True retention of nutrients on cooking of Australian retail lamb cuts of differing carcass classification characteristics Somkiat Kosulwat*, Heather Greenfield, Kenneth A. Buckle Department of Food Science and Technology, University of New South Wales, Sydney NSW 2052, Australia Received 7 June 2002; received in revised form 19 February 2003; accepted 21 February 2003 Abstract The true retention of nutrients (proximate principles and cholesterol) on cooking of three retail cuts from lambs classified by weight, sex and fatness score was investigated. Fat retentions of the total cut and of the lean portion of lamb legs and mid-loin chopswerenotaffectedbycarcassfatness,weightandsexortheirinteractions,however,thefatretentionofthetotalcutandofthe lean portion of forequarter chops was affected by fat score, with forequarter chops from fat score 1 retaining more fat than did chops of carcasses of higher fat score. Overall, fat was lost by all cuts (total cut) on cooking, with only 70–80% of fat being retained, but fat content of lean only increased on cooking (retention > 100%), indicating the passage of fat into the lean portion from the external fat cover during the cooking process. Carcass factors and their interactions had little or no effect on the protein, water and ash retentions of the total cut or the lean portions of the three cuts. Cholesterol retention by the lean portion of three cookedlambcutswasnotaffectedbyanycarcassfactorsortheirinteractions.Cholesterolretentionswere  99%fortotalcutsand tendedtobe  102% for the lean portions. # 2003 Elsevier Ltd. All rights reserved. Keywords: Lamb; True retention of nutrients; Fat retention; Carcass classification 1. Introduction In an effort to reduce the risk of coronary heart dis- ease, the National Heart Foundation of Australia has developed dietary advice that includes reducing intakes of total fat, saturated fat and cholesterol (NHF, 1999). Australian government health authorities also generally recommend a decrease in the total fat content of the diet,bothtoreducetheriskforotherchronicdiseasesas well as for coronary heart disease (National Health & Medical Research Council, 1992), emphasising the desirabilityofselectingleanmeatcuts.AUS-MEAThas introduced a carcass classification scheme as a guide to selection of leaner meats (Marketing guide to Australian lamb and mutton, undated), and the effects of the AUS- MEAT carcass classification on proximate, cholesterol and fatty acids of cuts from carcasses from different classeshavebeenstudiedforrawretaillamb(Kosulwat, Greenfield,&James,2002).However,nopublisheddata are available for controlled studies of cooking and its effects on the true retention of nutrients of lamb of var- ious carcass classes. The aims of this study were there- fore to investigate the effects of fatness class, weight, and sex and cooking on the true retention of nutrients (proximate principles, and cholesterol) of different Australian lamb cuts. 2. Materials and methods 2.1. Lamb carcasses and butchering A flock of over 200 Dorset Cross lambs of the same age and stock, raised on the same farm under identical husbandry conditions, and slaughtered under identical conditions on the same day provided lamb cuts for this study. Carcass characteristics of the lambs, butchering and position of the cuts (leg, mid-loin chops and fore- quarterchops)onthelambcarcasseshavebeendescribed by Kosulwat et al. (2002). 0309-1740/03/$ - see front matter # 2003 Elsevier Ltd. All rights reserved. doi:10.1016/S0309-1740(03)00063-9 Meat Science 65 (2003) 1407–1412 www.elsevier.com/locate/meatsci * Corresponding author. Tel.: +66-02800-2380x316; fax: +66- 02441-9344. E-mail address: nusks@mahidol.ac.th (S. Kosulwat).