People always want a popular vegetable or/and fruit chips, especially, natural nutrition keeping.
Vacuum frying, a promotional technology, seems to produce these crispy chips in true. Vacuum frying is defined as carrying out under atmospheric pressure, normally, bellow 6.5 KPa that will result a lower water boiling temperature.
There are many manufacturers that offer a wide range of vacuum fryer, classified in structural, it is vertical, horizontal, respectively; and according to operation, intermittent and continuous, respectively.
All the present vacuum fryer system includes a frying vessel associated with an oil heating and vacuum unit.
There is not difficult in technical view. How about the operation in the practical application?
1st, Vacuum In Vacuum Frying Process
Water in fruit and vegetable includes free and bound water. Free water is easy to be removed in the earlier frying stage, the higher the vacuum exists, the larger the vapour volume of moisture evaporation generates. Greater pressure difference between the ambient space and internal evaporated vapor causes a porous texture. That result easier to break the fibers of fruit and vegetable tissue which is one of the key to create senses of crispness. At mean time, vapor escape creates more channels.
Therefore, create and keep an approaching limiting vacuum, is essential.
2nd Frying Oil Temperature In Vacuum Frying Process
Frying temperature is determined as following factors; one is to avoid frying oil deterioration and another one is indeed keeping the natural nutrition in fresh vegetable and fruits.
Frying oil deterioration will be fast when the oil temperature is more than 100℃ , and also the natural ingredient are all sensitive to thermal processing, they are very easy to lose.
On the contrary, what the most important point is to keep the frying oil temperature during the whole frying process, from beginning to finishing.