JPH0418822B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pretreatment method for frying vegetables, fruits, etc. under reduced pressure to produce dry preserved foods.

Vacuum frying has been widely adopted as a method for producing dry preserved foods, and many inventions and ideas related to this have been filed. In general, in vacuum frying, heat is supplied to the raw material using oil or fat, which has excellent heat transfer efficiency and can be dehydrated and dried in a short time.Since it is under reduced pressure, it is possible to fry at low temperatures, which prevents quality deterioration such as browning and discoloration of the material. Because the process is carried out at low temperatures and low pressure, there is little oxidation or deterioration of the frying oil, and the oil content of the material is low, resulting in a product with excellent shelf life.

However, in vacuum frying, intense moisture evaporation is observed within 3 to 5 minutes after the start of frying, and during this period, approximately 70 to
80% of the water evaporates, and this rapid dehydration causes deformation and shrinkage of the raw material.This evaporation of water also causes the oil temperature to drop significantly, slowing down the drying speed. For this reason, as the amount charged at one time increases, it takes longer for the oil temperature to recover, and the frying time becomes unstable, resulting in a disadvantage that products of uniform quality cannot be obtained. In order to compensate for this drawback, various primary drying processes have been considered before vacuum frying in order to perform vacuum frying in a short time and improve productivity, but all of these processes require separate drying equipment. However, the drying time is long, and the process at high temperatures can cause deterioration in quality and change in color before frying.

The present invention is an improvement on the conventional pretreatment for vacuum frying, and the raw materials are immersed in a sugar solution so that they can withstand relatively high temperatures of 100 to 130 degrees Celsius. Even when frying, it dries in a short time without reducing quality, and by keeping the oil temperature at the beginning of frying higher than the temperature during frying, the oil temperature is stabilized, and by increasing the initial oil temperature, The present invention provides a pretreatment method for vacuum frying that increases the initial amount of moisture evaporation and shortens the frying time.

Next, the pretreatment method of the present invention will be explained. Vegetable and fruit raw materials are divided or sliced into shapes that are easy to fry, and saccharides with high osmotic pressure such as monosaccharides, disaccharides, dextrins, polysaccharides, starch syrup, etc. are used singly or in combination of two or more. The raw material is immersed in a sugar solution and frozen before and after this treatment step.

Suitable sugar solutions to be used include disaccharides, dextrins, polysaccharides, starch syrup, etc. These sugar solutions can be used alone or in combination of two or more of them, and the immersion in the sugar solution is usually carried out at room temperature. For raw materials that penetrate slowly at room temperature or that do not deteriorate even at high temperatures, it is possible to use the soaking sugar solution by heating or boiling it, and by taking such measures, productivity can be increased. can be improved. However, some raw materials cannot maintain their puffed state after frying even after being immersed in a sugar solution, or may undergo significant deformation or shrinkage. It is made into a porous state by freezing it once during the process, and is able to maintain the porous state even after fluorination. This is thought to be because freezing the raw material alters its structure and prevents deformation and shrinkage during dehydration. For example, carrots frozen with the same treatment are porous with almost no deformation or shrinkage, while carrots that are not frozen are deformed like cherry blossoms, 20 to 50% smaller than frozen carrots. A contraction was observed.

Next, the present invention will be specifically explained with reference to Examples.

Example 1 (Apple) After washing apples, remove the core and cut into 3 to 4 pieces.
Slice into ~5mm thick pieces. The slices are immersed in a 40% mixture of starch syrup and dextrin (1:1) at room temperature for 10 hours. After that, this soaked material was once frozen, and then it was stored in a vacuum chamber at 20 mHg to an initial temperature of 120 mHg.
Fry for 12 minutes at a final temperature of 98°C.

After frying, a product with good color and texture was obtained.

Example 2 (Onion) Onion was peeled, divided, sliced, blanched and frozen. Add this frozen product to a 40% mixture of starch syrup and dextrin = 1:1, add salt,
Season by adding spices and soak for 1 hour at 30℃. After draining the liquid, fry for 17 minutes at an initial temperature of 120℃ and a final temperature of 100℃ in a 20mmHg vacuum chamber. The resulting product was porous and had a pleasant texture with a residual onion aroma.

Example 3 (Carrot) After washing carrots, slice them into 2-3 mm rounds.98
Blanch for 2 minutes at °C. After blanching, quickly cool in cold water, drain and freeze. Add salt, spices to a 30% mixture of frozen starch syrup and dextrin = 2:1.
Add chemical seasonings and soak for 1 hour. After draining the liquid 20
Fry for 12 minutes at an initial temperature of 120℃ and a final temperature of 95℃ in a mmHg vacuum chamber. A porous product with a bright orange color and moderate sweetness and salty taste was obtained.

In the present invention, as a pretreatment for vacuum frying foodstuffs, the raw materials are immersed in a sugar solution as described above and then frozen, so that the raw materials do not deform or shrink even during rapid dehydration in the early stage of frying. It maintains a porous state and can be vacuum fried without quality deterioration such as browning or discoloration even under relatively high temperature conditions of 100 to 130 degrees Celsius. By selecting sugar, the acidity of the raw material, In addition to being able to adjust the sweetness, by adding salt, spices, chemical seasonings, etc. to the sugar solution, the flavor can be adjusted to match the ingredients, making it possible to obtain a dried food that is suitable as a snack for children or as a snack with alcohol. Moreover, since it can be fried in a short time, it prevents the loss of vitamins and other nutrients contained in the raw materials, making it possible to obtain innovative dry fried foods that cannot be found in conventional vacuum fried products. play.

Claims (1)

[Scope of Claims] 1. Raw materials are divided or divided and sliced into a single or mixed sugar solution of monosaccharides, disaccharides, dextrins, polysaccharides, starch syrup, and other saccharides having high osmotic pressure. A pretreatment method for vacuum frying, characterized by subjecting the raw material to a soaking process and then temporarily freezing the raw material during or after the soaking process. 2. The pretreatment method for vacuum frying according to claim 1, wherein the sugar solution is heated or boiled when the raw materials are immersed in the sugar solution.