Determination of taurine concentration during cheddar cheese manufacture and examination of antioxidant properties of whey, permeate, mother liquor, and taurine

Abstract

The objectives of this study were to determine the mass balance of taurine during the conversion of milk to cheese and during the processing of whey through lactose crystallization and to determine the antioxidant activity of whey fractions in ribosome and hemoglobin model systems. Raw milk was pasteurized and inoculated with a commercial lactic acid bacteria culture and sampled hourly until it coagulated. The concentration of taurine did not change during fermentation which showed that the bacteria did not use taurine as a nutritive source. Whey from Cheddar cheese was pasteurized at 63C̊ for 30 min, cooled to 5C̊, and centrifuged to remove fat and other particles. The clarified whey was subjected to ultrafiltration and the permeate concentrated by evaporation to about 40% total solids. Lactose was crystallized and separated from the remaining liquid. An HPLC method was employed to determine the concentration of taurine in milk, whey, permeate and mother liquor. The concentration of taurine in the milk, Whey, permeate, and mother liquor was 32, 26, 33, and 394 nmol/ml ( 41.2% total solids ), respectively. The pH of permeate of whey from Cheddar cheese was adjusted to 9.8 and subjected to anion exchange chromatography. Taurine was eluded from the column with 0.5 N acetic acid at pH 2.53. The percentage of taurine eluded from the column was determined by ¹⁴C radioactive labeling. The antioxidant activity of taurine and the whey fractions was tested in a ribosome system made from phosphatidylcholine using either FeCl₃ or lipoxidase as the catalyst and in a hemoglobin antioxidant model system. Antioxidant activity was observed for all whey fractions in the ribosome and hemoglobin antioxidant systems. Taurine did not exhibit antioxidant activity in the ribosome system but did have antioxidant activity in the hemoglobin system. These results indicate that taurine in whey fractions might have antioxidant activity but it is not responsible for the antioxidant activity observed using the ribosome model system. Antioxidant activity present in mother liquor indicates that the mother liquor might be useful as a food ingredient to prevent oxidation of food.