Understanding, predicting and controlling the physicochemical functionality of rice protein ingredients
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University College Cork
The aim of this research was to characterise the nutrient composition and protein profile of a range of intact and hydrolysed rice protein ingredients, to benchmark their physicochemical properties against those of selected commercial dairy protein ingredients, and to develop tailored solutions for understanding, predicting, modifying and controlling their functionality in food systems. The rice protein ingredients studied had protein contents in the range 32-78%, and lower levels of calcium and total essential amino acids compared to dairy protein ingredients. Intact rice protein ingredients had poor solubility in water and thus limited functionality; conversely, hydrolysed rice protein ingredients had solubility values >60% across the pH range 2-8, with those derived from rice endosperm being almost completely soluble and exhibiting very high heat stability and possessing excellent foaming properties. Rice protein hydrolysates were subsequently produced by controlled enzymatic hydrolysis of a rice protein concentrate ingredient. Three different proteases tested increased the solubility at neutral pH of the intact rice protein ingredient from 3% to values in the range 31-61%. This protein hydrolysis approach offers possibilities for the development of rice protein ingredients with tailored functional properties. An oil-in-water emulsion-based model nutritional beverage formulated using a rice endosperm protein hydrolysate was found to be physically unstable to flocculation and coalescence; inclusion of low molecular weight surfactants, including CITREM, DATEM and lecithin, considerably enhanced the stability of the emulsion towards creaming, with increasing levels of CITREM also enhancing its stability towards heat treatment and storage- induced changes. Overall, the studies presented in this thesis provide a comprehensive understanding of the potential and challenges in the use of rice protein ingredients in food formulations, and facilitate the targeted enhancement of their functional properties in order to expand their range of applications.
Rice proteins , Macronutrient composition , Protein composition , Physicochemical properties , Enzymatic hydrolysis , Protein functionality
Amagliani, L. 2016. Understanding, predicting and controlling the physicochemical functionality of rice protein ingredients. PhD Thesis, University College Cork.