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United States Department of Agriculture

Agricultural Research Service

Research Project: Rice As a Source and Delivery System for Nutrients and Lipophilic Bioactive Compounds

Location: Food Processing and Sensory Quality Research

2011 Annual Report


1a.Objectives (from AD-416)
Objective 1: Develop a continuous process for extraction of protein, lipids, starch, and fiber from rice bran in forms with desired functional, nutritional, and sensory properties for applications in human and domesticated animal diets using novel technologies, such as subcritical/low polarity water. Objective 2: Utilize rice starch as a matrix for the effective delivery of lipophilic bioactive compounds [e.g., Vitamin A, gamma oryzanol and related ferulate esters), Co-Q10, omega 3-DHA, lycopene, polyphenols] through the development of porous rice starch granules and beads, spherical aggregates, and nanocapsules. Objective 3: Test the performance of the starch encapsulates in model food systems.


1b.Approach (from AD-416)
A continuous extraction system scalable for industrial production of soluble rice bran protein concentrates (>70% protein) and isolates (>90% protein) will be designed employing subcritical water. The subcritical water process will be designed to also allow separation of the lipids with their associated lipophilic bioactive compounds, high demand lecithin, hydrolyzed starch, and fiber fractions for incorporation in food and beverage products. A suite of rice flour/starch encapsulation systems that are capable of a) delivering lipophilic bioactive compounds at desired levels, b) protecting these bioactive compounds against degradation during food processing and storage, c) masking flavor of bioactive compounds while not adversely affecting the sensory properties or stability of the final product, and d) delivering the bioactive compounds with desired bioavailability/bioactivity will be developed. How well the developed rice starch encapsulates perform in model fried, baked, and beverage products will be determined.


3.Progress Report
Work was started to develop rice starch technologies that would allow for encapsulation of nutraceutical and other healthful ingredients. Current work has focused on encapsulating Coenzyme Q10, a health-enhancing antioxidant. This enzyme was encapsulated in rice starch that was chemically modified to facilitate association with the enzyme. Modification of the rice was needed to improve compatibility of the starch with materials that are less hydrophilic, (i.e., components that are not very soluble in water). The particles were formed by modifying the starch, then forming an emulsion with the additives and spray-drying the mixture to produce dry particles. The resulting capsules have shown improved solubility in water, stability during storage, and bioavailability in the human digestion system.

As a second approach to use rice-based encapsulating materials, porous rice particles were prepared by alcoholic dehydration of gelatinized rice flour and starch slurries. The porous particles were then placed in contact with extracted blueberry plant phenolics, which also have good antioxidant properties. The treatment allowed some of the phenolics to be taken up in the pores of the starch. These products show superior solubility and stability properties, and could be useful as health-food supplements.

Edible films were also prepared using metal-ion cross-linked modified rice starch. The products, displaying improved textural and moisture-barrier properties, should be useful as carriers of flavor and nutritional additives and as barriers for separation, protection and preservation purposes. Testing of these properties is continuing.

A lexicon (a set of sensory descriptors) was developed to describe flavors of several types of whole grain rice, included brown, light brown, white, red, black/purple color rice varieties. This lexicon adds greater understanding of flavors associated with rice bran color to better explain the consumers’ reaction to whole grain rice flavor. The lexicon was used in the laboratory to evaluate the effect of adding salt and/or oil to the cooking of whole grain pigmented rice. Sensory data were collected on the effects of adding salt, oil and salt with oil to cooked brown, red and black/purple rice varieties. Also measured was oxygen radical absorbance capacity (ORAC), to determine if the addition of salt or oil affected the rice’s antioxidant properties. The addition of salt and salt with oil when cooking whole grain rice increases the corn/popcorn/buttery flavor and reduces the bitter taste and water-like/metallic flavor. The addition of salt and/or oil had no affect on the antioxidant capacity of pigmented rice varieties.


4.Accomplishments
1. Low-oil uptake frying batters. Frying batters enhance the sensory quality of food but they also absorb large amounts of oil, which could cause health concerns for consumers. ARS scientists from the Southern Regional Research Center in New Orleans, LA, working under a Cooperative Research and Development Agreement (CRADA) with CrispTek, LLC, of Columbia, MD, have developed rice-based low oil-uptake frying batters. The research promotes the use of rice and results in the development of less caloric and healthier fried foods. In addition, these products are of interest to persons with Celiac’s disease who cannot tolerate batters that contain wheat-based ingredients. The technology has been developed commercially by CrispTek, LLC.

2. Rice-based edible films. Edible film coatings are useful as carriers of flavor and nutrient additives. They are frequently used as barriers for separating ingredients, protection products from external contamination, and for food preservation. Free-standing edible films were prepared by food scientists from the Southern Regional Research Center in New Orleans, LA, using rice wax and pullulan (a good film-forming carbohydrate). Rice wax is a low-cost and under-used co-product from the processing of rice bran oil, and is a rich source of high molecular weight fatty alcohols (i.e., policosanols) that are beneficial in diets for lowing cholesterol levels. The hydrophobic rice wax and the hydrophilic pullulan combine to form composite films with various water resistant capacities. The films also provide a health-enhancing quality to food products. This development promotes the use of rice wax as a surplus agricultural commodity, and will be of interest to food processors and persons prone to hypercholesterolamia.


Review Publications
Rashida, A., Shih, F.F., Riaz, M. 2010. Processing and functionality of rice bran protein and peptides. Institute of Food Technologists. 233-246.

Champagne, E.T., Bett Garber, K.L., Thomson, J.L., Grimm, C.C., Lea, J.M., Fitzgerald, M.A., Resurreccion, A., Ohtsubo, K., Jongdee, S., Xie, L. 2010. Important sensory properties differentiating premium rice cultivars. Rice. 3:270-281.

Pan, Z., Khir, R., Bett Garber, K.L., Champagne, E.T., Thompson, J.F., Salim, A., Mohamed, S. 2011. Drying characteristics and quality of rough rice under infrared radiation heating. Transactions of the ASABE. 54(1):203-210.

Shih, F.F., Bett Garber, K.L., Champagne, E.T., Daigle, K.W., Lea, J.M. 2010. Effects of beer-battering on the frying properties of wheat or rice batters and their coated foods. Journal of Food Science. 90:2203-2207.

Shih, F.F., Daigle, K.W., Champagne, E.T. 2011. Effect of rice wax on water vapor permeability and sorption properties of edible pullulan films. Food Chemistry. 127:118-121.

Last Modified: 10/1/2014
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