Almond gum based hydrocolloid coating delays surface reddening and suppresses softening of harvested jujube ( Ziziphus mauritiana L.) fruit

Freshly harvested jujube fruit is prone to prompt surface reddening thereby resulting in rapid ripening and senescence. In the current study, fruit were treated with almond gum (10 %) and stored for 15 days (d) at 20 +/- 1 degrees C to investigate the impact of said edible coating on the ripening and softening of jujube. It was observed that almond gum application inhibited loss in physiological weight and reduced rotting rate concomitant with higher chlorophyll contents along with lower surface reddening and total anthocyanins accumulation. The almond gum treatment showed reduced oxidative stress related indicators as well as preserved membrane integrity and suppressed accumulation of malondialdehyde (MDA). In the same way, metabolic activities such as respiration rate and ethylene production were substantially suppressed which in turn resulted in reduced increase in the activity of cellulase (CX), pectin methylesterase (PME), R-galactosidase (R-gal) and polygalacturonase (PG) enzymes. The delayed increase in hydrolase enzymes activity in almond gum coated fruit ultimately resulted in higher firmness as well as CDTA-soluble pectin (CSP), Na2CO3 soluble pectin (NSP), protopectin (PRN), hemicellulose and cellulose along with reduced content of water soluble pectin (WSP). In addition, almond gum treatment was also effective in suppressing the decline in ascorbic acid content and titratable acidity (TA) and delaying the prompt increase in total soluble solids (TSS) and ripening index (RI) along with better sensory quality. In conclusion, almond gum could be used to delay softening of fresh jujube fruit during storage.