Aloe vera gel coating delays softening and maintains quality of stored persimmon (Diospyros kaki Thunb.) Fruits.

The effect of Aloe vera (AV) gel coating was studied on antioxidant enzymes activities, oxidative stress, softening and associated quality attributes of persimmon fruits. The fruits were coated with 0 and 50% AV-gel coating and stored for 20 days at 20 ± 1 ºC. AV-gel coated fruits exhibited considerably less weight loss, hydrogen peroxide level, electrolyte leakage and malondialdehyde content. AV-gel coated fruits had significantly higher ascorbate peroxidase, peroxidase, superoxide dismutase and catalase activities. In addition, AV-gel coating suppressed pectin methylesterase, polygalacturonase and cellulase activities and showed higher ascorbic acid, DPPH scavenging antioxidants and phenolics, and lower sugars and carotenoids. To the best of our knowledge, these results are the first evidence that AV-gel coating modulates the activities of cell wall degrading enzymes to delay ripening in climacteric fruits. So, AV-gel coating prohibited the onset of senescence by activating enzymatic antioxidant system, accumulating bioactive compounds and suppressing cell wall degradation. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-022-05412-5.

Phytomelatonin: An overview of the importance and mediating functions of melatonin against environmental stresses.

Recently, melatonin has gained significant importance in plant research. The presence of melatonin in the plant kingdom has been known since 1995. It is a molecule that is conserved in a wide array of evolutionary distant organisms. Its functions and characteristics have been found to be similar in both plants and animals. The review focuses on the role of melatonin pertaining to physiological functions in higher plants. Melatonin regulates physiological functions regarding auxin activity, root, shoot, and explant growth, activates germination of seeds, promotes rhizogenesis (growth of adventitious and lateral roots), and holds up impelled leaf senescence. Melatonin is a natural bio-stimulant that creates resistance in field crops against various abiotic stress, including heat, chemical pollutants, cold, drought, salinity, and harmful ultra-violet radiation. The full potential of melatonin in regulating physiological functions in higher plants still needs to be explored by further research.

Arsenic exposure through drinking groundwater and consuming wastewater-irrigated vegetables in Multan, Pakistan.

Arsenic (As) is one of the most toxic metalloids for humans. Above permissible levels of As cause severe health implications. Contaminated drinking water and food items may be the leading sources of As exposure to people all around the world. The current study assessed the levels of As in drinking water, vegetables, irrigation water, agricultural soils, and the human population (adult women and men) of rural and peri-urban areas of Multan (Pakistan). For a comparison between peri-urban (exposed site) and rural areas (control site), we sampled irrigation water, vegetables and vegetable-grown soils, drinking water, and human blood. In all sample types, As concentration was significantly higher at exposed site than at control site. Alarmingly, As concentration in drinking groundwater (34 µg As L-1) of exposed site was 3.4-folds higher than the permissible limit (set by WHO). Among the studied vegetables, the cumulative daily dietary intake of As was recorded maximum by the consumption of okra (474 ng d-1 on exposed site) and minimum by long melon (1 ng d-1 on control site). However, As intake via drinking water was estimated to contribute ≥ 98% of total As intake at both sites. Hence, the health risks associated with drinking As-contaminated groundwater were recorded much higher than the health risks associated with the consumption of As-contaminated vegetables. Blood As levels in most of the subjects at exposed site exceeded the safe limit of 12 µg L-1. Conclusively, the findings of the current study indicated that drinking contaminated groundwater may be the major cause of As-associated health risks in the region.

Impact of Drying Method on the Evaluation of Fatty Acids and Their Derived Volatile Compounds in 'Thompson Seedless' Raisins.

Air- and sun-dried raisins from Thompson Seedless (TS) grapes were analyzed under GC/MS to evaluate fatty acids (FAs) and their derived volatile compounds, coming from unsaturated fatty acids oxidation. A total of 16 FAs were identified in TS raisins, including 10 saturated fatty acids (SFAs) and 6 unsaturated fatty acids (USFAs). The contents of C18:0, C15:0, and C16:0 among SFAs and C18:3, C18:2 and C18:1 in USFAs were significantly higher. Furthermore, USFAs such as C16:1 and C20:1 were only identified in air-dried raisins. The principal component analysis showed the increased content of FAs and FA-derived compounds were in air-dried and sun-dried raisins, respectively. Among FA-derived compounds, 2-pentyl furan, 3-octen-2-one, 1-hexanol and heptanoic acid were more potent. This study shows that air-drying is more favorable for the production of fatty acids (SFAs and USFAs), whereas sun-drying is more advantageous in terms of fatty acid-derived volatiles.

