Shelf life of Khasi mandarin (Citrus reticulata Blanco) fruits as influenced by plant extracts, essential oils and natural coatings

Abstract
The experiment was conducted during 2017-18 in the Post-harvest laboratory of the Department of Horticulture and Department of Plant Pathology, Assam Agricultural University, Jorhat. The objective of this investigation was to study the effect of plant extracts, essential oils and natural coatings on shelf life of Khasi mandarin fruits and also to determine the physico- chemical and organoleptic changes during storage. The experiment was taken up in two parts .In the first experiment in vitro pathological study was taken up to test the effect of selected plant extracts and essential oils against Penicillium digitatum (green mold). The results of in vitro studies revealed that, out of the various plant extracts 100% inhibition of Penicillium digitatum was observed in Neem extract and cinnamon extract treatments. Similarly amongst the oils, clove oil, Thyme oil and lemongrass essential oil showed maximum inhibition (100%) of the fungi. The two of the best plant extracts and essential oils were selected for next experiment. In the second Experiment, Khasi mandarin fruits were treated with two best Plant extracts and essential oils (as obtained in the first experiment) alone or in combination with two natural coatings viz. Aloe vera gel and chitosan. After the treatment the fruits were wrapped in perforated 50 micron polyethylene bags and stored under ambient condition and various physicochemical and sensory evaluations were taken up across the storage period. The results revealed that during 20 days of storage period maximum decay loss was observed in the control treatment. On the other hand fruits treated with Bavistin, Neem extract and combination of Aloe vera gel + Neem extract treatments, no decay loss was observed during the 20 days of storage period. As regard the number of days taken for 50% decay of fruits; it was observed that the fruits treated with Bavistin treatment took the maximum number of days for 50% decay of fruits i.e.35 days followed by Neem extract treatment (33.66 days) and combination of Aloe vera gel + Neem extract (29.33days) treatments. Though Bavistin treatment recorded higher values with respect to physic-chemical and sensory evaluation; there was no significant difference between the Bavistin treatment and Neem extract treatment and also with the combination of Aloe vera gel (1%)+ Neem extract(10%) (in some of the observations). Since plant extracts are environment friendly and do not leave any chemical residue as against use of chemical fungicides (like Bavistin), use of Neem leaf extract and combination of Aloe vera gel (0.1%) + Neem extract(10%) can be advocated for enhancing shelf life of Khasi mandarin fruits.
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