Chinese yam fermented beverage and preparation method thereof

Abstract

The invention discloses a Chinese yam fermented beverage and a preparation method thereof, and relates to the technical field of food processing. The Chinese yam is processed through enzymolysis-extrusion puffing, the molecular weight of Chinese yam starch is reduced, the solubility of the Chinese yam starch is improved, the viscosity of the Chinese yam is reduced, the digestibility of nutritional ingredients such as starch and protein is improved, and release of phenolic substances is promoted. The compound probiotics are adopted for fermentation, the characteristics of reducing sugar and amylose are comprehensively utilized, the content of total sugar (including starch and reducing sugar) in fermentation liquor is reduced, beneficial metabolites such as beta-glucosidase and glucan are generated, and the nutritional value and flavor of the product are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of food processing, and in particular to a fermented yam beverage and a preparation method thereof. Background Art

[0002] Chinese yam is a food resource that can be used as both medicine and food. It is rich in starch, glycoprotein, allantoin, polyphenols, polysaccharides and other nutritional active substances. Chinese medicine records that it has many functions such as invigorating kidney qi, strengthening spleen and stomach, stopping diarrhea, and reducing phlegm. However, Chinese yam is a plant tuber with obvious seasonality, high water content and thin skin. It is easy to be damaged, rotten and browned during transportation and storage, which restricts its industrial development. Therefore, the prospect of developing a series of deep-processed yam products is very broad.

[0003] At present, yam processing mainly involves starch preparation and simple rough processing, and there are few types of deep-processed products. However, due to the high starch content, yam powder has high viscosity and a high glycemic index, which is not conducive to consumption by diabetics.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] In order to overcome the shortcomings and deficiencies of the prior art, the object of the present invention is to provide a method for preparing a fermented yam beverage.

[0006] Another object of the present invention is to provide a fermented yam beverage prepared by the above preparation method.

[0007] The purpose of the present invention is achieved through the following technical solutions: A method for preparing a fermented yam beverage comprises the following steps: (1) Pretreatment: The yam is cleaned and sliced, then placed in a color-protecting liquid, subjected to ultra-high pressure color protection, dried and crushed to obtain yam powder; (2) Enzymatic hydrolysis and extrusion: adding compound enzyme solution and extrusion; (3) Fermentation: After enzymatic hydrolysis, extrusion and puffing, water is added to the mixture for slurry mixing and sieving. After sterilization and cooling, the mixture is inoculated with a composite bacterial liquid for fermentation to obtain a fermentation liquid. (4) Homogenization and sterilization: Emulsifiers and thickeners are added to the fermentation liquid, and the fermented yam beverage is obtained by high-pressure homogenization, sterilization, and aseptic filling.

[0008] Preferably, in step (1), the slice has a thickness of 2 mm to 4 mm and is quickly placed in a color protection solution, wherein the ascorbic acid concentration in the color protection solution is 0.1% to 0.3% w / v (preferably 0.2% to 0.3% w / v), and the citric acid concentration is 0.1% to 0.5% w / v (preferably 0.2% to 0.5% w / v); the ultrahigh pressure pressure is 300 MPa to 600 MPa, the temperature is 60 to 70 °C (preferably 60 to 65 °C), and the treatment time is 10 to 15 min; the drying condition is 45 to 55 °C (preferably 50 to 55 °C) and the time is 6 to 8 h.

[0009] Preferably, in step (2), the complex enzyme solution is composed of cellulase, pectinase, neutral endoprotease and α-amylase, wherein the amount of cellulase, pectinase and neutral endoprotease is 0.05-0.1% w / w (preferably 0.05-0.06% w / w) of the total mass of the yam powder, and the α-amylase is preferably high-temperature α-amylase, and its addition amount is 0.1-0.6% w / w (preferably 0.15%-0.2% w / w) of the total mass of the yam powder; before extrusion puffing, the moisture content is adjusted to 12-40% w / w (preferably 12-15% w / w), the extrusion puffing temperature is 150-165°C, and the screw speed is 180-200 rpm.

[0010] Furthermore, the mass ratio of the cellulase, pectinase, neutral endoproteinase and α-amylase is (25-50): (25-50): (25-50): (50-300); further, (25-30): (25-30): (25-30): (75-100).

