreatment reduced the generation of 5-hydroxymethylfurfural by 25% and 15% respectively.

CONCLUSION

Cold plasma is a promising green alternative method to chemical pretreatment for drying processes of whole jujube. © 2021 Society of Chemical Industry.

Elevated CO2 Enhanced the Antioxidant Activity and Downregulated Cell Wall Metabolism of Wolfberry (Lycium barbarum L.)

Modified atmosphere packaging (MAP) has been widely known to delay the postharvest fruit senescence; nevertheless, its effect on antioxidant activity and cell wall metabolism of wolfberry fruit is largely unknown. The present study investigated the impact of elevated CO₂ on the quality attributes and cell wall degradation of wolfberry fruit during storage. The results showed that 10% CO₂ better maintained the physiological quality and conferred the reduction in weight loss, decay index, and color change. Higher 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 1,1-diphenyl-1-picrylhydrazil (DPPH) radical scavenging activity, total phenol and flavonoid content, and superoxide dismutase (SOD) and catalase (CAT) activity of wolfberry were detected at elevated CO₂ concentrations. Elevated CO₂ atmosphere contributed to the maintenance of the cell integrity, the decrease of cell wall degradation (polygalacturonase, pectate lyase, cellulase, and β-glucosidase), and the increase of cellulose and proto pectin content. Overall, we revealed the potential mechanism of elevated CO₂ on the antioxidant activity enhancement and cell wall homeostasis of fresh berry fruit.

Effect of cold plasma pretreated hot-air drying on the physicochemical characteristics, nutritional values and antioxidant activity of shiitake mushroom

BACKGROUND

Shiitake mushroom is one of the most popular delicious vegetables, although fresh shiitake mushroom has short shelf life as a result of biochemical degradation. Drying can prolong the shelf life of mushroom. Additionally, application of cold plasma pretreatments (CPT) before drying can preserve the product quality, processing costs and nutritional values. Therefore, we aimed to explore the effect of cold plasma pretreated hot-air drying at 50, 60 and 70 °C on the physicochemical characteristics, nutritional values and antioxidant activity of shiitake mushroom.

RESULTS

Scanning electron microscopy micrographs showed that CPT induced the surface modification of fresh shiitake (such as cellular disarrangement, cellular shrinkages, disruption or break down of cell walls, and intracellular spaces and cavities) and facilitate the rapid drying than control samples. Furthermore, CPT improved the powder qualities (bulk density, water retention and swelling index) and preserved higher nutritional attributes (sugars, vitamins, phenolic acids contents and antioxidant activity) compared to the control groups.

CONCLUSION

Conclusively, CPT could be a suitable alternative technique for improving drying characteristics and preserving nutritional attributes of agro-based products. © 2021 Society of Chemical Industry.

Fermentation characteristics of Pixian broad bean paste in closed system of gradient steady-state temperature field

A closed system of gradient steady-state temperature field (GSTF) was constructed to ferment Pixian broad bean paste (PBP). The contents of physicochemical factors and organic acids in the fermentation under GSTF (FG) were closer to those in the traditional fermentation (TF). The taste intensities of 8 free amino acids in the FG were higher than those in the constant temperature fermentation (CTF), but 14 in the TF showed the highest among the processes of FG, CTF and TF. The FG product had the most volatiles with 87, and its flavor properties were more stable. The FG produced great effects on the microbe evolutions especially improved the fungal diversity. Bacillus were identified as the core microbes in the FG while the roles of Staphylococcus, Lactobacillus and Pantoea were strengthened. The results indicated that the fermentation characteristics in the FG had been further improved compared with the CTF.

Optimization and kinetic modeling of ultrasonic-assisted extraction of fucoxanthin from edible brown algae Sargassum fusiforme using green solvents

The development of green and sustainable extraction technologies for various naturally active biomaterials is gaining increasing attention due to their environmentally friendly advantages. In this work, the ultrasonic-assisted extraction of fucoxanthin from edible brown algae Sargassum fusiforme using different green solvents was presented. Ethyl lactate, limonene, soybean oil, and sunflower oil were used in place of traditional organic solvents. Ethyl lactate showed similar performance to organic solvents, whereas limonene and vegetable oil exhibited higher selectivity for fucoxanthin. Moreover, the effects of various extraction factors, including liquid/solid ratio, extraction time, extraction temperature, as well as amplitude were studied. The optimal conditions were optimized as follows: liquid/solid ratio, 40 mL/g; extraction time, 27 min; extraction temperature, 75 ℃; amplitude, 53%; and solvent, ethyl lactate. Optimal model of second-order kinetic parameters (rate constant, equilibrium concentration, and initial extraction rate) was successfully developed for describing the dynamic ultrasonic extraction process under different operating conditions.

