Sample Solution

proteins, which can be induced by hydrogen bonding, hydrophobic, ionic, and covalent interactions. Besides, these interactions can be affected by several factors such as pH, temperature, phenolic structure, molecular weight, and amino acids compositions in that medium29. Apostolidis et al.16 reported that herbal enriched cheese samples, did not have significantly (P > 0.05) higher WSPC, when compared with plain cheese. Also heat treatment of fortified samples could influence the WSPC.

There were no significant difference between AOA levels of PCT samples and control samples at first days of storage. However, AOA level of control sample was significantly (P < 0.05) higher than PCA samples. Generally, AOA levels of samples decreased during storage (Tables 6 and 7). This might be due to interactions occurred between phenolic molecules of tomato and asparagus and proteins, especially whey proteins with active group (-SH). These reactions reduce the influence of antioxidant compounds. So many enzymes such as tyrosinase which can be produced by starters, could convert polyphenols especially luteolin, the important flavones having AOA, to highly active quinines. Quinones can react with amino and sulfhydryl groups of proteins and enzymes as well as with anthocyanins. These secondary reactions can change the physical, chemical, and nutritional characteristics of proteins and may also affect sensory properties of food products30. On the other hand, after 1 month of storage, decreasing in AOA levels in control sample, were more than those of fortified samples and levels of AOA in fortified samples were higher than control sample (Tables 6 and 7). Apostolidis et al.16 reported that the antioxidant activities of the herbal-enriched cheeses were significantly (P < 0.05) higher when compared to the nonenriched samples. Fadavi and Beglaryan8 also, reported that although peppermint has a rich source of antioxidant compounds, i