Effects of Germination on Protein, γ-Aminobutyric Acid, Phenolic Acids, and Antioxidant Capacity in Wheat.

Mi Kim,Han Kwak,Sang Kim

doi:10.3390/molecules23092244

Abstract

Germinated wheat is a food material with potential health benefits due to its high phenolic and antioxidant content, but the reason why germination increases this content is unclear. The aim of this study was to investigate the relationships between protein changes (determined by two-dimensional gel electrophoresis (2-DE)), phenolics, γ-aminobutyric acid (GABA) levels, and antioxidant capacity of wheat germinated for various periods (24, 48, 72, and 96 h) compared to control. Each phenolic acid tended to increase with increasing germination time. The GABA content was highest (39.98 mg/100 g dwb) after 96 h of germination. The total oxygen radical absorbance capacity (ORAC) was 1.97 times higher after 96 h than in ungerminated seeds. Fifteen proteins, among 82 proteins separated by 2-DE, were highly related with ORAC and were identified by peptide mass fingerprinting (PMS). The PMS revealed strong expression of granule bound starch synthase (GBSS) and glutathione S-transferase (GSTF) after 96 h of germination. Overall, the ORAC at 96 h exhibited a close relationship with the levels of phenolic acids, GABA, and proteins such as GBSS and GSTF. In conclusion, these findings add to the existing knowledge of wheat protein changes and their relationship to the antioxidant properties of germinating wheat seeds.

Highlights

Wheat (Triticum aestivum L.), one of the three major grains, is harvested worldwide because it grows well in dry climates
Whole wheat products are rich in dietary fiber, minerals, vitamins, and phytochemicals, and their consumption is associated with reduced occurrences of certain diseases, such as cancer, diabetes, and coronary cardiovascular disease [2]
Ferulic acid was the predominant phenolic acid identified in all five wheat samples, in agreement with similar findings in two previous studies [11,12]

Summary

Introduction

Wheat (Triticum aestivum L.), one of the three major grains, is harvested worldwide because it grows well in dry climates. Whole wheat products are rich in dietary fiber, minerals, vitamins, and phytochemicals, and their consumption is associated with reduced occurrences of certain diseases, such as cancer, diabetes, and coronary cardiovascular disease [2]. One method to improve the nutritional quality of cereal products is to germinate the grain [3,4,5,6]. The increased activation of the starch-degrading α-amylase and various proteases reduces total dry matter [9], while the significant increases in free amino acids, soluble dietary fiber, γ-aminobutyric acid (GABA), vitamins, minerals, and phytochemicals enhance the potential health benefits of germinated cereals [4,5,8,10]

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Conclusion