CN105132493B - A kind of product and preparation method thereof rich in low viscosity resistant starch - Google Patents

Abstract

The invention provides a product rich in low-viscosity resistant starch, the preparation method of which comprises the following steps: 1) mixing the original starch with a buffer solution of pH 4.0-7.5 at a mass volume ratio of 1:7-1:13 Evenly serve as the substrate, add pullulanase to the substrate at a ratio of 20-350U/g, pour it into a vacuum packaging bag, seal it, and perform enzymatic hydrolysis under the conditions of 50-450MPa and 45-75°C for 10- 90min; 2) Continue the enzymatic hydrolysis reaction at normal pressure, 45-75°C for 5-48h, stirring at 90-150rpm, then inactivate the enzyme activity in an ice bath at 0-4°C for 10-20min, then centrifuge to remove The supernatant is obtained after drying, grinding and sieving. The viscosity of the resistant starch product obtained by the preparation method provided by the invention is as low as 60cP, and the resistant starch is as high as 43% or more. It can be added to high-fiber foods as a functional food raw material, and can also be used as a low-energy filler in low-sugar, low-fat and diet foods.

Description

A product rich in low-viscosity resistant starch and its preparation method

technical field

The invention relates to functional food raw materials, in particular to a product rich in low-viscosity resistant starch and a preparation method thereof.

Background technique

Generally, starch is composed of two types of α-D-glucose polymers, amylose and amylopectin. Starch is a homopolymer of glucose composed of α-1,4 linear links and α-1,6 branched links. In order to improve the application of native starch in industry, different modification methods are applied, including physical modification (such as ultra-high pressure), chemical modification (such as cross-linking) and enzymatic modification (such as dextrin, demyelinated starch). In the food industry, high viscosity severely limits the modification of high-concentration starch, and starch debranching enzymes can selectively hydrolyze the α-1,6 glycosidic bonds present at the branch points, thereby reducing the viscosity of starch paste. At the same time, debranching produces indigestible linear starch chains that can be used as resistant starches, sustained release agents, gel excipients, and even as fat substitutes and emulsifiers.

Starch is one of the main components of carbohydrate-rich foods and root vegetables, and its consumption after steaming or gelatinization can lead to an increase in the glycemic index (GI). With the improvement of people's living standards, excess energy intake in the human body leads to a series of related chronic diseases, such as obesity, diabetes and hypertension. Therefore, low GI foods are more desirable for patients with obesity, diabetes and high blood pressure, or for healthy people. Studies have shown that resistant starch has the physiological functions of preventing obesity, controlling diabetes, promoting the absorption of calcium, zinc and magnesium ions in the human body, and preventing constipation, colon cancer and other diseases.

The Chinese patent application with publication number CN104593452A discloses a method for preparing resistant starch using microwave technology. Specifically: (1) prepare raw starch into starch emulsion, and pregelatinize the starch with microwave; (2) autoclave the pregelatinized material at an appropriate temperature and pressure; after the material is cooled, use high temperature resistant α-amylase Hydrolyze the starch with pullulanase until the chain length is 20-120DP; (3) Spread the material on a plate, store it at 4°C for 3-5 hours, heat the material to 30-50°C with microwave, cool to room temperature, and repeat the temperature Circulate 2-4 times until the moisture content of starch is less than 14%, crush and sieve to obtain resistant starch A; (4) add water to resistant starch A, heat treatment; adjust pH to 1.5-2, shake reaction, Adjust the pH to 7-8, add trypsin to enzymatically hydrolyze, filter, and dry the filter cake with air flow until the moisture content is below 14%, crush it and pass it through a 100-mesh sieve to obtain high-purity resistant starch B. However, the above-mentioned technical solution requires high temperature, high energy consumption, and complicated steps.

The Chinese patent application with publication number CN102277399A discloses a new raw material of a new type of resistant starch, and also discloses a preparation method of high-content resistant starch and its food. The preparation method is mainly through the preparation of plantain taro starch coarse powder, after adding dilute hydrochloric acid to adjust the pH to 3.5-5.5, adding pullulanase at 40-70°C and performing steps such as heat preservation, heating and cooling to remove residual acid or impurities , to prepare resistant starch, which can be stored in cold water for a long time. The above-mentioned technical solution also requires high-temperature heating and consumes a lot of energy.

