Changes of proteolysis and angiotensin-I converting enzyme-inhibitory activity in white-brined cheese as affected by adjunct culture and ripening temperature

The effects of use of adjunct cultures (Lactobacillus helveticus and Lb. casei) and ripening temperatures (6 or 12 degrees C) on proteolysis and angiotensin-I converting enzyme (ACE)-inhibitory activity in white-brined cheeses were investigated during 120 d ripening. Proteolysis was monitored by urea-polyacrylamide gel electrophoresis (urea-PAGE) and reversed phase-HPLC (RP-HPLC) of water-insoluble and -soluble fractions of the cheeses, respectively. Urea-PAGE patterns of the samples revealed that the intensities of the bands representing casein fractions decreased in the experimental cheeses, being more pronounced in the cheeses made with adjunct cultures. Similarly, peptide profiles and the concentrations of individual and total free amino acids were influenced by both the adjunct cultures and ripening temperatures. The ACE-inhibitory activity of the water-soluble extracts of the cheeses were higher in the cheeses made using adjunct cultures (especially Lb. helveticus) and ripened at 12 degrees C. The ACE-inhibitory activity did not decrease during ripening. The contribution of Lb. helveticus to the development of proteolysis and ACE-inhibitory peptide activities were higher than that of Lb. casei. To conclude, the use of Lb. helveticus as adjunct culture in white-brined cheese and ripening at 12 degrees C would be recommended to obtain white-brined cheese with high ACE-I-inhibitory peptides activity and higher levels of preoteolysis.