Polygalacturonase Activity Research Articles

Morin Treatment Delays the Ripening and Senescence of Postharvest Mango Fruits.

A 0.005% and 0.01% morin treatment was applied to treat mango fruits stored under ambient conditions (25 ± 1 °C) with 85-90% relative humidity, and the effects on quality indexes, enzyme activity related to antioxidation and cell wall degradation, and gene expressions involved in ripening and senescence were explored. The results indicate that a 0.01% morin application effectively delayed fruit softening and yellowing and sustained the nutritional quality. After 12 days of storage, the contents of soluble sugar and carotenoid in the treatment groups were 68.54 mg/g and 11.20 mg/100 g, respectively, lower than those in control, while the vitamin C content in the treatment groups was 0.58 mg/g, higher than that in control. Moreover, a morin application successively enhanced the activity of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), but reduced the activity of polygalacturonase (PG) and pectin lyase (PL). Finally, real-time PCR and correlation analysis suggested that morin downregulated the ethylene biosynthesis (ACS and, ACO) and signal transduction (ETR1, ERS1, EIN2, and ERF1) genes, which is positively associated with softening enzymes (LOX, EXP, βGal, and EG), carotenoid synthesis enzymes (PSY and, LCYB), sucrose phosphate synthase (SPS), and uncoupling protein (UCP) gene expressions. Therefore, a 0.01% morin treatment might efficiently retard mango fruit ripening and senescence to sustain external and nutritional quality through ethylene-related pathways, which indicates its preservation application.

Preharvest Foliar Spraying Combined with Postharvest Salicylic Acid Treatment Regulates Panzao (Ziziphus jujuba Mill. cv. ‘Jingcang1’) Fruit Quality and Softening during Storage

Panzao (Ziziphus jujuba Mill. cv. ‘Jingcang1’) have a short shelf-life, which hampers their marketability. To investigate effects of combined pre- and postharvest treatments on quality and softening during storage, preharvest Guomantian foliar fertilizer (FF) spray and postharvest salicylic acid (SA) dip were applied to panzao. By day 63 of storage, fruit firmness responded to treatment in the order of FF+SA treatment > FF or SA treatments > Control. All treatments inhibited fruit reddening during storage and, compared with those of the control, alleviated the decline in total soluble solids, ascorbic acid, and phenol contents and decreased the oxidative aging process, which was consistent with the change in firmness. The FF+SA treatment reduced the activities of amylase, cellulase, polygalacturonase, and β-glucosidase, which decreased the degradation of macromolecules including starch, cellulose, and pectin. Principal component analysis showed that FF+SA exhibited a synergistic effect and was the most effective treatment for maintaining fruit quality during storage. FF increased accumulation of nutrients during growth and improved quality, while SA delayed the decline in fruit quality and reduced softening. These results provide the theoretical basis and technical knowledge for improving the shelf-life of panzao during storage and long-distance transportation.

Abscisic acid enhances storability of winter jujube by regulating cell wall and phenylpropane metabolisms during cold storage

Winter jujube is extremely susceptible to softening and reddening after harvest, resulting in serious quality deterioration. The influences of abscisic acid (ABA) on the storage quality, cell wall metabolism, phenylpropane metabolism, and differentially expressed genes of winter jujube were investigated. The results showed that low concentration of ABA (0.2 mmol L−1) treatment maintained the firmness and greenness of winter jujube, while inhibiting respiration rate and ethylene production after harvest. Compared with control group, ABA treatment inhibited the activities of pectin methylesterase, polygalacturonase, β-1,3-glucanase, α-l-arabinofurosidase, and phenylalanine ammonia-lyase, but improved the activities of cinnamate-4-hydroxylase, 4-coumaric acid CoA ligase, and chalcone synthase. Transcriptome analysis revealed a total of 13,068 differentially expressed genes among control (0 d and 30 d) and ABA (30 d) groups, which were enriched in the phenylpropanoid metabolism, secondary metabolic biosynthesis, and plant hormone signal transduction pathways. In addition, ABA regulated 33, 29, 35, and 30 genes involved in cell wall metabolism, phenylpropane metabolism, plant hormone signal transduction, and related transcription factors respectively, thereby inhibiting softening and reddening, and delaying ripening and senescence to ultimately maintain the storage quality in winter jujube. These results supply a theoretical basis for investigating postharvest biology and developing storage and preservation techniques of winter jujube.

