Browning Rate Research Articles

Metabolomic analysis of the browning and browning inhibition pulp of Fuji apple at different ripening stages

Apples at different ripening stages display distinct processing properties and browning characteristics in products. This study aimed to identify differential metabolites and metabolic pathways of browning pulp and browning inhibition pulp of Fuji apple across four ripening stages (M1–M4), corresponding to days after full bloom (DAFB: 148, 155, 162, and 171). We investigated the physicochemical characteristics, browning-related enzyme activities, and metabolomic profiles of apples at the four stages, revealing defensive metabolic changes associated with browning throughout ripening. Specifically, the browning rate in apples increased with ripening, peaking before declining in the late stages, and exhibited positive correlations with activities of polyphenol oxidase (PPO), peroxidase (POD), and catalase (CAT), and negative correlations with superoxide dismutase (SOD), phenylalanine ammonia-lyase (PAL), and H2O2 levels. Metabolomic profiling identified 315, 393, and 243 distinct metabolites in fresh control (FC), browning pulp (BR), and browning-inhibited pulps (CM) of apple at the four ripening stages, respectively. KEGG enrichment analysis revealed that FC and BR of the four ripening apples were differentiated by phenylpropanoid biosynthesis, while CM was featured by flavonoid biosynthesis. The characterized differential metabolites in BR were changed to α-linolenic acid metabolism with ripening, while those in CM were from flavonoid and phenylpropanoid biosynthesis. Furthermore, the in-depth analysis revealed 40 significantly differential metabolites associated with amino acid, nucleotide, coenzyme, and vitamin metabolism, potentially modulating the stress-responsive cellular redox balance. This research provides critical insights for browning prevention in the processing of fruits at various ripening stages.

Effects of 60Coγ-irradiation combined with sodium dehydrogenate on post-harvest preservation and physiological indices of Volvariella volvacea.

Volvariella volvacea is a mushroom known for its high palatability and nutritional value. However, it is susceptible to spoilage thus making it challenging to preserve and keep fresh after harvest, resulting in constraints in long-distance transportation and long-term storage. This study aimed to investigate the feasibility of using irradiation and sodium dehydrogenate (SD) as a preservative in the preservation process of V. volvacea. The effects of three treatments of 0.8 kGy 60Coγ irradiation (B), 0.04% SD (C), combined with 0.04% SD and 0.8 kGy 60Coγ irradiation (A) on the postharvest freshness of V. volvacea were investigated. The assessment indices for V. volvacea, including appearance, browning rate, weight loss, respiration rate, MDA content, antioxidant enzyme activities, vitamin C (Vc), and soluble protein content, were measured and compared. The three treatments were compared to determine the changes in storage time over 7 days post-harvest. The results demonstrated that the hardness of the fruiting body exhibited a significant increase of 81.19%, 97.96% and 168.81% in comparison to the control, B and C, respectively, following the application of the treatment A. Compared to the control group, the soluble protein content was significantly increased by 20.28%. Respiration intensity and browning rate were significantly lower in the control treatment, decreasing by 35.07% and 45.49% respectively. On the 6th day of storage, the activities of SOD and POD increased by 81.06% and 73.71%, respectively, compared to the control, which significantly delayed the senescence of the fruiting bodies. The Vc content was significantly increased by 50.27%, 133.90%, and 101.39% in treatment B, which received 0.8 kGy 60Coγ irradiation alone, compared to the control, treatment A, and treatment C, respectively. The treatment C alone significantly reduced respiratory intensity and MDA variables by 39.55% and 31.01%, respectively, compared to the control. The findings can provide theoretical references and technical support for extending the preservation period of V. volvacea after harvesting by using irradiation and sodium dehydrogenate as a preservative.

Novel Pink Pigments Produced by Thermal Interaction of Theaflavins, Theanine, and Glucose: Color Formation, Isolation, and Structural Characterization.