Layer by layer application of chitosan and carboxymethyl cellulose coatings delays ripening of mango fruit by suppressing cell wall polysaccharides disassembly.

Mango is a climacteric fruit that ripens quickly after harvest due to its climacteric nature. Edible coatings have been reported to delay the ripening of various harvested fruit. The efficacy of the applied edible coatings could be improved by using in combination as a layer-by-layer (LBL) approach. So, the influence of LBL application of chitosan (CH) and carboxymethyl cellulose (CMC) was studied on mangoes during postharvest storage at 15 °C for 20 days. Mangoes were coated with monolayers of CH (1 % w/v) and CMC (1 % w/v) as well as LBL application of CH and CMC and were compared with control. The treatment of mangoes with CH and CMC-based LBL treatment resulted in lower decay percentage and weight loss along with higher total chlorophyll pigments and suppressed total carotenoid accumulation. The LBL application of CH and CMC showed lower activity of chlorophyll degrading such as chlorophyllase (CPS), pheophytinase (Phe), Mg-dechalatase (MGD) and chlorophyll degrading peroxidase (Chl-POD) enzymes as well as reduced changes in b*, a* and L* along with a suppressed increase in ethylene (EP) and CO2 production (CPR) rates having higher antioxidant such as catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD) and superoxide dismutase (SOD) enzymes activity. In addition, mangoes coated with LBL treatment of CH and CMC exhibited lower water-soluble pectin (WSP) and higher protopectin (PP) having higher concentrations of chelate soluble (CSP) and sodium carbonate-soluble pectin (SCP). Similarly, LBL-coated mangoes showed significantly higher hemicellulose (HCLS) and cellulose (CLS) contents in contrast with control. It was observed that mangoes coated with CH and CMC-based LBL coating exhibited higher flesh firmness and showed suppressed cellulase (CS), pectin methylesterase (PME), polygalacturonase (PG) and ß-galactosidase (ß-Gal) enzymes activity. The concentrations of total soluble solids and ripening index were markedly lower and titratable acidity was higher in the LBL-based coating treatment in comparison with control. In conclusion, LBL treatment based on CH and CMC coatings could be used for the delay of ripening and softening of harvested mangoes.

Vanadium toxicity was alleviated by supplementation of silicon in tomato seedlings: Upregulating antioxidative enzymes and glyoxalase system.

The primary goal of this research is to investigate the mitigating effect of silicon (Si; 2 mM) on the growth of tomato seedlings under vanadium (V; 40 mg) stress. V stress caused higher V uptake in leaf, and enhanced concentration of leaf anthocyanin, H2O2, O2•-, and MDA, but a decreased in plant biomass, root architecture system, leaf pigments content, mineral elements, and Fv/Fm (PSII maximum efficiency). Si application increased the concentrations of crucial antioxidant molecules such as AsA and GSH, as well as the action of key antioxidant enzymes comprising APX, GR, DHAR, and MDHAR. Importantly, oxidative damage was remarkably alleviated by upregulation of these antioxidant enzymes genes. Moreover, Si application enhanced the accumulation of secondary metabolites as well as the expression their related-genes, and these secondary metabolites may restricted the excessive accumulation of H2O2. In addition, Si rescued tomato plants against the damaging effects of MG by boosting the Gly enzymes activity. The results confirmed that spraying Si to plants might diminish the V accessibility to plants, along with promotion of V stress resistance.

The combined application of Arabic gum coating and γ-aminobutyric acid mitigates chilling injury and maintains eating quality of 'Kinnow' mandarin fruits.

