Impact of pulsed electric field pre-treatment on nutritional and polyphenolic contents and bioactivities of light and dark brewer's spent grains. (June 2019)

• Record Type: Journal Article
• Authors: Kumari, Bibha; Tiwari, Brijesh K.; Walsh, Des; Griffin, Tomás P.; Islam, Nahidul; Lyng, James G.; Brunton, Nigel P.; Rai, Dilip K.
• Is Part Of: Innovative food science & emerging technologies. Volume 54(2019)
• Page Start: 200
• Page End: 210
• Publication Date: 2019-06
• Subjects: Pulsed electric field -- Brewer's spent grain -- Antioxidant activity -- Antimicrobial activity -- Immunomodulatory activity; Food -- Biotechnology -- Periodicals; Food industry and trade -- Technological innovations -- Periodicals; Aliments -- Biotechnologie -- Périodiques; Food -- Biotechnology; Periodicals; Electronic journals; 664.005
• DOI: 10.1016/j.ifset.2019.04.012
• Languages: English
• ISSNs: 1466-8564

Abstract

Abstract: Pulsed electric field (PEF) pre-treatment, at 2.8 kV/cm with 3000 pulses of 20 μs pulse-width, was applied on brewer's spent grains (BSG) followed by aqueous extraction at 55 °C, 220 rpm for 16 h. PEF pre-treatment showed significantly increased yields ( p < 0.05) of carbohydrate, protein, starch and reducing sugar in extracts from dark BSG compared to untreated samples. Light BSG extracts had significantly higher ( p < 0.05) levels of freed -glucose and total free amino acids (18.5–33.3 and 21–25 mg/g dry weight extract (Dwe)), compared to dark extracts (5 and 1.2 mg/g Dwe respectively). Dark BSG extracts showed significantly higher ( p < 0.05) total phenolics (3.97–4.88 mg GAE/g Dwe) compared to light BSG extracts (0.83–1.40 mg GAE/g Dwe). Furthermore, PEF treated light BSG showed higher antimicrobial activity with minimum inhibition concentration (MIC) of 50 and 25 mg/mL against Salmonella typhimurium and Listeria monocytogenes, respectively compared to the untreated extracts (>50 mg/mL) with lowest MIC value of 1.56 mg/mL against Staphylococcus aureus . All the BSG extracts induced the release of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α) and chemokines (IL-8, MCP-1 and MIP-1α) confirming immunomodulatory activity. Highlights: PEF pre-treatment enhanced the extraction of proteins and reducing sugars from BSGs. Dark BSG extracts have higher phenolics and antioxidant activity than light BSG extracts. Light BSG extracts has ~20 times higher total free amino acid content. Light BSG extracts displayed better antimicrobial and immunomodulatory activities. All the essential amino acids except tryptophan were present in all the extracts.