Phytochemical properties in the waste by-products of peach: optimization and storage stability studies

Waste by-products of peach, which are potential antioxidant sources, were evaluated in terms of total phenolic and anthocyanin substance amounts and antioxidant activity values. The results are given in comparison with the juice of the respective fruit. Peach peel had the highest content regarding all three dependent variables. It has been observed that the peels contain 6–7 times higher phenolic substances than peach pulp and juice. Considering the leaves, it was seen that the peach peels contain 6 times more anthocyanins than the peach leaves. Therefore, studies continued with peach peels. Peels were extracted using ultrasound-assisted extraction (UAE). The experimental design of UAE, the effects of the process parameters on the system, the modeling of the experimental data, and the optimization of the conditions were carried out with central composite design (CCD) of response surface methodology (RSM). According to the optimization study of central composite design with the Design-Expert software, the highest total phenolic substance (12.64 mg GAE/g FM) and total anthocyanin (0.107 mg cyn-3-glu/g FM) yields were obtained with 30.3% ethanol solvent system with 10% of the energy treatment by using 0.1 g fresh peel. It has been observed that the quadratic model equations derived for both systems successfully represent the experimental data based on the analysis of variance test. The degradation rate of the phytochemical content in the sample stored at room temperature in light environment is the highest for each measured quality parameter value. It was observed that the rate of degradation increased regularly with the increase in storage temperature.