The use of dried cheese in food production and food preparation sectors is becoming increasingly widespread. Dried cheese is preferred because of their longer shelf life at room temperatures, smaller packaging sizes, practical use, and their ease of homogenization in food products. Various technologies are currently being used for the drying of cheese and efforts are still being made to develop new methods. Freeze drying is a highly preferred technique for the production of dried cheese due to high quality of the final product. Instant removal of water and low process temperatures ensure an effective prevention of chemical and microbial deterioration. In this study, White, Kashar and Tulum cheeses were dried by freeze-drying method. Physicochemical analyses were carried out on the first day in order to determine the initial quality of cheese samples. The moisture and salt content were highest in White cheese, titratable acidity and fat content were highest in Tulum Cheese. Freze dried cheese samples were stored in room conditions for 6 months and changes in microbial populations such as mesophilic aerobic bacteria, yeast and moulds, lactic acid bacteria, Staphylococci spp. and coliform group bacteria were determined. The results showed that Tulum Cheese contained highest microbial counts in general. The number of bacteria was 7.71±0.10 log cfu/g in Tulum Cheese, 5.70±0.07 log cfu/g in White cheese. Total counts of yeasts and molds were 7.37±0.06 log cfu/g for Tulum cheese and 4.92±0.07 log cfu/g for Kashar Cheese. Statistical analysis was performedby using Minitab Statistical Package Program to evaluate the results of microbiological analysis on dried cheese samples.

Yogurt powder was produced by freeze drying and with added candied chestnut puree at ratios of 5, 10, and 20 % by weight. Moisture sorption isotherms of yogurt powder samples, plain (YP), and containing 5, 10, 20% candied chestnut puree (CCP) were determined at 25°C using the standard, static-gravimetric method. The experimental adsorption data of yogurt powders at 25°C were fitted to 14 sorption equations which are most widely used to fit experimental sorption data of various food materials. The parameters of the sorption models were estimated from the experimental results by using the nonlinear regression analysis. The GAB model gave the closet fit to the sorption data of freeze dried yogurt powders with candied chestnut puree at 25°C. BET, Ferro Fanton, Henderson, Halsey, Oswin and Modified Oswin models are also acceptable for describing the adsorption isotherms for freeze dried yogurt with candied chestnut puree at 25°C.