CN1749279A - Preparation method and application of microwave acidolysis and esterification modified composite modified starch - Google Patents

Abstract

The present invention belongs to the field of denatured starch technology. Under normal pressure or vacuum microwave condition, starch is acidolyzed and esterified simultaneously to prepare compositely denatured starch product. The compositely denatured starch product has the properties of both esterified starch and acidolyzed starch, and may be used as fat substituent in producing low fat butter, ice cream, salad paste, and as Arabic gum substituent as microcapsule material. The present invention combines acidolysis, esterification and microwave treatment, and has the advantages of short reaction time, high reaction efficiency, less environmental pollution and excellent product performance.

Description

Preparation method and application of microwave acidolysis and esterification modified composite modified starch

technical field

The invention relates to a preparation method and application of compound modified starch which is simultaneously modified by acid hydrolysis and esterification under the condition of microwave radiation, and belongs to the technical field of modified starch.

technical background

Fatty acid starch ester is an esterification product obtained by reacting starch and its derivatives with fatty acid, fatty acid methyl ester, fatty acid chloride or fatty acid anhydride. Due to the introduction of hydrophobic organic carbon chains, the hydrophobicity of starch increases, which makes it possess the amphiphilic properties of hydrophilic and lipophilic, and has emulsifying properties, which can be used in food, medicine, daily chemicals and other fields. Fatty acid starch esters with a high degree of substitution have high emulsifying ability and can be used in microencapsulated products to obtain a high embedding rate, replacing expensive gum arabic; fatty acid starch esters with a low degree of substitution can be used as fat substitutes. There have been many reports abroad about the preparation of fatty acid starch esters by the organic solvent method. Only Saiyavit Varavinit etc. synthesized starch stearate of sago and cassava by dry method. There is no report about the process of preparing compound modified starch by simultaneous acid hydrolysis and esterification of starch by microwave method.

Contents of the invention

The purpose of the present invention is: to provide a kind of preparation method of fatty acid starch ester by direct esterification of fatty acid and starch under the condition of microwave radiation. Since acid is used as a catalyst in this reaction, the starch will be acidolyzed during the reaction process, so the acidolysis and esterification reactions are carried out simultaneously in the preparation process, and the product has many excellent characteristics. In this reaction, hot absolute ethanol is used to dissolve the fatty acid, and it is fully mixed with the starch. During the reaction, the ethanol will completely volatilize, so the present invention belongs to dry preparation.

The technical scheme of the present invention: a kind of acidolysis and esterification compound modified starch is prepared by adopting microwave (atmospheric pressure or vacuum) method to carry out the preparation method of acidolysis and esterification denaturation at the same time, so that the product has both acidolysis and esterification properties of modified starches.

The method for preparing the compound modified starch with acid hydrolysis and esterification modification at the same time is to use starch as raw material, dissolve the esterification agent in hot absolute ethanol solvent, add a certain amount of acid, and add an appropriate amount of water to adjust the reaction The water content of the system is slowly added to the starch and stirred continuously, and the obtained slurry is subjected to acidolysis and esterification reactions under microwave radiation (atmospheric pressure or vacuum) at the same time to obtain acidolysis and esterification compound modified starch.

The starch raw material can be corn starch, wheat starch, potato starch and the like.

The esterification agent used for esterification denaturation can be a higher fatty acid, such as stearic acid, lauric acid, myristic acid, palmitic acid, oleic acid, linoleic acid, arachidic acid, etc., and the solvent used for dissolving the esterification agent can be anhydrous ethanol.

Acid hydrolysis reagents used for denaturation are volatile acids such as hydrochloric acid, acetic acid or formic acid.

The microwave reaction can be carried out under conditions such as normal pressure and vacuum.

Recipe for the preparation process:

Starch, dry basis mass 100

Esterifying agent, by mass 2～4

Absolute ethanol, by volume 80～120

Acid, by mass 0.05～0.20

Water, by volume 0～40

The specific formula in the laboratory is:

Starch (dry basis) 100g

Esterifying agent 2～4g

Absolute ethanol 80～120ml

Acid 0.05～0.20g

Water 0～40ml

Reaction process conditions: after the esterification agent is first dissolved in hot absolute ethanol, a catalyst acid is added, and water is added or not to adjust the reaction system until the water mass fraction is 14% to 42%, and then the esterification agent solvent is slowly added to the starch, And keep stirring to obtain a homogeneous mixture reaction slurry. The power of the microwave reaction is 700-1200W, and the reaction time is 3-10min. It adopts 30s intermittent heating under normal pressure and rapid stirring, or adopts continuous heating under vacuum, and the vacuum degree is 0.08-0.1Mpa. The slow addition of the esterifying agent solvent is carried out under constant stirring. It is better to control the water mass fraction of the reaction slurry at 14% to 30% during the microwave reaction.