A color-deepening effect of theaflavins on the theanine-glucose thermal reaction model was revealed. Generated chromogenic intermediates in the initial stage and an accelerated browning rate through the promoted degradation of theanine-glucose Amadori rearrangement product in the intermediate and final stages are responsible for the color-deepening effect. Four pink-to-red theaflavin-theanine intermediates were verified as theaflavinies referencing the nuclear magnetic resonance and liquid chromatography-mass spectrometry information on theaflavins and l-theanine, including one accurately identified as theaflavinie 4. Theaflavinie 4 showed two maximum absorption peaks at 401 and 506 nm with parallel intensities, which resulted in a significant dichromic color change from pale pink to orange and red. Theaflavinies also could undergo further thermal reactions to yield brown polymers under higher temperatures (130 and 140 °C). This research provided new insight into realizing thermally formed polymers during black tea processing, which may be formed by oxidation products and amino acids or proteins through non-enzymatic thermal reactions.

Analyzing cold hardiness (Based on DTA) of one-year-old branches of peaches.

In this study, we conducted a low-temperature exothermic (LTE) investigation on 1-year-old (1a) branches of sixteen peach cultivars through a differential thermal analysis (DTA) procedure. We used a three-point approach to determine the lethal injury temperature (LT-I) of the xylem, the LTE correlation indexes, and the subordinate function value method were applied to compare cold hardiness of sixteen peach varieties. The results showed that the slope of the LT-I for the xylem of sixteen peach cultivars was different, and the LTE indexes were significantly different. Among all the studied varieties, the cold hardiness was strongest in Donghe No.1, followed by Wangjiazhuangmaotao No.2 and Hunchun. Qiuyan and Yanhong are second, and belong to the cold-resistant type; Qiuyi, Okubo, Zhongnongjinhui, and Chunmei, exhibited medium cold hardiness. Zhongtaohongyu, Spring snow, Yufei, and Zhongyou No.8 varieties exhibited low hardiness; while the 21st century, Golden Honey No. 1 and Zhonghuashoutao have the worst cold hardiness and are the weakest cold-hardiness types. In addition, the injury degrees of xylem from LT-I analysis were significantly related to the browning rates (BR) and electrolytic leakage (EI) from traditional low temperature freezing analysis. It is demonstrated that the LTE analysis is a simple, accurate, and practical method for identifying the cold hardiness of 1a branches of peach.

Metabolomics and histopathological analysis of two tomato cultivars after co-infection with soil-borne pathogens (Southern root-knot nematode and Fusarium wilt fungus)

Southern root-knot nematode (Meloidogyne incognita) and Fusarium wilt fungus (Fusarium oxysporum) are one of the most predominant pathogens responsible for substantial agricultural yield reduction of tomato. The current study planned to assess the effects of M. incognita (Mi) and F. oxysporum (Fo) and their co-infection on two tomato cultivars, Zhongza 09 (ZZ09) and Gailing Maofen 802 (GLM802). The present study examined the effects of co-infection on leaf morphology, chlorophyll content, leaf area, and histopathology. The present study used metabolomics to evaluate plant-pathogen interactions. The outcomes of the current study revealed that chlorophyll content and leaf area decreased more in GLM802 during co-infection. In co-infection (Fo + Mi), the chlorophyll content reduction in ZZ09 was 11%, while in GLM802 the reduction reached up to 31% as compared to control. Moreover, the reduction in leaf are in ZZ09 was 31%, however, in the GLM802 reduction was observed 54% as compared to control plants. Similarly, GLM802 stems exhibited larger brown patches on their vascular bundles than ZZ09 stems. The rate of browning of GLM802 stems was 247% more than ZZ09, during co-infection. Moreover, GLM802 roots exhibited a higher abundance of hyphae and larger galls than ZZ09 roots. In metabolic studies, glutathione, succinic acid, and 2-isopropylmalic acid decreased, whereas spermine and fumaric acid increased in GLM802 co-infected stems. It indicates that GLM802 is weakly resistant; therefore, F. oxysporum and other pathogens readily damage tissue. In the co-infected stem of ZZ09, L-asparagine and shikimic acid increased, but pipecolic acid, L-saccharine, and 2-isopropylmalic acid declined. L-asparagine was crucial in preserving the stability of nitrogen metabolism, chlorophyll synthesis, and leaf growth in ZZ09. Shikimic acid's substantial accumulation could explain the limited extent of browning observed in the vascular bundles of ZZ09. Thus, the present study provides insight into M. incognita and F. oxysporum co-infection in two tomato cultivars, which may aid breeding efforts to generate commercially viable resistant cultivars. However, further research on the relationship between M. incognita and F. oxysporum in different host plants is required in the future.

