Abstract: A food material placed into a frying box 3 is immersed into an impregnation tank 50 containing a processing liquid under a depressurization in a throw-in preliminary chamber 9 and then, the substitution of the water in the food material with the processing liquid is conducted by exposure to the atmosphere. The food material impregnated with the processing liquid in the above manner is subjected to a frying under a depressurization in a fryer body 1. A fried food product is oil-cut away under a depressurization in a discharge preliminary chamber 10 by an oil cutting-away vibrator and then cooled rapidly by a cooling gas blown from a pipe 49. This treatment causes the surface of the fried food product to be solidified rapidly, thereby providing an expanded fried product having a crispy eating feel without shrinkage.

Abstract: In a vacuum concentrating plant, a feed liquid supplied into a vacuum pan evaporator is heated indirectly by a latent heat by introducing depressurized vapor into a steam jacket added to an outer periphery of a lower portion of the vacuum pan evaporator. In this manner, the feed liquid in the vacuum pan evaporator is boiled and concentrated in a concentrating zone within the vacuum evaporator. The depressurized vapor used for heating the feed liquid is obtained by heating water in a depressurized vapor generator by means of a heating source in a heat pump. On the other hand, the vapor generated in the vacuum evaporator is cooled and condensed in a vapor condenser by means of a cooling source in the heat pump and removed in the form of a drain outside a circuit system. A concentrate as a product is withdrawn outside the circuit system through a concentrate withdrawing line by an operation of a pump.