Chinese patent application with publication number CN1995067 discloses a method for increasing the content of resistant starch in starch. Select starch with amylose content greater than 10% as raw material, prepare 3% to 25% starch emulsion, and gelatinize at 78°C or above; use pullulanase or debranching hydrolyzed starch to decompose amylopectin to form a large amount of amylose Starch: cross-link amylose and debranched amylose with an acidic environment of pH 3.5-6.5 and di- and tricarboxylic acid functional groups such as citrate, and the ion concentration of the functional group is 1%-15% of the starch raw material; at the freezing point The following uses 3 to 4 freezing cycle aging processes to promote the formation of resistant starch crystal nuclei and the growth of crystals, and increase the yield of resistant starch during the cycle; the starch emulsion is spray-dried, roller-dried, Different drying methods such as fluidized bed drying and filtration-hot air drying are used to obtain dried products. The above-mentioned technical scheme adopts gelatinization, debranching, cross-linking, freezing cycle aging, etc. to process starch successively, and the production cycle is long and the operation is complicated.

It can be seen that most of the existing technologies require high-temperature heating, and the process is complicated, which is not conducive to realizing industrial production.

Contents of the invention

In order to solve the problems in the prior art, the object of the present invention is to provide a product rich in low-viscosity resistant starch and a preparation method thereof.

In order to achieve the purpose of the present invention, the present invention firstly provides a product rich in low-viscosity resistant starch, and its preparation method comprises the following steps:

1) Mix raw starch and buffer solution with pH 4.0-7.5 at a mass volume ratio (w/v, g/mL or kg/L or ton/m ³ ) of 1:7-1:13 as a substrate, Add pullulanase to the substrate at a ratio of 20-350U/g, pour it into a vacuum packaging bag, seal it, and enzymolyze it at 50-450MPa and 45-75°C for 10-90 minutes;

2) Continue the enzymolysis reaction at normal pressure and 45-75°C for 5-48 hours, with a stirring speed of 90-150rpm, then inactivate the enzyme activity in an ice bath at 0-4°C for 10-20 minutes, then centrifuge to remove the supernatant Liquid, dried, milled and sieved to obtain.

Further, the original starch is selected from potato starch, corn starch, sweet potato starch, tapioca starch, wheat starch, rice starch, bean starch or sorghum starch. But not limited to this.

Further, the buffer solution is one of sodium acetate buffer solution, phosphate buffer solution or Tris-HCl buffer solution, with a pH of 5.0-6.0.

Preferably, the addition ratio of the enzyme is 40-320 U/g.

Preferably, the step 1) enzymatically reacts for 30-60 minutes under the conditions of 200-400 MPa and 55-65°C.

Preferably, the step 2) continues the enzymolysis reaction at normal pressure and 55-65°C for 10-20 hours, and the stirring speed is 100-130rpm,

Further, the drying method is hot air drying or freeze drying.

Preferably, the drying method is freeze-drying, and the freeze-drying is carried out in a vacuum freeze-drying machine under the following conditions: the degree of vacuum is 50-100 Pa, the temperature is -50-70°C, and the time is 36-60 hours. Preferably 48h;

Further, pre-freeze in a refrigerator at -20°C to -40°C for 24h to 36h before freeze-drying.

The present invention also provides a method for preparing a product rich in low-viscosity resistant starch, which comprises the following steps:

1) Mix raw starch and pH4.0-7.5 buffer at a mass volume ratio of 1:7-1:13 as a substrate, and add pullulanase to the substrate at a ratio of 20-350U/g , poured into a vacuum packaging bag, sealed, and enzymatically hydrolyzed at 50-450MPa, 45-75°C for 10-90min;

2) Continue the enzymolysis reaction at normal pressure and 45-75°C for 5-48 hours, with a stirring speed of 90-150rpm, then inactivate the enzyme activity in an ice bath at 0-4°C for 10-20 minutes, then centrifuge to remove the supernatant Liquid, dried, milled and sieved to obtain.

The beneficial effects of the present invention are:

The present invention uses starch as raw material and adopts a method combining ultra-high pressure and pullulanase to prepare a product with low viscosity and high resistant starch content. The treatment conditions are mild, the process is simple, the cost is low, and it is easy to realize industrial production. Clean, and can achieve zero discharge of organic waste water, no pollution to the environment.

