Preparation of canola protein materials using membrane technology and evaluation of meals functional properties A. Ghodsvali a,b, * , M.H. Haddad Khodaparast c , M. Vosoughi d , L.L. Diosady e a Department of Food Science and Technology, University of Ferdosi, Mashad, Iran b Golestan Agricultural Research Center, Department of Agricultural Engineering, Shahid Beheshti Avenue, P.O. Box. 49156-77555, Gorgan, Iran c Department of Food Science and Technology, Faculty of Agriculture, University of Ferdosi, Mashad, Iran d Department of Chemical and Petrolium Engineering, Sharif University, Tehran, Iran e Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ont., Canada M5S 1A4 Received 10 August 2004; accepted 21 October 2004 Abstract 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 iso- lates 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. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Rapeseed/canola; Alkaline extraction; Isoelectric precipitation; Phytic acid; Protein isolates; Ultrafiltration; Diafiltration 1. Introduction Rapeseed is an important oilseed crop and ranks sec- ond in the world production of oil bearing seeds. World rapeseed/canola production now exceeds forty million metric tons per year (USDA, 2004), with china as the largest producer and Canada as the leader in the large- scale-production of a modern, genetically improved, and high-quality of rapeseed varieties which are low in both erucic acid (<2%) and glucosinolate (<30 lmol/g in the meal). Canola is a new oilseed crop and although there will be, at least initially, some difficulties with growing canola because of insects and diseases, most of these problems can be minimized or eliminated through care- ful management and continued experience in growing canola. Rapeseed/canola is an attractive cash crop for the agricultural producers. In addition, its production provides the opportunity to break up disease, insect and weed cycles associated with traditional wheat pro- duction system. Approximately 90% of edible oil con- sumed in Iran is imported from other countries and 0963-9969/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodres.2004.10.007 * Corresponding author. Tel.: +98 171 3350063; fax: +98 171 3359813. E-mail address: qodsevali@yahoo.com (A. Ghodsvali). www.elsevier.com/locate/foodres Food Research International 38 (2005) 223–231