Aroma components and biological activities of vinegar produced from whey

Whey is a liquid by-product of cheese production. It contains almost all of the lactose, half of the dry matter, and approximately 20% of the protein of milk. Leaving this by-product to the environment as a waste material causes environmental pollution, loss of nutritional value, and economic loss. In our study, four types of whey vinegar (PASS, PASS 5%, PASS 10%, and PASS 15%) were produced using whey (PAS) and whey supplemented with lactose (5%, 10% and 15%) as raw materials. The whey vinegar will be an important alternative to the evaluation methods of whey. Lactose and protein amounts, antimicrobial and antioxidant activity parameters, and aroma components of whey and whey vinegars were investigated. Additionally, the total acid amounts of four whey vinegars were determined. Antimicrobial activities were studied by different methods such as agar well diffusion, minimum inhibition concentration (MIC), maximum tolerable concentration (MTC), and minimum bactericidal concentration (MBC). In order to determine the antioxidant activity parameters, total oxidant level (TOS), total antioxidant level (TAS), glutathione (GSH) level, and catalase (CAT) enzyme activity analyses were performed. According to the results, the total acid values of the vinegars were determined between 5.92-14.97 g/100 mL. The lactose amounts of PAS, PASS, PASS 5%, PASS 10%, and PASS 15% were determined as 32.912, 0.540, 0.615, 3.477, and 50.798 g/L (respectively); protein amounts were determined as 0.948, 0.308, 0.423, 0.423, and 0.432 g/100 g (respectively). It was found that whey did not exhibit antimicrobial activity against test bacteria. Moreover, MIC values were determined as 25-50, 6.25-50, 6.25-50, and 6.25-25 µL/mL for PASS, PASS %5, PASS %10, and PASS %15, respectively. It was observed that PASS has a weaker antimicrobial effect than the other vinegars. No TOS activity was found except for PASS, and TAS was found at an average level in all groups. When the aroma components are examined, it is seen that ethanol and acetic acid are the dominant components in all vinegars.