Changes in fruit texture and cell structure of different pumpkin varieties (lines) during storage

After harvest, the pumpkin fruit has strong respiration and metabolic activities, which easily induce quality deterioration, shortening the storage period and shelf life, which affects the farmers' income. To understand the quality change mechanisms of pumpkins and extend the storage period, the fruit cell wall components, related enzyme activities, and fruit texture of Baimi No. 2, Baimi No. 3, Baimi No. 5, Baimi No. 10 and 2020-X1 pumpkin varieties (lines) were monitored during storage at 18 ± 2 °C after harvest.The pumpkin fruit texture was analyzed via the texture profile analysis (TPA) method, and the cell structure changes in peel and pulp cells were monitored using paraffin sections. The results revealed that the hardness, brittleness, viscosity, and elasticity of the five pumpkin fruits were decreased, while the adhesiveness, cohesion, recovery, and chewiness were first increased before decreasing with the prolongation of storage time. In addition, the protopectin, cellulose, and hemicellulose contents were decreased, while the soluble pectin content was increased. In addition, the polygalacturonase activity was increased, and the β-galactosidase, Cx cellulase, and pectinesterase activities were decreased. The cell wall components and enzymatic activities in Baimi No. 10 had minor changes, implying it is storage resistant. In addition, its peel and pulp cells were small and tightly arranged, with minor cellular changes. The peel cells were nearly square, and the pulp cells nearly round, rendering this variety more storable. Baimi No. 5 pulp cells were large and loosely arranged, with large intercellular spaces, rendering this variety short-lived.

Increased weight loss and internal air space, degraded starch and pectin combined to cause pulp mealiness in ‘Oregon Spur Ⅱ’ apples during ambient storage

Pulp mealiness is a common phenomenon in ‘Delicious’ apples during ambient storage, but the underlying mechanism remains poorly understood. In the present study, fruit physiological and quality parameters, the volume of internal air space and the degree of mealiness as well as cell wall-degrading enzyme activities and pectin material content were measured in ‘Oregon Spur Ⅱ’ apple fruit during ambient storage. The results showed that the peaks of respiration rate and ethylene production of ‘Oregon Spur Ⅱ’ fruit occurred at 5 d and 10 d of storage, respectively, during which the starch and malic acid contents and firmness decreased significantly, while the fruit weight loss, the volume of internal air space and the degree of mealiness increased rapidly. Meanwhile, the activities of pectin methylesterase (PME) and pectin lyase (PL) showed a unimodal change during storage, whereas the activity of polygalacturonase (PG) decreased, and the activities of α-L-arabinofuranosidase (α-AFase) and β-galactosidase (β-Gase) as well as the contents of water-soluble pectin (WSP), chelator-soluble pectin (CSP), and sodium carbonate-soluble pectin (NSP) increased with increasing storage time. Correlation analysis showed that α-AFase, β-Gase, WSP, CSP, weight loss, the volume the air space, firmness, starch, and malic acid were significantly correlated with the degree of pulp mealiness (|r|>0.9). In conclusion, increased weight loss and internal air space, degraded starch and pectin combined to cause pulp mealiness in ‘Oregon Spur Ⅱ’ apples during ambient storage.

Integrated analysis of postharvest storage characteristics of seven apple cultivars and transcriptome data identifies MdBBX25 as a negative regulator of fruit softening during storage in apples

Apple is classified as a climacteric fruit, characterized by a rapid surge in ethylene levels at the onset of ripening. However, there is significant variation in the degree and timing of ripening and softening among different apple cultivars. Understanding the molecular mechanisms underlying fruit softening and the associated changes in cell wall integrity is crucial for improving fruit quality and extending shelf life. In this study, we conducted a comparative analysis of fruit firmness and ethylene production among seven apple cultivars with different softening patterns during storage. We also examined the expression patterns of genes and enzyme activities involved in cell wall metabolism. Our results showed that fruit firmness was negatively correlated with ethylene production rate, respiration rate, soluble pectin content, cellulase activity, polygalacturonase activity, and β-glucosidase activity, while it was positively correlated with protopectin content and cellulose content. Furthermore, we identified a BBX transcription factor gene, MdBBX25, that was negatively correlated with fruit softening during storage. Overexpression of MdBBX25 resulted in delayed fruit softening by suppressing ethylene biosynthesis and cell wall-related genes, whereas silencing of MdBBX25 accelerated fruit softening by promoting ethylene biosynthesis and cell wall-related genes in apple. Our findings provide insights into the role of MdBBX25 as a negative regulator of fruit softening through the modulation of ethylene biosynthesis and cell wall degradation during storage.