Novel postharvest processing strategies for value-added applications of marine algae

Marine algae are regarded as a promising nutrients resource in future as they can be sustainably cultured without land and high investment. These macroalgae are now widely processed into food and beverages, fertilizers and animal feed. Furthermore, bioactive compounds such as polysaccharides and polyphenols in seaweeds have proven to have antibacterial, antiviral and antifungal properties that can be utilized in cosmeceuticals, nutraceuticals and pharmaceuticals. As a key procedure in seaweed production, the postharvest process not only requires more laboured and energy but also affect the quality of the final product significantly. This article reviewed all current postharvest processes and technologies of seaweed and addressed potential postharvest strategies for seaweed production. © 2021 Society of Chemical Industry.

Drying Operation Effects on the Pigments and Phytochemical Properties of Rose Cultivars

BACKGROUND

Roses are flowers which contain various phytochemicals and have been used for food and medicinal purposes in many countries. Materials, including flowers, are available for limited periods when plants can be cultivated.

OBJECTIVE

To evaluate the quality of rose petals on the basis of cultivars and drying methods, chromaticity, phytochemical contents, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity.

METHOD

Petals of three rose cultivars were dried by hot air drying (HD) and freeze drying (FD). Subsequently, the chromaticity and the contents of pigment, total flavonoids, and ascorbic acid, and DPPH radical scavenging activity were analyzed.

RESULTS

The total color difference (△E)values of rose red (RR, Calypso) and rose orange (RO, Lambada) were low in FD. In contrast, in rose yellow (RY, Ileos), there was no significant difference in chromaticity regulation regardless of the drying methods. The pigment contents were generally increased by drying. The carotenoid content in the RR and anthocyanin and carotenoid contents in RO were higher in FD than in HD. The drying operations increased the flavonoid and ascorbic acid content and antioxidant activity in roses, but the difference between the drying methods was not significant. Correlation coefficient analysis revealed ascorbic acid and anthocyanin to have a high positive correlation (r = 0.843), followed by flavonoid and DPPH radical scavenging activity.

CONCLUSIONS

This study showed that the drying operations increased the flavonoid and ascorbic acid contents, and the chromaticity and pigment content of some cultivars was higher in FD.

HIGHLIGHTS

Comparison of the color change, phytochemical content, and antioxidant activity by the drying methods (FD and HD treatment) in the three rose cultivars with red, orange, and yellow petals showed the increased phytochemical contents and antioxidant activity after drying, and chromaticity and pigment content were more stable and higher in FD.

Microwave and Ultrasound Pre-Treatments for Drying of the "Rocha" Pear: Impact on Phytochemical Parameters, Color Changes and Drying Kinetics

The objective of this research was to evaluate the effect of drying temperature and innovative pre-treatments (i.e., microwave and ultrasound) on “Rocha” pear drying behavior and quality characteristics, such as color, total phenolic content and antioxidant activity. Experiments were carried out with pear slabs subjected to microwaves (2450 MHz, 539 W, 4 min, microwave oven) and ultrasounds (35 kHz, 10 min, in an ultrasonic bath) as well as control samples. The drying process was conducted in a tray dryer at three different temperatures (50, 55 and 60 °C) and a fixed air velocity of 0.75 m/s. Microwave technology resulted in a higher quality deterioration in dried pear samples compared to those of controls and ultrasound pre-treated samples. The combined application of ultrasound pre-treatment and the higher drying temperature of 60 °C was characterized by the lowest color changes (ΔE = 3.86 ± 0.23) and higher preservation of nutritional parameters (total phenolic content, TPC = 345.60 ± 8.99; and antioxidant activity, EC₅₀ = 8.80 ± 0.34). The drying characteristics of pear fruits were also analyzed by taking into account empirical models, with the Page model presenting the best prediction of the drying behavior. In conclusion, ultrasound application is a promising technology to obtain healthy/nutritious dried “Rocha” pear snacks as dietary sources for consumers.

