بررسي ويژگي‌هاي فيزيكي، شيميايي، ميكروبي و حسي كشك خشك شده با روش آفتابي و هواي داغ

Investigation of physical, chemical, microbiological and sensory properties of Kashk dried by sun and hot air

در توليد كشك كه از محصولات لبني سنتي ايران مي­باشد به ­دليل شرايط بهداشتي نامناسب و زمان طولاني خشك شدن،محدوديت هايي وجود دارد . لذا با تغيير توليد از حالت سنتي به صنعتي مي ­توان محصول استاندارد و ايمن توليد كرد. در اين تحقيق، نمونه‌هاي كشك با دو روش آفتابي و هواي داغ در دماهاي 50، 60 و 70 درجه سانتي گراد خشك شدند. بعد از خشك­ كردن، ميزان ماده خشك، درصد پروتئين، چربي، خاكستر، نمك، مقدار اسيديته، pH، aw، جذب آب نمونه‌ها، شمارش كل ميكروبي، كلي‌فرم و كپك و مخمر، پارامترهاي رنگ‌سنجي L*، a*، b*، H، C، ΔE و سفتي نمونه‌ها اندازه‌گيري شد. نتايج نشان داد كه بين مقادير پروتئين، چربي، خاكستر و نمك كشك‌ها اختلاف معنادار وجود ندارد (0/05

Kashk, which is a traditional dairy product in Iran, is produced as limited due to unsuitable hygienic conditions and long drying period. It can be produced as standard and safe with transferring from traditional to industrial production scale. In this study, Kashk was produced in two drying methods: sun drying and hot air drying at 50, 60 and 70°C temperatures. After drying, the amount of dry matter, protein, fat, ash, salt, acidity, pH, aw, water absorption, total microbial count, coliform, mold and yeast, color parameters including L*, a*, b*, H, C and ΔE, and hardness in samples were measured. Results showed that there was no significant difference in protein, fat, ash, and salt content of Kashks (p>0.05). Maximum acidity and minimum pH were seen in sundried Kashks. In the hot air method, with increasing temperature acidity and hardness increased and pH and water absorption decreased. Microbiological analysis showed the highest total microbial count in samples dried at 50°C and the lowest count in Kasks dried at 60 and 70 °C. The lowest ΔE was found in both of samples dried at 60°C and sundried. Similarly, sensory evaluation showed the highest overall acceptance in samples dried at 60°C and sundried. According to the result of this study, temperature of 60°C is recommended for drying of Kashk.