Dual complexation using heat moisture treatment and pre-gelatinization to enhance Starch–Phenolic complex and control digestibility

Abstract

Phenol is a competitive inhibitor for digestive enzymes, moreover, it can form complexes with starch either inclusion (V-type) or non-inclusion. These complexes can resist enzymatic digestion and are considered as RS type 5. However, phenol is usually bulky and does not easily enter the amylose helix cavity. The dual starch–phenolic complexation was proposed to increase single helix using heat moisture treatment (HMT) altogether with pre-gelatinization. The dual complexation of rice starch and Riceberry extract (HMT-RSP-Riceberry) exhibited the highest V-amylose and % crystallinity (30.8%, 31.5%) compared with native starch (14.5%, 19.8%). The high total phenolic and hydroxycinnamic acid content especially ferulic acid in Riceberry extract were effectively inhibited α-amylase activity. The complexing index of HMT-RSP-Riceberry was double (10.2%) the conventional process (5.1%). The single helix fraction which promote loose structure, allowing more phenol to move inside and between the helix cavities, increased noticeably in the HMT-RSP-Riceberry (30.7%) compared with native starch (4.3%). HMT-RSP-Riceberry had lower RDS but higher SDS and RS (77.2%, 7.1%, 15.8%) than conventional process using 15% gallic acid (positive control) (87.6, 5.3, and 7.1%), and native starch (negative control) (95.9, 1.5, 2.6%, respectively). The dual complexation process was more applicable in terms of reasonable amount of phenol used, no undesirable taste, and no chemical used during process. This physically modified inclusion complexes could improve starch digestibility with potential application in healthy foods.