Aoife L. McCarthy

Immunomodulatory potential of a brewers’ spent grain protein hydrolysate incorporated into low-fat milk following in vitro gastrointestinal digestion

Abstract Brewers’ spent grain (BSG) protein rich fraction was previously hydrolysed using Alcalase (U) and three additional fractions were prepared by membrane fractionation; a 5-kDa retentate (U > 5), a 5-kDa permeate (U < 5) and a 3-kDa permeate (U < 3). In the present study, these fractions were added to milk, subjected to simulated gastrointestinal digestion (SGID) and their anti-inflammatory potential was investigated. The digestates caused a significant reduction (p < 0.05) in interleukin-6 (IL-6) production in Concanavalin-A (ConA)-stimulated Jurkat T cells. The samples did not significantly alter the production of IL-6 in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. IL-2 and interferon-γ (IFN-γ) production in stimulated Jurkat T cells and IL-1β and tumor necrosis factor-α (TNF-α) production in stimulated RAW 264.7 cells were not affected in the presence of the digestates. Results show that a SGID milk product supplemented with BSG hydrolysate and its associated ultrafiltered fractions can confer anti-inflammatory effects in Jurkat T cells.

Cellular in vitro bioactivity of protein hydrolysates from brewers' spent grain

Protein hydrolysates have been used as components of nutrition products, including geriatric and sports products, and in weight-control diets. Brewers’ spent grain (BSG), a co-product of the brewing industry, represents a unique source of protein hydrolysates. The aim of this study was to assess the in vitro bioactivity of BSG hydrolysates and fractionated hydrolysates. Hydrolysates (designated U-W) were prepared from BSG using either Alcalase 2.4L, Corolase PP or Flavourzyme. Cytotoxicity was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in both U937 and Jurkat T cells. The antioxidant activity of the hydrolysates was determined in U937 cells by two methods – ability to protect against hydrogen peroxide (H2O2)-induced (100mM 60min) oxidative stress, by the SOD assay and H2O2-induced (50mM · 30min) DNA damage, by the comet assay. An enzyme-linked immunosorbent assay (ELISA) was used to measure the effect of the samples on concanavalin-A (con-A) stimulated production of interferon-g (IFN-g) in Jurkat T cells, indicating their immunomodulatory potential.