Encapsulation of soy isoflavone extract by freeze drying, its stability during storage and development of isoflavone enriched yoghurt

Soybean is a natural source of isoflavone. Its extract has a bitter and astringent taste and undergoes through oxidative deterioration. The study aimed at encapsulation of isoflavone extract using different carrier material through freeze drying. Maltodextrin, β-cyclodextrin, and tapioca starch were employed in 1:3 while sodium alginate and carboxymethyl cellulose in 1:1.25 as extract to carrier material ratio for encapsulation. Carrier material reflected significant (< 0.05) effect on encapsulation efficiency, isoflavone content and morphology of encapsulated extract. Maltodextrin was selected as the best material for encapsulation of isoflavone extract reflecting significantly higher encapsulation efficiency along with homogenous coating on the particle surface as examined through SEM. The band stretching in FTIR analysis also indicates the retention of functional groups after encapsulation. The encapsulated extract packed in ambered glass vials can be stored safely for a period of 6 months with a higher withholding of isoflavones under refrigerated conditions. Furthermore, encapsulated isoflavone extract was incorporated in yoghurt @ 50 mg isoflavone which improved its functional and sensory properties. About 96.83% of isoflavone was retention in yoghurt containing encapsulated extract compared to yoghurt having extract without encapsulation.