11-9 |
Enzymatic hydrolysis of quinoa proteins to produce functional and bioactive peptides |
R. E. ALUKO and E. Monu. Dept. of Human Nutritional Sciences, Univ. of Manitoba, 400-A Human Ecology Bldg., Winnipeg, MB R3T 2N2, Canada Food utilization of quinoa seed proteins depends on prior removal of the toxic seed coat saponins. However, the process of saponin extraction has been shown to cause decreases in the functional properties of quinoa seed proteins. Enzymatic protein modification can be used to increase functional properties of native proteins. In addition to increase in functional properties, enzymatic modification can lead to the production of bioactive peptides suitable for use in human nutrition. The objective was to use extensive proteolysis to convert the less functional quinoa seed proteins into highly functional and bioactive protein hydrolysates. Extensive proteolysis of quinoa protein concentrate was done with Alcalase followed by ultrafiltration using 5000 and 10000 molecular weight cut-off membranes. The results showed that protein solubility and foaming capacity of the hydrolysate and membrane permeates were significantly higher (p<0.05) than those of the protein concentrate. The protein concentrate had significantly higher (p<0.05) emulsifying activity index than the protein hydrolysate and membrane permeates. Membrane fractionation of the protein hydrolysate into lower molecular weight peptides significantly reduced (p<0.05) foaming properties, but it improved radical scavenging activity as well as ability to inhibit activity of angiotensin converting enzyme. The results suggest that functional and bioactive properties were dependent on the molecular size of peptides in the quinoa protein hydrolysates. This work is significant because it demonstrated the potential for value-added utilization of quinoa seed proteins in food as well as in functional foods and nutraceuticals industries. For example, increased protein solubility of the hydrolyzed products can be utilized to fortify acidic food drinks for increased nutritional quality. The hydrolyzed quinoa protein can also be used to improve the quality of foamed food products. The low molecular weight peptides can be used as antihypertensive agents as well as free radical quenching agents that promote cellular integrity.
Session 11, Food Chemistry: Proteins I
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