Seaweed-based biostimulants improves quality traits, postharvest disorders, and antioxidant properties of sweet cherry fruit and in response to gibberellic acid treatment

The main aim of this research was to determine whether seaweed-based biostimulants (BIO) have the potential to offset the delaying of fruit maturation and improve fruit quality and antioxidant properties in gibberellic acid (GA3)-treated cherries. Compared to the control, 5 g L−1 BIO applied twice at pit hardening (PH) and straw color (SC) or 3 times at PH, SC, and 1 week before harvest (1WBH) in mid-maturing ‘Bing’ cherries accelerated color development, increased soluble solids content (SSC), titratable acidity, total phenolics (TP), and DPPH radical scavenging activity at harvest. However, these treatments resulted in smaller and softer fruit. For late-maturing ‘Lapins’ cherries, BIO had no effect on fruit coloration, but increased the levels of antioxidants and antioxidant capacity at harvest, especially in 3 applications. Spraying 5 g L−1 BIO 3 times plus a single application of 10 mg L−1 GA3 at PH on ‘Bing’ cherries effectively increased fruit firmness (FF) and size, but showed a strong delaying effect on color development and SSC at harvest, and reduced resistance to disorders after 4 weeks of storage at 0°C if the combination-treated fruit were late harvested. Decreasing GA3 concentration from 10 to 5 mg L−1, increasing BIO concentration from 5 to 10 g L−1, and extending the harvest date by 5 d could impair the delaying effect of GA3 on fruit maturation, restore the normal fruit size, reduce the rates of decay, stem browning (SB), and surface pitting (SP), and maintain high FF and DPPH radical scavenging activity. In conclusion, pre-harvest 3 applications of 10 g L−1 BIO and 5 mg L−1 GA3 once at PH have the potential to curtail the GA3’s inhibition on fruit maturation, extend the harvest window, improve fruit quality, and increase antioxidants and antioxidant capacity in ‘Bing’ cherries.

Litchi postharvest physiology and handling

AbstractLitchi (Litchi chinensis Sonn.) fruit, with its bright red color and sweet and juicy aril, is an important fruit crop in Asia, Africa, Australia, and South America. A major cause of the postharvest loss of litchi fruit is browning and decay. Chlorophyll breakdown and flavonoid synthesis occur simultaneously during the maturation of this nonclimacteric fruit. However, once litchi fruit is harvested, pericarp desiccation and membrane breakdown occur, which leads to browning with the rate of browning and later microcracking paralleling water loss rate. In addition, chilling injury can contribute to and increase pericarp browning and membrane leakage. Polyphenol oxidase and peroxidase are possibly key enzymes in the early stages of browning. An increase in the leakage of the pericarp membrane also occurs that correlates with browning. Many chemical treatments have been evaluated to retard pericarp browning, such as melatonin, hot water, acidified calcium sulfate (ACS), adenosine triphosphate, and tea seed oil. During long distance transportation, chemical treatments that involve sulfur are used, including SO2 fumigation, acid dip after SO2 fumigation, SO2 fumigation and sulfur sheet package, or SO2 fumigation followed by controlled atmosphere (CA), if approved by the importing country. Other treatments that avoid the use of SO2 include melatonin, ACS, and hot water brushing combined with an acid dip, CA, and modified atmosphere packaging. Anthracnose is a common disease that accelerates browning and decay. Penicillium species as a saprophyte is also common with fruit infection occurring in the field, during harvest, in the packhouse, cold rooms, and shipping containers. Sulfur sheet or CA is used to reduce fruit rot after SO2 fumigation and Sportak (prochloraz) for the control of penicillium. However, a replacement for postharvest SO2 use is still urgently needed.