Low temperature storage of citrus generally extends the storage potential but leads to chilling injury appearance on the rind of fruits. The said physiological disorder has been found associated with changes in the metabolism of cell walls and other attributes. In this work, the influence of Arabic gum [AG (10 %)] and γ-amminobutyric acid [GABA (10 mmol L-1)] either alone or in combined form was studied on fruits of 'Kinnow' mandarin during storage at 5 ± 1 °C for 60 days. The results exhibited that the combined AG + GABA treatment significantly suppressed weight loss (5.13 %), chilling injury (CI) symptoms (2.41 score), incidence of disease (13.33 %), respiration rate [(4.81 µmol kg-1 h-1) RPR] and ethylene production [(0.86 nmol kg-1 h-1) EPR]. In addition, AG + GABA application reduced relative electrolyte (37.89 %) leakage (REL), malondialdehyde [(25.99 nmol kg-1) MDA], superoxide anion [(15.23 nmol min-1 kg-1) O2•-] and hydrogen peroxide [(27.08 nmol kg-1) H2O2] along with lower lipoxygenase [(23.81 U mg-1 protein) LOX] and phospholipase D [(14.07 U mg-1 protein) PLD] enzyme activities compared with control. The AG + GABA treated 'Kinnow' group showed higher glutamate decarboxylase [(43.18 U mg-1 protein) GAD] and lower GABA transaminase [(15.93 U mg-1 protein) GABA-T] activity having higher endogenous GABA (42.02 mg kg-1) content. The fruits treated with AG + GABA exhibited higher cell walls (CW) components such as Na2CO3-soluble pectin [(6.55 g kg-1) NCSP], chelate-soluble pectin [(7.13 g kg-1) CSP] and protopectin [(11.03 g kg-1) PRP] concentrations along with lower water-soluble pectin [(10.64 g kg-1) WSP] compared to control. In addition, 'Kinnow' fruits treated with AG + GABA showed higher firmness (8.63 N) and lower activities of CW degrading such as cellulase [(11.23 U mg-1 protein) CX], polygalacturonase [(22.59 U mg-1 protein) PG], pectin methylesterase [(15.61 U mg-1 protein) PME] and ß-galactosidase [(20.64 U mg-1 protein) ß-Gal] enzymes. The activity of catalase [(41.56 U mg-1 protein) CAT], ascorbate peroxidase [(55.57 U mg-1 protein) APX], superoxide dismutase [(52.93 U mg-1 protein) SOD] and peroxidase [(31.02 U mg-1 protein) POD] was also higher in combined treatment. In addition, AG + GABA treated fruits showed better biochemical and sensory attributes than the control. So, combined AG + GABA could be used for CI mitigation and storage life prolongation of 'Kinnow' fruits.

Enhancement of Salinity Stress Tolerance in Lettuce (Lactuca sativa L.) via Foliar Application of Nitric Oxide.

Salt stress negatively affects the growth, development, and yield of horticultural crops. Nitric oxide (NO) is considered a signaling molecule that plays a key role in the plant defense system under salt stress. This study investigated the impact of exogenous application of 0.2 mM of sodium nitroprusside (SNP, an NO donor) on the salt tolerance and physiological and morphological characteristics of lettuce (Lactuca sativa L.) under salt stress (25, 50, 75, and 100 mM). Salt stress caused a marked decrease in growth, yield, carotenoids and photosynthetic pigments in stressed plants as compared to control ones. Results showed that salt stress significantly affected the oxidative compounds (superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX)) and non-oxidative compounds (ascorbic acid, total phenols, malondialdehyde (MDA), proline, and H2O2) in lettuce. Moreover, salt stress decreased nitrogen (N), phosphorous (P), and potassium ions (K+) while increasing Na ions (Na+) in the leaves of lettuce under salt stress. The exogenous application of NO increased ascorbic acid, total phenols, antioxidant enzymes (SOD, POD, CAT, and APX) and MDA content in the leaves of lettuce under salt stress. In addition, the exogenous application of NO decreased H2O2 content in plants under salt stress. Moreover, the exogenous application of NO increased leaf N in control, and leaf P and leaf and root K+ content in all treatments while decreasing leaf Na+ in salt-stressed lettuce plants. These results provide evidence that the exogenous application of NO on lettuce helps mitigate salt stress effects.

Tragacanth gum coating suppresses the disassembly of cell wall polysaccharides and delays softening of harvested mango (Mangifera indica L.) fruit.

