Advantages                                                                                                    

• Quality of product independent of reducing sugar content in potatoes
• No blanching required
• Improved natural potato taste of the product
• Lower frying temperature better for frying-oil quality
• Consistent product quality throughout the year
• Less discoloration of the finished product
• Capacity up to 1500 kg/h finished product
• Fully automatic process control

Introduction

Aspects such as health, convenience and proper nutrient balance clearly demand process innovations. In order to respond to these trends, FLORIGO has reintroduced vacuum frying (initial units were supplied during the sixties and seventies), which opens new possibilities to applications in the potato, vegetable and fruit processing industry.

The unique aspect of vacuum frying is based on the fact that much lower temperatures can be applied during frying. Therefore it is easier to maintain natural colours and flavours of the product. Besides that, vacuum frying has many other advantages e.g. the use of various types of oil (no oxidation risk) and the absence of frying vapor emission.

In the latest development of vacuum frying, the Multi Stage Fryer, we benefit from the advantages of atmospheric frying as well as vacuum frying. To meet with the industrial requirement of capacities, the Multi Stage Fryer is developed for a capacity of 1.500 kg/h finished product. Colour is formed by the reaction between reducing sugars and amino acids (Maillard reaction). This reaction becomes excessive when the moisture content falls below ca. 20% and the frying temperature is above 120ºC. Only decreasing the frying temperature under equal atmospheric conditions is not a practical thing to do, moreover it seriously affects the quality of the product because of the low rate of evaporation. However with the Multi Stage Fryer the product is finished fried under vacuum conditions which ensures a sufficient rate of evaporation and - because of the non-critical conditions with low frying temperatures and absence of oxidation - results in producing crisps with unchanged colour, texture and oil content. Due to the lower temperatures the nutrient balance improved (reduced Maillard reaction) which gives the product a more natural potato taste. The Multi Stage Fryer is a combination of an atmospheric pre-fryer and vacuum finish fryer. Both fryers are connected to each other, by rotary valve in order to eliminate the transfer time of the product and cooling down of the pre fried product. Therefore all parameters like oil flow, frying temperature, frying vapours and vacuum pressure are controlled independent for each fryer. The Multi Stage fryer requires a good preparation of the sticks which means mass flow control and separation of sticks. Therefore FLORIGO designed a cutting and washing section which meets all these requirements. Due to the lower frying temperatures in the vacuum fryer, blanching of the sticks is no longer necessary.