Location: Food Processing and Sensory Quality Research
2019 Annual Report
Objectives
Objective 1: Enhance the human bioactive properties of resistant starch and slowly digestible starch in commercial table rice (milled, brown, and colored) while maintaining sensory texture characteristics.
Sub-Objective 1.1. In this sub-objective research will characterize the sensory characteristics related to resistant starch, slowly digestible starch, and the optimization of healthy starch in cooked rice.
Sub-Objective 1.2. Under this sub-objective several methods to produce high-resistant rice starch in flour will be examined in a baked food product. Resistant starch has many colonic health-promoting properties, but often does not formulate well as an ingredient in baked foods.
Objective 2: Enable new commercial functional food products using whole grain rice and rice co-products.
Sub-Objective 2.1. In joint research with CrispTek research in this sub-objective will focus on adding resistant starch, fiber, and protein to current low-oil absorbing frying batters utilizing rice foods and co-products. Nutritionally-enriched baked and fried foods will be developed that sustain sensory quality.
Sub-Objective 2.2. Healthier rice milk beverages and improvement of rice bran soluble protein extraction for food and beverage use will be developed.
Sub-Objective 2.3. The proposed research will develop and compare several methods to produce unique rice prebiotics combined with phenolics from blueberry pomace and spent green tea. The effectiveness of each prebiotic will be evaluated utilizing in vitro fermentations and a mouse model for colonic health.
Approach
Rice varieties vary in amylose content that lead to differences in digestibility. Cooked table rice from different varieties will be evaluated for the amount of resistant, slowly digestible, and rapidly digestible starch based on in vitro digestion times. Thermal processes and physicochemical methods will be used to produce high resistant starch content in rice flour and starch, which will be tested as ingredients in baked foods. In collaboration with CrispTek, research will focus on adding resistant starch, fiber, and protein from rice foods and co-products to current low-oil absorbing frying batters. Nutritionally-enriched baked and fried foods will be developed with sustained or enhanced sensory qualities. Rice beverages will be developed that incorporate green technologies (e.g. focusing on raw materials and enzymatic treatments that do not rely upon previous stabilization). Lastly, methods will be evaluated to produce prebiotics from rice that include thermal and physiochemical methods and encapsulation technologies.
Progress Report
Progress was made on the two objectives, all of which fall under National Program 306, Quality and Utilization of Agricultural Products recognizes this research need as part of Problem Statement 1.C: New Bioactive Ingredients and Functional Foods. The Problem Statement relays that the development of functional foods requires delivery systems to carry, protect, and deliver health-promoting food ingredients to their specific site of action at the right time and at a specific rate. Under Subobjective 1.1, we made significant progress in examining the effect of excess water during cooking of rice on sensory texture and starch composition. Research showed that cooking rice with excess water decreased resistant starch content. Further sensory evaluations are planned to determine texture differences after rice cooking with varying water-to-rice ratios. Under Subobjective 1.2, progress was made in determining the effect of baking on resistant starch in rice batters. Baked batters were prepared from several rice varieties and analyzed for resistant starch. Resistant starch content after baking were all lower compared to resistant starch contents of cooked table rice (from same varieties). Sensory evaluation of baked food texture with different rice batters are planned.
Under Subobjective 2.1, progress was made at characterizing fried batters and foods, and baked foods. Food batters after frying were evaluated for color, texture quality, and oil content. Studies on fried rice batters containing resistant starch did not alter the benefits of lowered oil uptake and texture (hardness/crispness). Completed sensory studies on fried rice batters containing added resistant starch maintained the low oil uptake in batters and retained sensory texture (hardness/crispness). Further sensory studies with baked foods using rice batters containing resistant starch are underway. Under Subobjective 2.2, significant progress was made with the pilot plant scale-up of rice milk with filtration, centrifugation and soluble bran protein characterization. Progress has been made evaluating both oil (lipid components including stearic, linoleic and linolenic acids, free fatty acids, sterols, diacylglycerols and oryzanol) and protein constituents (native and SDS-PAGE gels and biuret solubility test) in the control versus optimized germinated brown rice beverages. During the process, endogenous enzymes activate catabolic processes affect native protein, oil and fiber, which along with exogenous enzyme-induced starch hydrolysis into soluble solids and oligosaccharides, appears to have resulted in an unstable emulsion. Inorganic arsenic has been a concern in U.S. rice, and bran is reported to have higher levels compared to white rice. Significantly lower inorganic arsenic levels, below the current U.S. threshold level, were found in germinated brown rice compared to the starting brown rice and white rice. The developed germinated brown rice beverage formulation created by ARS researchers in New Orleans, Louisiana has resulted in an unstable emulsion. Subsequently, further emulsification and/or homogenization has not been required. Sensory evaluation of the rice beverages is being planned. Under Subobjective 2.3, in vitro fermentations were initiated to compare different rice prebiotics, but complete bacterial population analysis from fermentations have not been completed.
