Preparation of canola protein materials using membrane technology and evaluation of meals functional properties

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Suitable conditions for the extraction and precipitation of proteins from Iranian canola ( Brassica napus, cv. Quantum, PF, and Hyola) meals were determined using a membrane-based process which consisted of extraction of hexane-defatted canola meals at pH 9.5–12.0 and precipitation, at pH values between 3.5 and 7.5, to recover a precipitated protein isolate (PPI). Acid soluble protein isolate (SPI) was then prepared by ultrafiltration (UF) followed by diafiltration (DF) and drying. The highest protein yield was obtained by alkaline extraction at pH 12.0 with all meals investigated. The maximum yield of precipitated protein was observed at pH values between 4.5 and 5.5, depending on variety and dehulling treatment. Almost 90% of the proteins were recovered in three products: PPI and SPI containing (81–98% protein, N*6.25), and the meal residue (35% protein). The glucosinolate content of all meals tested and their protein products was low, and in some cases they were below the detection limit of glucosinolates. Both isolates were low in phytic acid. Some functional properties (protein dispersibility index, water absorption, fat absorption, emulsifying activity, and foaming properties) were evaluated. Iranian canola meals were compared with soybean meal in terms of functional properties. All canola meals tested showed a high PDI and WA, and were superior to soybean meal in fat absorption, emulsifying activity and foaming properties.