The application of acidolysis and esterification modified composite modified starch under microwave conditions is mainly used as an emulsifier in the food industry, used in many products such as emulsified flavors and microencapsulated products, and can also be used as Fat substitute in low-fat cream.

Beneficial effects of the present invention: The present invention aims at the application of microwave technology in modified starch and the special requirements of food processing for modified starch, and develops a new process and new product of modified starch in a targeted manner. A microwave dry method reactor is used to carry out acidolysis and esterification denaturation of starch simultaneously, especially to prepare a fatty acid starch ester with dietary fiber function. In the preparation process of the invention, the acidolysis and esterification reactions of starch are carried out simultaneously. The product has many excellent characteristics. Due to the introduction of fatty acid groups in starch, it has hydrophilic and lipophilic amphiphilic groups, so it has certain emulsifying properties, and high temperature acid hydrolysis reduces the viscosity of starch. Due to the change of molecular structure, indigestible dextrin (dietary fiber function) is formed, which has certain health care effects. The obtained product can be used in many products such as emulsified essence, as microcapsule wall material for microencapsulated products, and can replace the current high-priced gum arabic, propylene glycol alginate, etc., and can also be used to replace part of non-dairy cream Grease, low-fat non-dairy cream, ice cream, salad dressing, etc. The addition of fatty acid starch ester reduces the amount of emulsifier and stabilizer in the formula, thereby reducing the cost and having good economic benefits. This process organically combines the two denaturation methods of acidolysis and esterification, and uses a microwave dry reactor for the reaction. The reaction time is significantly lower than that of the ordinary dry method, the reaction efficiency is significantly improved, it is easy to implement, and the environmental pollution is small. .

Description of drawings

Fig. 1 is a schematic diagram of the preparation process of simultaneous acid hydrolysis and esterification modified composite modified starch under microwave conditions.

Detailed ways

Example 1

Weigh 2g of stearic acid, dissolve it in 80ml of 70°C dehydrated ethanol, add 0.05g of hydrochloric acid, keep the temperature at 70°C without adding water, then slowly add 100g of starch (dry basis), and keep stirring to obtain a uniform mixture. Put the mixture into a container and place it in a 700W microwave oven for reaction, heat intermittently for 30s, stir rapidly, and irradiate with microwaves for 3 minutes, cool and pulverize to obtain the finished starch stearate. The microwave oven is the NJL07-3 experimental microwave oven produced by Nanjing Jiequan Microwave Equipment Co., Ltd., the same below.

Prepare stearyl starch ester with stearic acid and starch reaction, adopt common pressure dry method, microwave normal pressure dry method and microwave vacuum dry method three different methods to prepare the product performance of stearic acid starch ester as shown in table 1 . The reaction efficiency is the ratio of the actual degree of substitution to the theoretical degree of substitution. It can be seen from the table that the reaction time of the product prepared by the microwave method is significantly lower than that of the ordinary dry method, the reaction efficiency is obviously improved, and the emulsification property is improved.

Table 1: Comparison of microwave dry method (atmospheric pressure or vacuum) and ordinary dry method method Reaction time/min Degree of substitution Reaction efficiency/% retrograde Emulsifying/% Solubility/%(30℃) Viscosity/mpa.s(20%, 30℃) 1 240 0.0034 20 Retrogradability is greater than native starch 10 9 190 2 5 0.0060 35 There is a little precipitation in the lower part, and the upper part is clear and transparent 25 35 160 3 10 0.0101 59 Clarity and transparency 35 94 90

Note: Method 1 is dry preparation under normal pressure. The reaction conditions are: initial moisture mass fraction 22%, temperature 150°C, stearic acid mass fraction 3% (calculated on starch dry basis), reaction time 4h, HCl 0.08% (calculated on starch dry basis)

Method 2 is microwave dry preparation under normal pressure. The reaction conditions are: the moisture content before the reaction is 28%, the mass fraction of stearic acid is 3% (calculated on the dry basis of starch), the microwave reaction power is 800W, the reaction time is 5min, and HCl0.12% (calculated on the dry basis of starch)