Production of a rice functional beverage. Plant-based protein and value-added functional beverage markets and product development are growing rapidly. ARS researchers in New Orleans, Louisiana have developed a low-input green, “free-flowing” processing method to germinate and thermally soften brown rice that is wet-milled, gelatinized and processed with enzymes. The process does not rely upon stabilization to produce value-added sprouted beverages. To date, the process does not require stabilization, oils, emulsifiers, fortification or additives. During the process, endogenous enzymes activate catabolic processes affect native protein, oil and fiber, which along with exogenous enzyme-induced starch hydrolysis into soluble solids and oligosaccharides, appears to have resulted in an unstable emulsion. Inorganic arsenic has been a concern in U.S. rice, and bran is reported to have higher levels compared to white rice. Significantly lower inorganic arsenic levels, below the current U.S. threshold level, were found in germinated brown rice compared to the starting brown rice and white rice. Sprouting significantly decreased (more than 3-fold) phytic acid levels. Health beneficial plant compounds (polyhenolics and aminobutyric acid) increased slightly in germinated brown rice however, increases were not maintained throughout processing. Full pilot plant scale-up including emulsification and/or homogenization followed by pasteurization will ultimately generate enough materials to further characterize oil and protein interactions. Plant-based drinks are rapidly becoming a strong segment in the functional beverages marketplace as the global dairy alternatives plant-based beverage market is expected to surpass $34 billion by 2024. Developing plant-based, protein-rich functional beverages with a cheap input ingredient with proven heath-beneficial attributes will have positive economic impact.
Accomplishments
1. High resistant starch rice reduces fat with a high fat diet. An estimated 160 million Americans are either obese or overweight. Obesity is associated with increased risks for type 2 diabetes mellitus and heart disease, and cancer. Further research has identified gut microbial populations that are altered with obesity. After eating rice, normal rice starch is rapidly digested and absorbed as glucose, potentiating a hyperglycemic response and triggering insulin secretion and tissue-specific intracellular uptake of glucose that can then result in hypoglycemia. Newer rice varieties have been developed that contain higher amounts of resistant starch that are not rapidly digested. In collaborative research between the ARS in Stuttgart, Arkansas, New Orleans, Louisiana, and Beltsville, Maryland, ARS researchers conducted an 8 week rodent feeding study with low and high fat diets utilizing cooked rice with varying amounts of resistant starch: low (0.1% resistant starch), medium (1% resistant starch) and high (8.6% resistant starch). The results showed the fat (epididymal adipose) mass gain with a high fat diet was attenuated in the medium and high resistant starch groups. ARS researchers, in this study conducted microbiome analysis and determined a resistant starch concentration-dependent decrease in opportunistic pathogens and bacteria associated with obesity. This data suggests that daily intake of rice containing resistant starch attenuates fat deposit induced by a high-fat diet, and can exert a concentration-dependent effect on the gut microbiome that may be protective of intestinal inflammation and obesity risk.
Review Publications
Cao, H., Sethumadhavan, K., Li, K., Boue, S.M., Anderson, R.A. 2019. Cinnamon polyphenol extract and insulin regulate diacylglycerol acyltransferase gene expression in mouse adipocytes and macrophages. Plant Foods for Human Nutrition. 74(1):115-121. https://doi.org/10.1007/s11130-018-0709-7.
Hatami, M., Kalantari, S., Soltani, F., Beaulieu, J.C. 2019. Storing Dudaim melon fruits (Cucumis melo var. dudaim) harvested at different stages of maturity. HortTechnology. 29:3. https://doi.org/10.21273/HORTTECH04057-18.
Boue, S.M., Daigle, K.W., Beaulieu, J.C., Heiman, M. 2019. Rice bran and flour enriched with blueberry polyphenols increases storage stability and decreases arsenic content in bran. Foods. 8(7):276. https://doi.org/10.3390/foods8070276.
