Letter to the Editor The effect of addition of skimmed milk on the characteristics of Myzithra cheeses S. Kaminarides ⇑ , E. Ilias-Dimopoulos, E. Zoidou, G. Moatsou Laboratory of Dairy Science and Technology, Department of Food Science and Human Nutrition, Agricultural University of Athens, Iera Odos 75, 11855 Athens, Greece article info Article history: Received 28 February 2014 Received in revised form 20 November 2014 Accepted 19 January 2015 Available online 7 February 2015 Keywords: Reduced fat whey cheese Whey proteins Myzithra cheese abstract Myzithra cheese is a traditional Greek whey cheese. Three types of Myzithra cheese were produced from A: 100% whey; B: 90% whey + 10% ovine milk and C: 90% whey + 10% skimmed ovine milk and were evaluated. The addition of skimmed milk to whey resulted in a new dietary product, containing 9.24% fat, with good quality, a harder texture and higher levels of ash, Ca, Mg and K than those of experimental cheeses A and B. Electrophoretic patterns and HPLC chromatograms of the proteins of Myzithra cheeses revealed the presence or not of a s -CN to the whey cheeses. In addition, SDS–electrophoresis of proteins under special preparation of samples permitted for first time the separation of whey-cheese protein (WP) components that had been denatured during cooking of the whey. Ó 2015 Elsevier Ltd. All rights reserved. 1. Introduction Whey is the aqueous portion of milk remaining after milk coagulation and removal of the curd. It is an opaque liquid possess- ing a greenish-yellow colour, produced in large quantities in the dairy industries and usually discarded, causing major environmen- tal pollution due to its high organic load. World production of whey is approximately 120,000,000 tons per annum and the major whey producers are the EU and the US (Kevin Stiles, 2012). Cheese whey is composed of 92–95% w/w water and 5–8% w/w dry mat- ter, of which around 60–80% is lactose, 10–20% proteins, as well as minerals, vitamins, fat, lactic acid and trace elements (Gonzalez, 1996). The concentrations and ratios of major proteins in ewe and goat whey differ from those in bovine whey (Moatsou, Hatzinaki, Samolada, & Anifantakis, 2005). A large por- tion of whey is used for the production of whey cheeses in the Mediterranean region. The production of whey cheeses is based on denaturation and coagulation of the water soluble milk proteins present in the whey b-lactoglobulin (b-Lg), a-lactalbumin (a-La), immunoglobulins (Igs) and serum albumin (SA) when it is heated at temperatures above 85 °C(Pearce, 1989). Myzithra is a tradi- tional Greek whey cheese made by heating the whey at a tem- perature of 88–92 °C. Myzithra is sent to the market one day after manufacture and when kept at 4 °C is normally consumed within 2 weeks. Fresh Myzithra cheese is not usually salted. On the contrary, dry Myzithra cheese and Xynomyzithra cheese are salted (Greek Codex Alimentarius, 2011). For better quality Myzithra, whole milk is added to the whey in a proportion of 10%. Recently, the production of low-fat cheese has increased con- siderably in response to the increasing demand by consumers for this kind of cheese for health and nutritional reasons. The con- sumption of saturated fat causes serious health problems, such as obesity, atherosclerosis, cardiovascular damage, coronary heart disease, diabetes in adults, as well as certain forms of cancer in the breast and large intestine. In the National Dairy Council (NDC, 2009), to use a ‘‘reduced’’ claim, there must be at least a 25% reduction per reference amount for the nutrient amount of fat or saturated fat, cholesterol calories or sugars. So, the term reduced fat cheese generally refers to cheeses whose fat content is at least 25% lower than that of the corresponding full fat variety. The novelty and aims of this study were: (a) the production of reduced fat Myzithra cheese, (b) the ability to separate and distinguish the different serum proteins of Myzithra cheese because during the heat treatment a complex of proteins is created, which is hard to separate. 2. Materials and methods 2.1. Composition of whey and ovine milk Sweet whey was derived from ovine milk after the production of Halloumi cheese (Anifantakis & Kaminarides, 1983). The mean values (±) the standard errors of means of the whey constituents, determined by the Milkoscan apparatus (model 255 A/B, type 25700, Fosselectric, Denmark) were: 0.54% ± 0.02 fat, 1.67% ± 0.05 http://dx.doi.org/10.1016/j.foodchem.2015.01.086 0308-8146/Ó 2015 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +30 1 5294641; fax: +30 1 5294672. E-mail address: skamin@aua.gr (S. Kaminarides). Food Chemistry 180 (2015) 164–170 Contents lists available at ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem