Flavor development in peach fruit treated with 1-methylcyclopropene during shelf storage

Silk protein: A novel antifungal and edible coating for strawberry preservation

In this study, an antimicrobial component, silk protease inhibitors (SPIs), was extracted from discarded silkworm cocoons, and a suitable degumming method for obtaining regenerated silk fibroin (SF) was screened. An edible antimicrobial coating was prepared by mixing SPIs with SF for evaluation of potential in strawberries preservation. Results demonstrated that SPI could effectively inhibit mycelial growth and spore germination. The alkaline protease method exhibited the highest degumming rate of 24.4 %. The SPI-SF coating exhibited excellent mechanical properties, high water vapor permeability, and easy washability. Within 10 days, seedlings treatment with SPI-SF coating solution showed a germination rate of 94.3 %, and exhibited good biocompatibility with HepG2 cells. Coating with SPI-SF led to increase in the storage period of strawberries to 10-14 days, concurrent with considerable reduction in decay rate at room temperature. Conclusively, this study demonstrates the potential of SPI-SF edible coating in strawberries preservation.

1-Methylcyclopropene Delays Browning and Maintains Aroma in Fresh-Cut Nectarines

The color and aroma of nectarines experience adverse effects from cutting, resulting in the fast senescence of fruit tissue. Therefore, 1-methylcyclopropene (1-MCP) was used to treat postharvest nectarines before cutting, and its effect on the surface browning and aroma alteration were investigated. The results indicated that 1-MCP restrained the soluble quinone (SQC) accumulation in fresh-cut nectarines by regulating the peroxidase (POD) and polyphenol oxidase (PPO) activities and the metabolism of phenolic compounds. Compared with the control, 1-MCP pre-cutting treatment maintained the ultrastructural integrity of the cell wall in fresh-cut nectarines, which also showed reduced malondialdehyde (MDA) content and reactive oxygen species (ROS) and enhanced the 1,1-Diphenyl-2-Picrylhydrazyl (DPPH) radical scavenging activities. Electronic nose and GC-MS analysis revealed that the aroma profiles presented significant differences in the control and 1-MCP treatment during the storage at 0 °C for 10 days. The browning value of the 1-MCP pre-cutting treatment was 29.95% lower than the control, which prevented the loss of aroma on day 10. The fresh-cut nectarines could still maintain the characteristic flavor, while the flesh maintains its firmness. The 1-MCP pre-cutting treatment improves the sensory and aroma characteristics of fresh-cut fruits, which is beneficial to the preservation of fresh-cut fruits, improves transportation efficiency, and then improves the overall quality and market attractiveness of the fruit.

Effect of coatings containing 1-methylcyclopropane or mandarin peel extract on the freshness and metabolic profiles of cold stored strawberry

The application of coatings is a strategy for maintaining the freshness of highly perishable fruits. This research aimed to evaluate the quality indices of strawberries (Amaou) coated with new coatings based on the sodium carboxymethyl cellulose (CMC) and cellulose nanofibres (CNF) with incorporated mandarin peel extract (ME) or 1-methylcyclopropene (1-MCP) during storage at 20days at 5 °C and 85% relative humidity (RH). Dissolving the coating solution containing ME in 1-MCP maintained its colour for up to 50 days. Coatings enhanced with ME and/or 1-MCP maintained fresh strawberries more effectively than the control, reducing weight loss and maintaining firmness, total soluble solids (TSS), citric acid, colour, and total phenolic content. The CCM2-2 coating solution showed superior effects on the weight loss and relative percentages of strawberry metabolites compared to the other coatings, as confirmed by the different components.

