Effects of different pretreatments and implemented drying methods on total phenolic content and antioxidant activity in the apple

The present study had been carried out in order to produce apple crisps where phenolic substances that are critical for health and antioxidant activity are maintained. In this study, Starking delicious, Lutz golden apples from 2012 and 2013 harvest had been used as raw material. For both of the apple types, pH, ash, humidity, protein, fat amount, oBriks and refractive index determinations and similar analyses had been carried out. In the study, the effects of the apple species, dipping solution, drier type on drying time of apple slice had been determined and tried to design a process where phenolic materials and antioxidant activity loss shall remain minimum. In the study, three different driers had been used, these are Microwave, Vacuum drier and Freeze driers. Dipping solutions had been prepared with ascorbic acid and citric acid solutions. In apple crisps production, the apple type, pre-treatments applied, selected drier type is effecting the product quality, production time and costs in different ratios. According to the information obtained from the study, the fastest drying had been performed by microwave drier but the best quality in terms of phenolic substance and antioxidant activity had been ensured by use of freeze drier. Since the drying time in vacuum drier where phenolic substances and loss of antioxidant activity is the least, is acceptable when compared with the other two methods, Lutz golden apples without peel for which 1:6 dipping solution concentration applied was the most appropriate raw material for crisps production. In the analysis carried out, in terms of phenolic substances and antioxidant activity, the average product was the apple crisps produced by using Starking delicious without peel, dried in microwave without being subjected to pre-treatment.