आईएसएसएन: 2329-888X
Ahmed Hamid Ziena, Sahar A. Nasser, Hamid Morsy Ziena
The solar heating system was used for the production of yoghurt. The possibility of reaching the temperature of the solar heating room at 42 degrees Celsius for about 7 hours per day was maintained. The experiment was conducted in two stages. The 1st stage was carried out using the solar dryer system equipped with a fan and a turbine to facilitate the heat of the solar heated air upwards (S1) and it was compared to the yogurt prepared in the traditional method (T1). The 2nd stage was conducted after turning off both the fan and the turbine in the solar heating system and to find a source of pure water to reduce the speed of the solar heated air and maintain the level of relative humidity (S2) and compare it with the traditional way (T2). Total solids, protein, fat, acidity (%) and pH were estimated. The rheological properties, viscosity of yoghurt, lactic acid bacteria, yeasts, fungi, coliform group and sensory tests were determined. The yoghurt was also stored for one week in the refrigerator at 4°C. Data showed the success of yoghurt production by solar energy, especially after modification, with a high quality close with that produced by the traditional method.