Effect of grinding and extraction conditions on the determination of antioxidant activity and phenolic acids in barley

Bing Zhou,Paul B Schwarz,Yin Li,Zhao Jin

doi:10.1007/s11694-021-00964-0

Abstract

In the present study, the objective was to evaluate the effects of barley kernel size, grind level, and extract solvent on the antioxidant activities associated with total phenolic content and phenolic acid compositions. Three barley varieties (Kindred, Azure, and Tradition), were used and the results showed that with the exception of superoxide anion radical scavenging activity, thin kernel size fraction (2.0 mm) showed much higher antioxidant activities and total phenolic content than those in the 2.4 mm and 2.8 mm fractions when averaged across barley cultivar, grind level, and extract solvent. A similar trend was found for individual phenolic acid compositions among kernel sizes. Simple correlation analysis revealed that total phenolic content showed strong correlation with DPPH· scavenging activity, ABTS + scavenging activity, and reducing power. Generally, fine grind and 80% acetone extract showed averaged highest values in antioxidant activities, total phenolic content, and individual phenolic acid compositions. Stepwise linear regression showed that extract solvent was the most important factor for DPPH· scavenging activity, ABTS + scavenging activity, reducing power, and iron chelating activity. The sum of syringic acid and caffeic acid exhibited a dominant role in explaining the major variation in antioxidant activities except for superoxide anion radical scavenging activity.

Highlights

Barley (Hordeum vulgare), an annual cereal grain, is one of the oldest cultivated cereal grains
There was no significant difference in DPPH· scavenging activity between fine and medium grinding for the Tradition sample (Fig. 1a)
The current study evaluated the impact of cultivar, kernel size, grind particle size and extraction solvent on antioxidant activities, total phenolic content (TPC) and phenolic acids in barley

Summary

Introduction

Barley (Hordeum vulgare), an annual cereal grain, is one of the oldest cultivated cereal grains. Phenolic compounds in grains act as growth regulators during plant metabolism and exhibit antioxidant capabilities to scavenge free radicals and active oxygen, generate relatively stable phenoxyl radicals, function as reducing agents and chelate metal ions [8, 9]. Since these bioactive compounds do not present in grain parts (e.g. endosperm, germ and bran) uniformly present in grain tissues (e.g. endosperm, germ, and bran), it is suggested to consume the whole grain as food resources [12]. Research has indicated that the functional effects of whole grain in human health may be due to the comprehensive effects of nutrients and bioactive phytochemicals in whole grain or foods from

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Discussion

Conclusion