JPH0436144A - How to manufacture and preserve frozen vegetables - Google Patents

Abstract

PURPOSE:To obtain frozen vegetable having excellent color stability and crisp texture by dipping vegetable in hot water containing sugar alcohol and edible oils and fats, freezing and preserving below a specific temperature. CONSTITUTION:Vegetable such as spinach, CHINGENSAI (a sort of rape), broccoli, eggplant, KOMATSUNA (a sort of Chinese cabbage), leaf mustard or asparagus is dipped in hot water containing sugar alcohol (e.g., sorbitol or reduced maltose) and edible oils and fats at 80-110 deg.C for 20-70sec and frozen below -35 deg.C, then preserved below -35 deg.C.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a method for producing and preserving frozen vegetables.

BACKGROUND OF THE INVENTION Conventionally, frozen vegetables have been prepared by washing vegetables with water, cutting them, blanching them in hot water for several minutes, freezing them at any temperature, and storing them at about -20°C.

Problems to be Solved by the Invention Frozen vegetables produced by conventional methods tend to be too soft and crisp after thawing. Furthermore, since the storage temperature of frozen vegetables is about -20° C., frozen vegetables tend to turn brown during storage, making the product unable to withstand long-term storage.

There is a need for a method for producing and preserving frozen vegetables that have good texture (particularly crispness) and do not brown during storage.

Means for solving problem U The present invention provides vegetables with sugar alcohols and edible fats and oils at a temperature of 8.
This invention relates to a method for manufacturing and preserving frozen vegetables, which comprises immersing the vegetables in hot water at 0-110°C for 20-70 seconds, freezing the soaked vegetables at -35°C or lower, and then storing them at -35°C or lower.

Vegetables are generally washed with water and cut into small pieces before being soaked in hot water.

Examples of vegetables include spinach, bok choy, broccoli, eggplant, komatsuna, mustard greens, and asparagus.

Examples of sugar alcohols include sorbitol, reduced maltose, etc., and the concentration used is 2-20 wt% (hereinafter, % is w).
t%).

Examples of edible oils and fats include vegetable oils such as soybean oil, rapeseed oil, cottonseed oil, corn oil, rice oil, sesame oil, and palm oil, and animal oils such as lard and chicken oil, and the concentration used is 5-20. %.

The immersion is carried out in hot water containing sugar alcohol and edible oil at a temperature of 80-110°C for 20-70 seconds.

The soaked vegetables are immersed again in water at a temperature of 5-20°C to lower the temperature of the vegetables to room temperature, and then the vegetables are taken out of the water and frozen at -35°C or below to obtain frozen vegetables.

Frozen vegetables should be stored at -35°C or below.

A microwave oven, steam, etc. are used as a means for defrosting frozen vegetables.

Next, the effects of sugar alcohols and edible fats and oils will be explained.

Experimental Example 1 After thoroughly washing 1 kg of bok choy with water, it was cut into approximately 15 cm pieces. This was placed in an immersion liquid having the composition shown in Table 1, and then immersed at 95°C for 60 seconds.

The bok choy was then re-soaked in water (approximately 10°C) and then frozen at -40°C for 20 minutes to obtain 0.9 kg of frozen bok choy. Frozen bok choy stored at -20°C for 7 days was thawed by steam treatment (100°C) for 5 minutes, and its quality was examined. The results are shown in Table 1.

As is clear from Table 1, the texture (crispness) was improved by using sorbitol and white soybean oil, but browning occurred at a storage temperature of -20°C.

Next, browning due to storage temperature will be explained.

Experimental Example 2 After thoroughly washing 1 kg of bok choy with water, approximately 15 C1n
It was cut to. This was immersed for 40 seconds in 100°C hot water containing 3% solhit and 6% soybean oil. Next, the bok choy was taken out, immersed in water (approximately 10° C.) again, and then drained. This was frozen at -45°C for 20 minutes to obtain 0.9 kg of frozen bok choy.

Next, put the frozen bok choy in a polyethylene bag and
As shown in the table, after storing for 3 months at -20, -30, -35 and -40℃,
Processed and thawed for a minute. Changes in browning of bok choy after thawing were investigated, and the results are shown in Table 2.

As is clear from the table, when the storage temperature is 135°C or lower, no browning is observed and the results are good.

Examples are shown below.

Example 1 After washing 1 kg of spinach thoroughly with water, about 5 CIl
Cut into l pieces and add 3% sorbitol and 5 liters of soybean white squeezed oil.
% in 100°C hot water for 30 seconds. Then,
The temperature of the spinach was lowered to room temperature by immersing it again in water (approximately 10°C). -40℃ after draining soaked spinach
The spinach was frozen for 30 minutes to obtain 0.95 kg of frozen spinach. Place frozen spinach in a polyethylene bag, -4
It was stored at 0°C for 6 months. When the preserved frozen spinach was thawed in a microwave for 5 minutes and its quality was examined, it was found to have a bright green color and a crisp texture.

Example 2 After thoroughly washing 1 kg of bok choy with water, it was cut into approximately 15 cm pieces and immersed in hot water at 95°C containing 5% reduced maltose and 7% cottonseed oil for 20 seconds.

The bok choy was then immersed again in water (approximately 15° C.) and the temperature of the bok choy was lowered to room temperature. After draining the soaked bok choy, -
Freeze 0.9 kg of frozen bok choy at 45℃ for 20 minutes.
I got it. Place frozen bok choy in a polyethylene bag, -3
It was stored at 5°C for 3 months. The preserved frozen bok choy was treated with steam (100° C.) for 10 minutes to thaw and then its quality was examined, and it was found to have a bright green color and a crisp texture.

Example 3゜Block! After washing l-1kg thoroughly with water, about 5cm
Adjust the head hole and add 2% sorbitol and 3% reduced maltose.
%, 100℃ containing 3% corn oil and 4% rapeseed oil
immersed in hot water for 40 seconds.

Next, the temperature of the broccoli was lowered to room temperature with cold air, and then frozen at -35°C for 40 minutes.
Obtained 3 kg. Frozen broccoli was placed in a polyethylene bag and stored at -40°C for 6 months.

When the preserved broccoli was thawed in a microwave for 5 minutes and its quality was examined, it was found to have a bright green color and a crisp texture.

Effects of the Invention According to the method of the present invention, frozen vegetables having good color stability and crisp texture can be produced and stored.

Claims (1)

[Claims] Vegetables containing sugar alcohol and edible fats and oils at a temperature of 80-11
A method for producing and preserving frozen vegetables, which comprises immersing vegetables in hot water at 0°C for 20-70 seconds, freezing the soaked vegetables at -35°C or lower, and then storing them at -35°C or lower.