Morphological, Functional, and Physico-Chemical Properties of Non-Conventional Starch Derived from Discarded Immature Apples

Abstract

The starch yield of 23–28% (db) with 35–43% amylose content is recovered from different immature apple varieties. Scanning electron microscopy reveals the presence of the dome to spherical shaped granules of 3.1–11.62 µm size. The transition temperatures, onset temperature, peak temperature, conclusion temperature, and enthalpy of gelatinization are calculated using differential scanning calorimetry (DSC) ranges between 61.62 and 64.48 °C, between 64.61 and 68.07 °C, between 68.64 and 72.37 °C, and between 4.35 and 17.49 J g−1, respectively. The water absorption capacity and oil absorption capacity of starches range between 1.036 and 1.372 mL g−1 and between 0.876 and 1.125 mL g−1, respectively. The peak viscosity of 638–1942 cP is achieved in 3.8–6.10 min at a pasting temperature of 65–71 °C. A yield stress of 10–39 Pa is sufficient to instigate the Herschel Bulkley flow. The paste of Mollie's Delicious starch is more structured and elastic; its gel has a hardness of 3.5 N and maximum recovery strength.