Improving phenolic bioactive-linked functional qualities of sweet potatoes using beneficial lactic acid bacteria-based biotransformation strategy

Authors: CHINTHA, PRADEEPIKA - North Dakota State University; SARKAR, DIPAYAN - North Dakota State University; PECOTA, KENNETH - North Carolina State University; Dogramaci, Munevver; SHETTY, KALIDAS - North Dakota State University

Submitted to: Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/29/2021
Publication Date: 9/27/2021
Citation: Chintha, P., Sarkar, D., Pecota, K., Dogramaci, M., Shetty, K. 2021. Improving phenolic bioactive-linked functional qualities of sweet potatoes using beneficial lactic acid bacteria-based biotransformation strategy. Horticulturae. 7(10). Article e367. https://doi.org/10.3390/horticulturae7100367.
DOI: https://doi.org/10.3390/horticulturae7100367

Interpretive Summary: Improving access and supply of well-preserved and nutritionally-superior vegetables is essential to address food security and public health challenges globally. Sweet potatoes with rich human health protective bioactive profiles and balanced nutritional composition are good dietary targets for advancing food security and diet-influenced public health solutions. However, nutritional qualities of sweet potatoes deteriorate rapidly during postharvest storage and processing stages. Therefore, improving, preserving and optimizing nutritional qualities of sweet potatoes is important for their effective integration in health-focused food solutions. Such improvements can be achieved through enhancing retention, stability, and functional qualities of human health protective bioactives of sweet potatoes at postharvest processing stage. In this research, a novel and effective bioprocessing strategy was targeted to improve human health relevant nutritional qualities in sweet potatoes. Cold water extracts of sweet potato varieties with different flesh colour (white, orange, and purple) were fermented and nutritionally-linked functional qualities were determined. Overall, improvement in retention of human health protective bioactive compounds were observed after fermentation. Similarly, anti-diabetic properties of sweet potato varieties also enhanced after fermentation. Results of this study have identified novel strategies to improve retention and stability of human health protective bioactives of sweet potatoes for dual functional benefits of enhancing food quality and improving shelf-life.

Technical Abstract: Beneficial lactic acid bacteria (LAB) based fermentation is an effective biotransformation strategy to preserve and improve human health supporting functional qualities of plant-based food substrates. In this study, food grade strain of Lactiplantibacillus plantarum was recruited to improve retention, stability, and bioavailability of phenolic bioactives to enhance antioxidant, anti-hyperglycemic, and anti-hypertensive functional qualities of 3 flesh-coloured sweet potato varieties, Murasaki (off-white-fleshed), Evangeline (orange-fleshed) and NIC 413 (purple-fleshed). Liquid (cold water) extracts of sweet potatoes, which is relevant for food grade applications, were fermented for 72 h at 37°C. Total soluble phenolic content, phenolic profile, antioxidant, anti-hyperglycemic, and anti-hypertensive benefits relevant functional properties of fermented and unfermented sweet potato extracts were evaluated at 0-, 24-, 48-, and 72-h time points using in vitro assay models. Overall, high total soluble phenolic content and total antioxidant activity were observed at 24 h, subsequently retaining this higher level even after 72 h fermentation. Additionally, moderate to high a-amylase, a-glucosidase, and angiotensin-I-converting enzyme inhibitory activities were also observed in fermented and unfermented sweet potatoes. Results suggested that beneficial LAB-based fermentation is an effective post-harvest processing strategy for higher retention of phenolic bioactives and concurrently improving human health protective bioactive functional qualities of sweet potatoes.