Development and application on strawberries of edible coatings based on yam and corn starch added with Rio Grande cherry

Abstract

This work aimed to evaluate the properties of biofilms based on corn and yam starch incorporated with Rio Grande cherry (Eugenia involucrata DC) and its encapsulates and use them as a coating on strawberries. The extraction of phenolic compounds from the Rio Grande cherry was optimized, and total flavonoids, antioxidant, and antimicrobial activity were analyzed for the best point. Five compositions of the film-forming solution based on yam and corn starch were evaluated and analyzed for thickness, opacity, moisture content, solubility, antioxidant activity and antimicrobial activity. In addition, antifungal analyses, water loss and color change were performed on the strawberries with and without coating. The cherry extract had a total phenolic content of 526.85 mg EAG 100 g−1 and high antioxidant activity (16.99 μM Trolox g−1 in ABTS; 31.71 mM ferrous sulfate g−1 in FRAP; 94.96% in b-carotene assay), as well as inhibition of Escherichia coli, Staphylococcus aureus and Klebsiella pneumoniae microorganisms. Adding 2% of starch and 20% of plasticizer in relation to the starch had the best overall results. Films with 0.5% fruit content had greater antioxidant activity than those with 0.03% encapsulate. Film thickness increased when encapsulated agents or fruit were incorporated, but opacity decreased. The solubility of the films changed from 0.34% for corn starch to 0.30% for encapsulate and 0.37% for fruit; yam starch films were completely soluble. Strawberries with yam starch film had the lowest water loss. Films without plasticizers showed colony formation on the seventh day of analysis. Thus, it is suggested that incorporating Rio Grande cherry fruit and its encapsulates in edible toppings could be feasible.