Method 3 is microwave dry preparation under vacuum. The reaction conditions are: the moisture content before the reaction is 28%, the mass fraction of stearic acid is 3% (calculated on the dry basis of starch), the microwave reaction power is 700W, the reaction time is 10min, and HCl 0.12% (calculated on the dry basis of starch)

Example 2

Weigh 4g of lauric acid, dissolve it in 120ml of 70°C absolute ethanol, add 0.2g of acetic acid, and at the same time add 40ml of water to maintain the temperature at 70°C, then slowly add it to 100g of starch (dry basis), and keep stirring to obtain a homogeneous mixture , Put the mixture into a container and place it in a 1200W microwave oven to evacuate it for reaction. The microwave radiation time is 10 minutes. After cooling, it is pulverized to obtain the finished starch laurate ester.

Example 3

Linoleic acid is used as esterifying agent, and all the other prescriptions and operating conditions are the same as embodiment 1 or embodiment 2, and make finished product linoleic acid starch ester.

Example 4

Myristic acid is used as esterifying agent, and all the other prescriptions and operating conditions are with embodiment 1 or embodiment 2, make finished product starch myristate.

Example 5

Palmitic acid is used as esterifying agent, and all the other prescriptions and operating conditions are with embodiment 1 or embodiment 2, make finished product palmitic acid starch ester.

Example 6

Oleic acid is used as esterifying agent, and all the other prescriptions and operating conditions are with embodiment 1 or embodiment 2, make finished product oleic acid starch ester.

Example 7

Arachidic acid is used as an esterifying agent, and all the other recipes and operating conditions are the same as in Example 1 or Example 2 to obtain the finished product arachidonic acid starch ester.

Example 8

Industrialized production, the starch feeding amount is 18-400kg/h, the microwave oven is the NJ series tunnel microwave oven of Nanjing Jiequan Microwave Equipment Co., Ltd., or the NJZ series vacuum microwave oven, and the other formula ratios and operating conditions are the same as in Example 1 or Example 2. The finished fatty acid starch ester is obtained, and the raw material starch is corn starch, wheat starch or potato starch.

Claims (6)

1, the preparation method of a kind of acidolysis and esterification modification composite modified starch, it is characterized in that with starch being raw material, esterifying agent is dissolved in the hot anhydrous ethanol solvent, and add a certain amount of acid and water, the esterifying agent that will be dissolved in hot ethanol slowly joins in the starch, constantly stir, the slurry that obtains carries out acidolysis and esterification simultaneously and is prepared under microwave condition

(1) prescription is:

Starch, butt quality meter 100

Esterifying agent, in mass 2～4

Dehydrated alcohol, by volume 80～120

Acid, in mass 0.05～0.20

Water, by volume 0～40

(2) preparation reaction slurry:

After esterifying agent is dissolved in hot dehydrated alcohol earlier, add catalyst acid, adding or do not add water conditioned reaction system to moisture massfraction is 14%-42%, then the esterifying agent solvent is slowly joined in the starch, and constantly stirs, the thing that is uniformly mixed reaction slurry;

(3) microwave reaction:

To react slurry and pack in the container, and place microwave oven to react, adopt the heating of atmosphere intermission formula, and stir fast; Or adopt vacuum to heat continuously.

2, preparation method according to claim 1 is characterized in that prescription is:

Starch, butt meter 100g

Esterifying agent 2～4g

Dehydrated alcohol 80～120ml

Acid 0.05～0.20g

Water 0～40ml

Microwave reaction power is 700～1200W, and the reaction times is 3～10min; Adopt normal pressure intermittent type heating in 30 seconds, and stir fast, or adopt vacuum to heat vacuum tightness 0.08-0.1Mpa continuously.

3, preparation method according to claim 1 is characterized in that starch is is raw material with W-Gum, wheat starch or potato starch.

4, preparation method according to claim 1 is characterized in that the employed catalyst acid of acidolysis sex change is hydrochloric acid, acid or glacial acetic acid.

5, preparation method according to claim 1 is characterized in that the esterification sex change, and employed esterifying agent is: stearic acid, lauric acid, tetradecanoic acid, palmitinic acid, oleic acid, linolic acid or eicosanoic acid; The solvent that uses is dehydrated alcohol.

6, preparation method according to claim 1, the moisture content massfraction of reaction slurry is controlled at 14%～30% when it is characterized in that microwave reaction.