Changes in physicochemical characteristics of wheat flour and quality of fresh wet noodles induced by microwave treatment

Fresh wet noodles (FWN) are popular staple foods due to its unique chewy texture and favorable taste. However, the development of FWN is limited by its short shelf life and high browning rate. It has been found that the quantity of original microorganisms in wheat flour produced by traditional method is relatively high, which is detrimental to the processing quality and storage stability of FWN. Consequently, it becomes imperative to decrease microorganisms in wheat flour. Microwave treatment has been regarded as a promising method in the food industry due to its potential in inhibiting microbial growth and inactivating enzymes without causing adverse effect on the food quality. This study aims to investigate the effects of microwave treatment of wheat kernels under different powers (1, 2, 3, 4, 5 kW) on the physicochemical properties of wheat flour and the quality of FWN. The results revealed that microwave treatment had a significant effect on microbial inhibition and enzyme inactivation, wherein the total plate count (TPC) and yeast and mold counts (YMC) decreased by 0.87 lg(CFU/g) and 1.13 lg(CFU/g) respectively, and PPO activity decreased from 11.40 U to 6.31 U. The dough quality properties, such as stability, extensibility, and starch viscosity, improved significantly under different microwave conditions. Confocal laser scanning microscopy (CLSM) images indicated that starch and proteins aggregated gradually in treated flour, altering rheological properties of dough. From the results of scanning electron microscopy (SEM), microwave treatment led to the appearance of disrupted structure in the gluten proteins, but the secondary structure of proteins altered slightly. Rheological properties of dough confirmed that the microwave treatment greatly affected processing characteristics of wheat flour products, with significant advantageous consequences on product quality, especially for textural properties of FWN. Furthermore, FWN darkening could be inhibited noticeably after microwave treatment, thereby prolonging its shelf life. Therefore, microwave treatment could thus be an effective, practical technology to produce low-bacterial flour and thereby enhance its product quality.

Ready, steady, chop! Investigating the impact of chop size on zoo food nutritional quality

It is common for animal keepers to chop food up for their animals into small pieces, yet there is limited information as to why this practice is done. Anecdotally, many collections also prepare their zoo animal diets the day before feeding, and store them in the fridge overnight. The potential impact of these food preparation and storage methods on food nutritional quality is unknown. To address this, this study investigated the impact of preparing six types of produce into four sizes (0.5, 2, and 4 cm3 cubes, or whole) on the desiccation, browning and pH scores. Samples were stored either under ambient, room temperatures, or stored in a fridge and analysis was conducted over a 24-hour period. The most severe desiccation levels occurred in finely chopped feeds, for both ambient and fridge-stored samples. Time significantly affected the rate of desiccation and browning, and food chop size was a significant predictor of both browning and pH. These results suggest that serious nutritional changes occur in chopped feeds, especially when they are finely chopped and especially when food is stored for more than a couple of hours prior to feeding. Practitioners who care for animals should consider whether their animals benefit from finely chopped feeds, and should avoid the practice of storing chopped food overnight.

Seasonal variation in contamination and browning of Acacia nilotica nodal explants in vitro