Effects of ultraviolet C on the quality and aroma volatile in peach fruit during postharvest storage

The study investigated the impact of UV-C irradiation on peach fruit quality during postharvest storage, with a focus on aroma changes and the mechanisms involving lipoxygenase metabolism. Results showed that UV-C irradiation at a dosage of 1.5 kJ/m2 was found to preserve the quality attributes of peach fruit during ambient storage, as evidenced by high flesh firmness, inhibition of weight loss and respiration rate, as well as high values of L* and ascorbic acid. Meanwhile, UV-C irradiation led to an increase in the contents of aroma-related volatiles, particularly esters and lactones, compared to non-irradiated fruit. Our results suggested that the enhanced emission of aroma-related volatiles in UV-C irradiated peach fruit was linked to elevated levels of unsaturated fatty acids. Besides, UV-C induced the expressions and activities of enzymes in the lipoxygenase pathway, thus promoting the synthesis of esters and lactones, which contribute to the enhanced aroma in peach fruit.

Combined application of sucrose and 1-MCP alleviated the senescence of Gynura bicolor DC through regulating hexose accumulation

As a leaf vegetable, Gynura bicolor DC (G. bicolor) experiences a rapid deterioration after harvest including insufficient supply of sugar and destruction of cell membranes. In this research, four treatments were experimented on G. bicolor including the control (CK), 12% (g/g) sucrose (ST), 10 μL L-1 1-MCP (MT), and the combination of sucrose and 1-MCP (SMT). The results showed that three treated groups reduced respiratory rate, inhibited hexose consumption and promoted the decrease of starch and sucrose, which was converted into hexose including glucose and fructose to maintain cell membrane integrity. Meanwhile, the activities of AI, NI, SS-C, amylase, and corresponding gene expression levels were significantly up-regulated in three treated groups at 1 d, among which AI played a crucial role in regulating the accumulation of hexose. Furthermore, ST exerted a pronounced effect on hexose accumulation at the beginning while MT reduced hexose consumption through lowered respiratory metabolism during storage. Notably, SMT exhibited an optimum preservation effect on inhibited respiratory metabolism, maintaining cell membrane integrity, enhancing the retention of hexose, indicating that a synergistic effect of ST and MT were developed during storage.

Biochemical dynamics during postharvest: Highlighting the interplay of stress during storage and maturation of fresh produce

The lifecycle of fresh produce involves a sequence of biochemical events during their ontology, and these events are particularly significant for climacteric fruits. A high demand during ripening is observed in these plant products, which is reflected in a high rate of respiration and ethylene production. Increased respiratory demand triggers the activation of secondary pathways such as alternate oxidase, which do not experience critical increases in energy consumption in non-climacteric fruit. In addition, biochemical events produced by external factors lead to compensatory responses in fresh produce to counteract the oxidative stress caused by the former. The dynamics of these responses are accompanied by signaling, where reactive oxygen species play a pivotal role in fresh product cell perception. This review aims to describe the protection mechanisms of fresh produce against environmental challenges and how controlled doses of abiotic stressors can be used to improve quality and prolong their shelf-life through the interaction of stress and defense mechanisms.

Influence of Post-Harvest 1-Methylcyclopropene (1-MCP) Treatment and Refrigeration on Chemical Composition, Phenolic Profile and Antioxidant Modifications during Storage of Abate Fétel Pears

'Abate Fétel', a winter cultivar, is the most important pear cultivar in Italy; its fruits are appreciated by consumers for their aroma, texture and balanced sweet and sour taste. Maintaining high-quality characteristics to prolong the shelf-life of fruit and preserve the sensory and nutritional quality is a priority for the food industry. The aim of our study was to test the effectiveness of 1-methylcyclopropene (1-MCP) and cold storage in prolonging the shelf-life of these fruits, which were harvested at maturity at two different times. This work focused on the effects of different storage treatments and two ripening times on (i) the chemical composition of Abate Fétel pulp fruits to preserve their sweet taste and aroma and (ii) the phenolic profile composition and antioxidant activity of the peel, which is naturally rich in phytochemicals and important for the fruit's shelf-life and in the functional food industry for its high nutritional value. Abate Fétel fruits were harvested at the optimal commercial maturity stage, first on 15 September, having been treated with 1-MCP and stored for 2 months at cold temperatures; the other fruits were harvested at the end of September and stored in a cold cell for 2 months. The fruit pulp was tested for glucose and fructose, pH, acidity and organic acids (malic, citric, fumaric and shikimic), phenolic content and phenolic compounds (chlorogenic and caffeic acids, rutin, hyperoside, kaempferol-3-rutinoside and isoquercitrin), and the antioxidant activities in the fruit peels were measured. Treating the fruits with 1-MCP better preserved the phytochemical compounds compared to simple refrigeration, preserving the fruit's quality and prolonging its shelf-life. All the treatments help to maintain the glucose and fructose content and the acidity, preserving the aroma and organoleptic characteristics.

