Study on the effect of prawn (Machrobrachuim rosenbergii) chitosan coating on peeled shallot (Allium ascalonicum)

Abstract

Shallot (Allium ascalonicum) is the most important commercial vegetable crop grown in India. Shallot peeling is tough and consumes time. The availability of peeled shallots in markets will reduce the time consumed on peeling shallots for cooking. But peeled shallot does not have longer shelf life. Edible coating for peeled shallots can reduce spoilage and can inhibit microbial growth too. The Chitosan coating of shallots was based on the dipping method of coating fruits and vegetables. The study on coating chitosan in shallots and different parameters with varying composition were analyzed. The physio-chemical parameters like protein content, carbohydrate content, calcium content and total phenols content and weight loss shows that there is a significant difference with coated and uncoated Shallot stored at 4°C for a period of 15 days. The microbial studies and physical characteristic studies show that number of microbes and decay is significantly less for coated onion samples compared with uncoated samples respectively. The inhibitory effect of chitosan produced from prawn shell against fungi was studied by adding 0.2% oregano oil, 0.4% of Tween 80 (polysorbate 80) and 0.7% of Glycerol. The Zone of inhibition was obtained has which were found to be 3.1cm, 1.5cm and 2.9cm for Oregano (Or), Thyme (Th) and Mint (M) leaves. Addition of 0.1% Tween 80 to 1.5 % chitosan in acetic acid solution improved the effectiveness of coating on the Shallot skin. The above study revealed that Chitosan coatings were in effect on successful quality improvement and extending shelf life of Shallot by delayed ripening, lowered respiration rate, regulated gas exchange, decrease in transpiration rate, retaining fruit firmness, reduction in weight loss etc.