thesis

Innovative edible coatings to improve storage of small fruits and fresh-cut

Abstract

Tese de doutoramento, Ciências Agrárias, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2016Edible coatings enriched with essential oils or their constituents have been studied for their effect on increasing food storage life. The objective of the present study was to find the best edible coating formulations based on polysaccharides enriched with essential oils compounds to increase storage life of small fruit and fresh-cut. In the first year of this study, edible coating formulations based on alginate and pectin enriched with citral and eugenol were tested on Arbutus unedo berries, strawberries, raspberries and fresh-cut „Bravo de Esmolfe‟apples. General quality parameters [color CIE (L*hºC*), firmness, soluble solids content (SSC), weight loss, trolox equivalent antioxidant capacity (TEAC), microbial growth and taste panels] were evaluated through cold storage. From them, two edible coatings which better preserved shelf-life for each polysaccharide (alginate and pectin) were chosen. The previous selected edible coatings were tested for cytotoxicity, then applied to the same fruit for studying their effect on nutritional and sensory parameters [color CIE (L*hºC*), firmness, soluble solids content, weight loss, microbial growth, taste panels, phenol compounds (total phenols, flavonoids, anthocyanins), sugars, organic acids, antioxidant activity (TEAC, ORAC (oxygen radical absorbance capacity) and DPPH (1,1-diphenyl-2-picrylhydrazyl) and taste panels]. Ethylene and CO2 production as well as ethanol and acetaldehyde were also measured. The edible coating which better preserved fruit quality while increasing storage life was selected for commercial recommendation. Those were for arbutus berries alginate 1% + eugenol 0.1% + citral 0.15%, for fresh-cut „Bravo de Esmolfe‟ apple was alginate 2% + eugenol 0.1% plus dip in ascorbic acid, strawberries was alginate 2% + citral 0.15 % + eugenol 0.1% and for raspberrieswas pectin 1% + citral 0.15%+ eugenol 0.1%

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