Postharvest storage and quality management of citrus cvv. Kinnow mandarin (Citrus nobilits Lour. X Citrus delicious tenora)".

Abstract

Citrus is an important fruit crop of world as well as in Pakistan. It is very rich source of vit.C along with sugars and minerals. Citrus fruits also contain bioactive compounds in juice i.e., flavonoids, polyphenols, carotenoids and antioxidants which help to reduce risk of cancer and cardiovascular diseases in human. After harvesting and storage, some internal changes continue which deteriorate fruit quality by affecting the nutritional status of fruits and heavy losses occur. Some pre storage treatments slow down these changes therefore research project was planned to investigate the effects of different techniques (radiation, wax and salicylic acid) on fruit quality of citrus cv. ‘Kinnow’ mandarin under cold storage (5°C). A series of experiments were executed and first two experiments were carried out to investigate the effects of different radiation doses (0-1000 Gy) on fruit quality of ‘Kinnow’ during 90 days. It was observed that 800 Gy radiation treatments effectively minimized the fruit decay 25 to 11% after 90 days of storage. Minimum weight loss (11.44%), SSC: Acid ratio (8.56) maximum total phenolic contents (147.45 mg GAE 100g-1), total antioxidants (63.98% % inhibition) POD (0.70 U mg-1 protein) and SOD (112.1 U mg-1 protein) were also found in fruits of same treatment. In 3rd experiment, two local fruit coatings (PHRC wax and benzaldehyde) were compared with two commercial waxes and found that PHRC wax performed at par to commercial waxes to minimize fruit decay during 90 days storage. PHRC wax also maintained peel: pulp ratio (1.64) and SSC: Acid ratio (9.26) in optimum range with higher values of total phenolic contents (230.62), total antioxidants (62.10), CAT (15.26), POD (0.68) and SOD (131) after 90 days. Two experiments were conducted to optimize a best level of SA (2-12 mM) and it was found that 4 mM performed best to minimize the fruit rot from 23-4%, weight loss from28-16% with higher values of SSC: Acid ratio (9.11), total phenolic contents (185.58 mg GAE 100g-1), antioxidants (58.99%), CAT (19.2 U mg-1 protein), POD (0.6 U mg-1 protein) and SOD (123.49 U mg-1 protein). Comparison of radiation, wax coating and salicylic acid showed that treatment of pre storage treatment with SA was found best to minimize fruit rot (2%) with maximum TPC (253.99 mg GAE 100g-1 FW), antioxidants (77.38%), CAT (17.71 Umg-1 protein), POD (0.67 Umg-1 protein ) and SOD (123.46 Umg-1 protein) after 90 days storage. It is concluded that ‘Kinnow’ fruits can be stored for 90 days at 5°C with pre-storage treatment of 4 mM SA to maintain the fruit quality.