Effect of radio frequency explosion puffing on physicochemical, functional and crystalline properties, and in vitro digestibility of yam flour

Abstract

Yam flour was modified by radio frequency explosion puffing at different moisture content, puffing temperature, and puffing pressure difference. After puffing, the protein content and lipid content increased by 0.56-1.28 % and 0.23-0.39 %, respectively. Puffing caused the flour granules to aggregate, increasing the thermal transition temperatures and reducing the pasting viscosities, enthalpy, 1047/1022 cm^-1 ratio, and relative crystallinity. Puffing reduced the intensity of the infrared spectrum peak at 1641 cm^-1 by breaking the hydrogen bonds without changing A-type crystalline structure. Puffing promoted the conversion of random-coil and α-helix protein structure to β-turn and β-sheet. Puffing retarded in vitro digestibility by reducing rapidly digestible starch content by 7.04-11.12 % and rising slowly digestible starch content and resistant starch content by 4.02-4.89 % and 2.77-3.10 %, respectively. Radio frequency explosion puffing altered flour's physicochemical, functional and digestibility properties by destroying the protein structure and promoting the interaction of starch and proteins/lipids.

Keywords: Crystalline structure; In vitro digestibility; Physicochemical properties; Radio frequency explosion puffing; Yam flour.