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Abstract

This review examines the parameters of enzymatic browning in apple and apple products that is, phenolic compounds, polyphenoloxidases, and other factors (ascorbic acid and peroxidases), both qualitatively and quantitatively. Then the relationships between intensity of browning and the browning parameters are discussed, including a paragraph on the methods used for browning evaluation. Finally, the different methods for the control of browning are presented.
... The reaction mechanism of enzymatic browning is shown in Figure 3. The extensive difference in the hue and intensity of color pigments relies on the source of polyphenols and environmental causes of the oxidation process during the browning process [23]. enzymes are located in the cytoplasm. ...
... The reaction mechanism of enzymatic browning is shown in Figure 3. The extensive difference in the hue and intensity of color pigments relies on the source of polyphenols and environmental causes of the oxidation process during the browning process [23]. ...
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Color is an important indicator for evaluating the quality of natural rubber (NR). Light-colored standard rubbers are widely used in high-grade products and have high economic value. This paper first introduces the history and test standards of the standard light-colored rubber. The origin of color deepening in NR processing, color substances, and its biosynthetic pathway are reviewed. Then, the discoloration mechanism of NR is studied from the perspectives of enzymatic browning (caused by polyphenol oxidase and polyphenols) and non-enzymatic browning (including Maillard reaction and lipid oxidation). Finally, the strategies to control the discoloration of NR will be described.
... On the contrary, ethanol treatment inhibited the activities of POD, PPO, and PAL, which are the main enzymes inducing enzymatic browning in horticultural crops (Vamos-Vigyazo and Haard, 1981;Nicolas et al., 1994;Lopez-Serrano and Barcelo, 2002;Jhin and Hwang, 2015). Phenylalanine could be converted to ammonia and trans-cinnamic acid by PAL, while the latter could be ulteriorly converted to phenylpropanoid compounds, including monophenol and o-diphenol. ...
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Papaya is the fourth most favored tropical fruit in the global market; it has rich nutrition and can be used for medicine and food processing. However, it will soften and mature in a short time after harvest, resulting in a lot of economic losses. In this study, papaya fruits were soaked in 0, 12.5, 25, 50, and 100 ml/L ethanol solutions for 2 h and stored at 25°C for 14 days, by which we explored the effects of ethanol treatment in papaya after harvest. At an optimal concentration of ethanol treatment, color changing of the papaya fruits was delayed for 6 days, and decay incidence and average firmness of the fruits were shown as 20% and 27.7 N, respectively. Moreover, the effect of ethanol treatment on antioxidant systems in the papaya fruits was explored. It was observed that ethanol treatment contributed to diminish the development of malondialdehyde (MDA), ethylene, and superoxide anions. Furthermore, the activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) were promoted than those of control group, while the activities of peroxidase (POD), phenylalanine ammonia-lyase (PAL), and polyphenol oxidase (PPO) were brought down. In addition, the principal component analysis (PCA) showed that PAL, ethylene, and superoxide anions were the main contributors for the maturity and senescence of postharvest papaya. In this experiment, ethanol treatment had the potential of delaying the ripening and maintaining the storage quality of papaya fruits.
... These include inhibitors of polyphenol oxidases (PPOs) and peroxidases (PODs) through the action of their thiol group, such as compounds L-cysteine, DTT, and sodium thiosulfate. They are commonly used to reduce enzymatic browning in food processing caused by deposition of tannins (Nicolas et al., 1994;Ghidelli et al., 2014). Polyvinylpyrrolidone (PVP), DTT, L-cysteine, glutathione, α-LA, L-ascorbic acid, and citric acid have been confirmed to decrease tissue necrosis of explants used for Agrobacterium-mediated transformation (Barampuram and Zhang, 2011). ...
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Soybean is one of the important food, feed, and biofuel crops in the world. Soybean genome modification by genetic transformation has been carried out for trait improvement for more than 4 decades. However, compared to other major crops such as rice, soybean is still recalcitrant to genetic transformation, and transgenic soybean production has been hampered by limitations such as low transformation efficiency and genotype specificity, and prolonged and tedious protocols. The primary goal in soybean transformation over the last decade is to achieve high efficiency and genotype flexibility. Soybean transformation has been improved by modifying tissue culture conditions such as selection of explant types, adjustment of culture medium components and choice of selection reagents, as well as better understanding the transformation mechanisms of specific approaches such as Agrobacterium infection. Transgenesis-based breeding of soybean varieties with new traits is now possible by development of improved protocols. In this review, we summarize the developments in soybean genetic transformation to date, especially focusing on the progress made using Agrobacterium-mediated methods and biolistic methods over the past decade. We also discuss current challenges and future directions.