Mango is a climacteric fruit and is prone to high perishability. The rapid softening and ripening (due to degradation and disassembly of cell wall polysaccharides) are the major limitations in extending the storability of the harvested mango fruits. Various types of gum-based edible coatings have been reported for the shelf life extension of mango fruits. Tragacanth gum (TCG) also has appropriate coating properties. Its use as an edible coating has been reported on certain fruits. However, the effect of TCG coating in the regulation of harvested mango fruits ripening and softening has not been reported yet. So, the objective of this work was to investigate the effect of TCG (control, 0.5 %, 1 % and 1.5 %) coating on postharvest softening and ripening of harvested mango fruits. TCG coating affected the ripening and softening of mango in a dose-dependent manner. Results exhibited that mango fruits coated with 1.5 % TCG showed substantially lower disease incidence and weight loss. The 1.5 % TCG-coated mangoes showed substantially lower ethylene biosynthesis and respiration rate peaks as well as superoxide anion and hydrogen peroxide contents compared with the control. In the same way, 1.5 % TCG-coated mango fruits had markedly higher total chlorophyll content and lower L*, b* and a* along with substantially lower total carotenoids in peel tissues. Mango fruits coated with 1.5 % TCG exhibited markedly lower water-soluble pectin and higher chelate-soluble pectin, Na2CO3-soluble pectin, protopectin, cellulose and hemicellulose in flesh tissues compared with control. The activity of polygalacturonase (PG), cellulase (CX), pectin methylesterase (PME), ß-galactosidase (ß-Gal) and ß-glucosidase (ß-Glu) were significantly lower in flesh of 1.5 % TCG treated fruits along with substantially higher firmness in contrast with control. In addition, 1.5 % TCG coating treatment showed significantly higher activity of antioxidative enzymes and delayed the increase in soluble solids content (SSC) and ripening index (RI) along with considerably higher titratable acidity (TA) compared with the untreated control. So, pre-storage TCG based edible coating (1.5 %) could be applied to delay ripening and softening in mango fruit industry under postharvest ambient conditions.

Hydrogen Sulfide Mitigates Chilling Injury of Postharvest Banana Fruits by Regulating γ-Aminobutyric Acid Shunt Pathway and Ascorbate-Glutathione Cycle.

This study aimed to determine the effect of hydrogen sulfide on chilling injury (CI) of banana (Musa spp.) during cold storage (7°C). It was observed that hydrogen sulfide application (2 mmol L-1) markedly reduced the CI index and showed significantly higher chlorophyll contents, along with suppressed chlorophyll peroxidase and chlorophyllase enzyme activity. The treated banana fruits exhibited substantially higher peel lightness (L*), along with significantly a lower browning degree and soluble quinone content. The treated bananas had substantially a higher endogenous hydrogen sulfide content and higher activity of its biosynthesis-associated enzymes such as D-cysteine desulfhydrase (DCD) and L-cysteine desulfhydrase (LCD), along with significantly lower ion leakage, lipid peroxidation, hydrogen peroxide, and superoxide anion concentrations. Hydrogen sulfide-treated banana fruits showed an increased proline content and proline metabolism-associated enzymes including ornithine aminotransferase (OAT), Δ1-pyrroline-5-carboxylate synthetase (P5CS), and proline dehydrogenase (PDH). In the same way, hydrogen sulfide-fumigated banana fruits accumulated higher endogenous γ-aminobutyric acid (GABA) due to enhanced activity of glutamate decarboxylase (GAD) and GABA transaminase (GABA-T) enzymes. The hydrogen sulfide-treated fruits exhibited higher total phenolics owing to lower polyphenol oxidase (PPO) and peroxidase (POD) activity and stimulated phenylalanine ammonia lyase (PAL). The treated banana exhibited higher ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR), and superoxide dismutase (SOD) activity, along with higher glutathione (GSH) and ascorbic acid (AsA) concentrations and a significantly lower dehydroascorbic acid (DHA) content. In conclusion, hydrogen sulfide treatment could be utilized for CI alleviation of banana fruits during cold storage.

Melatonin: First-line soldier in tomato under abiotic stress current and future perspective.

