The objective of this study was to evaluate the effect of edible coatings as a barrier to oil incorporation during the process of frying frozen pre-fried structured products made from cassava roots. Three different hydrocolloids were used in six coating formulations, three being composed of pectin and milk whey protein, and the other three of hydroxypropyl methyl cellulose and milk whey protein in the proportions of 1:4, 1:1 and 4:1, respectively. Films made with the same formulations were evaluated for their characteristics of water vapor permeability, water solubility and thickness, as well as their mechanical properties (tensile strength and stretching). The cassava products were evaluated for their moisture and lipid contents, color, instrumental texture and sensory attributes. The milk whey protein concentration influenced the characteristics of the bio-films, causing a decrease in solubility, increase in thickness and increase in the permeability value of the bio-films containing pectin, and a significant reduction of the same parameters in the bio-films composed of hydroxypropyl methyl cellulose and milk whey protein. The hydroxypropyl methyl cellulose based coatings resulted in higher moisture contents and lower lipid contents in the cassava products, the 1:4 combination giving a 32.30% reduction in the amount of lipid absorption. The hydroxypropyl methyl cellulose coating in the 1:4 proportion resulted in crispier products with a golden color, desirable attributes in this type of product. The products only presented statistically significant sensory differences for the attributes of texture and crispiness. As from these results it was concluded that the interaction of hydroxypropyl methyl cellulose with milk whey protein in the 1:4 proportion, when applied to frozen pre-fried structured cassava products, resulted in reduced lipid retention and adequate crispiness and internal texture.
Cassava; Edible coatings; Freezing; Oil absorption; Frying
