Development of functional edible coating(s) for fresh fruits and vegetables
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Date
2015
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CCSHAU
Abstract
The present investigation was carried to develop functional edible coatings to improve shelf life of ber, guava, cucumber and brinjal. Edible coatings of 12 types, four types each of polysaccharide
(starch, methyl-cellulose, hydroxy-propyl-methyl-cellulose and chitosan), protein (gluten, soyprotein, whey protein concentrate and zein) and lipid (bee wax, paraffin wax, olive oil and mustard oil), each in two different concentrations were prepared and analysed for their water vapour transmission rate (WVTR), gas (O2 and CO2) permeability and viscosity. The best edible coating screened for respective fruit/vegetable on the basis of screening parameters was used further for development of functional edible coating by incorporating functional ingredients viz., texture enhancers, antioxidants, antisenescent and antimicrobials. The influence of functional edible coatings on fresh fruits and vegetables was studied under room temperature and low temperature storage conditions on the basis of evaluation of physiological, biochemical parameters, enzymatic activity, surface microbial count and organoleptic qualities.
It was observed that chitosan based coating with composition of 1% chitosan+ 2% calcium gluconate + 0.2% + 100ppm Kinetin + 1.5% tulsi extract; olive oil based coating with composition of 5
% olive oil + 2% calcium chloride + 0.2% tocopherol + 200ppm Kinetin + 1 % tulsi extract; bee wax based coating with composition of 6 % bee wax + 2% calcium chloride + 0.5 % tocopherol + 100ppm
Kinetin + 1.0 % tulsi extract; and olive oil based coating with composition of 10% olive oil + 2% calcium gluconate + 0.2% tocopherol + 200 ppm kinetin + 1.0% tulsi extract were developed as the most effective functional edible coatings for guava, ber, cucumber and brinjal, respectively. During storage study, coated fruits and vegetables showed significantly reduced PLW, ripening, decay loss, enzymatic activity, respiration rate and total surface microflora as compared to control, both at RT and LT conditions. Moreover, there was significantly better retention of firmness, total soluble solids (TSS), acidity, ascorbic acid, total chlorophyll, total carotenoids and pectin in coated fruits and vegetables. Whereas, there were no significant differences in total sugars, total phenols, ethylene production rate, ethanol and acetic acid content of coated and uncoated fruits and vegetables, both at RT and LT storage conditions. The application of respective functional edible coating enhanced the shelf life of guava by 4 days at RT and 8 days at LT conditions, ber by 4 days both at RT and LT conditions, cucumber by 2 days at RT and 4 days at LT conditions, and brinjal by 2 days at RT and 4 days at LT storage conditions.
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Keywords
fruits, storage, polysaccharides, acidity, proteins, vegetables, cucumbers, guavas, application methods, vitamins