Decline In Fruit Firmness Research Articles

Effects of Storage Temperature at the Early Postharvest Stage on the Firmness, Bioactive Substances, and Amino Acid Compositions of Chili Pepper (Capsicum annuum L.).

The commercial and nutritional quality of chili peppers deteriorates rapidly after harvest. So far, little is known about the effect of temperature on postharvest chili pepper quality. This study elucidated the effects of two temperatures (20 °C and 30 °C) on chili peppers' postharvest firmness, flavor, and nutritional attributes. We found that compared to 20 °C, 30 °C escalated the decline in fruit firmness, capsaicin content, and dihydrocapsaicin content, while enhancing the increment in water loss and electrical conductivity, as well as total carotenoids and ascorbic acid content. The contents of most amino acids (AAs) decreased significantly during postharvest storage compared to their initial values, whether stored at 20 °C or 30 °C; however, 30 °C had a more substantial impact than 20 °C. Meanwhile, as for soluble protein and amino acid compositions, the effect of storage temperature was genotype-dependent, as reflected by differential changes in total AA contents, single AA contents, essential AA ratio, delicious AA ratio, etc., under the 20 °C or 30 °C treatments. In conclusion, our findings reveal the influence of temperature on pepper quality, showing that the storage temperature of 20 °C was better for maintaining chili quality than 30 °C from the perspective of overall commercial attributes.

Changes in the VOC of Fruits at Different Refrigeration Stages of 'Ruixue' and the Participation of Carboxylesterase MdCXE20 in the Catabolism of Volatile Esters.

Aroma is a crucial quality attribute of apple fruit, which significantly impacts its commercial value and consumer choice. Despite its importance the volatile aroma substances produced by the new variety 'Ruixue' after harvest remain unclear. In this study, we utilized headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) to investigate the changes in volatile substances, fruit hardness, crispness, and related aroma synthase activity of commercially mature 'Ruixue' apples during cold storage. Our findings revealed a gradual decline in fruit firmness and brittleness of 'Ruixue' apples during cold storage, with hexyl acetate, hexyl caproate, and hexyl thiocyanate being the main hexyl esters detected. To gain a better understanding of the metabolic pathway of esters, we identified 42 MdCXE gene members that are associated with ester degradation. Through RT-qPCR analysis, we discovered that carboxylesterase MdCXE20 exhibited higher expression levels compared to other MdCXE genes during cold storage. To confirm the role of MdCXE20, we conducted a transient injection of apple fruits and observed that overexpression of MdCXE20 led to the degradation of esters such as hexyl hexanoate, butyl hexanoate, butyl 2-methylbutyrate, hexyl butyrate, and hexyl 2-methylbutyrate. The results of the study showed that the virus-induced gene silencing of MdCXE20 found the opposite results. Additionally, the esters of OE-MdCXE20 callus showed a lower content of ester VOC than the control callus, according to the homologous stable transformation of 'Wanglin' callus. Overall, these findings suggest that the MdCXE20 gene plays a crucial role in the decrease of esters in 'Ruixue' apples, which ultimately affects their flavor.

Gaseous ozone regulates reactive oxygen species metabolism and ascorbate–glutathione cycle to delay the senescence of fresh-cut red pitaya (Selenicereus undatus) fruit

Mechanical damage during processing can accelerate the senescence and deterioration of fresh-cut red pitaya (Selenicereus undatus), thereby affecting its nutritional quality and commodity value. In this study, the effects of a low-concentration and long-term (10 μL L−1 for 60 min) gaseous ozone treatment on the quality, reactive oxygen species (ROS) metabolism, and enzyme and non-enzyme antioxidant activities of fresh-cut red pitaya fruit were investigated. The results showed that ozone treatment delayed the decline in fruit firmness, total soluble solids, and titratable acid content. Ozone treatment also maintained a higher free radical scavenging capacity and lower membrane lipid peroxidation than the control treatment. It prevented the rapid increase in ROS level by improving the activity of antioxidant enzymes, including superoxide dismutase, peroxidase, and catalase. Additionally, the treatment activated the ascorbate–glutathione cycle. Compared with the control group, ozone treatment maintained the activities of ascorbic acid peroxidase, dehydroascorbic acid reductase, monodehydroascorbic acid reductase, and glutathione reductase. Although the contents of ascorbic acid (AsA) and dehydroascorbic acid (DHA) decreased within 10 days of storage, the AsA/DHA and glutathione/oxidized glutathione ratios in the ozone-treated group were higher than those in the control group from day 0 to day 6. Thus, ozone treatment regulated ROS metabolism, enhanced the ROS-scavenging system, maintained the redox balance of fresh-cut red pitaya, and delayed senescence.

