Rice Utilization and Product
Development - 2005

 

 

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Project Leader and Principal  Investigators

Zhongli Pan, research engineer, USDA-ARS, Albany, CA

 

 

 

Broken rice and rice bran are produced in large quantities as byproducts from rice processing. Currently, they have low economic value and are not well utilized. However, both are high in protein and could be used as raw materials for producing high-value functional food ingredients and nutritional supplements.

Food protein-based molecules called polypeptides are effective at fighting hypertension and are safer than conventional drugs. New processing methods for producing functional polypeptides from rice protein are necessary for economic development as a food product.

Ultrasonic technology has many advantages over conventional practices to extract proteins and to reduce the use of enzymes in the production of polypeptides. This increases both the functionality of the end product and reduces the production time needed for extraction.

 The research objectives for 2009 were:

  • Optimize the processing conditions of ultrasonic-assisted extraction and pretreatment.

  • Study the antihypertensive properties of different fractions of peptides separated with ultrafiltration.

  • Investigate the stability of the antihypertensive polypeptides and their effectiveness on experimental rats.

Four commercial enzymes were tested for their effectiveness in breaking down rice proteins into polypeptides. The protease Alcalase, manufactured by Novozymes, was determined most effective. Optimal “digestion” conditions, such as temperature and pH, were also determined.

To accelerate enzymatic digestion and to enhance the bioactivity of polypeptides, rice protein was pretreated ultrasonically. This significantly increased the production of the polypeptides’ antihypertensive effect.

Polypeptides were also separated by molecular weight with a centrifuge and tested for effectiveness. Results showed that rice polypeptides with the highest antihypertensive effect were those with the lowest molecular weight.

The next step of this research should be the development of pilot-scale processing capabilities. Large amounts of treated rice polypeptides will be necessary for more testing on animals and for clinical trials with humans.

 

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