CN111171344A

CN111171344A - Preparation method of alcohol-induced low-alkali konjac gel

Info

Publication number: CN111171344A
Application number: CN202010103828.5A
Authority: CN
Inventors: 程永强; 武靓靓; 周韵; 朱崇阳; 唐宁
Original assignee: China Agricultural University
Current assignee: China Agricultural University
Priority date: 2020-02-20
Filing date: 2020-02-20
Publication date: 2020-05-19
Anticipated expiration: 2040-02-20
Also published as: CN111171344B

Abstract

The invention discloses a preparation method of alcohol-induced low-alkali konjak gel. The method comprises the following steps: 1) preparing konjac glucomannan sol (hereinafter referred to as konjac sol); 2) adding alkali into the sol, and uniformly stirring; 3) adding absolute ethyl alcohol into the mixture obtained in the step 2), and uniformly stirring; 4) and (3) carrying out constant temperature treatment on the mixture obtained in the step 3). The konjak gel is induced to form by adding ethanol under the condition of extremely low alkali content. The method reduces the consumption of alkali by additionally adding ethanol; the gelling temperature of the konjak gel and the swelling ratio of the konjak gel are reduced; white opaque brittle konjac gel is induced by the method of the invention.

Description

Preparation method of alcohol-induced low-alkali konjac gel

Technical Field

The invention belongs to the field of food processing, and particularly relates to a preparation method of alcohol-induced low-alkali konjac gel.

Background

Konjac Glucomannan (KGM) is a polysaccharide extracted from underground tubers of amorphophallus konjac which is a perennial herb of Araceae, is a high-quality soluble dietary fiber, has the physiological functional characteristics of losing weight, reducing blood fat, regulating intestinal flora and the like, and is called as a blood purifying agent and a gastrointestinal tract scavenger. In addition, the konjac glucomannan has good physical and chemical properties such as gel property, water solubility, water retention property, thickening property, film forming property, cohesiveness, biocompatibility and the like, and is widely applied to the food industry, wherein the alkali-induced thermal irreversible gel property is the most unique property of KGM.

In the food industry, konjac glucomannan sol (not less than 3 wt%) is heated (80-90 ℃) under alkaline conditions (pH 11-13) to prepare konjac gel products, such as konjac tofu, konjac shreds, konjac bionic squids, and the like. However, almost all konjac gel foods prepared under high alkali conditions show obvious defects, such as high water precipitation rate of the products, easy generation of syneresis phenomenon in the storage process, and need to be stored in alkali water, which causes increase of alkali dosage, inconvenience in transportation and waste of water resources; moreover, the gel product has heavy alkali taste and needs to be repeatedly rinsed by clear water or acid water, so that the flavor and the gel performance of the product are weakened, and the quality of the product is influenced; in the sense aspect, the traditional konjak gel product is not easy to color and endow flavor, and the market acceptance of the konjak product is reduced. In order to overcome these problems caused by strong alkali, it is necessary to invent a novel method for preparing konjac gel.

Disclosure of Invention

The invention aims to overcome the defects of the existing alkali-induced gel technology and provide a preparation method of alcohol-induced low-alkali konjac gel.

The method for preparing alcohol-induced low-alkali konjac gel provided by the invention comprises the following steps:

1) preparing konjac glucomannan sol (hereinafter referred to as konjac sol);

2) adding alkali into the sol obtained in the step 1), and uniformly stirring;

3) adding absolute ethyl alcohol into the mixture obtained in the step 2), and uniformly stirring;

4) and (3) carrying out constant temperature treatment on the mixture obtained in the step 3).

In the step 1), the mass concentration of the konjac sol is between 0.5% and 5% (preferably, the concentration is between 0.6% and 1.2%, and specifically, 0.8%), and the konjac sol is kept in a continuous slow stirring state for at least 30 minutes before other steps are carried out, so that the konjac glucomannan is fully swelled.

In step 2) of the above method, the alkali may be sodium carbonate, sodium hydroxide, calcium hydroxide, etc., preferably sodium carbonate. The addition amount of the alkali is 0.01-2% (preferably 0.02-0.08%, more preferably 0.02-0.04%) of the total mass of the konjac sol, and the stirring time is controlled within 1 hour (preferably 1-3 minutes, and specifically 2 minutes). The alkali can be added in the form of a solution, and the mass concentration of the alkali solution can be 0.1-10%, and preferably 0.4-1.6%.