Post-harvest ripening affects drying behavior, antioxidant capacity and flavor release of peach via alteration of cell wall polysaccharides content and nanostructures, water distribution and status

Effect of post-harvest ripening on cell wall polysaccharides nanostructures, water status, physiochemical properties of peaches and drying behavior under hot air-infrared drying was evaluated. Results showed that the content of water soluble pectins (WSP) increased by 94 %, while the contents of chelate-soluble pectins (CSP), Na₂CO₃-soluble pectins (NSP) and hemicelluloses (HE) decreased during post-harvest ripening by 60 %, 43 %, and 61 %, respectively. The drying time increased from 3.5 to 5.5 h when the post-harvest time increased from 0 to 6 days. Atomic force microscope analysis showed that depolymerization of hemicelluloses and pectin occurred during post-harvest ripening. Time Domain -NMR observations indicated that reorganization of cell wall polysaccharides nanostructure changed water spatial distribution and cell internal structure, facilitated moisture migration, and affected antioxidant capacity of peaches during drying. This leads to the redistribution of flavor substances (heptanal, n-nonanal dimer and n-nonanal monomer). The current work elucidates the effect of post-harvest ripening on the physiochemical properties and drying behavior of peaches.

Cinnamon essential oil vapor alleviates the reduction of aroma-related volatiles in cold-stored "Feicheng" peach using HS-GC-IMS

"Feicheng" peach is popular for its unique aroma, but its defect of being highly sensitive to chilling injury (CI) often leads to aroma loss and internal browning. Essential oils (EOs) are often used to enhance the antioxidant capacity of plants and fruits, as well as to trigger their defense against biotic/abiotic stresses. This study aimed to examine the effect of cinnamon essential oil (CEO) vapor treatment on the aroma quality of peach fruit during cold storage using HS-GC-IMS. The results showed that 50 μL/L CEO vapor reduced the severity of internal browning (IB) in peaches at the stage of 7 ~ 21 d during refrigeration (Significantly, the L* value was higher and the IB index was lower than that of control, p < 0.05). Meanwhile, the evident reduction or loss of aroma content caused by CI was restored to a higher level than the control (p < 0.05). Furthermore, CEO treatment promoted the release of aroma-related volatiles as evidenced by more propyl acetate, and the dimer of amyl acetate, isoamyl acetate, butyl acetate detected than that on harvest day and no-treated group after 21 d of cold storage plus 2 d of shelf life. Genes of PpLOX1, PpLOX2, PpHPL1 and PpADH1 associated with aroma-related volatile biosynthesis revealed higher transcript abundance in peach fruits treated with CEO than the control (p < 0.05). Overall, our study demonstrated that CEO in vapor phase may be beneficial to alleviate the quality deterioration in aroma and flesh color of "Feicheng" peaches caused by CI, which lays a theoretical reference for maintaining postharvest quality of peach fruits.

