Free amino acid and rheological measurements on hydrolyzed lactose cheddar cheese during ripening

Three lots each of conventional Cheddar and hydrolyzed lactose Cheddar cheese (HLCC) were analyzed for free ammo acid content and examined for texture properties at 28day intervals during an eight‐month ripening period. The average increases in total free amino acids in the control and the HLCC were from 500 μg/g in each cheese to 9,967 μg/g and 14,564 μg/g, respectively. Aspartic acid, proline and histidine were the only amino acids not significantly different between the two cheeses. Arginine, glycine, alanine, methionine and isoleucine increased slowly during ripening and accounted for 12% of the total free amino acids. Valine, tyrosine, phenylalanine, glutamic acid, leucine and lysine showed greater increases and accounted for about 80% of the total amount of free amino acids at all stages of ripening. Leucine increased the most, from 23.2 μg/g to 1959.5 μg/g in the control cheese and from 68.2 μg/g to 2875.9 μg/g in the HLCC. Arginine and methionine were the only two amino acids whose mole percentages did not significantly differ between the control and the HLCC. The mole percentages of aspartic acid, tyrosine, histidine, alanine, proline, lysine and glutamic acid decreased during the study in both the control and the HLCC. The mole percentage of leucine increased the most, from 5 to 15% in the control cheese and from 12% to 25% in the HLCC. The texture measurements for toughness, mechanical hysteresis, and modulus of elasticity showed significant (α0.05) treatment effects, but the changes during ripening were not significant. The toughness of the HLCC after eight months was 69% higher than in the control. Stiffness (modulus of elasticity) was 54% less and the damping capacity (mechanical hysteresis) was 93% more in the HLCC cheese than in the control. The differences in the texture measurements (toughness, mechanical hysteresis, and modulus of elasticity) on the controls and HLCC were greatest after 3 or 4 months and remained relatively constant thereafter. Therefore, proteolysis is related to texture and quality of cheese and accelerated ripening does seem to enhance desirable body and texture characteristics.