Melatonin is a natural, multifunctional, nontoxic, regulatory, and ubiquitous biomolecule, having low molecular weight and pleiotropic effects in the plant kingdom. It is a recently discovered plant master regulator which has a crucial role under abiotic stress conditions (salinity, drought, heat, cold, alkalinity, acid rain, ozone, and metals stress). In the solanaceous family, the tomato is highly sensitive to abiotic stresses that affect its growth and development, ultimately hampering production and productivity. Melatonin acts as a strong antioxidant, bio-stimulator, and growth regulator, facilitating photosynthesis, delaying leaf senescence, and increasing the antioxidant enzymes system through direct scavenging of reactive oxygen species (ROS) under abiotic stresses. In addition, melatonin also boosts morphological traits such as vegetative growth, leaf photosynthesis, root architecture system, mineral nutrient elements, and antioxidant activities in tomato plants, confirming their tolerances against salinity, drought, heat, cold, alkalinity, acid rain, chemical, pathogen, and metals stress. In this review, an attempt has been made to summarize the potential role of melatonin for tomato plant endurance towards abiotic stresses, along with the known relationship between the two.

Foliar application of ascorbic acid enhances growth and yield of lettuce (Lactuca sativa) under saline conditions by improving antioxidant defence mechanism.

Lettuce (Lactuca sativa L.) production is low because of different environmental stresses. Salt stress significantly reduces lettuce growth and yield. Foliar application of ascorbic acid is considered as a possible way to mitigate the adverse salinity effects on plants. This current study investigated the effect of foliar spray of ascorbic acid (control, 100, 200, 300 and 400mg/L) to mitigate negative effects of salinity (0, 50, 100 and 150mMNaCl) in lettuce plants in 2019 and 2020. Salinity level of 200mMNaCl significantly reduced growth and yield traits; i.e. leaf length and diameter, number of leaves, fresh plant weight, number of roots, root length and root dry weight and these traits increased under foliar application of ascorbic acid concentration of 400mg/L. Two salinity levels (150 and 200mMNaCl)×400mg/L ascorbic acid enhanced superoxide dismutase (SOD) content in lettuce plants. Peroxidase (POD) content increased in 200mMNaCl and 400mg/L ascorbic acid. Catalase (CAT) content increased in 100, 150 and 200mMNaCl and 400mg/L ascorbic acid. Ascorbic acid was significantly greater in 200mMNaCl and 400mg/L ascorbic acid. Phenolic content was the maximum in 200mMNaCl and 300mg/L and 400mg/L ascorbic acid. Titratable acidity was higher in 0, 50, 100, 150 and 200mMNaCl and control of ascorbic acid. We conclude that ascorbic acid had potential to mitigate the adverse effects of salinity by reducing oxidative injury in agricultural crops especially lettuce.

Tolerance and adaptation mechanism of Solanaceous crops under salinity stress.

Solanaceous crops act as a source of food, nutrition and medicine for humans. Soil salinity is a damaging environmental stress, causing significant reductions in cultivated land area, crop productivity and quality, especially under climate change. Solanaceous crops are extremely vulnerable to salinity stress due to high water requirements during the reproductive stage and the succulent nature of fruits and tubers. Salinity stress impedes morphological and anatomical development, which ultimately affect the production and productivity of the economic part of these crops. The morpho-physiological parameters such as root-to-shoot ratio, leaf area, biomass production, photosynthesis, hormonal balance, leaf water content are disturbed under salinity stress in Solanaceous crops. Moreover, the synthesis and signalling of reactive oxygen species, reactive nitrogen species, accumulation of compatible solutes, and osmoprotectant are significant under salinity stress which might be responsible for providing tolerance in these crops. The regulation at the molecular level is mediated by different genes, transcription factors, and proteins, which are vital in the tolerance mechanism. The present review aims to redraw the attention of the researchers to explore the mechanistic understanding and potential mitigation strategies against salinity stress in Solanaceous crops, which is an often-neglected commodity.

Melatonin Improves Drought Stress Tolerance of Tomato by Modulating Plant Growth, Root Architecture, Photosynthesis, and Antioxidant Defense System.