... Apples are rich in lots of nutrients, such as vitamin, fiber, pectin, and polyphenol which are good for the health. The major apple producers around the world are China, Italy, France, and United States (Nicolas et al., 1994). The total apple yield all over the world in 2014 was 84.56 × 10 6 and 40.92 × 10 6 tons in China, accounting for 48.39% of the total yield (Li et al., 2018). ...
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The thinned young apple is a by-product and is generally discarded in the orchard during fruit thinning. The polyphenol content of thinned young apples is about 10 times more than that of ripe apples. In our study, the antibacterial effect of thinned young apple polyphenols (YAP) on the halitosis-related bacteria including Porphyromonas gingivalis , Prevotella intermedius , and Fusobacterium nucleatum was investigated. The minimum inhibitory concentrations of YAP against P. gingivalis , P. intermedia , and F. nucleatum were 8.0, 8.0, and 12.0 mg/ml, while the minimum bactericidal concentrations were 10.0, 10.0, and 14.0 mg/ml, respectively. The scanning electron microscopy and transmission electron microscopy analyses showed that after YAP treatment, the membrane surface of halitosis-related bacterial cells was coarse and the cell wall and membrane were separated and eventually ruptured. The integrity of the cell membrane was determined by flow cytometry, indicating that the cells with the integrity membrane significantly reduced as the YAP concentration treatment increased. The release of proteins and nucleic acids into the cell suspension significantly increased, and the membrane potential reduced after the YAP treatment. This research illustrated the antibacterial mechanism of YAP against halitosis-related bacteria and provided a scientific basis of utilizing the polyphenols from the discarded thinned young apples.
... Therefore, it is of great value for improving the quality of fruit that uncover the reasons and mechanisms of apple browning. About 20 years ago, the higher activity of polyphenol oxidase (PPO) was found that is a main reason of apple browning (6)(7)(8)(9). In recent years, antibrowning apple (Arctic R Apples) was developed by reducing the expression of PPO gene (10). ...
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Browning seriously affects the quality of fresh-cut fruits, and its mechanism was thought to be polyphenol oxidase (PPO) in the past. A way of non-different PPO browning was found in our previous studies. However, the landscape of this browning way is still unclear in “Fuji” apples. Multi-omics (methylomics, transcriptomics, and proteomics) methods were performed to the global profiles of DNA methylation and gene and protein expression. We employed two natural bud mutation varieties of apple as materials and found a positive correlation between browning index (BI) and methylation (5mC%, MdCMT3 , and MdCMT3c ) and a negative correlation between BI and demethylation ( MdROS1 and MdDME ). DNA methylation inhibitor 5-azacytidine can delay apple browning. Further analysis showed that methylated- NCA1 and OMT1 increased significantly in apple browning. Methylated- NCA1 might inhibit NCA1 gene expression and resulted in the decline of catalase activity, thereafter significantly increased apple browning. These findings insight into a new pathway and landscape that DNA hypermethylation significantly accelerated the browning in “Fuji” apple.
... These studies found that healthy tissues contain higher AsA content than the brown areas of damaged fruit (de Castro et al., 2008;Franck et al., 2003;Rabus and Streif, 2000). Ascorbic acid can convert o-quinones back to their precursor diphenols, preventing the formation of brown pigments (Amiot et al., 1993;Nicolas et al., 1994). Thus, under anoxic conditions, fruit with higher AsA/Ca ratios may convert more o-quinones back to the colourless diphenols than fruit with lower AsA/Ca ratios. ...
