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Pulse fractionation and by-product utilization
R. TYLER (1). (1) University of Saskatchewan, Saskatoon, SK, Canada

Both dry and wet processes are employed in the commercial production of concentrated protein products from pulses (starchy grain legumes). Typically, fine grinding and air classification of yellow field pea yields protein-rich and starch-rich fractions containing 50-55% protein and 85-90% starch, respectively, along with a hull (seed coat) fraction containing 90-95% dietary fibre. The primary markets for air-classified fractions from field pea are in feed and industrial applications, with a significant amount of hull fibre used in food. Both the starch and protein fractions from dry milling can be further purified or modified by aqueous or other means. Alkali or acid extraction of yellow field pea, followed by recovery of protein from the extract by isoelectric precipitation or membrane filtration, yields a protein product containing approximately 85% protein, along with high-purity starch, cotyledon fibre, hull fibre and an effluent stream as by-products. Commercialization of a micellar (salt extraction and precipitation) process for isolation of protein from field is in progress. The primary markets for wet-milled fractions are in the food industry. Starch is the major product from both dry and wet fractionation of pea. Its utilization is hampered by its intermediate amylose content and its associated unique functionality. The hull fraction is light in colour and bland in flavour, and when finely ground exhibits interesting water absorption and thickening properties, and has a variety of food uses. The cotyledon fibre product from wet milling is white in colour and high in water absorption, and again sees application in food products. The effluent stream from wet milling of pea represents both a disposal cost and a loss of solubles, which may include high quality protein. A variety of methods have been investigated for recovery of protein from the effluent stream.

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