The Effects of Vacuum Cooling on Some Physico-chemical and Microbiological Properties of Shortened Cake

Subject Areas : Microbiology

M. Malmir ¹ ( دانش آموخته کارشناسی ارشد گروه علوم و صنایع غذایی، واحد علوم و تحقیقات تهران، دانشگاه آزاد اسلامی، تهران، ایران )
B. Ghiassi Tarzi ² ( استادیار دانشکده علوم و مهندسی صنایع غذایی، واحد علوم و تحقیقات تهران، دانشگاه آزاد اسلامی، تهران، ایران )
G. H. Assadi ³ ( استادیار دانشکده علوم و مهندسی صنایع غذایی، واحد علوم و تحقیقات تهران، دانشگاه آزاد اسلامی، تهران، ایران )
H. Mirsaeed Ghazi ⁴ ( استادیار مهندسی صنایع غذایی، گروه فناوری صنایع غذایی، پردیس ابوریحان، دانشگاه تهران، پاکدشت، ایران )
B. Delkhosh ⁵ ( استادیار گروه زراعت، دانشکده کشاورزی و منابع طبیعی، واحد علوم و تحقیقات تهران، دانشگاه آزاد اسلامی، تهران، ایران )

Received: 2016-08-25 Accepted : 2016-08-25 Published : 2016-09-22

Keywords: Air Cooling, Cooling Time, Cake, Hardness, Vacuum Cooling, Weight loss,

Abstract :

Introduction: In the bakery industry, it is required to cool the product as soon as possible after the product is taken out of the oven and prior to packaging in order to avoid vapour condensation inside the wrapping. The object of this study is the design of vacuum cooling system and to compare the effects of different cooling methods on some physico-chemical and microbiological properties of shortened cake. Materials and Methods: After baking the products were allowed to cool down by different methods namely still air cooling (24 ℃), forced air cooling (air velocity was 1.5 m/s) and vacuum cooling (40 mbar). The cooling process ended when the center temperature of the samples reached the temperature of 30 °C. Cooling time, mass loss, hardness, moisture content, water activity and sensory quality were investigated after cooling.  Results: The results showed that the weight loss of 4.58% was obtained concerned with shortest cooling time of 94 seconds for vacuum cooling in comparison to air cooling and forced air cooling cakes (p<0.01). Crumb of vacuum cooling cakes was harder with lower moisture content, water activity and microbial spoilage (p<0.01). The results did not show significant differences in water activity and hardness of crumb between air cooling and forced air cooling cakes. Sensory evaluation indicated lower moisture content for vaccum cooling cakes as compared to other cooling methods, but there were not significant differences (p>0.05) between overall acceptability  of the cake samples. Conclusion: Vacuum cooling has provided and demonstrated benefits, regarding the shortening of cooling time and minimization of microbial growth. It is expected that its application will become more competitive and widespread in the future.