Tomato is an important vegetable that is highly sensitive to drought (DR) stress which impairs the development of tomato seedlings. Recently, melatonin (ME) has emerged as a nontoxic, regulatory biomolecule that regulates plant growth and enhances the DR tolerance mechanism in plants. The present study was conducted to examine the defensive role of ME in photosynthesis, root architecture, and the antioxidant enzymes' activities of tomato seedlings subjected to DR stress. Our results indicated that DR stress strongly suppressed growth and biomass production, inhibited photosynthesis, negatively affected root morphology, and reduced photosynthetic pigments in tomato seedlings. Per contra, soluble sugars, proline, and ROS (reactive oxygen species) were suggested to be improved in seedlings under DR stress. Conversely, ME (100 µM) pretreatment improved the detrimental-effect of DR by restoring chlorophyll content, root architecture, gas exchange parameters and plant growth attributes compared with DR-group only. Moreover, ME supplementation also mitigated the antioxidant enzymes [APX (ascorbate peroxidase), CAT (catalase), DHAR (dehydroascorbate reductase), GST (glutathione S-transferase), GR (glutathione reductase), MDHAR (monodehydroascorbate reductase), POD (peroxidase), and SOD (superoxide dismutase)], non-enzymatic antioxidant [AsA (ascorbate), DHA (dehydroascorbic acid), GSH (glutathione), and GSSG, (oxidized glutathione)] activities, reduced oxidative damage [EL (electrolyte leakage), H2O2 (hydrogen peroxide), MDA (malondialdehyde), and O2•- (superoxide ion)] and osmoregulation (soluble sugars and proline) of tomato seedlings, by regulating gene expression for SOD, CAT, APX, GR, POD, GST, DHAR, and MDHAR. These findings determine that ME pretreatment could efficiently improve the seedlings growth, root characteristics, leaf photosynthesis and antioxidant machinery under DR stress and thereby increasing the seedlings' adaptability to DR stress.

Incorporation of ascorbic acid in chitosan-based edible coating improves postharvest quality and storability of strawberry fruits.

Recent postharvest studies have shown that adding an antioxidative agent in a polysaccharide-based edible coating reduces postharvest losses and extends the shelf life of a coated fruit. Therefore, the effect of addition of ascorbic acid (AA, 1%) in chitosan-based coating (CH, 1%) on strawberry fruits under cold storage conditions at 4 ± 1 °C and 85 ± 5% RH was investigated for 15 days. It was observed that addition of AA in CH coating reduced weight loss, decay percentage, malondialdehyde content and hydrogen peroxide compared to CH alone. The combined CH + AA application also suppressed fruit softening by reducing cell wall degrading enzymes (i.e. polygalacturonase, cellulase and pectin methyl esterase) activities. In addition, AA incorporation catalyzed ROS scavenging enzymes (i.e. ascorbate peroxidase, catalase, peroxidase and superoxide dismutase) activities. CH + AA treatment also maintained fruit quality by conserving higher total soluble solids, titratable acidity, ascorbic acid content, total phenolics and antioxidant activity. Sensory quality (color, taste, glossiness and overall acceptability) of fruits coated with CH + AA treatment was also stable during storage. Conclusively, the combined CH + AA application is an effective approach to maintain the postharvest quality of strawberry fruits under cold storage.

Sewage wastewater reclamation with sand column filter and reduction of heavy metal accumulation in tomato and okra.

Heavy metal accumulation has much increased in edible parts of fresh fruits and vegetables due to use of industrial waste/effluent, and wastewater. In the current work, sewage wastewater was reclaimed through a column filled with sand having a mesh size of 0.5 mm and its effect was investigated on concentration of different heavy metals, vegetative growth, and yield of okra and tomato. The use of unfiltered sewage wastewater (UFSW) had considerably higher concentrations of heavy metals but it substantially increased plant height, leaf number, and leaf area in both okra and tomato plants in contrast to filtered sewage wastewater (FSW). The application of UFSW resulted in a significantly higher accumulation of lead (Pb), nickel (Ni), iron (Fe), and copper (Cu) in roots and edible parts of okra and tomato as compared with FSW treatment. However, FSW and UFSW did not significantly influence concentrations of chromium (Cr) and cadmium (Cd) in roots and edible parts of both okra and tomato. In conclusion, sand column filtration technique could be efficiently used for the reclamation of sewage wastewater, and reduction of various heavy metals present in sewage wastewater-irrigated crops.

