The science is becoming more often a tendency to develop new products or even to explore new ways of getting the same product using more effective and cheapest processes, improving businesses income by creating new products. In the food industry some drying processes are used to guarantee the quality of the product. By using these processes it is also possible to create new products. In this work the cheese will be analysed, more precisely the ball cheese edges whose transformation will be made by using multiple drying, methods such as hot-air drying, freeze drying and micro waves drying. The purpose is to create a new product (a snack) based on the cheese industry ball edges, and to assess which process is better. The previously mentioned drying methods will be analysed based on time and costs for the creation of the new product. The micro wave drying is becoming more used in the food industry because it’s faster with lower costs. The nutritional value, texture and colours are also important factors for this product. For the three drying processes different temperatures, times and powers were used. For hot-air drying temperatures of 43 ºC and 52 ºC were used and air speed of 1,2m/s. In the freeze drying process three drying times were used: 6 hours, 16 hours and 24 hours. The microwave drying process was the most focused process in this study by using 5 different microwave power: 350W, 500W, 650W, 750W and 850W. The drying times for this process was variable according to the power used. In all processes tthere was used a common factor: the water activity value (aw), which value should be between 0.3 and 0.4, assuring the food safety of the product. Some evaluations were performed analysing the colour and texture of the product obtained by each process, and a nutritional analysis for the hot-air drying processes carried out at 52 ºC and for the microwave processes with the 750W and 850W powers. A sensory test was also made, with a panel used to taste cheese in order to evaluate the final opinion of the consumers. The results showed that the temperature is relevant for the drying time, as well as it is important for the hardness of the obtained product. The microwave power increase induces the reduction of the drying time. The power used alters the texture of the resulting product. The 850W power reduced the drying time, and the colour parameters where better preserved, showing that this power is interesting for the product dehydration.
- Mestrado em Engenharia Alimentar
Estudos de desidratação de queijo
Pinho, A. R. D. C. (Student). 3 May 2016
Student thesis: Master's Thesis