The underlying mechanism of resistant starch production through esterification a substitution or crosslinking by citric, malic, and lactic acid after freezing pre-treatment: Comparative study on production efficiency, digestibility, pasting, and thermal properties

This study investigates the efficiency of resistant starch production by malic, citric, and lactic acids after freezing-thawing pre-treatments led to an increase in degree of substitution (DS) for esterified FTFS (EFTFS) than esterified native starch (ENS). EFTFS and ENS exhibit new characteristic peaks absorption peaks near 1760 cm⁻¹. Microscopic analysis further revealed that the unique granular structure and morphology of EFTFS underwent gelatinization and aggregation, which reduced swelling capacity. In this regard, the RS produced by lactic acid showed the least swelling capacity, followed by malic and citric acid due to the merged and coarse structure. Paste viscosities were significantly lower in all modified starches than native starch, with the lowest viscosities observed for EFTFS treated with lactic acid. The resistant starch created from FTF depicted slowly digestible malic and citric acid content due to the creation of significant cross-linkage compared to lactate and native starch. FTF pre-treatment caused reduced heat energy and time consumption.