1a. Objectives (from AD-416):
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.
1b. Approach (from AD-416):
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.
3. Progress Report:
Different starch types (rapidly digestible, slowly digestible, and resistant starch) can impact sensory evaluation with the potential to alter consumer preferences. Sensory texture data was completed on diverse starch type rice cultivars. Rice was planted in two locations (Stuttgart, AR and Crowley, LA). ARS scientists from the Food Processing and Sensory Quality Unit of the Southern Regional Research Center in New Orleans, LA then compared the texture attribute differences between the rice cultivars with diverse concentrations of starch types and determined the effect of starch type on the sensory texture attributes. We completed the initial research on the diverse resistant/slowly digestivle starch rice cultivars and analyzed the data. ARS scientists from the Food Processing and Sensory Quality Unit of the Southern Regional Research Center in New Orleans, LA are exploring unique methods to create highly resistant starch that is decreases digestibility. One method is the addition of lipids (fatty acids and emulsifiers) and certain phenolic (antioxidant) compounds that interact strongly with starch. Preliminary experiments using different lipids combined with rice starch indicated fatty acids increased resistant starch content. Synergy Flavors Company has provided spent (one-time extracted) green tea, black tea, and coffee for research evaluation. These one-time extracted materials are often disposed of as waste, but still contain valuable phenolics that include tannins that can bind to rice starch and increase resistant starch content. Blueberry phenolics (antioxidants) in pomace (waste after juice processing), that in the past was a waste product, have been encapsulated in porous rice particles prepared by alcoholic dehydration of gelatinized rice flour and starch slurries. The treatment allowed some of the phenolics and anthocyanins (colored antioxidants) to be taken up in the pores of the rice starch and flour. These products show superior solubility and stability properties when compared to normal starch and flour, and can be used in different baked foods and beverages. Further development of a rice bran-blueberry prebiotic (food that promotes growth of beneficial gut bacteria) was completed in collaboration with Microbiome Therapeutics Company. Rice bran was complexed with blueberry juice to form a low sugar, high phenolic (antioxidant) prebiotic. Additionally, rice bran and blueberry pomace (leftover pulp from juice manufacturing) are typically low value waste products. Both blueberry juice and pomace extracts are being used to complex with the protein component of rice bran. By complexing rice bran with blueberry phenolics and anthocyanins a value-added food product for prediabetics is formed without the added sugar from juice/fruit. The rice-blueberry complexes will be used in foods to treat prediabetic patients. ARS scientists from the Food Processing and Sensory Quality Unit of the Southern Regional Research Center in New Orleans, LA are working with international collaborators to examine six red rice varieties that have been cultivated at the Africa Rice Center in the Republic of Benin. Rice samples are being examined for their ability to inhibit a-amylase and a-glucosidase at the USDA laboratories in New Orleans, LA. The ability of these rice varieties to inhibit digestive enzymes (proteins that break down foods) will provide additional health benefits of African rice. Soluble and insoluble starch levels have been determined during freshly milled brown rice processing with various milling techniques and enzyme concentrations. Additionally, starch gelatinization during rice milk processing has been assessed using Rapid Visco Analysis.
1. Development of rice-blueberry prebiotics to promote health. Rice bran (outer layer of brown rice containing antioxidants) and flour combined with blueberry phenolics (antioxidants) produce unique food ingredients that function as prebiotics (food that promotes growth of beneficial gut bacteria). Each year tons of rice bran and fruit pomace (leftover pulp after juice production) are generated as waste material with low value. Development of rice bran+blueberry prebiotics and rice products+blueberry food ingredients have been completed. Rice bran and flour with blueberry pomace extracts have been combined to form value-added prebiotics with the potential to promote healthy blood sugar levels. ARS scientists from the Food Processing and Sensory Quality Unit of the Southern Regional Research Center in New Orleans, Louisiana in cooperation with Microbiome Therapeutics have complexed rice bran and flour with blueberry phenolics (anthocyanins) to produce value-added food products for prediabetics. Data collected indicate beneficial anthocyanins and phenolics are retained by rice bran and flour. Recent data indicate extended phenolic and color stability after several months of storage. Additionally, methods used to produce rice prebiotics reduce arsenic levels in rice bran samples.
2. Varying rice starch types affects sensory evaluation. ARS scientists from the Food Processing and Sensory Quality Unit of the Southern Regional Research Center in New Orleans, Louisiana conducted sensory analysis on rice with different starch types and the data analysis of the diverse resistant/slowly digestible starch rice confirmed that 70% of the sensory variation is due to amylose content. Only 9% is due to the rapidly digestible starch fraction in rice. Meanwhile, 8% of the sensory variation is due to resistant starch fraction. Approximately 6% is due to the slowly digestible starch content. When it comes to mechanical breakdown of the starch, 22% of the variation in the rapid visco analyzer data is due to resistant starch, while 14% is due to slowly digestible starch fraction. This indicates that sensory differences in rice are partly due to the resistant, slowly digestible, and rapidly digestible starch fractions.
3. Colored rice bran is beneficial to diabetics by two mechanisms. Improved blood glucose balance is important for the treatment of Type II diabetes and prediabetes. ARS scientists from the Food Processing and Sensory Quality Unit of the Southern Regional Research Center in New Orleans, Louisiana found colored rice bran increased glucose uptake in apidocytes. This past year, research determined that both red and purple rice bran delayed starch digestion through inhibition of the digestive enzymes a-amylase and a-glucosidase. The inhibition of both a-amylase and a-glucosidase delays digestion and absorption of carbohydrates, and leads to slower increases in blood glucose after a meal. These results point to specific rice varieties with potential for improving glucose imbalances in patients with Type II diabetes and prediabetes.
5. Significant Activities that Support Special Target Populations:
Boue, S.M., Fortgang, I., Levy, R.J., Bhatnagar, D., Burow, M., Fahey, G., Heiman, M.L. 2016. A novel gastrointestinal microbiome modulator from soy pods reduces absorption of dietary fat in mice. Obesity. 24(1):87-95.
Bateman, M., Strong, A.L., Burow, M., Wang, G., Boue, S.M., Bunnell, B.A. 2015. Bone formation: roles of genistein and daidzein. Book Chapter. 2015:111-168.
Bett Garber, K.L., Lea, J.M., Watson, M.A., Grimm, C.C., Lloyd, S.W., Stein, R., Andrzejewski, B., Marshall-Shaw, D.A., Beaulieu, J.C. 2015. Flavor of fresh blueberry juice and the comparison to amount of sugars, acids, anthocyanidins, and physicochemical measurements. Journal of Food Science. 80(4):S818-S827.
Beaulieu, J.C., Stein-Chisholm, R.E., Lloyd, S.W., Bett Garber, K.L., Grimm, C.C., Watson, M.A., Lea, J.M. 2016. Volatile, anthocyanidin, quality and sensory changes in rabbiteye blueberry from whole fruit through pilot plant juice processing.. Journal of the Science of Food and Agriculture. DOI: 10.1002/jsfa.7748.