Effects of melatonin on blueberry fruit quality and cell wall metabolism during low temperature storage

Melatonin is known to influence various physiological processes, including plant ripening; however, the effect of melatonin on postharvest blueberry fruit softening is unknown. Herein, the effects of melatonin at different concentrations (100, 300, and 500 μmol L-1) on the quality parameters, cell wall substances, cell-wall-degrading enzymes, and cell wall ultrastructure of blueberry fruits were investigated during low-temperature storage. Melatonin treatment was found to effectively delay the decline in fruit firmness, slow the loss of soluble solids and titratable acids, and decrease the respiration rate and decay rate of blueberry fruits. The blueberry fruits treated with 300 μmol L-1 melatonin exhibited the best quality. Melatonin treatment promoted anthocyanin accumulation, delayed ascorbic acid degradation, maintained a low relative membrane permeability in pulp, inhibited increases in lipoxygenase (LOX) activity, and reduced membrane lipid peroxidation. Moreover, melatonin controlled the formation of soluble pectin by inhibiting the activities of pectin methylesterase (PME), polygalacturonase (PG), cellulase (Cx), and β-glucosidase (β-Glu) while maintaining high contents of protopectin and cellulose. These results indicate that melatonin can effectively improve blueberry fruit quality and antioxidant capacity as well as and delay fruit softening by inhibiting the degradation of cell wall substances.

Effects of nitric oxide fumigation treatment on retarding cell wall degradation and delaying softening of winter jujube (Ziziphus jujuba Mill. cv. Dongzao) fruit during storage

Winter jujube (Ziziphus jujuba Mill. cv. Dongzao) fruit were fumigated with 20 μL L−1 of nitric oxide (NO) for 3 h and then stored at 0 ± 1 ºC with 90–95 % relative humidity for 75 d. The effects of NO fumigation on changes in fruit firmness, activities of cell wall degrading enzymes, the compositions of the cell walls, as well as the cell wall ultrastructure in the winter jujube fruit were investigated during storage. The results showed that the decline in fruit firmness, contents of CDTA-soluble pectin (CSP), Na2CO3-soluble pectin (SSP), hemicellulose, and cellulose, as well as the increase in water-soluble pectin (WSP) of the winter jujube fruit could be delayed by NO treatment relative to the control. NO treatment also suppressed the activities of pectin methylesterase (PME; EC 3.1.1.11), polygalacturonase (PG; EC 3.2.1.15), β-galactosidase (β-Gal; EC 3.2.1.23) and cellulase (EC 3.2.1.4) during storage. Furthermore, ultrastructural observations revealed that NO treatment delayed the disruption of cell wall structure of the winter jujube fruit. These results indicated that retarding the disassembly of cell walls polysaccharides via inhibition of an array of cell wall degrading enzymes activities, which in turn would help maintain the intactness of the cell walls, might be one possible mechanism by which NO treatment can help prevent softening of the winter jujube fruit.

Postharvest hot water dipping and hot water forced convection treatments alleviate chilling injury for zucchini fruit during cold storage

The effects of hot water dipping (HWD) and hot water forced convection (HWFC) treatments on the quality and membrane integrity of zucchini fruit were investigated during cold storage at 4 °C. Zucchini fruit were treated with hot water dipping at 40 °C for 25 min or hot water forced convection at 40 °C at a water flow rate of 2 m/s for 20 min, each of which produced the same heat absorption inside the fruit. Then, all fruit were placed into refrigerated storage at 4 ± 0.5 °C with 85–90 % humidity for 15 d. The results indicated that treatment with HWD or HWFC alleviated chilling injury (CI) in zucchini fruit compared with an untreated group (CK). Nevertheless, the HWFC treatment was more effective in reducing CI, maintaining quality and alleviating membrane injury than was HWD, which decreased the decline in fruit firmness, Total soluble solids (TSS) content and ascorbic acid (AsA) content and reduced relative electrolyte leakage (EL), malondialdehyde (MDA) content and weight loss in zucchini fruit during cold storage. In addition, analysis of heat transfer progress characteristics indicated that the effect of heat treatment on the quality and membrane integrity of zucchini fruit during cold storage was related not only to heat temperature and time but also to heat transfer modes, including forced convection and natural convection. Yielding the same heat absorption inside the zucchini fruit during hot water treatment, the HWFC treatment with a forced convection heat transfer mode could shorten the heating time and provided more advantages in zucchini fruit preservation during cold storage than did the HWD treatment under a natural convection heat transfer mode.

