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.

Postharvest Biology and Technology of Loquat (Eriobotrya japonica Lindl.).

Loquat (Eriobotrya japonica Lindl.) fruit is a rich source of carotenoids, flavonoids, phenolics, sugars, and organic acids. Although it is classified as a non-climacteric fruit, susceptibility to mechanical and physical bruising causes its rapid deterioration by moisture loss and postharvest decay caused by pathogens. Anthracnose, canker, and purple spot are the most prevalent postharvest diseases of loquat fruit. Cold storage has been used for quality management of loquat fruit, but the susceptibility of some cultivars to chilling injury (CI) consequently leads to browning and other disorders. Various techniques, including cold storage, controlled atmosphere storage, hypobaric storage, modified atmosphere packaging, low-temperature conditioning, heat treatment, edible coatings, and postharvest chemical application, have been tested to extend shelf life, mitigate chilling injury, and quality preservation. This review comprehensively focuses on the recent advances in the postharvest physiology and technology of loquat fruit, such as harvest maturity, fruit ripening physiology, postharvest storage techniques, and physiological disorders and diseases.

Peelu (Salvadora oleoides Decne.): An Unexplored Medicinal Fruit with Minerals, Antioxidants, and Phytochemicals.

The Peelu (Salvadora oleoides Decne.) fruit is well known for its nutritional and medicinal values. The current study analyzed the chemical composition of Salvadora oleoides fruit. Fresh Peelu fruits were harvested, and physicochemical properties, proximate composition, macro- and micronutrients, and phytochemical properties were determined. Moreover, ethanol and methanol fruit extract was analyzed for physicochemical properties. The Peelu fruit seemed to be a potential source of essential macro- ((nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg)) and micronutrients (zinc (Zn), manganese (Mn), iron (Fe), and copper (Cu)). The fruit had significant biochemical properties (total soluble solids (TSS), total acidity (TA), and TSS : TA ratio) with appreciable moisture, crude fiber, and ash contents. The fruit extracts demonstrated significantly higher antioxidants and phenolics, ascorbic acid contents, and carotenoids. Phytochemical screening of fruit revealed the presence of coumarins, flavonoids, phlobatannins, tannins, and terpenoids. Physicochemical and sensory evaluation of extracts indicated its potential for further in vivo study trials. The Peelu fruit was found to be a good source of mineral nutrients, proximate contents, vitamins (ascorbic acid and carotenoid), phytochemicals (total phenolic sand antioxidant contents), and pharmaceutically important metabolites that can be used as functional drink.

Potential of Aloe vera gel coating for storage life extension and quality conservation of fruits and vegetables: An overview.

Aloe vera (ALV) with its unique nutritional profile is being used for food, health, and nutraceutical industries globally. Due to its organic nature, ALV gel coating has created lot of interest for exploring its potential in extending the shelf and storage life of fresh produce. ALV gel coating plays imperative role in delaying fruit ripening by lowering ethylene biosynthesis, respiration rate, and internal metabolic activities associated with fruit softening, color development, enzymatic browning, and decay. ALV gel coating reduces the microbial spoilage due to its antifungal properties and maintains visual appearance, firmness, sugar: acid ratio, total antioxidants, and phenolic contents with conserved eating quality. ALV coated fruits and vegetables showed reduced weight loss, superoxide ion ( O2-∙ ), hydrogen peroxide (H2 O2 ), ion leakage, and soluble solids content and exhibited higher acidity, anthocyanins, ascorbic acid, catalase (CAT), superoxide dismutase (SOD), and ascorbate peroxidase (APX) activities. It also delayed the enzymatic browning by inducing peroxidase (POD) activity during storage. Recent local studies also revealed that ALV gel coating markedly conserved higher consuming quality and extended storage period (>1.34-fold) of different fruits and vegetables. Overall, Aloe vera gel coating alone or in combination with other organic compounds has shown great potential as a food-safe and eco-friendly coating for maintaining the quality of fruits and vegetables over extended period and reducing postharvest losses in the supply chain. PRACTICAL APPLICATIONS: ALV gel is a plant-based natural coating of eco-friendly nature. The present review summarizes the updated information of ALV gel coating application, methods of extraction, combinations with other postharvest coatings, and its impact on quality of various fruits and vegetables. It also provides future insights for the development of commercially applicable ALV gel coating protocols through simulation studies. So, being a natural coating, ALV gel has tremendous potential to be used in fruit and vegetable industries around the globe.

Effect of postharvest oxalic acid application on enzymatic browning and quality of lotus (Nelumbo nuciferaGaertn.) root slices.