The Quality of Red Bell Pepper Subjected to Freeze-Drying Preceded by Traditional and Novel Pretreatment

It has been demonstrated previously in the literature that utilization of PEF or a combination of a pulsed electric field (PEF) and ultrasounds (US) can facilitate dehydration processes and improve the quality of dried products even better than the application of thermal methods such as blanching. The aim of the study was to evaluate the quality of red bell pepper subjected to freeze-drying preceded by blanching or PEF or US treatment applied in a single and combined mode. Furthermore, the freeze-drying was preceded by shock freezing or vacuum freezing performed inside the freeze-dryer as a result of pressure drop during the first stage of freeze-drying. All of the analyzed technological variants enhanced the drying kinetics when compared to the intact material. Freeze-dried bell pepper subjected to non-thermal pretreatment exhibited higher vitamin C, total phenolic and carotenoids content than blanched material despite the fact that blanching reduced drying time the most compared to all other analyzed methods.

Effect of combined Bacillomycin D and chitosan on growth of Rhizopus stolonifer and Botrytis cinerea and cherry tomato preservation

BACKGROUND

Synthetic fungicides are most commonly used for controlling postharvest disease of fruit, although they can cause the emergence of drug-resistant strains, environmental pollution and fruit safety issues. Bacillomycin D (BD), a novel antifungal lipopeptide, and chitosan (CTS) are applied for the preservation of cherry tomato.

RESULTS

The combination of BD and CTS showed an additive inhibition on the growth of Rhizopus stolonifer and Botrytis cinerea compared to that of its individual compound. In addition, BD + CTS reduced the incidence of soft rot and gray mold in cherry tomato caused by R. stolonifer and B. cinerea, respectively. Tomato treated with BD + CTS exhibited a lower weight loss and higher firmness and higher contents of total soluble solids, titratable acidity and ascorbic acid compared to those treated with sterile water (control). The kinetics models demonstrated that the shelf life of cherry tomato treated with BD + CTS could be extended by approximately 15 days longer than the control.

CONCLUSION

The utilization of BD + CTS provided a novel strategy for reducing postharvest fungal rot and maintaining the storage quality of cherry tomato. © 2020 Society of Chemical Industry.

Influence of high hydrostatic pressure pretreatment on properties of vacuum-freeze dried strawberry slices

Effects of high hydrostatic pressure (HHP) (50, 100, 150, 200 and 250 MPa) pretreatment on water mobility and distribution, drying duration, microstructure, color, cell wall fraction and tissue structure of strawberry slices were investigated. HHP significantly increased water mobility of the strawberry slices, resulting in the reduction of drying duration by 9-24%. As the pretreatment pressure was increased, redness value and anthocyanin content continuously increased, soluble pectin (SBP) content increased and then decreased, while the contents of protopectin (PTP) and cellulose decreased. After the HHP pretreatment, chromoplasts and moisture was distributed more uniformly in the strawberry slices. Microscopy images showed the formation of microscopic holes or channels in the matrix and the breakdown of tissue structure by HHP. Results suggested HHP pretreatment disrupted the integrity of the fresh strawberry which enhanced the drying efficiency and migration of the chromoplasts during the vacuum-freeze drying process.

Characterization of the flavor in traditional Pixian Doubanjiang by polyphasic quantitative detection technology

In the present research, four different samples were investigated by multiple analyzing technology to reveal the common unique flavor and taste of traditional Pixian Doubanjiang (PXDBJ). These samples were manufactured by inheritor according to the intangible skills and ripened for two years in different enterprises. Citric acid, malic acid, Glu and Asp were the dominant non-volatiles, the proportion of both organic acids ranged from 54.78% to 65.61%, while that of both free amino acids ranged from 22.49% to 29.39%. Ethyl palmitate, ethyl laurate, γ-cis-himachalane, (+)-valencene and β-ionone were identified as typical volatile constituents by three kinds of GC techniques combined with three pretreatment approaches. These results suggested that these five volatiles and the proportion of four non-volatiles could be used as indicators of flavor and taste to discriminate with other types of traditional fermented soy pastes (miso, dajiang, gochujiang, etc), and were also proofed by sensory evaluation. It laid a vital foundation for revealing the contribution of the traditional skill to unique quality of PXDBJ and the correlation between microbial community diversity and their metabolic regulation.