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Previous studies examining the causes of internal browning (IB) and strategies to reduce its incidence in ‘Braeburn’ apple grown in Southwest Germany have shown conflicting results. However, most studies have been conducted during only one season, requiring multi-seasonal evaluations to obtain robust data and information. IB has been associated with fruit mineral content in ‘Braeburn’ apple, and in other cultivars, ascorbic acid (AsA) is linked to IB. Few studies have investigated the possible role of the balance between mineral and AsA content on fruit susceptibility to IB. The objectives of this study were to use a four-year dataset to analyse the seasonal variation of mineral and AsA content at harvest and their relation to IB incidence in ‘Braeburn’ apple grown in Southwest Germany and stored under controlled atmosphere conditions. According to our results, the average seasonal IB incidence was highly associated with AsA and calcium contents in fruit. Fruit calcium content was positively correlated with IB incidence, whereas AsA content was negatively associated with IB. Seasonal variation in the AsA/Ca ratio at harvest followed the opposite trend to IB incidence, with a higher ratio occurring in years with lower IB incidence. Principal component analysis revealed that the relative humidity (RH) during the first 42 days after bloom (42-DAB) was positively correlated with AsA content and negatively correlated with fruit calcium content and IB incidence. Our results indicate that higher AsA and lower calcium content, due to higher RH during the first 42-DAB, are important to reduce ‘Braeburn’ apples’ susceptibility to IB during controlled atmosphere storage.
... Therefore, blanching temperatures of 110, 120, and 130 • C at blanching durations ≥60 s were selected to study the impact of the blanching temperature on the drying kinetics and drying quality of pigment peppers (Figure 4). Nicolas [55] showed that, when the processing temperature exceeded 40 • C, PPO activity was destroyed. Zhu [56] reported that the PPO of apple slices treated at 60-80 • C was also destroyed, but studies have shown that hot-water and other blanching methods require a long time [15]. ...
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With a high moisture content, fresh peppers are perishable and rot easily. Drying is essential for shelf-life extension. The natural thin wax layer on the pepper surface hinders moisture transfer. Traditionally, chemical dipping or mechanical pricking is used to remove this wax layer. However, in chemical dipping, chemical residues can trigger food-safety issues, while the low efficiency of mechanical pricking hinders its industrial application. Feasible pretreatment methods are advantageous for industrial use. Here, an emerging pretreatment technique (high-humidity hot-air impingement blanching, HHAIB) was used for peppers before drying and its effects on drying characteristics, microstructure, and polyphenol oxidase (PPO) activity were explored. The impact of drying temperature on color parameters and red pigment content of pulsed-vacuum-dried peppers was also evaluated. PPO activity was reduced to less than 20% after blanching at 110 °C for 60 s. HHAIB reduced drying time and PPO activity and promoted chemical-substance release. Effective water diffusivity was highest (5.01 × 10−10 m2/s) after blanching at 110 °C for 90 s, and the brightness value and red pigment content were highest (9.94 g/kg) at 70 °C. HHAIB and pulsed vacuum drying are promising pretreatment and drying methods for enhancing the drying rate and quality of red peppers.
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The present review documents the current knowledge and hypotheses on how polyphenols−saliva interactions may modulate the bioaccessibility or bioavailability of nutrients and highlights research prospects in the field. After an updated description of the different classes of dietary polyphenols and their modifications by food processing or digestion, an overview of interactions between salivary proteins and polyphenols (with an emphasis on tannins) is provided. In vitro studies show that the solubility of salivary protein−tannin complexes in gastric conditions depends on the degree of tannin polymerization, while complexes are partly solubilized by bile salts. Salivary proteins−polyphenols interactions may affect digestive processes. For example, polyphenols can bind to and inhibit salivary amylase, with downstream consequences on starch digestion. Some salivary proteins (PRPs) prevent tannin-induced reduced protein digestibility, probably through binding tannins before they interact with digestive proteases. Salivary proteins may also act as scavenger molecules to limit the intestinal uptake of tannins.
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Trimmed young coconut (TYC) contributes to global economic trade but is impacted by microbial and browning spoilage during the cold chain operation. TYCs were dipped in salt/acid solution (SA; 10% sodium chloride and 10% citric acid) and stored at 2 °C for 8 weeks in three different controlled atmosphere (CA) conditions with normal atmospheric condition as the control. Qualities and bacterial profiles of TYCs were determined. TYC treated with SA+CA (5% O2 + 7.5% CO2) showed the lowest average browning index of 29.13. Titratable acidity, total soluble solid content and pH ranged 0.026–0.071%, 6.86–8.96 °Brix and 5.38–6.51, respectively. Aerobic plate count and total yeast and mold counts were less than 4 log CFU/area of each shoulder, body and bottom area of TYCs. Leuconostoc mesenteroides and Pseudomonas sp. were undetected by PCR-DGGE analysis. Results suggested that SA+CA (5% O2 + 7.5% CO2) offered a non-allergenic hurdle technology to prolong the shelf life of TYC.