Determination of Thermal Properties and Oxidative Stability of Whey Butter by Differential Scanning Calorimetry

Whey is the liquid by-product obtained by separating the coagulum from milk during cheesemaking. Although being considered as a waste by-product of dairy industry, whey has been utilized for several decades to valuable products (whey concentrate, whey powder, whey protein concentrate/isolates and lactose). Whey contains 0.3-0.5℅ of fat depending on the source of milk and type and processing steps of cheese. The present study was conducted to determine the thermal properties and oxidative stability of butter samples produced in a laboratory scale from wheys collected from four different cities in Turkey. Two commercially produced milk butters were used as control samples. The butter sample (10-15 mg) was placed in a 50 µL- aluminum pan and heated dynamically at heating rate 5 oC from –60 to 40 oC or at heating rates of 5, 10, 15 and 20 oC/min from 100oC to 400 oC under nitrogen or oxygen gases. Milk and whey butters showed similar melting endotherms, and no significant difference was found in their Tonset (–18.55 oC), Tpeak (12.23 oC), Tend (33.06 oC) and enthalpy (93.20 J/g). When the samples were heated under oxygen atmosphere from 100 oC to 400 oC, a broad exothermic peak was observed with 190.50 oC Tonset, 289.93 oC Tpeak, 357.44 oC Tend and 3274 J/g enthalpy, which was not observed under nitrogen atmosphere. Each 5 oC increase in the heating rate shifted the peak to 10 oC higher and made the peak sharpen, but the enthalpy decreased by 4-8%. These results indicated that whey butter have similar thermal and oxidative properties to milk butter. Therefore, it has potential to bring an economic gain to countries.