Ripening quality of Dusehri mango in relation to harvest time.

The effect of different harvesting time on ripening quality of mango cv. Dusehri was investigated under sub-tropics of northwestern India. Fruits were harvested at 101, 106 and 111days after fruit set (DAFS) and kept at 25°C in temperature controlled chamber for ripening. Fruits were analyzed periodically for physico-chemical characteristics at the time of harvest (0h) and after 72, 96 and 120h of ripening period. With advancement in ripening period, an increase in physiological loss in weight, soluble solids content (SSC), sensory quality rating, β-carotene and pulp colour development of mango fruits was recorded. While a decline in fruit firmness and titratable acidity (TA) was observed with ripening period. Fruits picked at 111 DAFS recorded highest SSC (8.01%), sensory rating (4.67), β-carotene (0.427mg/100g) vis-à-vis lowest fruit firmness (15.3 lbf) and TA content (1.56%). The luminosity of fruit pulp decreased with the storage period. The redness and yellowness of the fruit pulp represented by a* and b* values, respectively increased with delay in harvesting period. The rate of ripening was rapid in late harvested fruits as compared to early harvested fruits. After 96h of ripening period, fruits harvested at 111 DAFS showed very much desirable quality whereas fruits harvested at 101 DAFS showed moderately desirable quality. Results showed that harvesting of mango fruits can be extended to 111days and such fruits attained optimum ripening quality after 96h at 25°C.

Evaluating effects of ellagic acid on the quality of kumquat fruits during storage

To assess the preservative effects of the active ingredients in the leaves of Liquidambar formosana Hance, the present study assessed the antioxidant activity of ellagic acid using various antioxidant assays; 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid, 1,1-diphenyl-2-picrylhydrazyl, superoxide anion radical scavenging activity and reducing power. The results of these assays were combined with principal component analysis to analyze the effect of ellagic acid treatment on the overall quality of kumquat. Whole kumquat fruit were immersed in different concentrations of ellagic acid (0, 100 and 300 mg L−1) for 5 min, naturally dried then stored at room temperature (14–16 °C) for 18 days. During storage, the percentage weight loss and decay, firmness, total soluble solids, titratable acid and contents of malondialdehyde, superoxide dismutase and vitamin C were measured every 3 days. The results showed that, by 1,1-diphenyl-2-picrylhydrazyl scavenging activity and reducing power, the antioxidant activity of ellagic acid was more effective than butylated hydroxyanisole or ascorbic acid. Compared with untreated kumquat fruit, ellagic acid treatments can delay the decline in fruit firmness, total soluble solids, titratable acid and vitamin C contents, inhibit increases in malondialdehyde and enhance superoxide dismutase activity. The comprehensive evaluation of the results using principal component analysis was consistent with the experimental results, namely that ellagic acid treatment can significantly reduce the rate of deterioration in the quality of kumquat fruit, with the 300 mg L−1 treatment being better than the 100 mg L−1 treatment. The results show that ellagic acid has good prospects as a preservative treatment for kumquat fruit.

