Mechanical Grinding Effects on Health-Related Functional Properties of Dietary Fiber Powder from White Cabbage By-products

Abstract

—Health-beneficial effects of Dietary Fiber (DF) are significantly related to its functional properties, which may in turn be altered by fiber structural modification during processing. Although, the potential use of outer leaves of white cabbages ( Brassica oleracea L. var. capitata ), residues obtained during industrial processing and selling in the market, as a starting material for production of DF powder has been reported, the effect of processing on the health-related functional properties has not been studied. This work aimed at determining the effect of mechanical grinding on capillary porous structure of DF powder (particle size of less than 450 µm) prepared from white cabbage outer leaves on Glucose Adsorption Capacity (GAC), Glucose Retardation Index (GRI) and Bile acid Retardation Index (BRI). The results showed that DF powder with larger sizes possessed higher GAC, GRI and BRI. The DF product with particle size in the range of 300  450 µm exhibited the highest GAC, GRI and BRI among all samples studied. Scanning electron microscopic (SEM) results showed that applying such an intense mechanical force as grinding to reduce the particle size resulted in rupture of xylem vessels and other tissues. Thus resulted in the collapse of the tube and loss of ability to trap glucose or bile acid into fiber matrix, which hence gave an adverse effect on DF functional