Effect of Foliar Calcium Fertilization on Fruit Quality, Cell Wall Enzyme Activity and Expression of Key Genes in Chinese Cherry

ABSTRACT Chinese cherries are early flowering and early fruiting, with both edible and ornamental values. This study aims to explore the effects of pre-harvest spraying with different concentrations of CaCl2, amino acid calcium, and sugar alcohol calcium on the quality of Chinese cherry and the expression of genes related to cell wall softening. The goal is to identify suitable calcium-based agents for pre-harvest spraying on Chinese cherry. The results of the study demonstrated that all three exogenous calcium treatments significantly increased the mineral content compared to the control group. Moreover, these treatments also led to a significant increase in various fruit quality parameters such as hundred fruit weight, firmness, soluble solid, soluble sugar, titratable, vitamin C, soluble protein, β-Carotene content and superoxide dismutase, peroxidase activities. Additionally, they were found to effectively reduce rot rate, polyphenol oxidase activity, malondialdehyde content and relative conductivity. The activity of pectin methylesterase, polygalacturonase, cellulase and β-galactose was reduced by amino acid calcium and sugar alcohol calcium. All three types of exogenous calcium down-regulated the expression of PME and ChCaBP1. Additionally, amino acid calcium and sugar alcohol calcium decreased the expression of PG, Cx, and BGal. Exogenous calcium reduces the size of stomata in the fruit epidermis, leading to a decrease in both fruit respiration rate and transpiration. Of the three calcium preparations, amino acid calcium and sugar alcohol calcium were more effective than CaCl2, with 0.12 g·L−1sugar alcohol calcium and 0.06 g·L−1 amino acid calcium being the most effective.

Polygalacturonase Production by Sarocladium strictum T4 Isolate using Apricot Pulp as Substrate in Non-Sterile Culture Conditions

In this study, 34 molds showing pectin degradation activity were isolated from the soil of orchards, by several tests. By using these isolates, pectinase group enzymes; studies on pectin lyase and polygalacturonase production were performed in the batch system and under non-sterile culture conditions. 5 isolates denoting polygalacturonase activity were coded as: T1, T2, T3, T4, T5 and the best polygalacturonase activity among these isolates was determined as 354.4 U/L in T4 isolate. Thus, optimization analyses continued by the use of this isolate. Initial apricot pulp concentration, temperature, pH and incubation period were tested as optimization parameters. The effects on enzyme activities were investigated by changing the initial apricot pulp concentration in the range of 5-100 (g/L), and in this regard, polygalacturonase activity was determined as 397.4 U/L at 50 g/L. In addition, the pH parameter was analyzed in each unit between pH = 3 – 8, and the temperature was tested by increasing 5 units in the range of 5-25°C. Consequently, the maximum polygalacturonase activity was determined as 405.7 U/L at pH 5 and 406.3 U/L at 15°C. Besides, the effect of the incubation period was studied within 1-5 days and the maximum polygalacturonase activity was determined as 429.0 U/L on the 4th day (after 96 hours). As a result, the above-mentioned T4 isolate, with which the optimization studies were conducted, was identified as Sarocladium strictum (Top ekinküfü) T4 by molecular methods.

Effects of dry-salting and brine-pickling on physicochemical properties and flavor of spaghetti squash shreds

The effects of dry-salting and brine-pickling on the physicochemical properties and flavor of spaghetti squash shreds were investigated. The results showed that dry-salting had a positive effect on the contents of total acid, soluble sugars, reducing sugars and Vc of squash shreds compared to brine-pickling, except for the acceleration of water loss. The pH of dry-salted and brine-pickled shreds were 4.65 and 4.83 at day 12, respectively. Additionally, after 12 d of pickling, higher brittleness (34.11% higher) was observed in dry-salted shreds than in brine-pickled shreds, accompanied by higher levels of protopectin (15.31% higher), cellulose (60.71% higher) and lignin (18.75% higher) and lower activities of polygalacturonase (27.58% lower) and cellulase (13.30% lower) as well as a more intact cell structure. Furthermore, this study characterized the shred flavor by using electronic tongue and electronic nose combined with GC-MS analysis, and found that dry-salting resulted in a more pronounced salt and umami taste and a faster development of more intense aroma. These results demonstrate the benefits of dry-salting in pickling spaghetti squash shreds and provide new ideas for developing related pickled products.