Major problems encountered in establishing axenic cultures are contamination and browning of explants and media. Contamination is initiated in explants excised from soil-borne tissues or adult trees. Several sterilizing agents (Tween 20, chlorine water, silver nitrate, mercuric chloride, etc.) or a wash in antibiotic solution are recommended to reduce this. . Establishing in vitro cultures of Acacia nilotica old tree nodal explants was a serious problem. The present study was undertaken to create a suitable protocol for in vitro micropropagation of nodal explants of Acacia nilotica subsp. indica. Contamination was controlled by sterilizing the explants by washing in polysan (5%, v/v along with 500mg/l PVP), thorough washing under tap water, 70% alcohol treatment and 0.1% HgCl2 treatment. Plant tissues release phenolic substances through their cut ends, which turn the media dark brown and toxic. Addition of various antioxidants or/and transfer of explants to fresh medium twice or thrice, at a few days’ intervals may overcome the problem. Collection of explants in antioxidant solution and a wash in antioxidant solution prior to inoculation was helpful in reducing the phenolic exudation in the present investigations. The addition of antioxidant (citric acid) to the medium also checked browning to some extent. The rate of infection and browning of explants varied in different seasons, the maximum being during winters and the minimum during summers of 2019. This was inversely related to the morphogenic response of explants i.e. maximum caulogenesis occurred in vitro during July (6.3±1.4 shoots per explant). The in vitro raised shoots showed 100% rooting on 2mg/l IBA augmented Nitsch’s (N) medium.

Browning prevention of oil palm somatic embryos in the temporary immersion system with antioxidant mixture and modification of basal media

Browning on in vitro culture is one of the problems in somatic embryo regeneration that leads to growth inhibition and death of explants. This study aimed to prevent and control browning of oil palm somatic embryos (SE) in the Temporary Immersion System (TIS). The research was conducted in two stages; the first stage was applying an antioxidant mixture at concentrations of 20, 50, and 100 mg L-1 on the browning palm oil SE in TIS. The second stage was carried out by modification of the basal media, namely DF (control), MS, SM, and SMT. The explants used in experiment 2 were browning and fresh SE. The results showed that using 50 ppm antioxidants mixture increased the formation of new SE by up to 15 embryos per flask. Applying SMT basal media on browning SE could decrease browning rate sharply after two cycle cultures by up to 60% browning rate reduction. In this media, it was also seen that the number of new SE increased by up to 250 embryos and produced 15 germinants, while in control, only 60 SE and five germinants were formed. Whereas using SMT basal medium on fresh embryos could prevent browning and increase the formation of new embryos and germinants. In conclusion, using 50 ppm antioxidants can stimulate the formation of new embryos. Using SMT basal media could prevent browning and overcome the occurrence of browning in embryos by increasing the formation of new embryos and germinants.

Screening and evaluation of the biocontrol efficacy of a Trichoderma brevicompactum strain and its metabolite trichodermin against banana Fusarium wilt

The banana Fusarium wilt (BFW) caused by Fusarium oxysporum f. sp. cubense tropical race4 (FocTR4) is difficult to control worldwide, which causes a huge economic losse to banana industry. The purpose of this study was to screen Trichoderma strains with antagonistic activity against FocTR4, to isolate and purify the active compound from the fermentation broth, so as to provide important biocontrol strains and active compound resources. In this work, Trichoderma strains were isolated and screened from the rhizosphere soil of crops, and the strains capable of efficiently inhibiting FocTR4 were screened by plate confrontation, and further confirmed by testing inhibition for the conidial germination and mycelial growth of FocTR4. The phylogenetic tree clarified the taxonomic status of the biocontrol strains. Moreover, the active components in the fermentation broth of the strains were separated and purified by column chromatography, the structure of the most active component was analyzed by nuclear magnetic resonance spectroscopy (NMR), the BFW control effect was tested by pot experiments. We obtained a strain JSHA-CD-1003 with antagonistic activity against FocTR4, and the inhibition rate from plate confrontation was 60.6%. The fermentation broth of JSHA-CD-1003 completely inhibited the germination of FocTR4 conidia within 24 hours. The inhibition rate of FocTR4 hyphae growth was 52.6% within 7 d. A phylogenetic tree was constructed based on the ITS and tef1-α gene tandem sequences, and JSHA-CD-1003 was identified as Trichoderma brevicompactum. Purification and NMR identification showed that the single active compound was trichodermin, and the minimum inhibitory concentration (MIC) was 25 μg/mL. Pot experiments showed that the fermentation broth of strain JSHA-CD-1003 was effective against BFW. The control rate of leaf yellowing was 47.4%, and the rate of bulb browning was 52.0%. Therefore, JSHA-CD-1003 effectively inhibited FocTR4 conidial germination and mycelium growth through producing trichodermin, and showed biocontrol effect on banana wilt caused by FocTR4, thus is a potential biocontrol strain.