Comparative Metabolomic Analysis of the Nutritional Aspects from Ten Cultivars of the Strawberry Fruit

Strawberry (Fragaria × ananassa) is among the most widely cultivated fruits with good taste and rich nutrients. Many strawberry species, including white strawberries, are planted all over the world. The metabolic profiles of strawberry and distinctions among different cultivars are not fully understood. In this study, non-targeted metabolomics based on UHPLC-Q-Exactive Orbitrap MS was used to analysis the metabolites in 10 strawberry species. A total of 142 compounds were identified and were divided into six categories. Tochiotome may differ most from the white strawberry (Baiyu) by screening 72 differential metabolites. Histidine, apigenin, cyanidin 3-glucoside and peonidin 3-glucoside had potential as biomarkers for distinguishing Baiyu and another 11 strawberry groups. Amino acid metabolisms, anthocyanin biosynthesis and flavonoid biosynthesis pathways were mainly involved in the determination of the nutrition distinctions. This research contributes to the determination of the nutrition and health benefits of different strawberry species.

Effect of postharvest 1-methylcyclopropene application on reactive oxygen species scavenging and sucrose metabolism in Gynura bicolor DC

After harvest, the metabolism of Gynura bicolor DC (G. bicolor) is vigorous, resulting in sugar scarcity and reactive oxygen species (ROS) accumulation, thus aggravating the quality deterioration. 1-Methylcyclopropene (1-MCP) shows crucial effect in alleviating the postharvest metabolism of vegetables and fruits. This research aimed to evaluate the effect of 1-MCP on ROS scavenging and sucrose metabolism in G. bicolor. In this research, G. bicolor was treated with 10 μL L^-1 1-MCP for 12 h, followed by storage at 20 ± 2 °C and 90 ± 5% relative humidity in darkness for 7 days. During storage, the increases in the respiration rate, electrolytic leakage, weight loss rate, ROS levels, and membrane lipid oxidation were effectively inhibited by 1-MCP. Moreover, starch and hexose degradation was decreased in the 1-MCP group, as were sucrose synthesis and catabolism. Correlation analysis indicated that sugar starvation was associated with respiration, activities regulation of CAT, SOD, and enzymes involved in sucrose metabolism were associated with the levels of hydrogen peroxide at the early storage. In conclusion, 1-MCP delayed postharvest quality deterioration of G. bicolor by alleviating respiration, inducing oxidative stress to enhance ROS scavenging, and inhibiting sucrose metabolism.

Effects of Different Postharvest Precooling Treatments on Cold-Storage Quality of Yellow Peach (Amygdalus persica)

The rapid precooling of yellow peaches after harvest can minimize the tissue damage and quality deterioration of yellow peaches during postharvest storage. Refrigerator precooling (RPC), cold-water precooling (CWPC), strong-wind precooling (SWPC), fluidized-ice precooling (FIPC), and vacuum precooling (VPC) were used to precool the fresh yellow peaches. The yellow peaches after different precooling treatments were stored at 4 °C for 15 days. CWPC and RPC can effectively retard the respiration and ethylene peak production, reduce the quality loss of yellow peaches during postharvest storage, maintain the color and fruit hardness of yellow peaches, inhibit browning, maintain the contents of soluble solids, titratable acids, and ascorbic acid, increase the activity contents of superoxide dismutase (SOD) and peroxidase (POD), inhibit the decrease in the phenylalanine ammonia-lyase (PAL) activity, and delay the increase in the polyphenol oxidase (PPO) activity. The shelf life of yellow peaches with cold-water precooling and refrigerator precooling reached 15 days, which was 6 days longer than those of the VPC- and FIPC-treated samples, and 3 days longer than that of the SWPC-treated samples. Therefore, CWPC and RPC were effective methods to prolong the storage period and maintain the quality of yellow peaches during postharvest storage.

