LAUSR

Abstract Postharvest chilling injury (CI) of 'Baladi' mandarin is related to the activity of antioxidant enzyme activities (AEAs) during cold storage. The performance of pectin/polyvinyl-alcohol (PC/PVA) blending in ascorbic acid (AA) to increase storability tolerance of mandarin fruit under cold otherwise the impacts of PC/PVP-AA on antioxidant enzymes were assessed. The mandarins were harvested manually from trees aged-8-years on April 15th when the fruits reached commercial maturity stage. Fruit were coated with PC/PVA biopolymer with AA at the different concentration (0, 3, 6 and 9 mM). The experiment was conducted during two growth seasons (2017–2018). Fruits coated by PC/PVA-AA for 20 min and stored at low temperature (4 ± 1 °C and 95 ± 1% RH) for 60 days. The studies were distinguished within a pair of groups: physical and chemical assessments. The physical measurements chilling injury index (CI-index), weight loss%, and mandarin peel color profile (lightness, Chroma, Hue) were monitored. However, the chemical analysis for instance soluble solid content (SSC%), titratable acidity (TA%), SSC/TA-ratio, for evaluating mandarin fruit maturity were estimated. The AEAs were evaluated: ascorbate peroxidase (APX), catalase (CAT), granulation reductase (GR), and superoxide dismutase (SOD). Plus, malondialdehyde (MDA), and cell membrane ion leakage (IL%) were considered. Further, the O2 and H2O2 production rate were measured beside the scavenging activity and inhibition (DPPH and ABTs). Results indicate that the coated mandarin by PC/PVA-AA 9 mM exhibited less CI. Also, it forced AEAs in activities much more compared to other treatments. Moreover, it reduced the formation of O2• radical and H2O2 and more scavenging activities (DPPH and ABTs) during cold storage. Therefore, the coating treatment PC/PVA-AA 9 mM for mandarin fruits provided more tolerant to cold storage stress.