Effect of heating and acid on the yield and quality of cheese produced from UF-concentrated whey

Whey was UF-concentrated before heating. Lactic, citric or hydrochloric aci d were used for acidification. The effects of heating rate combined with co ncentration level and type of acid, on process yield, protein and solids re tention and quality characteristics of the product were examined. UF-whey concentrated to 5:1 resulted in 3.6% cheese yield and 14.8% whey so lids retention in the cheese. Higher concentration level (20:1) negatively affected the total solids retention (10.5%) and led to 2.0% product yield. The protein retention was 73.4% and 55.4% for the UF-whey concentrated to 5 :1 and 20:1, respectively. Slow heating rates of 1-1.5 degrees C/min result ed in higher solids retention and consequently in better product yield (2.5 %) compared to the faster heating rate of 3 degrees C/min (2.1%). The best results concerning the solids retention were obtained when lactic or hydroc hloric acid was used at a heating rate of 1-1.5 degrees C/min and ranged be tween 14.1-14.9%. Citric acid resulted in about 12.4-12.6% solids retention with no significant difference between the heating rates. The sensory char acteristics of the products were not affected by any of the factors studied .