The Effect of Traditional and Non-Thermal Treatments on the Bioactive Compounds and Sugars Content of Red Bell Pepper

The aim of the study was an investigation of the effect of traditional and non-thermal treatment on the bioactive compounds of red bell pepper. As a thermal process, blanching in water and in steam was studied, while for non-thermal the sonication, pulsed electric field treatment and their combination were used in this experiment. The red bell peppers were evaluated based on quality attributes such as: total carotenoids content; polyphenols; vitamin C; antioxidant activity and sugars content. Vitamin C and sugar content were analyzed using liquid chromatography and other measurements were determined based on the spectrophotometric method. Results showed that the blanching in water or in steam reduced bioactive compounds concentration; whereas non-thermal treatments as pulsed electric field (PEF) applied separately or in combination with ultrasound (US + PEF) let to obtain similar or slightly lower content of bioactive compounds in comparison to untreated peppers. When sonication (US) and combined treatment as PEF + US were applied; in most cases reduction of bioactive compounds concentration occurred. This effect was probably related to the effect of relatively long (30 min) ultrasound treatment. The application of appropriate parameters of non-thermal processing is crucial for the high quality of processed material.

Dry pasteurization of paprika (Capsicum annuum L.) by short time intensive microwave-infrared radiation: Inactivation of Salmonella Typhimurium and Aspergillus flavus considering quality degradation kinetics

The inactivation of S. Typhimurium and A. flavus along with quality degradation kinetics was studied during combined microwave-infrared (MW-IR) heating of paprika. The spatial changes in the distribution of temperature and variation in water activity (a_w) of the paprika samples resulted in a 7.389 log reduction in S. Typhimurium, and 6.182 log reduction in A. flavus. During heating, the deterioration of red pigments was more pronounced compared to that of the yellow pigments. The alteration of color was observed to be due to the increase in a large number of brown pigments. The inhibition of DPPH radicals accelerated with an increase in the power level of MW-IR radiation; the inhibition rate increased from 0.0859 to 0.1485 s^-1. Also, the pungency of dried paprika was found to increase due to moisture reduction, inactivation of peroxidase, and the short-duration of heating.

Effects of vacuum-steam pulsed blanching on drying kinetics, colour, phytochemical contents, antioxidant capacity of carrot and the mechanism of carrot quality changes revealed by texture, microstructure and ultrastructure

An emerging blanching technology, namely vacuum-steam pulsed blanching (VSPB) was employed to blanch the carrots and its effects on blanching efficiency, microstructure and ultrastructure, drying kinetics, colour, texture, phytochemicals (phenolics and β-carotene) and antioxidant capacity of carrot slices were explored and compared with the traditional hot water blanching. Results showed that both blanching treatments enhanced the drying velocity and shortened the drying time by 25.9% compared with untreated samples. VSPB yielded higher blanching efficiency, better colour (more red and yellow), greater antioxidant capacity and higher preservation of phytochemicals compared with hot water blanched samples. Especially, compared to hot water blanched carrots, the p-hydroxybenzoic acid, ferulic acid, and caffeic acid content of VSPB samples increased of 106.6%, 42.0%, and 19.0%, respectively. Interestingly, the chlorogenic acid content in the blanched carrot increased more than 220 times compared to fresh samples. Ultrastructure and microstructure observation clarify the mechanism of quality enhancement of VSPB.

