# Co-modification of corn flour by Lactobacillus HR and transglutaminase reduces glycemic index and enhances functional properties

## TL;DR

A new method using bacteria and an enzyme improves corn flour's nutrition and processing by lowering its glycemic index and enhancing its structure.

## Contribution

A novel co-modification approach using Lactobacillus HR and transglutaminase to improve corn flour's glycemic index and functional properties.

## Key findings

- Co-modification reduced the glycemic index to 48.87 and increased resistant starch by 51.19%.
- Treated flour showed a 29.7% increase in gel strength and a more compact internal structure.
- FTIR analysis indicated increased starch molecular order and resistance to digestion.

## Abstract

The complex protein structure, high glycemic index (GI), coarse taste and poor formability of corn significantly hinder its deep processing performance and represent key technical bottlenecks in the industrialization of corn-based food products.

In this study, co-modification with optimized lactic acid bacteria (Lactobacillus HR) and transglutaminase (TGase) effectively converted corn flour into a low-glycemic index (GI) product, primarily due to flour’s high starch content.

The results revealed that fermentation under the optimum circumstances (36.83 °C, fermentation time of 49.25 h, inoculum level of 1.03 × 108 CFU/mL, and enzyme dosage of 2.58‰) produced flour with significant nutritional improvements. Co-modification yielded the lowest GI (48.87) and enhanced the nutritional profile, with increased soluble protein content (5.96  mg/g) and resistant starch levels (51.19%). FTIR analysis revealed an increase in the (1047/1022) cm−1 absorbance ratio, suggesting a higher degree of starch molecular order and consequently, enhanced resistance to enzymatic digestion. Compared with untreated corn flour, the treated samples showed a 10.3% decrease in water-holding capacity and a 29.7% increase in gel strength.

The co- modification of Lactobacillus HR and TGase caused a more compact internal structure, which further reduced the hydrolyzability of corn starch. Based on the above results, this study indicates that the integrated biological treatment is a feasible method for improving the nutritional quality and functional properties of cereal flours.