The multifactorial phenomenon of enzymatic hydrolysis resistance in unripe banana flour and its starch: A concise review

Abstract

Unripe banana flour starch possesses a high degree of resistance to enzymatic hydrolysis, a unique and desirable property that could be exploited in the development of functional food products to regulate blood sugar levels and promote digestive health. However, due to a multifactorial phenomenon in the banana flour matrix-from the molecular to the micro level-there is no consensus regarding the complex mechanisms behind the slow enzymatic hydrolysis of unripe banana flour starch. This work therefore explores factors that influence the enzymatic hydrolysis resistance of raw and modified banana flour and its starch including the proportion and distribution of the amorphous and crystalline phases of the starch granules; granule morphology; amylose-amylopectin ratio; as well as the presence of nonstarch components such as proteins, lipids, and phenolic compounds. Our findings revealed that the relative contributions of these factors to banana starch hydrolytic resistance are apparently dependent on the native or processed state of the starch as well as the cultivar type. The interrelatability of these factors in ensuring amylolytic resistance of unripe banana flour starch was further highlighted as another reason for the multifactorial phenomenon. Knowledge of these factors and their contributions to enzymatic hydrolysis resistance individually and interconnectedly will provide insights into enhanced ways of extraction, processing, and utilization of unripe banana flour and its starch.