Resistant structure of extruded starch: Effects of fatty acids with different chain lengths and degree of unsaturation. (16th April 2022)

• Record Type: Journal Article
• Authors: Cai, Canxin; Tian, Yaoqi; Sun, Chunrui; Jin, Zhengyu
• Is Part Of: Food chemistry. Volume 374(2022)
• Publication Date: 2022-04-16
• Subjects: Reactive extrusion -- Amylose-lipid complex -- Complex formation -- Starch digestibility -- Predicted glycaemic index; Food -- Analysis -- Periodicals; Food -- Composition -- Periodicals; 664
• DOI: 10.1016/j.foodchem.2021.131510
• Languages: English
• ISSNs: 0308-8146

Abstract

Highlights: Complexes with shorter carbon chain fatty acid have higher thermal stability. Complexed content increased as carbons and degree of fatty acid saturation decrease. Amylose, amylopectin and unsaturated fatty acid form an enzyme-resistant structure. Adding linoleic acids via extrusion can lower glycemic index value of starch. Abstract: This study investigated the formation mechanism of enzyme-resistant structures in extruded starch, specifically, fatty acid–starch complexes (FASCs). The effects of fatty acids (FAs) with different carbon-chain lengths (C12–C18) and degrees of unsaturation (C18:0–C18:2) on complex formation were evaluated, with fluorescence microscopy verifying complex formation. The complexed-lipid content and degree of relative crystallinity increased with the carbon-chain length and degree of FA unsaturation. FAs with fewer carbons were more likely to generate stable complexes (e.g., form II, melted at 100–120 °C), while FAs with more carbons tended to produce relatively unstable complexes (e.g., form I, melted at 80–100 °C). After reheating and cooling, a new amylose–lipid complex and an amylose-amylopectin network was formed in the unsaturated FASC samples, which restricted the penetration of enzymes into starch granules. A starch-linoleic acid complex exhibited the highest resistant starch content (15.7%) and lowest predicted glycaemic index (88.4).