Progress 07/01/03 to 06/30/06
Outputs
The growing concern on healthy eating among consumers has increased the value of oligosaccharides as a food ingredient. Non-digestible oligosaccharides are generally categorized as prebiotics and benefit the colon by stimulating the growth of beneficial microflora and repressing the growth of pathogenic ones. Rice bran is an inexpensive, underutilized bio-resource. Its inherent oligosaccharide content is about 5-6% and presents a tremendous potential to offer unique health benefits should extraction yields can be further increased. This project aimed to increase the yield of oligosaccharides from rice bran by physical, chemical, and enzymatic means. The use of dilute hydrochloric acid, ethanol, boiling, homogenization, ultrasonication, xyllanase, cellulase, and/or combination was investigated. The optimized extraction procedure made use 1.0% cellulase (based on bran weight), carrying out the extraction at 50oC for 1 hour, arresting the enzymatic reaction by boiling for
15 min, precipitating out residual starch and protein by the addition of equal volume of ethanol, centrifugation, and then drying the supernatant at 40oC. Extraction yield ranged from 13.4 to 39.9%. Total carbohydrates, reducing sugars, and residual protein were 44.5-77.4%, 13.1-62.3%, and 7.1-11.6%, respectively. As determined by high-performance anion-exchange chromatography with pulsed amperometric detector, the oligosaccharide components in the extracts with prebiotic significance were triose (raffinose, cellotriose, and maltotriose), tetraose, and pentaose. Glucose was still the predominant sugar in the extracts and may consists of inherent bran glucose and glucose produced by the degradation of cellulose-rich bran matrix. In vitro digestibility with salivary and pancreatic α-amylase was very low compared with the original bran sample and potato dextrin.
Impacts
Rice bran is an inexpensive, underutilized bio-resource. The extraction of high-value, nutritionally important food ingredient like oligosaccharides will therefore enhance the economic value of rice bran and will increase the benefits that can be derived from rice farming, thus a potential impact to the rice industry and health of consumers.
Publications
- Wang, L., Patindol, J., and Wang, Y.J. 2005. Increasing oligosaccharides content in rice bran by physical and enzymatic means. Book of Abstracts. American Association of Cereal Chemists Annual Meeting.
- Patindol, J., Wang, L., and Wang, Y.J. 2006. Cellulase-catalyzed extraction of oligosaccharides from defatted rice bran. Book of Abstracts. Institute of Food Technologists Annual Meeting and Exposition.
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Progress 01/01/05 to 12/31/05
Outputs
Non-digestible oligosaccharides have been classified as "prebiotics" because they benefit the colon by selectively stimulating the growth of bifidobacteria and decreasing the toxicity of the colon contents. The growing concern on "healthy-eating" among consumers has increased the value of oligosaccharides as a food ingredient. This research focuses on the extraction and identification of oligosaccharides present in rice bran. Rice bran is an inexpensive, underutilized bio-resource. Oligosaccharides from rice bran has been reported to be about 5-6% and present a tremendous potential to offer unique health benefits if the oligosaccharides content can be further increased. This study has demonstrated that the yield of oligosaccharides from rice bran can be increased by physical and enzymatic means. When rice bran is extracted with 40-80% ethanol, the yield of oligosaccharides ranges 10-12%. When ultrasonication is combined with ethanolic extraction, no further increase
in oligosaccharide yield is observed. The main oligosaccharide in the extract is raffinose as determined by high-performance anion-exchange chromatography with pulsed amperometric detection. The yields of soluble sugars are 13 and 16% for 1 h, and 14 and 24% for 16 h of stirring with xylanase or cellulose, respectively, when rice bran (10% solid in water) is treated with xylanase or cellulase at room temperature. When the mixture is blended at a high speed for 2 min after the cellulase treatment, the extract yield is increased to 33%. When rice bran is first boiled in water for 5 min before the cellulase hydrolysis and high-speed blending, the extract yield is increased to 49%. However, no significant improvement in the extract yield is noted for those treated with xylanase. A combination of boiling, cellulase and blending treatments is an effective way to increase the amount of extractable oligosaccharides from rice bran.
Impacts
Rice bran is an inexpensive, underutilized bio-resource. The extraction of high-value, nutritionally important food ingredient like oligosaccharide will therefore enhance its economic value and will increase the benefits that can be derived from rice farming, thus, a significant impact to the rice industry and health-conscious consumers.
