Vacuum Frying: An Alternative to Obtain High-Quality Dried Products

Abstract

Vacuum frying is an alternative way to improve the quality of the fried food and could reduce the final oil uptake in the product. The product is heated at low pressure thus decreasing the boiling points of the frying oil and the water in the product. Moreover, the absence of air during vacuum frying may inhibit lipid oxidation and enzymatic browning, and therefore, the color and nutrients of samples can be largely preserved. Many food research projects involving snack food industries therefore attempt to understand oil uptake during the vacuum-frying process in order to control and reduce the fat content of fried products without deteriorating their desirable organoleptic characteristics. This article is an update of the state-of-the-art in vacuum-frying technology, showing the effect of pretreatments and frying conditions on quality characteristics of the products. Facts pertaining to equipment and operation conditions are included. On the other hand, mathematical models to describe oil uptake and water loss are also mentioned. The effect of this treatment on color, texture, and nutritional value of the final products is also discussed.

Vacuum processing of food–a Mini Review

“…Andres-Bello et al 1 identified three vacuum frying equipment based on size: laboratory, pilot and industrial scale system and in terms of processing requirements: for batch or continuous processes. The authors have accordingly elaborated on three examples of vacuum frying systems.…”

“…6 The foremost factors that impact fried products are the frying time-temperature combination of the process; the correct combination is necessary to produce a food product with acceptable physical attributes. 1 Dueik & Bouchon 6 reported that vacuum frying pointedly lowered the final oil content in comparison to atmospheric fried food products and it also significantly reduced the rancidity of the oil used for frying. Most of the benefits from vacuum frying could be attributed to usage of low temperatures (105°C), the minimal exposure to oxygen, which diminishes the adverse effects on the oil quality.…”

Effect of Vacuum Frying on Quality Attributes of Fruits

“…Dueik and Bouchon [28] put emphasis on the microstructure, methods to reduce oil uptake, oil quality, bioactive compound degradation, and toxic compound generation. Andres-Bello et al [8] reviewed the vacuum-frying processing for producing highquality fried products, focusing on equipment types, pre-treatments, and vacuum-frying conditions.…”

Texture, Oil Adsorption and Safety of the European Style Croquettes Manufactured at Industrial Scale

“…When this type of croquette is manufactured at industrial scale, the next processing steps are carried out: (1) stirfrying of some ingredients; (2) mixing of all ingredients with water and boiling for making dough which constitutes the filling of the croquettes; (3) dough cooling with cold air; (4) dough extruding, dividing and forming for achieving the required shape and size of the croquettes; then, (5) coating is applied to the croquettes, first with a batter, and secondly with breadcrumbs; and the croquettes are conveyed to the (6) continuous freezing, and (7) packaging later as precooked frozen croquettes, or they are directly conveyed to packaging and cooling for obtaining precooked refrigerated croquettes. Before consumption, at the foodservice sector (for example the kitchen of the restaurant or canteen), or at the home kitchen, the croquettes are generally deep-fried to create a golden and crunchy outer crust.…”