The role of β-hexosaminidase in peach (Prunus persica) fruit softening

To determine the role of β-hex in peach fruit softening, we cloned two β-hexosaminidase (β-hex) gene homologs, Pphex1 and Pphex2. Results showed that the full cDNA length of Pphex1 (JQ979080) was 1859bp, containing an open reading frame (ORF) with 1689bp and encoding a polypeptide of 562 amino acides. Pphex2 (JX069961) was 2018bp in length, containing an ORF with 1794bp and encoding a polypeptide of 594 amino acides. Pphex1 and Pphex2 showed different expression patterns during peach fruit development and storage period. During peach fruit development, the Pphex1 expression initially decreased, but later increased towards ripening. However, Pphex2 expression was very low during fruit developmental stage, and then increased significantly towards ripening. During fruit storage, β-hexosaminidase activity increased in the first 6 days. The expression peak of Pphex1 occurred at the second day during storage. Pphex2 showed relative high expression during the whole storage period. Treatment with 2-Acetaindo-1,2-dideoxynojirimycin (2-ADN) caused inhibition in Pphex1 and Pphex2 transcription and β-hexosaminidase activity, at the same time, the rapid decline in fruit firmness was also delayed. Suppression of 2-ADN treated fruits in ethylene production, as well as the expression of PpACO and PpACS, and the activities of cell wall degrading enzymes (endo-PG, exo-PG, PME, and β-Gal) were also observed. Our study suggests the involvement of β-hex in the regulation of fruit softening in peach.

Expression of genes associated with ethylene‐signalling pathway in harvested banana fruit in response to temperature and 1‐MCP treatment

Little attention has been paid to characterising the ethylene-signalling pathway genes in relation to abnormal ripening of harvested banana fruit during storage at high temperature. The aim of the present study was to investigate banana fruit abnormal ripening and the expression of ten genes associated with the ethylene-signalling pathway, namely MaACS1, MaACO1, MaERS1-4 and MaEIL1-4, at high temperature. Changes in these parameters of banana fruit at high temperature in response to 1-MCP pretreatment were also investigated. High temperature accelerated the decline in fruit firmness, increased ethylene production and inhibited degreening in banana fruit, resulting in fruit abnormal ripening. In addition, the expression of MaACS1, MaACO1, MaERS2, MaERS3, MaERS4, MaEIL1, MaEIL3 and MaEIL4 was enhanced in banana fruit stored at high temperature. However, application of 1-MCP prior to high temperature storage delayed fruit abnormal ripening and simultaneously suppressed the expression of MaACS1, MaERS2, MaERS3, MaEIL1, MaEIL3 and MaEIL4. The findings of this study suggested that the expression of genes associated with the ethylene-signalling pathway might be involved in banana fruit abnormal ripening at high temperature. Application of 1-MCP suppressed the expression of genes associated with the ethylene-signalling pathway, which may be attributed at least partially to 1-MCP delaying fruit abnormal ripening at high temperature.

MODIFICATIONS IN CELL WALL COMPOSITION AFTER STORAGE OF 1-MCP-TREATED PEACH FRUIT

Rapid softening of peach (Prunus persica L. Batsch) fruit after harvest considerably limits commercial life of produce. The decline in fruit firmness during ripening and storage is largely the result of partial disassembly of the primary cell wall arising from compositional changes. In this work, suitability of controlled atmosphere (CA) storage and 1-methylcyclopropene (1-MCP) treatment to delay these changes and to extend storage potential of a late-harvesting peach cultivar was tested. Cell wall materials were extracted and fractionated 0 and 7 d after storage to assess possible relationships to changes in fruit firmness. The yield of soluble materials increased during the shelf life period at 20°C, consistent with a decline in the contents of cell wall materials and of pectin-containing fractions, possibly in relation to the decrease in flesh firmness. The increase in the yield of soluble fractions after storage was attenuated by 1-MCP treatment, which proved more effective than CA storage in delaying solubilisation of cell wall polymers.

Pawpaw [Asimina triloba (L.) Dunal] Fruit Ripening. I. Ethylene Biosynthesis and Production

Pawpaw fruit ethylene production, 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS) and ACC oxidase (ACO) activities, and tissue content of the ethylene precursor ACC and conjugate malonyl-ACC (MACC) were measured during postharvest ripening. Fruit were harvested near the advent of the ripening process and were ripened at room temperature. The fruit displayed increases in ethylene production and respiration rate during ripening with maxima for both 3 days after harvest. Mean ethylene maxima on a fresh weight basis were 4.7 and 7.6 μg·kg-1·h-1 and mean respiratory (CO2 production) maxima on a fresh weight basis were 220 and 239 mg·kg-1·h-1 in 1999 and 2001, respectively. The increase in ethylene evolution coincided with an increase in respiration and a rapid decline in fruit firmness. Internal and external fruit firmness declined in a parallel manner. The ethylene climacteric peak occurred after the greatest decline in fruit firmness, indicating that low levels of ethylene may be sufficient to initiate the ripening process. The ethylene climacteric peak also coincided with the highest activities of both ACS and ACO as well as the maximum tissue ACC content. As ACC content increased, MACC content declined, suggesting a regulation of ethylene production via free ACC levels by malonylation of ACC. Thus, the climacteric development of ethylene production may be regulated by an increase of ACS activity and a decrease in ACC malonyltransferase activity, making more free ACC available for the production of ethylene by increased activity of ACO.