The viscosity of the resistant starch product obtained by the preparation method provided by the invention is as low as 60cP, and the resistant starch is as high as 43% or more. It can be added to high-fiber foods as a functional food raw material, and can also be used as a low-energy filler in low-sugar, low-fat and diet foods.

Description of drawings

Fig. 1 is the process flow diagram of the preparation method of the product rich in low viscosity resistant starch of the present invention;

Fig. 2 is an electron microscope image of native starch and products rich in low-viscosity resistant starch described in Example 1 and Example 2 of the present invention.

Detailed ways

The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

Embodiment 1 is rich in the preparation of the product of low-viscosity resistant starch

1) Mix raw starch and pH 5.5 buffer at a mass volume ratio (w/v, g/mL) of 1:10, add pullulanase at a concentration ratio of enzyme to substrate of 160 U/g and pour into vacuum packaging In the bag, seal; put the sample into the ultra-high pressure equipment, set the pressure of the ultra-high pressure equipment to 400MPa, and enzymatically hydrolyze at 60°C for 40min.

2) Place the sample obtained in step 1) under normal pressure at 60°C for 10 hours of enzymatic hydrolysis with a stirring speed of 130rpm, then passivate the enzyme in an ice bath at 4°C for 10 minutes, centrifuge to remove the supernatant, dry and grind Flour and sieve to obtain a product with low viscosity and high resistant starch content.

Example 2: Preparation of products rich in low viscosity resistant starch

1) Mix raw starch and pH 5.5 buffer at a mass volume ratio (w/v, g/mL) of 1:10, add pullulanase at a concentration ratio of enzyme to substrate of 320 U/g and pour into vacuum packaging In the bag, seal; put the sample into the ultra-high pressure equipment, set the pressure of the ultra-high pressure equipment to 200MPa, and enzymatically hydrolyze at 60°C for 40min.

2) Place the sample obtained in step 1) under normal pressure at 60°C for 10 hours of enzymatic hydrolysis with a stirring speed of 130rpm, then passivate the enzyme in an ice bath at 4°C for 10 minutes, centrifuge to remove the supernatant, dry and grind Flour and sieve to obtain a product with low viscosity and high resistant starch content.

Example 3 Determination of gelatinization properties, resistant starch content and microstructure of products rich in low-viscosity resistant starch

1) Determination of pasting properties

The gelatinization properties of the original potato starch and products with low viscosity and high resistant starch content (Example 1 and Example 2) were investigated using a rapid viscometer (RVA). Accurately weigh 3.0g of starch into the matching aluminum box, add 25ml of distilled water and mix well. The operation was performed using a fixed temperature ramp-down program with constant shear strain rate. The sample is kept at 50°C for 1min, heated to 95°C at a rate of 9.5°C/min, kept for 2.5min, then cooled to 50°C at a rate of 11.84°C/min, and kept at 50°C for 2min, the sample measurement time is 13min, and finally RVA viscosity curve of starch paste. Recording parameters include: peak viscosity (Peak viscosity, PV), valley viscosity (Trough viscosity, TV), collapse viscosity (Breakdown viscosity, BDV), final viscosity (Final viscosity, FV), setback value (Setback, SBV), peak time ( Peaking time, Pt) and pasting temperature (Pasting temperature, PT). The test uses TCW (Thermal cline for windows) supporting software to record and analyze data.

Table 1 The gelatinization characteristics of potato native starch and low viscosity high resistant starch content products (embodiment 1 and embodiment 2)

It can be seen from Table 1 that potato native starch has higher peak viscosity (PV), valley viscosity (TV), collapse viscosity (BDV), final viscosity (FV) and retrogradation value (Setback, SBV). The peak viscosity (PV) of the low viscosity high resistant starch content products (Example 1 and Example 2) was significantly lower compared to native potato starch, 58 and 66 cP, respectively.

2) Determination of resistant starch content

Disperse 0.5 g of the product with low viscosity and high resistant starch content in 10 mL of distilled water, add 10 mL of guar gum solution (5 g/L guar gum dissolved in 0.05 M HCl) and 5 mL of 0.5 M sodium acetate solution, and then add 10mL hydrolase solution (α-amylase 290U/mL, glucosidic amylase 15U/mL), put it in a shaker, and carry out 120min water bath (water bath temperature is 37 ℃) treatment at a speed of 170rpm After the reaction, take 0.5mL of the suspension in a test tube, and add 4mL of 80% ethanol, then measure the glucose content in the reacted suspension, and calculate the resistant starch content in the sample.