Publications
- Wang, L., J. Patindol, and Y.-J. Wang. 2005. Increasing oligosaccharides content in rice bran by physical and enzymatic treatments. (Abstract) American Association of Cereal Chemists Annual Meeting.
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Progress 01/01/04 to 12/30/04
Outputs
The growing concern on healthy-eating among consumers has increased the value of oligosaccharides as a food ingredient. Oligosaccharides (3 to 20 monomers) are generally categorized as prebiotics due to their potential to promote human intestine health by stimulating the growth of beneficial intestinal microflora and repressing the growth of pathogenic ones. This research is focused on the extraction and identification of oligosaccharides present in rice bran. Rice bran is an inexpensive, underutilized bio-resource. The extraction of high-value, nutritionally important food ingredient like oligosaccharide will therefore enhance its economic value and will increase the benefits that can be derived from rice farming, thus, a significant impact to the rice industry and health-conscious consumers. Extraction experiments were done using deionized water, 80% ethanol, and dilute HCl (0.1N). Different extraction time and temperature combinations were tested for each solvent
(overnight shaking at room temperature, heating in a 40oC water bath/shaker for 2 hours, heating in a water bath/shaker at 80oC for 2 hours, and boiling by reflux for 1 or 2 hours). High-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) was used to separate the components of the oligosaccharide extracts according to degree of polymerization. With deionized water as extractant, crude oligosaccharide yield ranged from 11 to 16%. HPAEC-PAD analysis revealed that the water-extracted oligosaccharides consisted of 55.0% sucrose, 13.7% glucose, 12.0% maltose, 10.8% raffinose, 5.8% fructose, and 2.8% melibiose. With 80% ethanol as extractant, crude oligosaccharide yield ranged from 9.0 to 9.5%. HPAEC-PAD analysis showed that the ethanol-extracted oligosaccharides consisted of 64.9% sucrose, 18.1% glucose, 8.0% raffinose, 6.9% fructose, and 2.2% melibiose. With dilute HCl as extractant, extraction yields were higher, ranging from 14.0 to 50.0%. HPAEC-PAD
analysis showed complicated saccharide profiles, and components with a degree of polymerization of up to 50 were even detected. This result implies that the oligosaccharides obtained with dilute HCl were not natural and could be acid-degradation products from starch and fiber. Work continues to use enzymatic and sonication methods to enhance extraction of the more nutraceutically-relevant oligosaccharide fractions (DP 3 to 20).
Impacts
Rice bran is an inexpensive, underutilized bio-resource. The extraction of high-value, nutritionally important food ingredient like oligosaccharides will therefore enhance the value of rice bran and will increase the benefits that can be derived from rice farming, thus, a significant impact to the rice industry.
Publications
- No publications reported this period
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Progress 01/01/03 to 12/31/03
Outputs
The growing concern on 'healthy-eating' among consumers has increased the value of oligosaccharides as a food ingredient. Oligosaccharides as prebiotics promote human intestinal health by stimulating the growth of beneficial intestinal microflora and repressing the growth of pathogenic ones. This research project is focusing on the extraction and characterization the composition and structure of oligosaccharides from rice bran. Dilute hydrochloric acid (0.1N HCl), deionized water, and ethanol (90%) were used for extraction. Extraction time and temperature were varied for the optimization of the extraction procedure. The crude extract yield using hydrochloric acid, water, and ethanol was 14.0-50.0%, 11.5-16.0%, and 9.0-9.5%, respectively. Refluxing rice bran in boiling dilute HCl for 2 h gave the highest yield (50.0%). Reducing the acid concentration from 0.1 to 0.05N for a one-hour reflux extraction reduced the yield from 45.5% to 20.0%. With water, extraction through
reflux also improved the yield. Extraction at 80 and 40 degrees C with water for 2 h were comparable with overnight room temperature extraction in terms of yield. With ethanol, extraction yield was not affected by extraction temperature and time. Chemical analyses of the crude extracts are in progress.
Impacts
Rice bran is an inexpensive, underutilized bio-resource. The extraction of high-value, nutritionally important food ingredient like oligosaccharides will therefore enhance the value of rice bran and will increase the benefits that can be derived from rice farming, thus, a significant impact to the rice industry.
Publications
- No publications reported this period
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