Kefir-culture mediated fermentation to improve phenolic-linked antioxidant, anti-hyperglycemic and human gut health benefits in sprouted food barley

Authors: RAMAKRISHNA, RAMNARAIN - North Dakota State University; SARKAR, DIPAYAN - North Dakota State University; Dogramaci, Munevver; SHETTY, KALIDAS - North Dakota State University

Submitted to: Journal of Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/13/2021
Publication Date: 9/17/2021
Citation: Ramakrishna, R., Sarkar, D., Dogramaci, M., Shetty, K. 2021. Kefir-culture mediated fermentation to improve phenolic-linked antioxidant, anti-hyperglycemic and human gut health benefits in sprouted food barley. Journal of Applied Microbiology. 1(2):377-407. https://doi.org/10.3390/applmicrobiol1020026.
DOI: https://doi.org/10.3390/applmicrobiol1020026

Interpretive Summary: “Functional” foods and beverages provide positive health protective function beyond basic nutritional needs and are becoming increasingly popular among consumers globally. In this rapidly growing food market, prebiotic and probiotic foods are specifically getting significant prominence due to their unique food and health quality attributes. Prebiotic foods are rich in dietary fibre and support the growth of beneficial microorganisms in human gut. Probiotic foods are made of with living microorganisms, mostly beneficial bacteria and yeast. Most prebiotics and probiotic foods currently available in the market are dairy-based. However, there is an increasing demand for non-dairy based prebiotic food alternatives, such as cereal grain-based fermented foods and beverages. In this context, food barley, which has a rich functional bioactive profile, are excellent substrate sources that can be targeted to develop fermented functional foods and beverages. In this research, we used inexpensive and simple bioprocessing strategies to improve specific bioactive-linked antioxidant, anti-diabetic, and anti-bacterial properties in three different food barley flour extracts. We identified conditions that resulted in higher stability of health protective bioactives, improved antioxidant and anti-diabetic functionalities. Enhanced antibacterial activity against human gut ulcer causing bacteria was also a significant outcome. Taken together, this study identified an effective bioprocessing strategy to develop food barley based functional foods and beverages with diverse human health benefits.

Technical Abstract: Bioprocessing strategy is an effective approach to improve bioavailability and stability of bioactive compounds for designing functional foods and ingredients. In this study, food barley was bio-transformed to improve functional bioactives by sprouting, coupled with beneficial lactic acid bacteria (LAB)-based fermentation. Dairy Kefir culture with mixed beneficial LAB strains was targeted to ferment aqueous extracts of sprouted food barley flour (three hull-less food barley unpigmented, purple, and black barley) for 72 h and modulation of phenolic-linked antioxidant and anti-hyperglycemic functionalities were evaluated using in vitro assay models. The biochemical parameters analyzed were total soluble phenolic (TSP) content, profile of phenolic compounds, total antioxidant activity, and anti-hyperglycemic property relevant a-amylase and a-glucosidase enzyme inhibitory activities. Furthermore, human gut health benefits relevant properties of fermented flour extracts were also evaluated based on growth of Kefir culture and subsequent determination of anti-bacterial potential against pathogenic human ulcer causing bacteria Helicobacter pylori. Kefir-culture mediated fermentation of 48 h sprouted barley flours improved the TSP content and associated antioxidant and anti-hyperglycemic functionalities. Additionally, anti-bacterial potential against H. pylori and sustaining active growth of viable LAB cells above the minimum level required for probiotic activity were also observed in response to fermented food barley flour extracts.