Spermidine synthase is essential for vegetative growth, stress response, secondary metabolism and pathogenicity in Alternaria alternata

Black spot, caused by the fungus Alternaria alternata, is one of the postharvest diseases that cause significant economic losses. Polyamine metabolism in fungi plays key roles in cellular processes and pathogen-host interactions. However, little is known about their detailed regulatory mechanisms on pathogenicity of plant fungi. In this study, we characterized the spermidine synthase AaSPDS in A. alternata. Knocking out AaSPDS caused a total loss of vegetative growth and sporulation which was partially restored by exogenous spermidine (Spd), so supplying 0.5 mM exogenous Spd to medium for evaluating the characteristics of WT and ΔAaSPDS. The deletion strain showed albino colonies, sparse mycelial tips and significant decreased biomass accumulation and melanin production. ΔAaSPDS strain was also more sensitive to osmotic stress, oxidative stress and cell wall-perturbing agents. Interestingly, the expression level of AaSPDS was greatly up-regulated during infection structure differentiation stage of A. alternata, and appressorium formation of the AaSPDS deletion strain was completely blocked. In addition, deletion of the AaSPDS gene led to a significant reduction in pathogenicity to pear fruit, altenuene (ALT) mycotoxin accumulation and the activities of cellulase (CL), β-glucosidase (β-GC) and polygalacturonase (PG). The results presented in this study suggested that AaSPDS influences the pathogenicity of A. alternata by regulating infection structure formation, cell wall degrading enzyme (CWDE) activity and mycotoxin production.

PhcX Is a LqsR-family response regulator that contributes to Ralstonia solanacearum virulence and regulates multiple virulence factors.

The bacterial wilt caused by the soil-borne phytopathogen Ralstonia solanacearum is one of the most destructive crop diseases. To achieve a successful infection, R. solanacearum has evolved an intricate regulatory network to orchestrate the expression of an arsenal of virulence factors and fine-tune the allocation of energy. However, despite the wealth of knowledge gained in the past decades, many players and connections are still missing from the network. The importance of our study lies in the identification of PhcX, a novel conserved global regulator with critical roles in modulating the virulence and metabolism of R. solanacearum. PhcX affects many well-characterized regulators and exhibits contrasting modes of regulation from the central regulator PhcA on a variety of virulence-associated traits and genes. Our findings add a valuable piece to the puzzle of how the pathogen regulates its proliferation and infection, which is critical for understanding its pathogenesis and developing disease control strategies.

Identification of lncRNA and weighted gene coexpression network analysis of germinating Rhizopus delemar causing mucormycosis

ABSTRACT Rhizopus delemar, an opportunistic fungal pathogen, causes a highly fatal disease, mucormycosis. Spore germination is a crucial mechanism for disease pathogenesis. Thus, exploring the molecular mechanisms of fungal germination would underpin our knowledge of such transformation and, in turn, help control mucormycosis. To gain insight into the developmental process particularly associated with cell wall modification and synthesis, weighted gene co-expression network analysis (WGCNA) was performed including both coding and non-coding transcripts identified in the current study, to find out the module of interest in the germination stages. The module-trait relationship identified a particular module to have a high correlation only at the resting phase and further analysis revealed the module to be enriched for protein phosphorylation, carbohydrate metabolic process, and cellular response to stimulus. Moreover, co-expression network analysis of highly connected nodes revealed cell wall modifying enzymes, especially those involved in mannosylation, chitin-glucan crosslinking, and polygalacturonase activities co-expressing and interacting with the novel lncRNAs among which some of them predicted to be endogenous target mimic (eTM) lncRNAs. Hence, the present study provides an insight into the onset of spore germination and the information on the novel non-coding transcripts with key cell wall–related enzymes as potential targets against mucormycosis.