Effects of dicamba and casein hydrolysate on in vitro growthand shoot regeneration of date palm (Phoenix dactylifera L.) cv. Barhee

Abstract The investigation was carried out to evaluate the influence of the dicamba (3,6-Dichloro-2-methoxybenzoic acid) (DIC) and casein hydrolysate (CH) on the callus growth, shoot multiplication, and some biochemical constituents of date palm cv. Barhee cultured in vitro. Both DIC and CH were required for callus growth and shoots regeneration. The medium supplemented with 4.0 mg l−1 DIC in combination with 1.0 g l−1 CH gave the highest callus weight (287 mg), while the maximum response rate and the number of shoots per jar (86.67% and 15.07 shoots/jar) were found in MS media equipped with 4 mg l−1 DIC and 0.5 mg l−1 CH combination. The total amount of phenolic compounds was significantly reduced to 0.82 and 0.79 mg GAE g–1 in shoots cultured in the medium equipped with 4.0 mg l−1 DIC with 0.5 and 1.0 g l−1 CH, which is reflected in the rate of browning. The results showed that the highest shoots content of endogenous IAA (3.71 and 3.50 μg g−1), were obtained in response to 4 mg l−1 DIC + 1.0 g l−1 CH and 4.0 mg l−1 DIC + 0.5 g l−1 CH, respectively. The macronutrient K, P, Ca, and free amino acids content significantly increased in the in vitro shoots regenerated on the media supplemented with 4.0 mg l−1 DIC + 1.0 g l−1 CH. The genetic stability of this study was confirmed by the DNA-based fingerprinting method RAPD. The RAPD binding patterns indicated no variation among tissue culture-derived plants. The in vitro propagation protocol described herein can be introduced to the production of genetically stable date palm plants.

Synthesis of Cassava Starch Biofilm with the Addition of Extract of Couroupita guianensis fruit by Casting Method

Brazil is now the world's fourth-largest banana producer in the world with an annual production of 6.953,747 tons per year. In Brazil, the banana (Musa spp.) stands out, not only because it is the most widespread, but also because it is the most consumed by all social classes. Cassava is a renewable, almost unlimited resource and one of the most abundant substances in nature. It is one of the most important starchy root crops of the tropics used for food and industrial purposes. The present study evaluated the use of biofilms based on cassava starch in maintaining the quality and shelf life of the 'Prata' banana at room temperature. The filmogenic solution was created using the casting technique, with adaptations. Additionally, 2.6% cassava starch (m/v) + 2 g of gelatin + 100 mL of the aqueous extract were used. Additionally, the biofilm was applied in the film-forming solution for 1 minute and suspended for further drying at room temperature. After this process, were evaluated the loss of fresh mass, and total soluble solids. The present study revealed the efficiency of biofilm coating with and without gelatin to reduce the rate of enzymatic browning and increase the shelf life of bananas. It was possible to verify a smaller reduction in fresh weight loss in the treatments. Besides, no significant difference was observed in the addition of gelatin to the parameters evaluated in the fruit.

Alternating dominant effects of temperature and precipitation along elevational gradient on the alpine and subalpine vegetation activities in southwestern China

