How non-thermal processing treatments affect physicochemical and structural attributes of tuber and root starches?

Abstract

Background: Given the unique characteristics of the starch extracted from tubers and roots, their successful use in various food and pharmaceutical formulations has been increasingly valued. However, owing to the ever-increasing range of applications of these starches, modifying their physicochemical characteristics through physical, chemical, and enzymatic approaches to engender new capabilities is inevitable. Scope and approach: The adverse influences of chemical modifications and the undesirable detrimental reactions upon thermal treatments have arisen the need for novel physical non-thermal approaches to treat food-related components. Accordingly, various non-thermal treatments including ultrasonication, high-hydrostatic pressure, pulsed electric field, ozonation, plasma treatment as well as irradiation have successfully been applied to manipulate the tuber and root starch attributes. The principal theory of these methods plus their impact on tuber and root starch characteristics are reviewed in this study, in detail. Key findings and conclusions: Due to the consumer attention toward the healthy diets, this review highlighted the impact of clean-labeled non-thermal modification approaches on physicochemical and structural characteristics of tuber and root starches. These treatments induced a versatile ranges of alterations in various attributes of tuber/root starches including formation of cracks, pores and channels on starch granules (specifically, upon sonication), disintegration of amorphous/crystalline fractions (particularly, at pressures >500 MPa upon HHP), reduction in viscosity, enhancing the paste clarity, formation of gel-like structures through aggregation of deformed granules treated with PEF, fabrication of cross-linked interactions during irradiation of starch with ionizing beams as well as enhancing the resistant starch content of granules upon HHP treatments through generation of amylose-lipid complexes. Moreover, from the systematic point of view of the literature, ultrasonication and HHP were the most applied and investigated methods in modifying tuber and root starches which induced the most promising alterations in starch.