Location: Grain Quality and Structure Research
Project Number: 3020-43440-002-026-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Jun 1, 2021
End Date: May 31, 2026
Objective:
The aim of this study is to develop fermented sorghum products using natural and microbial starters and to investigate the effects of fermentation on the functional properties of sorghum, especially on protein digestibility. The overall goal of the project will be achieved through two major objectives 1) evaluating how natural and starter cultures work when using sorghum grain and flour as a fermentation substrate, what changes occur to sorghum when fermented with different cultures and what secondary metabolites are formed and 2) evaluating how fermented sorghum grain and flour functions when used in foods and beverages, how fermentation impacts nutritional quality of sorghum, how fermentation impacts sorghum functionality in food systems and how these changes may impact end-use quality and consumer acceptance of fermented sorghum foods.
These objects are beneficial to sorghum value and utilization even though sorghum is widely grown all over the world for food and feed, due to the presence of anti-nutritional factors, such as trypsin and amylase inhibitors, phytic acid and tannins. These compounds are known to interfere with protein and carbohydrate digestion and mineral bioavailability. Controlled fermentation can represent a suitable strategy to improve sorghum protein digestibility and increase functional properties. Fermented sorghum foods and drinks are widely used in other parts of the world, especially in Africa, but are not common in the United-States despite the popularity of fermented products with American consumers. Fermented foods from Africa often rely on natural flora found on sorghum which may be different than flora found on sorghum grown in the U.S., hence the need for additional research in this area with U.S. sorghum hybrids. This research will add value to US sorghum be expanding markets and types of products available.
Approach:
Different types of sorghum-based fermented products (whole grain, flour and beverages) will be produced using both natural and starter cultures. An investigation of microbial community dynamics within product as well as antimicrobial properties of lactic acid bacteria will be performed before starting the fermentation processes. Several sorghum cultivars that vary in pericarp color (red, white and black pericarp), tannin content (tannin and non-tannin types) and starch composition (waxy starch and normal starch) as well as dried distillers grains will be used in fermentation experiments. Fermentation kinetics, microbial growth and changes in pH, acidity, protein solubility, digestibility, starch content, as well as iron availability will be monitored over time during fermentation to evaluate the effect of controlled fermentation on the functional properties of sorghum. Fermented products will then be used to develop fermented foods and drinks. Changes to nutritional properties of fermented sorghum will also be evaluated (protein digestibility, phytic acid levels, phytase levels). Food products properties, relating especially to physical, functional and sensory factors, will be manipulated and tested to develop foods and drinks with good consumer appeal in the U.S. market that have improved nutritional characteristics.