The test results are shown in Table 2. The content of resistant starch (RS3) in the product with low viscosity and high content of resistant starch and resistant starch product B was 71.15% and 74.02%, respectively, and the content of product B was higher.

The resistant starch content (wet weight) of table 2 low viscosity high resistant starch content product (embodiment 1 and embodiment 2)

sample Resistant starch/% Low viscosity high resistant starch content product (embodiment 1) 43.33 Low viscosity high resistant starch content product (embodiment 2) 44.93

Note: Different letters (a, b) indicate significant difference (P<0.05).

It can be seen from Table 2 that the resistant starch content of the two low-viscosity and high-resistant-starch-content products (Example 1 and Example 2) are both relatively high, being 43.33% and 44.93% respectively. Therefore, it can be added to high-fiber foods as a functional food raw material, and can also be used as a low-energy filler in low-sugar, low-fat and diet foods.

3) Determination of microstructure

The sample was sprayed on the palladium plated plate, and the structure of the original starch and the products with low viscosity and high resistant starch content (Example 1 and Example 2) were observed at 20KV using a scanning electron microscope. The obtained results are shown in Figure 2. The original potato starch is round or oval, with a smooth surface (Figure 2a). The granules of the two products with low viscosity and high resistant starch content were both crystalline and irregular lumps (Fig. 2b, Fig. 2c), indicating that the pullulan enzyme phase treatment under ultra-high pressure destroyed the granule integrity of the starch, and the pullulan Enzymes can act more efficiently on starch granules.

Although the present invention has been described in detail with general descriptions and specific embodiments above, it is obvious to those skilled in the art that some modifications or improvements can be made on the basis of the present invention. Therefore, the modifications or improvements made on the basis of not departing from the spirit of the present invention all belong to the protection scope of the present invention.

Claims (8)

1. a product rich in low-viscosity resistant starch, characterized in that its preparation method may further comprise the steps: 1) Mix raw starch and pH4.0-7.5 buffer at a mass volume ratio of 1:7-1:13 as a substrate, and add pullulanase to the substrate at a ratio of 20-350U/g , poured into a vacuum packaging bag, sealed, and enzymatically hydrolyzed at 200-400MPa, 55-65°C for 30-60 minutes; 2) Continue the enzymolysis reaction at normal pressure and 55-65°C for 10-20 hours, with a stirring speed of 100-130rpm, then inactivate the enzyme activity in an ice bath at 0-4°C for 10-20 minutes, then centrifuge to remove the supernatant Liquid, dried, milled and sieved to obtain. 2. product according to claim 1, is characterized in that, described native starch is selected from potato starch, corn starch, sweet potato starch, tapioca starch, wheat starch, rice starch, bean starch or sorghum starch. 3. The product according to claim 1, wherein the buffer is one of sodium acetate buffer solution, phosphate buffer solution or Tris-HCl buffer solution, and the pH is 5.0-6.0. 4. The product according to any one of claims 1-3, characterized in that the addition ratio of the enzyme is 40-320 U/g. 5. The product according to claim 1, characterized in that, the drying method is hot air drying or freeze drying. 6. The product according to claim 5, characterized in that the drying method is freeze-drying, and the freeze-drying is carried out in a vacuum freeze-drying machine under the following conditions: the degree of vacuum is 50-100 Pa, and the temperature is -50 ～-70℃, the time is 36～60h. 7. The product according to claim 6, characterized in that it is pre-frozen in a refrigerator at -20°C to -40°C for 24h to 36h before freeze-drying. 8. A method for preparing a product rich in low-viscosity resistant starch, characterized in that it comprises the steps of: 1) Mix raw starch and pH4.0-7.5 buffer at a mass volume ratio of 1:7-1:13 as a substrate, and add pullulanase to the substrate at a ratio of 20-350U/g , poured into a vacuum packaging bag, sealed, and enzymatically hydrolyzed at 200-400MPa, 55-65°C for 30-60 minutes; 2) Continue the enzymolysis reaction at normal pressure and 55-65°C for 10-20 hours, with a stirring speed of 100-130rpm, then inactivate the enzyme activity in an ice bath at 0-4°C for 10-20 minutes, then centrifuge to remove the supernatant Liquid, dried, milled and sieved to obtain.