Elevation plays a pivotal role in modulating hydroclimatic dynamics, changing vegetation activity and shaping vegetation distribution patterns in alpine regions. Nevertheless, a conspicuous knowledge gap persists regarding the interaction between climate drivers on vegetation activity. In this study, we investigated the spatio-temporal patterns of the Normalized Difference Vegetation Index (NDVI), a proxy for vegetation activity, and examined its interactions with temperature (T) and precipitation (P) along elevational gradient (EG) in the Alpine and Sub-alpine Woodlands of Southwest China (ASWSC) during 2001–2018. We found that approximately 24% vegetation in ASWSC exhibited significant greening trend, as a result of regional warming and slight wetting during the study period. The greening and browning rates were both elevational asymmetric, with higher rates at lower elevations. We also illustrated an alternating domination of T - P on vegetation activity along EG. This suggested a roughly antagonistic effect between the two drivers within the whole vegetation elevation range except for a synergistic effect in the sub-alpine forests zone between 2300 - 4200 m. The antagonistic effect tended to be more pronounced in warm and dry years, while the synergistic effect was more evident in cold and wet years. Specifically for different vegetation types, we found an insignificant T - P interactive effect along EG in indigenous evergreen needleleaf forest (ENF) and evergreen broadleaf forest (EBF), in contrast to the significant synergistic effect in the regenerated deciduous broadleaf forest (DBF) and mixed forest (MF) and antagonistic effect in shrubland and grassland types. In summary, our study revealed alternating-dominant effects of temperature and precipitation on vegetation activity along EG. These findings will deepen our understanding of vegetation resistance and resilience to climate change and eventually contribute to establishing a scientific foundation for effective ecosystem management and conservation practices in alpine region.

Utilization of perforated zipper‐lock packaging bags to improve the quality of stem‐on and stem‐free ‘Chelan’ and ‘Lapins’ sweet cherries during the storage and marketing periods

AbstractIn the current domestic market, improper packaging systems cause a significant amount of food loss and waste of sweet cherry fruit from the packinghouse to the table. The purpose of this study was to assess whether reducing the commercial zipper‐lock bags' perforation ratio (PR) from 2% to 0.5% or 0.05% had the potential to improve the quality and resistance to postharvest disorders of stem‐on (SO) and stem‐free (SF) ‘Chelan’ and ‘Lapins’ cherries during a series of 14 days at 0°C, 2 days at 10°C and 2 days at 20°C (the storage and marketing periods). Regardless of whether the stem was attached to the fruit, reducing PR from 2% to 0.5% or 0.05% resulted in a high relative humidity, an increased CO2 with a decreased O2 in bags and reduced weight loss of fruit and stems in both cultivars during the entire storage and marketing periods; furthermore, higher fruit firmness, skin brightness and stem green color with lower rates of surface pitting and stem browning and relative leakage of stems were observed in either SO or SF of ‘Chelan’ and ‘Lapins’ cherries packaged with 0.5% and 0.05% PR bags compared to 100 (air) and 2% PR‐treated cherries. However, the 0.05% PR packaging system retained a significant amount of condensation water in the bag; as a result, the decay incidence of SF cherries statistically increased. Overall, packing SO and SF ‘Chelan’ and ‘Lapins’ cherries in bags with a 0.5% PR provided great benefits in delaying weight loss and pathogen infection and maintaining the high eating and storage quality during the storage and marketing periods.

Maillard Reaction Process and Characteristic Volatile Compounds Formed During Secondary Thermal Degradation Monitored via the Change of Fluorescent Compounds in the Reaction of Xylose-Corn Protein Hydrolysate.

Until now, no effective method has been found to monitor the Maillard reaction process for complex protein hydrolysates. Dynamic changes in the concentration of α-dicarbonyl compounds, fluorescence intensity, and browning degree were investigated during the Maillard reaction of corn protein hydrolysates. When the fluorescence intensity reached the peak, deoxyosones would continue to be increased by ARP's degradation. However, the reaction node with the highest fluorescence intensity coincided with the turning point of the browning reaction, and the subsequent browning rate remarkably increased. Therefore, the change in fluorescence intensity could be used to monitor the degradation of ARP and the formation of browning melanoidin at different stages of the Maillard reaction of complex systems, thus effectively indicating the process of the Maillard reaction. When Maillard reaction intermediates (MRIs) with maximum fluorescent compounds were heated, the most abundant pyrazines were subsequently achieved. However, furan compounds would be progressively increased during the thermal process of MRIs with continuously enhanced browning.