Physiological and transcriptomic analysis of IAA-induced antioxidant defense and cell wall metabolism in postharvest mango fruit

Mango fruit tend to oxidize and senescence rapidly after harvesting, significantly reducing their commercial value. This study investigated the effect of exogenous auxin indole-3-acetic acid (IAA) on fruit quality, antioxidant system, and cell wall metabolism of mango fruit during storage. The results showed that the 1.0 mM IAA treatment delayed weight loss and maintained the firmness, pH and contents of total soluble solids (TSS) and titratable acidity (TA) of the mango fruit. The 1.0 mM IAA treatment increased the peroxidase (POD) and phenylalanine ammonia-lyase (PAL) activities and the ascorbic acid (AsA) and total phenols (TP) contents but decreased the polyphenol oxidase (PPO) activity in postharvest mango fruit. Moreover, beta-galactosidase (β-Gal) and polygalacturonase (PG) activities were increased, but the pectinesterase (PME) activity was decreased in the IAA-treated fruit. Transcriptome analysis showed that the differentially expressed genes (DEGs) in the IAA vs. control groups were mainly associated with oxidative stress responses, cell wall metabolism, and transcription factors (TFs). The IAA treatment upregulated the antioxidant-related genes (SOD, CAT1, PODs, GSTs, Prxs, and Trxs) and MYB TFs, and downregulated cell wall metabolism-related genes (PG, PME31 and two PME63) and 11 ethylene-responsive transcription factors (ERFs). These results suggested that exogenous IAA could improve the antioxidant system and maintain the storage quality of mango fruit by regulating gene expression and metabolic pathways. The results provide insights into the mechanisms involved in IAA-mediated delayed ripening and senescence of mango fruit.

Postharvest Quality Exploration of “Crystal” Grapes in Karst Mountainous Area: Regulatory Effect of High Concentration 1-MCP Fumigation

The comprehensive exploration and thorough understanding of the physicochemical characteristics of “Crystal” grapes in the Karst area of Southwest China can not only produce edible table grapes, but also offer significant theoretical backing for the management of rocky desertification in the Karst area and consequently generate enhanced social and ecological benefits. This study explored the regulatory effect of 1-MCP fumigation on the postharvest storage quality of "Crystal” grapes, aiming to provide some technical support for the development of the grape industry in the Karst mountainous areas. The results indicate that compared with the control group, both the 10.0 and 50.0 μL/L 1-MCP treatment groups effectively inhibited the increase in decay rate, browning rate, shedding rate, and color change of the grapes, significantly inhibited the enhancement of polyphenol oxidase (PPO), peroxidase (POD), and lipoxygenases (LOX) browning-related enzyme activities, improved the superoxide dismutase (SOD) activity of the fruits, hindered the decrease of ascorbic acid (AsA) and polyphenols, delayed the accumulation of malondialdehyde (MDA) content, and significantly postponed the peak period of polygalacturonase (PG) activity in the fruits and the degradation of protopectin to soluble pectin, thereby maintaining desirable texture characteristics. The utilization of 1-MCP for fruit fumigation yielded a heightened overall fragrance, thereby facilitating the emission of terpenes, alcohols, aldehydes, ketone aromatic compounds, and methyl aromatic substances within the fruit. Overall, both the M10 and M50 treatments are equally effective in preserving the storage quality of “Crystal” grapes. Under the condition of ensuring the excellent edible quality of crystal grapes, M2 can extend the shelf life of crystal grapes by about 5 days, and M10 and M50 can extend the storage period of crystal grapes by 10~15 days. Considering the cost, it is recommended that the industry employs a concentration of 10.0 μL/L of 1-MCP for “Crystal” grapes. Simultaneously, this study also provides theoretical support for the ecologically high-quality development of cultivated land in the Karst mountainous area of Guizhou and tree selection.