Post-cut surface browning is one of the major constraints for shelf-life extension of lotus root slices. In the present study, lotus roots slices were treated with 0, 5 and 10 mmol L-1 oxalic acid and stored at 20 ± 1 °C for 5 days. Results showed that 10 mmol L-1 oxalic acid treated lotus slices exhibited reduced browning, superoxide anion, hydrogen peroxide, electrolyte leakage and malondialdehyde content than control. The 10 mmol L-1 treated slices had better visual quality and higher ascorbic acid and total phenolic contents. In addition, 10 mmol L-1 treated slices showed reduced total bacterial count along with lower soluble quinones, peroxidase and polyphenol oxidase activities in contrast to control. Similarly, 10 mmol L-1 treatment showed higher superoxide dismutase, catalase and ascorbate peroxidase activities as compared to control. In conclusion, 10 mmol L-1 oxalic acid application could be considered suitable to delay post-cut browning of lotus root slices.

Postharvest application of antibrowning chemicals modulates oxidative stress and delays pericarp browning of controlled atmosphere stored litchi fruit.

Litchi fruit were treated with methionine [(0.25%) MN] and cysteine [(025%) CN] alone or in combination, and kept under 1% O2 + 5% CO2 controlled atmosphere (CA) at 5 ± 1ºC for 28 days. Among different treatments, CN was most effective to inhibit browning, than MN and CN + MN under CA conditions. Application of 0.25% CN significantly delayed browning index, reduced disease incidence, weight loss, malondialdehyde (MDA) contents, electrolyte leakage, hydrogen peroxide (H2 O2 ), superoxide anion (O2-• ) and polyphenol oxidase (PPO) and peroxidase (POD) activities with higher contents of total anthocyanins under CA-storage. In addition, 0.25% CN treatment showed higher contents of ascorbic acid, total phenolics (TPC), and 2,2-diphenyl-1-picrylhydrazyl-radical scavenging capacity and activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT) enzymes having maintained quality attributes. Therefore, 0.25% CN pre-treatment could be considered a promising way for managing browning, and conserving litchi fruit quality under CA-storage. PRACTICAL APPLICATIONS: Litchi fruit are highly perishable due to rapid pericarp browning having limited postharvest market potential. The browning takes place due to enzymatic reactions and phenolic oxidation. However, it can be delayed by exogenous antibrowning treatments and suitable storage environment. The delayed incidence of pericarp browning may help to maintain its quality with extended storage potential suitable for domestic and international markets. So, the outcomes of the current work may help to maintain overall quality and to extend its storage potential that would be helpful in extending its market life with maintained visual quality at domestic and international destinations.

Effect of controlled atmosphere storage on pericarp browning, bioactive compounds and antioxidant enzymes of litchi fruits.

'Gola' litchi fruits were stored under ten different CA-combinations at 5±1°C to investigate its effects on pericarp browning, biochemical quality and antioxidative activities. Control fruit turned completely brown after 28days of storage and were excluded from the study. Fruit-stored under CA7-combination (1% O2+5% CO2) showed reduced weight loss, pericarp browning, membrane leakage and malondialdehyde contents. Soluble solid contents, titratable acidity and ascorbic acid contents were higher in CA7-stored fruit. Activities of catalase and superoxide dismutase enzymes, levels of total anthocyanins, DPPH radical-scavenging-activity and phenolic contents were significantly higher in CA7-stored litchi fruit. In contrast, activities of polyphenol oxidase and peroxidase enzymes were substantially lower in fruit kept under CA7-combination. Fruit subjected to CA7-conditions also maintained higher organoleptic quality. In conclusion, 1% O2+5% CO2 CA-conditions delayed pericarp browning, maintained antioxidative activities and biochemical characteristics along with better organoleptic quality of litchi fruit for 35days.

Extraction of DNA suitable for PCR applications from mature leaves of Mangifera indica L.

Good quality deoxyribonucleic acid (DNA) is the pre-requisite for its downstream applications. The presence of high concentrations of polysaccharides, polyphenols, proteins, and other secondary metabolites in mango leaves poses problem in getting good quality DNA fit for polymerase chain reaction (PCR) applications. The problem is exacerbated when DNA is extracted from mature mango leaves. A reliable and modified protocol based on the cetyltrimethylammonium bromide (CTAB) method for DNA extraction from mature mango leaves is described here. High concentrations of inert salt were used to remove polysaccharides; Polyvinylpyrrolidone (PVP) and ß-mercaptoethanol were employed to manage phenolic compounds. Extended chloroform-isoamyl alcohol treatment followed by RNase treatment yielded 950-1050 µg of good quality DNA, free of protein and RNA. The problems of DNA degradation, contamination, and low yield due to irreversible binding of phenolic compounds and coprecipitation of polysaccharides with DNA were avoided by this method. The DNA isolated by the modified method showed good PCR amplification using simple sequence repeat (SSR) primers. This modified protocol can also be used to extract DNA from other woody plants having similar problems.