Browning Behavior of Calcium Maltobionate-water System.

The purpose of the present study was to clarify the browning behavior of calcium maltobionate (CaMb). CaMb samples with varying water content (0-50 %) and water activity (0-0.98) were prepared. Absorbance due to the browning of CaMb-water samples increased linearly with an increase in holding time, and the browning rate was evaluated as a pseudo-zero-order reaction at each temperature (353-413 K). The effect of temperature on the browning rate of CaMb samples was analyzed using the Arrhenius formula, and the pre-exponential factor and activation energy were determined. In addition, the browning rate at 298 K (typical ambient condition) was determined according to the Arrhenius behavior. The browning rate at 298 K slightly decreased, markedly increased, and then decreased with an increase in water content and water activity. This behavior can be explained by the monolayer effect, plasticizing effect, and dilution effect of water molecules. There was a linear relationship between the natural logarithm of the pre-exponential factor and activation energy according to the thermodynamic compensation rule. The effect of water content on the activation energy was fitted using the cubic function. From these results, an approach for prediction of the browning of CaMB during thermal condensation was established.

Impact of Pretreatment and Drying Factors on Chemical and Biochemical Attributes of Moroccan Thompson Seedless Grapes.

Drying is a common technique in the agrifood industry, but insufficient control in the drying process can result in changes to the fruit's appearance due to physiological damage during processing. The aim of this study was to investigate the impact of pretreatment and drying process parameters on Moroccan raisins' quality and safety. The experimental levels of pretreatment factors (blanching, browning agents) and drying temperature were defined at the beginning. Subsequently, a 24-factorial design was employed to provide a simple and reliable model capable of relating directly the response factor (drying time, color intensity change (E∗), chromaticity (C∗), and browning rate) to the variables (NaOH concentration, antibrowning agent concentration, temperature, and relative humidity). All four parameters had a statistically considerable effect on studied responses. Blanching for 5 minutes at 1% of NaOH solution, using an appropriate concentration of antibrowning agent (5% Na2S2O5), and drying at 70°C with 30% of relative moisture can lead to better preservation of grapes' appearance and quality (chromaticity (C∗) and color change (E∗)). Also, in these conditions, a lower browning rate (14.48%), a lower 5-hydroxymethylfurfural content (12.40 mg/100 g DW), and a higher level of polyphenols (135.79 ± 13.17 mg GAE/100 g DW) and flavonoid content (57.81 ± 3.08 mg Qeq/100 g DW) have been recorded while meeting international standards for SO2 content and microbial quality.

Intrinsic Molecular Mechanisms of Transformation between Isomeric Intermediates Formed at Different Stages of Cysteine-Xylose Maillard Reaction Model through Dehydration.

2-Threityl-thiazolidine-4-carboxylic acid (TTCA) and Amadori rearrangement product (ARP), the isomeric intermediates derived from the cysteine-xylose (Cys-Xyl) Maillard reaction model, possessed the ability to produce similar flavor profile during the thermal process, but the flavor formation or browning rate of heated TTCA was significantly lower than that of ARP. Macroscopically, the yield of TTCA reached the maximum when the moisture content of the reaction system just dropped to nearly 0% during the thermal reaction-vacuum dehydration process. During the subsequent dynamic intramolecular dehydration process, the reaction remained at an early stage of the Maillard reaction, and TTCA was the main intermediate. Thereinto, the water activity of the samples decreased with the increased dehydration time. From a molecular perspective, the dissipation of free water promoted the conversion of combined water to immobilized water and free water, increasing the intramolecular dehydration. Instantaneous high-temperature dehydration during the spray drying process revealed a higher efficiency than the thermal reaction-vacuum dehydration process, which facilitated the specific conversion of substrates to intermediates (TTCA, ARP). The loss of free water and immobilized water was a key driving force for the direct formation of TTCA/ARP, regulating the formation stages of MRIs. The increase of the inlet air temperature could alter the ratio of TTCA and ARP at the equilibrium state.