Evaluation of atmospheric and vacuum frying on properties of deep fat fried Reshte-Khoshkar

Vacuum frying is a new technology that can be used to improve the quality attributes of fried food because of the low temperatures employed and minimal exposure to oxygen. In this paper، the atmospheric and vacuum frying of Reshte-Khoshkar (a traditional Gilan-Iran sweet cookie) were compared. Four pressure levels (47. 4، 57. 83، 70. 1 and 101. 325 kPa)، with three frying times (130، 160 and 190 s) and three thermal driving forces (ΔT=40، 60، and 80°C، constant difference between the oil temperature and the boiling point of water at the applied pressure) were used for frying. The effects of frying time، vacuum level and frying temperature on physical properties، such as moisture loss، oil absorption، and shrinkage were investigated. Moisture loss and oil absorption of fried Reshte-Khoshkar were significantly affected by frying pressure، frying time and frying temperature. The results showed that the moisture content decreased with increasing the frying pressure، frying time and frying temperature and fat content increased. Interestingly، a strong relationship between water loss and oil content was observed in both techniques. Vacuum frying was shown to be a promising technique that could be used to reduce oil content in the fried Reshte-Khoshkar. Shrinkage was not directly related to the frying condition of Reshte-Khoshkar.