Changes in volatile compounds, sugars and organic acids of different spices of peppers (Capsicum annuum L.) during storage

Changes in sugars, organic acids and volatile compounds (VC) of red pepper flakes (RPF), traditional (TRI), and industrial (INI) isot peppers were evaluated during one year storage at the room condition. The changes in the flavor components were significantly affected by the production methods and storage time. Glucose content decreased gradually along storage and reduced by about 21.23, 47.22 and 56.65% for TRI, INI and RPF, respectively. However, fructose decreased significantly only in RPF (11.29%). Citric and succinic acids exhibited slight changes, but malic acid showed an increasing trend, especially in RPF (4-fold). Most of the VC in all samples decreased or disappeared after storage. The major quantitative losses in these compounds were found in TRI during the first 3 months as 81.76%. The storage was found to be caused deterioration flavor properties in red pepper spices and revealed the importance of appropriate storage conditions.

Impact of elevated O2 and CO2 atmospheres on chemical attributes and quality of strawberry (Fragaria × ananassa Duch.) during storage

Modified atmosphere has widely been evident to contribute to fruit quality maintenance, however the correlation among these quality traits was less known. To explore main factors of elevated atmosphere and reduce the detection indexes, we exposed strawberry to either high O₂ (80% O₂ + 20% N₂) or CO₂ (20% CO₂ + 20% O₂ + 60% N₂) atmosphere and compared quality characteristics. It was demonstrated that both atmospheres well maintained the fruit firmness, alleviated weight loss and decay rate. Elevated O₂ maintained the polyphenolic contents and cell integrity by significantly decreasing superoxide and hydrogen peroxide levels. PCA analysis implied that HO treatment mainly affected oxygen metabolism while HCO affected carbon metabolism more. Significantly positive correlation was observed between weight loss, anthocyanin content and decay rate in elevated O₂ and control groups. This study provided new insights into correlation and difference between impact of elevated O₂ and CO₂ to postharvest preservation.

Effects of processing techniques on drying characteristics, physicochemical properties and functional compounds of green and red chilli (Capsicum annum L.) powder

This study was aimed to investigate the effect of processing techniques on the characteristics of green and red chilli powder. Four samples, such as pretreated green chilli paste (PTGP), pretreated green chilli longitudinal slit (PTGL), pretreated whole red chilli (PTWR) and untreated green chilli paste (UTGP), were prepared and dried at 60 °C in a cabinet dryer. The pretreatment was blanching in acetic acid solution and soaking immediately in a combined solution of Na₂S₂O₅ and CaCl₂. Pretreated samples took a shorter drying time than the untreated sample in reducing moisture content from 86.31 to 8%. Pretreatment before drying resulted in retaining total chlorophyll (~ 86%), phenolic compounds (~ 32%), green color, and pungency of chilli. Analysis result indicated that more than 60% retention of β-carotene was found while retention of ascorbic acid was comparable. Conclusively, this research reveals a good nutritional profile in cabinet dried green chilli powder, which may open the scope for commercial production.

Modern pretreatment techniques for phytochemical extraction

Purpose

Modern thermal and non-thermal pretreatment techniques, namely, enzymatic treatment, gas phase plasma treatment and ohmic heating have become more pronounced over conventional techniques for enhanced coloured phytochemicals (pigments) extraction. Presently, numbers of pretreatment techniques are available with some unique feature. It is difficult to choose best pretreatment method to be employed for phytochemicals extraction from different sources. Therefore, this paper aims to discuss different modern pretreatment techniques for extraction with their potential results over conventional techniques.

Design/methodology/approach

Research and review articles targeting to the thermal and non-thermal pretreatment techniques were collected from Google Scholar. The required information has been tabulated and discussed which included qualities of modern pretreatment techniques over conventional techniques, phytochemical extraction and best pretreatment methods for optimized results.

Findings

Every pre-treatment has its own advantages and disadvantages for a particular phytochemical and its extraction from various sources. Enzymes can be used in combinations to enhance final yield like extraction of carotenoids (pectinase, cellulase and hemicellulase) from chillies and lycopene (pectinase and cellulase) from tomato. Utilization of each method depends upon many factors such as source of pigment, cost and energy consumption. CO2 pretreatment gives good results for carotenoid extraction from algae sources. Ohmic heating can yield high anthocyanin content. Modifications in conventional blanching has reduced final waste and improvised the properties of pigment.

Originality/value

This study comprises collective information regarding modern pre-treatment for extraction over conventional pre-treatments. The study also covers future trends and certain new hybrid approaches which are still less flourished.