# Molecular Properties of Starch–Water Interactions in the Presence of Bioactive Compounds from Barley and Buckwheat—LF NMR Preliminary Study

## TL;DR

This study uses LF NMR to explore how barley and buckwheat affect starch-water interactions, influencing food texture and stability.

## Contribution

The study reveals opposing effects of buckwheat hull and green barley on starch retrogradation using LF NMR.

## Key findings

- Waxy potato starch retrograded earlier than normal potato starch due to its high amylopectin content.
- Buckwheat hull fiber inhibited water binding in waxy starch gels by entrapping water in the amylopectin network.
- Green barley increased ordering in waxy starch gels, reducing water mobility, while buckwheat hull disrupted amylose-driven reorganization in normal starch.

## Abstract

The retrogradation of starch strongly influences the texture and stability of starchy foods. This study applied low-field nuclear magnetic resonance (LF NMR) to examine the effect of buckwheat hull (BH) fiber and green barley (GB) on water dynamics in normal (NPS) and waxy (WPS) potato starch gels. Relaxation times (T1, T2) and mean correlation times (τc) were monitored during 15 days of storage to evaluate changes in water mobility and starch–polymer interactions. Results showed that WPS, with its high amylopectin content, retrograded earlier than NPS. The addition of BH inhibited conformational changes associated with water binding in WPS gels, indicating that insoluble fiber entrapped water within the amylopectin network. Conversely, GB promoted higher τc values in WPS, reflecting enhanced ordering and reduced water mobility, while its impact on NPS was minor. In NPS systems, BH decreased τc, suggesting disruption of amylose-driven structural reorganization. These findings demonstrate that BH and GB exert opposite effects on starch retrogradation and highlight their potential as functional additives for tailoring texture and stability in starch-based food systems.