Combined application of ascorbic and oxalic acids delays postharvest browning of litchi fruits under controlled atmosphere conditions.

The effect of ascorbic acid [AA (40 mmol L-1)] and oxalic acid [OA (2 mmol L-1)] on browning of litchi fruit was investigated under 5% CO2 + 1% O2 controlled atmosphere (CA) and compared with air at 5 ± 1 °C for 28 days. The combined application of AA and OA suppressed browning index, soluble quinones, and activities of polyphenol oxidase and peroxidase under CA compared with control. The combination of CA along with AA + OA reduced weight loss and maintained higher anthocyanins, total phenolics, membrane integrity, ascorbate peroxidase, catalase, glutathione reductase and superoxide dismutase activities compared with control. In addition, AA + OA + CA combination showed markedly lower malondialdehyde, superoxide anion and hydrogen peroxide with substantially higher soluble solids content, ascorbic acid, titratable acidity and sensory quality compared with control. In conclusion, AA + OA combination could be considered appropriate to delay browning and to conserve litchi fruit visual appearance under CA storage conditions.

Effect of gum arabic coating on antioxidative enzyme activities and quality of apricot (Prunus armeniaca L.) fruit during ambient storage.

The effect of gum arabic (GA) coating was studied on apricot fruit at 20 ± 1°C for 8 days. GA coating substantially reduced weight loss, disease incidence, malondialdehyde concentration, and hydrogen peroxide compared to the control. GA coating resulted in significantly higher total phenols, ascorbic acid, and antioxidant activity in contrast to the control. GA coating also suppressed cellulase, pectin methylesterase, and polygalacturonase activity in contrast to the non-coated fruit. In addition, GA-coated apricot fruit had substantially higher catalase, peroxidase, ascorbate peroxidase, and superoxide dismutase enzymes activities in contrast with the control. Similarly, GA coating inhibited soluble solids content increase and inhibited the reduction in titratable acidity in coated fruit. The fruit coated with GA coating also had significantly better sensory and overall eating quality compared to the control apricots. In conclusion, GA could be considered an appropriate edible coating for quality conservation of apricots. PRACTICAL APPLICATIONS: Apricot is a well renowned and nutrients rich fruit. However, apricot has comparatively short shelf life potential due to its susceptibility to rapid senescence and deterioration under ambient conditions. GA is an eco-friendly and biodegradable coating which is considered relatively cheap as compared with other coating types. In our present work, application of gum arabic [GA (10%)] edible coating maintained significantly higher quality of harvested apricot fruit as compared with the control. The outcomes of the present work are of global significance with respect to apricot industry. So, GA coating could be considered an appropriate edible coating for quality conservation of the harvested apricot fruit.

Tragacanth gum coating modulates oxidative stress and maintains quality of harvested apricot fruits.

Tragacanth gum is a polysaccharide-based complex with a good coating property. However, its use in postharvest storage of fresh fruits and vegetables is very limited. In the current work, the effect of tragacanth gum (1%) was investigated on postharvest quality of apricot fruits during storage at 20 ± 1 °C for 8 days. Apricot fruits coated with tragacanth gum coating showed significantly reduced weight loss, decay and electrolyte leakage, hydrogen peroxide and malondialdehyde production. Tragacanth gum coating suppressed increase in total soluble solids and showed higher titratable acidity compared with control. The coated fruits had higher total phenolics and ascorbic acid along with greater 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity in contrast with control. Postharvest application of tragacanth gum coating maintained markedly higher activities of ascorbate peroxidase (APX), catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD) enzymes activities as compared with control. In addition, tragacanth gum application suppressed polygalacturonase (PG), pectin methylesterase (PME), and cellulase (CX) enzymes activities, thereby suppressed softening of apricot fruits. Sensory quality attributes such as taste, juiciness, aroma, appearance, and overall acceptability were also significantly higher in tragacanth gum coated fruits compared with control. In conclusion, tragacanth gum coating could be considered suitable for postharvest quality conservation of apricot fruits.