Black mulberry fruit drying by in hot air and closed cycled modified athmosphere processes

In this study, Morus nigra L. fruit on the final product properties of hot air and closed cycle modified atmosphere drying processes were investigated. In this context, hot air (21% O2) and closed cycle modified atmosphere (9% and 15% O2) drying processes at three different temperatures (70, 80 and 90 ºC) and three different air velocities (1, 2 and 3 m/s), moisture, water activity, anthocyanin profile (by HPLC), color change and browning index, pH, rehydration capacity, total monomeric anthocyanin changes were investigated. The optimization conditions of M. nigra fruits were determined according to the Box-Behnken experimental design using the response surface method. The differences in the results of the dried fruits were determined by the t test. Optimum drying conditions were 80°C, 3 m/s and 9% O2. Dried fruits were stored at room temperature for 60 days. Moisture, water activity, browning index, rehydration capacity, anthocyanin profile and total monomeric anthocyanin loss analysis were performed on the 30 and 60 days of storage. In this study, the black mulberry fruit, which initially had a moisture content of 82.55%, was dried to a moisture content of about 10%, and the water activity values of the fruits were found to be in the range of 0.36-0.41. Water activity value of dried fruits ranged between 0.41-0.46 on the 30th day of storage and 0.37-0.42 on the 60th day of storage. While the pH of fresh fruits was 3.66, the pH value after drying was 3.76-3.97. While the rehydration capacity which is known as an important quality indicator and desired to be high in dried products was found higher in KADMAK drying method, loss of anthocyanin and TMA was found less in KADMAK drying method. Anthocyanins which are high in mulberry fruits; delfinidine-3glycoside (1623.06 mg/kg), cyanidine-3-glycoside (316.52 mg/kg) and pelargonidine-3-glycoside (322.23 mg/kg). In dried black mulberry fruits, delfinidine-3-glycoside was determined between 403.64-1451.60 mg/kg, cyanidine-3-glycoside 140.38-242.64 mg/kg and pelargonidine-3-glycoside 285.02-289.76 mg/kg. In KADMAK system, the loss of delfinidine-3-glycoside was 10.56%, the loss of cyanidine-3-glycoside was 23.34% and the loss of pelargonidine-3-glycoside was 10.08%, found to be 75.13%, 55.65 and 11.55 in hot air drying, respectively. TMA loss of samples dried by KADMAK and hot air drying processes were 45.07% and 55.62, respectively. TMA loss of dried black mulberry samples stored for 30 days was over 63%. TMA loss in samples stored for 60 days was over 71%. As a result of this study, it was found that moisture and water activity values were reduced to values where microbial growth could be slowed down in both drying methods, rehydration capacity was higher in KADMAK dyring black mulberry samples and KADMAK method was superior to ATMK method and it has been concluded that anthocyanin losses are less in black mulberry fruits dried by KADMAK method.