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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.

Brewers' spent grain (BSG) is a major coproduct of the brewing industry and a potential valuable source of protein, cell wall polysaccharides, lignin, lipid, and phenolic compounds. The aim of this study was to assess the antioxidant potential of phenolic extracts isolated from BSG using cell wall degrading enzymes, Depol 740L, Shearzyme and, Ultraflo Max. The phenolic extracts were prepared from black BSG (derived from barley grains roasted at 200°C) and pale BSG (derived from malted barley grains). The phenolic extracts protected against hydrogen peroxide (H2O2)‐induced DNA single strand breaks in U937 cells as assessed using the comet assay. The extracts also protected against a H2O2 challenge in HepG2 cells, as assessed by measuring the cellular content of glutathione (GSH) and the activity of cellular antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT). Enzyme‐extracted black and pale BSG phenolic extracts protected against oxidant‐induced DNA damage and enhanced the cellular antioxidant activity in cells. Practical applications Enzyme‐extraction may be an effective alternative to conventional solvent extraction for the isolation of novel bioactive components, such as phenolics, from Brewers' spent grain. The BSG extracts may be used as a source of functional ingredients for the development of foods with potential benefits to human health.

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Protein hydrolysates from agricultural crops have shown encouraging bioactive and techno-functional characteristics that may be used in the development of functional foods (1) . It is important that bioactive protein hydrolysates demonstrate an ability to retain their bioactivity during digestion. Brewers' spent grain (BSG), a by-product of the brewing industry, is a potential source for the development of protein hydrolysates. The aim of this study was to incorporate a bioactive, BSG-derived protein hydrolysate into commercially available low-fat milk and assess the cytotoxicity and immunomodulatory effects of digestates, following in vitro gastrointestinal digestion.Hydrolysate U was obtained on Alcalase 2·4L digestion of a BSG protein-rich isolate. The hydrolysate was freeze-dried whole (U) or fractionated using 5 and 3 kDa molecular cut-off membranes, and permeates and retentate were designated U, U < 3, U < 5 and U > 5. Samples were added to low-fat milk at a concentration of 0·125% (v/v). A static gastrointestinal digestion model, as previously described (2) was used to mimic human digestion. The (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) assay was used to assess the effect of digestates (0-10% ; v/v) on Jurkat T cell proliferation. The effect of digestates on interferon-gamma (IFN-gamma) and interleukin-6 (IL-6) secretion in concanavalin-A (con-A) stimulated Jurkat T cells was measured by ELISA. Data were expressed as a percentage of untreated (control) cells.Treatment with digestates of milk with added hydrolysates U, U < 3 and U < 5 at 10% (v/v) and hydrolysates U > 5 at 5% and 10% (v/v), for 24 hours significantly reduced viability of Jurkat T cells. Following on from the cytotoxicity results, the highest non-toxic concentration of digestates (2·5%) was selected for further investigation. Preliminary results suggest that milk digestates with added >5 kDa hydrolysate can decrease IFN-gamma and IL-6 secretion in stimulated Jurkat T cells (data not shown). In conclusion, these results suggest that low-fat milk fortified with BSG hydrolysate can attenuate cytokine production in stimulated Jurkat T cells.