Effect of Cold Plasma Treatment on the Softening of Winter Jujubes (Ziziphus jujuba Mill. cv. Dongzao)

Cold plasma (CP) is a green and efficient preservation technology, but its effect on preventing the postharvest softening of fruits and vegetables is still unclear, and the effects of different CP intensities on the postharvest softening of winter jujubes (Ziziphus jujuba Mill. cv. Dongzao) have been little studied. In this study, we investigated the effects of different CP intensities (0 kV, 40 kV, and 80 kV) on the postharvest storage quality of winter jujubes and the activities of key enzymes related to softening during storage. The results showed that compared with the control group, the contents of firmness, total soluble solids (TSS), titratable acidity (TA), and vitamin C (VC) in the CP treatment group were higher and the respiratory intensity and weight loss rate were lower. In addition, CP treatment can also inhibit the degradation of protopectin and cellulose and the accumulation of soluble pectin. Moreover, CP treatment inhibited the activities of polygalacturonase (PG), pectin methyl esterase (PME), 3α-L-arabinoside (α-L-Af), 4β-galactosidase (β-gal), cellulase (Cx), and β-glucosidase (β-Glu). This shows that CP treatment has a positive effect on the preservation of winter jujubes, and the preservation effect of the 80 kV treatment was better than that of the 40 kV treatment. This provides a certain basis for cold plasma treatment in the preservation of winter jujubes.

Effects of D-Limonene Nanoemulsion Coating on Post-Harvest Quality and Physiology of Papaya

Papaya (Carica papaya L.) is a climacteric fruit, and its quality will rapidly decrease after ripening. Hence, the storage life of its fruit is short. D-limonene is a terpene compound in citrus essential oil and has antibacterial and antioxidant properties. The addition of D-limonene in edible coating can delay volatilization, prevent microorganism and pathogen invasion, decrease water loss, inhibit softening, decrease gas exchange, and extend the storage life of fruits. In this study, 0.25%, 0.5%, and 1% D-limonene nanoemulsion coatings were used for post-harvest immersion treatment of “Tainung No. 2” papayas and its effects on appearance, chlorophyll content, respiration rate, ethylene production, pectin methylesterase, polygalacturonase activity, decay loss, firmness, total soluble solid, titratable acidity, ascorbic acid, and total plate count were investigated. After the papayas were treated with 0.5% D-limonene nanoemulsion coating, polygalacturonase and pectin methylesterase activities decreased, fruit firmness was maintained, and ascorbic acid content was high. On the last day of storage, polygalacturonase and pectin methylesterase activities were 0.01 and 0.02 U/kg FW lower than the control group, respectively; firmness was higher than the control group by 1.75 N, and ascorbic acid content was higher than the control group by 31.97 mg/100 g FW. On Day 2, the treatment showed delay in total soluble solid accumulation and chlorophyll degradation, consequently delaying the color change in fruits. The coating decreased decay loss by 40% on Day 2, decreased respiration rate by 97.0 mg CO2 kg−1 h−1, and ethylene production by 5.7 µL kg−1 h−1 on Day 2. Simultaneously, the coating decreased the total plate count and resulted in a good appearance. Fruits coated with a 1% D-limonene nanoemulsion coating showed defects in color change. In summary, 0.5% D-limonene nanoemulsion coating delayed “Tainung No. 2” papaya ripening and decreased microbial infection, consequently extending its storage life.

Non-Saccharomyces Yeast Strains, Aromatic Compounds and Sensory Analysis of Italy and Negra Criolla Pisco from the Moquegua Region of Peru

In this study, we aimed to isolate and phenotypically characterize non-Saccharomyces yeast strains (NSYSs) from the skin of aromatic (Italy) and non-aromatic (Negra Criolla) grapes from vineyards in Moquegua, Peru, typically used for the production of pisco. Our second objective was to characterize the volatile compounds and sensory attributes of pisco made from these grapes. Pichia terricola (56%), Metschnikowia pulcherrima (31%), and Naganishia vaughanmartiniae (13%) were the main NSYSs isolated from the skin of aromatic Italy grapes and identified; meanwhile, Vishniacozyma carnescens (50%), Vishniacozyma heimaeyensis (30%), and Aureobasidium pullulans (20%) were identified on the skin of the non-aromatic Negra Criolla grapes. These NSYSs showed different capacities in terms of carbohydrate fermentation, polygalacturonase activity, ethanol tolerance, sulphite production, and nitrogen consumption. Moreover, the pisco resulting from these varieties of grape had different volatile profiles. Terpene alcohols such as citronellol, geraniol, linalool, and nerol were found in pisco made from Italy grapes, while higher contents of 2-phenylacetate and ethyl esters were found in Negra Criolla Pisco. Intermediate levels of both 1-hexanol and bencyl alcohol were also found in all the pisco. Sensory analysis performed by a trained pisco tasting panel showed that citric, floral, alcohol, and syrup descriptors were more marked in Italy Pisco, while nuts, syrup, alcohol, and floral were the most intense attributes of Negra Criolla Pisco. These results will contribute to determining the potential of indigenous grape yeasts from the Moquegua region as fermentation starters to improve the typical sensory qualities of the pisco produced in this region, which deserves further study.