Pawpaw [Asimina triloba (L.) Dunal] Fruit Ripening. II. Activity of Selected Cell-wall Degrading Enzymes

Pawpaw fruit were harvested at the advent of the ripening process and were ripened at room temperature. Based on fruit firmness and respiration and ethylene production rates at harvest and during ripening, fruit were classified into one of four categories: preripening (no to very slight loss of firmness; preclimacteric), early ripening (some softening; increasing rates of ethylene and CO2 production), mid-ripening (soft; at or just past climacteric), and late ripening (very soft; postclimacteric). The activities of the cell-wall degrading enzymes polygalacturonase (PG), endo-(1→4)ß-D-glucanase (EGase), and endo-ß-1,4-mannanase (MAN) were low in the preripening and early ripening stages, increased dramatically by mid-ripening coincident with the respiratory and ethylene climacterics, and decreased at late ripening. However, pectin methylesterase (PME) activity per milligram protein was highest at the green stage when the fruit firmness was high and decreased as ripening progressed. Tissue prints indicated both EGase and MAN increased as ripening proceeded. The EGase activity was evident near the seeds and the surface of the fruit at preripening and eventually spread throughout, while MAN activity was evident near the fruit surface at preripening and was progressively expressed throughout the flesh as fruit ripened. The greatest decline in fruit firmness occurred between pre- and early ripening, before the peak activities of PG, EGase, and MAN, although MAN exhibited the greatest relative increase of the three enzymes in this period. The data suggest that PME may act first to demethylate polygalacturonate and may be followed by the action of the other enzymes resulting in cell wall disassembly and fruit softening in pawpaw.

The effects of 1‐methylcyclopropene on peach fruit (Prunus persica L. cv. Jiubao) ripening and disease resistance

SummaryIn order to learn how 1‐methylcyclopropene (1‐MCP) affects ripening and disease‐resistance of peach fruit (Prunus persica L. cv. Jiubao) after harvest, they were treated with 1‐MCP and some were inoculated with Penicillium expansum. Treating peach fruit with 0.2 μL L−1 of 1‐MCP at 22 °C for 24 h effectively slowed the decline in fruit firmness. The minimal concentration of 1‐MCP able to inhibit fruit softening was 0.6 μL L−1. Changes in other parameters related to peach ripening, such as content of soluble solids, total soluble sugar, titratable acidity, soluble pectin and ethylene production were also significantly reduced or delayed by 1‐MCP. Repeated treatment of peach with 1‐MCP resulted in more effective inhibition of ripening. Post‐harvest decay of peach fruit was reduced by treatment with 1‐MCP and disease progress in fruit inoculated with P. expansum was reduced. The activities of phenylalanine ammonialyase, polyphenoloxidase and peroxidase in the inoculated fruit were also enhanced by 1‐MCP.

Ripening pawpaw fruit exhibit respiratory and ethylene climacterics

Abstract The ripening behavior of the native American pawpaw (Asimina triloba (L.) Dunal.) fruit was studied immediately after harvest and after 1 month of 4 °C storage. Fruit were harvested at two different maturity stages. Fruit that were unripe (minimal softening evident) at harvest exhibited respiratory and ethylene climacterics at 3 and 5 days postharvest, respectively, at ambient temperature, and a precipitous decline in fruit firmness was evident prior to the climacteric peaks. Fruit classified as having commenced ripening (some softening evident) at harvest exhibited both respiratory and ethylene climacteric peaks at 3 day at ambient storage temperature. Fruit in cold storage at 4 °C for 28 days exhibited minimal to no loss of firmness, and upon removal to ambient temperature both respiratory and ethylene climacterics occurred within 7 days for both harvest maturities. The maximum rates of respiration and ethylene production in these studies were: CO2 production 90 mg kg−1 h−1 and C2H4 production 14.4 μg kg−1 h−1, respectively. These results indicate that pawpaw fruit ripening is climacteric.