ORIGINAL RESEARCH Soya bean oil/soya protein isolate and carrageenan emulsions as fat replacer in fat-reduced Oaxaca-type cheese ALFONSO TOTOSAUS, 1 * ELADIO ROJAS-NERY 1 and M. JESUS FRANCO-FERN  ANDEZ 2 1 Food Science Lab & Pilot Plant, Tecnol ogico Estudios Superiores Ecatepec, Av. Tecnol ogico esq. Av. Central s/n, Ecatepec 55210, Estado de M exico, and 2 Instituto de Ciencias Agropecuarias, Universidad Aut onoma Estado Hidalgo, Av. Universidad km. 1, Tulancingo 43600, Hidalgo, M exico Milk fat was replaced in Oaxaca-type cheese with soya bean oil emulsions stabilised with soya pro- tein isolate and different carrageenans (kappa, iota and lambda). Inclusion of soya bean oil emul- sion increased yield, moisture and protein content and reduced fat content. Fat reduction and moisture incorporation provoked a tougher but less ductile texture. Specific interaction of car- rageenans with milk proteins resulted in larger spreading area when melted and a softer and more adhesive texture, particularly in samples containing lambda-carrageenan. These results are useful to improve the nutritional composition of Oaxaca-type cheese, allowing the control of textural properties during cheese melting. Keywords Cheese, Fat reduction, Textural profile analysis, Melting texture, Emulsion, Carrageenans. INTRODUCTION Oaxaca cheese is a fresh pasta filata type cheese, with a particular manufacturing process where the curd is immersed in hot water to stretch and knead the cheese strands, referred to as plastici- sation (Fox et al. 2000). Full-fat Oaxaca cheese has a wide compositional range (15–24% pro- tein, 17–25% fat, 2–4% ash, 1–4% salt, 12–61% moisture and pH 4.9–5.5) depending on the heating used (pasteurised or raw), reflecting structural differences due to the process of mechanical deformation and stickiness during plasticisation (M. De Oca-Flores et al. 2009; Villanueva-Carvajal et al. 2012). Lower fat con- tent in Oaxaca cheese resulted in the formation of larger and more compact fibres, where serum channels were interspersed, due to more pro- tein–protein interaction during the plasticisation manufacturing process, that is the kneading and stretching of hot curd. At higher fat content, protein–protein interactions within the matrix decreased and water–protein interactions increased, retaining more water within the pro- tein matrix (Col  ın-Cruz et al. 2012). In 2014, Oaxaca cheese production in Mexico was around 20 150 tons and was one of the most consumed fresh cheeses (SIAP, 2014). This kind of cheese is important as it is widely consumed for breakfast or dinner, as shredded cheese is used in ‘quesadillas’, a meal made by melting Oaxaca cheese inside a folded tortilla. Nonetheless, fat content in Oaxaca cheese could be a health issue. Dietary fat is often blamed as the major source of excess energy. Besides quantity, the type of dietary fat consumed is also an important factor contributing to the develop- ment of cardiovascular disease, cancer, diabetes and other degenerative diseases like fatty liver (Chang and Chow 2008). But the simple reduc- tion in dairy product consumption is not the ideal strategy to lower ingestion of saturated fatty acids (Livingstone et al. 2012). Substitu- tion of milk fat by vegetable oils can contribute to a healthier saturated/unsaturated fat balance in cheese (Fathi Achachlouei et al. 2013). In this case, the more plausible alternative to maintain the cost and improve nutritional quality of dairy products is to replace the milk fat by vegetable oils to alter the fatty acid composition. Emulsion *Author for correspondence. E-mail: alfonso.totosaus@ gmail.com © 2017 Society of Dairy Technology Vol 70 International Journal of Dairy Technology 1 doi: 10.1111/1471-0307.12397