Co-Application of 1-MCP and Laser Microporous Plastic Bag Packaging Maintains Postharvest Quality and Extends the Shelf-Life of Honey Peach Fruit

Honey peach (Prunus persica L.) is highly nutritious; it is an excellent source of sugars, proteins, amino acids, vitamins, and mineral elements. However, it is a perishable climacteric fruit that is difficult to preserve. In this study, “Feicheng” honey peach fruit was used as a test material to investigate the synergistic preservation effect of 1-methylcyclopropene (1-MCP) and laser microporous film (LMF). The peach fruits were fumigated for 24 h with 2 μL L⁻¹ 1-MCP, then packed in LMF. In comparison with the control treatment, 1-MCP + LMF treatment markedly decreased the respiration rate, weight loss, and rot rate of peach fruits. Moreover, the combination of 1-MCP and LMF suppressed the increase in soluble solids (SS) and reducing sugars (RS), as well as the decrease in titratable acid (TA) and ascorbic acid (AsA). The combined application also maintained a high protopectin content and low soluble pectin content; it reduced the accumulation of superoxide anions (O₂⁻) and hydrogen peroxide (H₂O₂). Except in a few samples, the catalase (CAT) and ascorbate peroxidase (APX) activities were higher when treated by 1-MCP + LMF. Conversely, the phenylalanine deaminase (PAL), peroxidase (POD), lipase, lipoxygenase (LOX), polygalacturonase (PG), β-glucosidase, and cellulase (Cx) activities were lower than in the control. Furthermore, 1-MCP + LMF treatment reduced the relative abundances of dominant pathogenic fungi (e.g., Streptomyces, Stachybotrys, and Issa sp.). The combined treatment improved the relative abundances of antagonistic fungi (e.g., Aureobasidium and Holtermanniella). The results indicated that the co-application of 1-MCP and LMF markedly reduced weight loss and spoilage, delayed the decline of nutritional quality, and inhibited the physiological and biochemical metabolic activities of peach during storage. These changes extended its shelf-life to 28 days at 5 °C. The results provide a reference for the commercial application of this technology.

Influence of post-harvest physiology on sensory perception, physical properties, and chemical compositions of Moris pineapples (Ananas comosus L.)

This study was conducted to evaluate consumer profiling of pineapple at five maturity stages using check-all-that-apply (CATA) method and to determine the influence of post-harvest physiological changes on the physical and chemical properties of the pineapple. Nineteen CATA terms describing sensory attributes of pineapples at five maturity stages were generated. Seventy-five consumers were involved in describing the changes in the organoleptic properties of pineapple using CATA questions. The relationship between physicochemical properties and sensory description of pineapples was analyzed using correspondence analysis (CA). The total variance of 97.7% and 92.2% obtained in the CA plot of the physical and chemical properties with the consumer profiling data suggests that consumers have effectively described the pineapple harvested at five maturity stages. Changes in physical and chemical compositions in pineapple upon maturation result in the development of pineapple's desirable organoleptic characteristics, characterized as fresh, attractive, and bright yellowish, with a soft, fibrous, and juicy texture, a sweet odor and pineapple aroma as well as sweet taste. Index 3 pineapple has been described as pale, hard, and crunchy in texture at the early stage of maturity and has a sour taste. The characteristic was transformed to bright yellow, soft, fibrous, and juicy texture after maturation, (25% ripeness onwards), as well as the production of sweet taste and aroma of pineapple. Instrument analysis of yellowness (b value) and carotenoid has strongly influenced the sensory attributes of brightness, freshness, and attractiveness of the pineapple. Changes in total soluble solids (TSS) and a ratio of TSS to total acids (TA) contributes to the development of aromatic compound which increases the appealing quality of the pineapple. Pineapple sensory characteristics, physical properties, and chemical compositions were significantly affected by post-harvest physiology. PRACTICAL APPLICATION: Sensory and instrumental methods were used to construct the properties of pineapple at different stages of post-harvest physiology. This article demonstrates that the Check-all-that-apply (CATA) analysis provides adequate sensory profiling information based on customer perceptions in relation to instrumental details, and it can be extended to other pineapple varieties and citrus fruits.