Low temperature inhibits pectin degradation by PpCBFs to prolong peach storage time.

Low-temperature storage is a widely used method for peach fruit storage. However, the impact of PpCBFs on pectin degradation during low-temperature storage is unclear. As such, in this study, we stored the melting-flesh peach cultivar "Fuli" at low temperature (LT, 6°C) and room temperature (RT, 25°C) to determine the effect of different temperatures on its physiological and biochemical changes. Low-temperature storage can inhibit the softening of "Fuli" peaches by maintaining the stability of the cell wall. It was found that the contents of water-soluble pectin and ionic-soluble pectin in peach fruit stored at RT were higher than those stored at LT. The enzyme activities of polygalacturonase (PG), pectate lyase (PL), and pectin methylesterase (PME) were all inhibited by LT. The expressions of PpPME3, PpPL2, and PpPG were closely related to fruit firmness, but PpCBF2 and PpCBF3 showed higher expression levels at LT than RT. The promoters of PpPL2 and PpPG contain the DER motif, which suggested that PpCBF2 and PpCBF3 might negatively regulate their expression by directly binding to their promoters. These results indicated that LT may maintain firmness by activating PpCBFs to repress pectin-degradation-related enzyme genes during storage.

The Effects of Poly-γ-Glutamic Acid on the Postharvest Physiology and Quality of Strawberry cv. Hongyan during Cold Storage.

This study investigated the effects of poly-γ-glutamic acid (γ-PGA) on the postharvest physiology and quality of the strawberry cv. Hongyan during cold storage. The results showed that all concentrations of γ-PGA improved decay control and strawberry preservation by enhancing antioxidant capacity, delaying the softening process, and maintaining fruit quality, especially for 100 mg·L-1 γ-PGA. After 14 days of treatment, compared with control, 100 mg·L-1 γ-PGA decreased weight loss, decay rate, and index by 21.9%, 75.0%, and 66.7% and increased the total antioxidant capacity by 43.5% through antioxidant enzymes. In addition, 100 mg·L-1 γ-PGA increased fruit firmness by 53.6% by decreasing the activities of polygalacturonase, pectin lyase, cellulase, and β-galactosidase. In terms of color quality, 100 mg·L-1 γ-PGA improved the values of lightness and yellowness by 30.9% and 52.8%. As regards nutritional quality, 100 mg·L-1 γ-PGA increased the contents of protein, soluble sugars, vitamin C, and total phenols by 106.6%, 80.6%, 51.2%, and 78.4%. In terms of sensory quality, 100 mg·L-1 γ-PGA increased the soluble solids' content by 19.0% and decreased the titrated acids' content by 21.1%, which increased the sugar-acid ratio by 50.9%. Our findings suggest that 100 mg·L-1 γ-PGA can be used to improve the decay control and preservation of strawberry cv. Hongyan under cold storage.

Prolonging the shelf-life of atemoya (Annona cherimola × Annona squamosa) using pulsed electric field treatments

This study aimed to investigate the effects of the pulsed electric field (25, 50, and 100 kV/m) on the ripening of atemoya (Annona cherimola × Annona squamosa) and explore the mechanism of delayed ripening. The results showed that the 50 kV/m pulsed electric field (PEF) treatment significantly affected atemoya preservation, inhibited browning for up to 18 days, and reduced firmness loss by 27% to prolong the shelf-life of the treated sample to 30 days. Regarding the mechanisms, the shelf-life extension was consistent with PEF-induced enzyme inactivation. The 50 kV/m PEF treatments inhibited the respiration rate peak from the 15th day to the 18th day and decremented the activities of pectin methylesterase, polygalacturonase, cellulase, and amylase by 17.0%, 36.2%, 32.3%, and 39.0%, respectively. These results suggest that PEF could extend the shelf-life of atemoya and probably other climacteric fruits.