In the step 3), the addition amount of the absolute ethyl alcohol is 0.01% -80% (preferably 10% -30%, more preferably 10% -20%, and specifically 20%) of the total mass of the konjac sol, the absolute ethyl alcohol can be slowly added for 1-10 times, stirring is required after each addition, the stirring time is controlled within 1 hour (preferably 2-6 minutes, and specifically 3 minutes), and the container is sealed after uniform stirring.

In the step 4), the temperature of the constant temperature treatment is 0 to 70 ℃ (preferably 50 to 70 ℃), and the treatment time is 1 minute to 24 hours (preferably 20 to 40 minutes, and specifically 30 minutes).

The konjak gel prepared by the method also belongs to the protection scope of the invention.

Compared with the prior art, the invention has the following beneficial effects:

the konjak gel is induced to form by adding ethanol under the condition of extremely low alkali content. The invention reduces the dosage of alkali by additionally adding ethanol; the gelation temperature of konjak gel is reduced; the swelling ratio of the konjak gel is reduced; white opaque brittle konjac gel is induced by the method of the invention.

Detailed Description

The present invention will be further illustrated with reference to the following specific examples, but the present invention is not limited to the following examples. The method is a conventional method unless otherwise specified. The materials are commercially available from the open literature unless otherwise specified.

The parameters used in the examples and comparative examples are shown in Table 1, and the procedure is as follows:

(1) preparing konjac glucomannan sol (hereinafter referred to as konjac sol) with mass concentration of 0.8%, and stirring for 12 hours to fully swell the konjac glucomannan sol;

(2) taking 20g of the sol prepared in the step 1), adding 1mL of prepared sodium carbonate solution with different mass concentrations, and stirring for 2 minutes;

(3) adding 2 times of anhydrous ethanol slowly into the mixture obtained in the step 2), adding 2mL of anhydrous ethanol each time, and stirring for 3 minutes each time. Comparative example no absolute ethanol was added;

(4) heating the mixture obtained in the step 3) at a constant temperature of 70 ℃ for 30 minutes, and heating the mixture obtained in the step 2) at a constant temperature of 85 ℃ for 30 minutes.

TABLE 1 technical parameters of examples and comparative examples

TABLE 2 comparison of appearance and performance of the examples and comparative examples

The present invention has been illustrated in accordance with the above examples and the results show that the production method of the present invention can significantly reduce the amount of alkali used, lower the gelation temperature, lower the swelling ratio of konjac gel, and induce the formation of white opaque brittle gel.

Claims

1. A preparation method of konjak gel comprises the following steps:

1) preparing konjac glucomannan sol;

2) adding alkali into the sol obtained in the step 1), and uniformly stirring;

2. The method of claim 1, wherein: in the step 1), the mass concentration of the konjac glucomannan sol is between 0.5 and 5 percent, and the preferred concentration is between 0.6 and 1.2 percent.

3. The method of claim 2, wherein: before the step 2), the konjac glucomannan sol is kept in a continuous slow stirring state for at least 30 minutes so as to ensure the full swelling of the konjac glucomannan.

4. The method according to any one of claims 1-3, wherein: in the step 2), the alkali is sodium carbonate, sodium hydroxide and calcium hydroxide, and the addition amount of the alkali is 0.01-2% of the total mass of the konjac sol, preferably 0.02-0.08%; the stirring time is controlled within 1 hour, preferably 1 to 3 minutes.

5. The method according to any one of claims 1-4, wherein: the alkali is added in the form of alkali solution, and the mass concentration of the alkali solution is 0.1-10%, preferably 0.4-1.6%.

6. The method according to any one of claims 1-5, wherein: in the step 3), the addition amount of the absolute ethyl alcohol is 0.01-80% of the total mass of the konjac sol, and is preferably 10-30%.

7. The method according to any one of claims 1-6, wherein: the absolute ethyl alcohol is slowly added for 1 to 10 times, stirring is needed after each addition, the stirring time is controlled within 1 hour, preferably 2 to 6 minutes, and the container is sealed after uniform stirring.

8. The method according to any one of claims 1-7, wherein: in the step 4), the temperature of the constant temperature treatment is 0-70 ℃, preferably 50-70 ℃; the treatment time is from 1 minute to 24 hours, preferably from 20 to 40 minutes.

9. A konjac gel produced by the method of any one of claims 1 to 8.