[0011] The enzymatic activity of the cellulase is 40 U / mg, the enzymatic activity of the pectinase is 50 U / mg, the enzymatic activity of the neutral endoproteinase is 80 U / mg; and the enzymatic activity of the α-amylase is 20 U / mg.

[0012] Preferably, in step (3), the amount of water is 5 to 9 times the weight of the raw material; the sieving is through a 100-200 mesh sieve (preferably through a 120-150 mesh sieve); sterilization: temperature: 90-100°C, time: 5-15 min (preferably 10-15 min); cooling to a temperature of 38-42°C (preferably 38-40°C); inoculating a composite bacterial solution of 1-3% v / w (preferably 2% v / w) of the raw material (the total colony concentration in the composite bacterial solution is 1*10 9CFU / mL or more), the composite bacterial solution is composed of bacterial solutions of Lactobacillus plantarum, Lactobacillus fermentum and Bifidobacterium, and the colony concentration ratio is 1:2:1; Lactobacillus plantarum is preferably Lactobacillus plantarum ACCC11095, Lactobacillus fermentum is preferably Lactobacillus fermentum CICC 25124; Bifidobacterium is preferably Bifidobacterium longum CICC 6214. The fermentation temperature is 25-35°C, and the fermentation time is 24 h-72 h.

[0013] Preferably, in step (4), the emulsifier is preferably sucrose fatty acid ester, and the addition amount is 0.04-0.06% w / v (preferably 0.05% w / v) of the fermentation broth; the thickener is preferably oat beta-glucan, and the addition amount is 0.2-0.4% w / v (preferably 0.3% w / v) of the fermentation broth; ultra-high temperature instantaneous sterilization is adopted, the sterilization temperature is 125-135°C (preferably 125-130°C), and the sterilization time is 10-20 s.

[0014] A new food ingredient, oat beta-glucan, was used as a thickening stabilizer. It was found that the addition of oat beta-glucan could synergistically increase the viscosity of the solution with yam fermented liquid and improve the stability of the product.

[0015] A fermented yam beverage is prepared by the preparation method.

[0016] Compared with the prior art, the present invention has the following advantages and effects: (1) The present invention uses enzymatic hydrolysis-extrusion puffing to process yam, thereby reducing the molecular weight of yam starch, increasing its solubility, reducing the viscosity of yam, improving the digestibility of nutrients such as starch and protein, and promoting the release of phenolic substances.

[0017] (2) The present invention uses composite probiotics for fermentation, taking into account their characteristics of utilizing reducing sugars and amylose, to reduce the content of total sugars (including starch and reducing sugars) in the fermentation broth, and to produce beneficial metabolites such as β-glucosidase and glucan, thereby improving the nutritional value and flavor of the product. DETAILED DESCRIPTION

[0018] The present invention is further described in detail below in conjunction with the examples, but the embodiments of the present invention are not limited thereto. The experimental methods in the following examples where specific experimental conditions are not specified are usually carried out under conventional experimental conditions or according to the experimental conditions recommended by the manufacturer. The materials, reagents, etc. used are reagents and materials obtained from commercial sources unless otherwise specified.

[0019] The cellulase, pectinase and neutral endoproteinase used in the examples were purchased from Shanghai Ruiyong Biotechnology Co., Ltd.; the high temperature α-amylase was purchased from Ningxia Xiasheng Industrial Group Co., Ltd.

[0020] The plant lactobacillus used in the examples is plant lactobacillus ACCC11095, the fermented lactobacillus is fermented lactobacillus CICC 25124, and the bifidobacterium is bifidobacterium longum CICC 6214.

[0021] The determination method of the relevant parameters in the embodiment: Determination of resistant starch content: Accurately weigh 0.3 g of yam powder sample, add 10 mL of 0.2 mol / L, pH 5.2 acetate buffer and stir evenly, then add 10 mL of mixed enzyme solution (the concentrations of porcine pancreatic α-amylase and saccharifying enzyme are 290 U / mL and 15 U / mL, respectively), and shake in a water bath at 37 °C and 120 r / min. After reacting for 0 min, 20 min, and 120 min, take 1 mL of enzymatic solution, add a small amount of deionized water to dilute, immediately inactivate the enzyme in a boiling water bath for 5 min, cool with running water, centrifuge at 6000 r / min for 10 min, and take the supernatant to volume. The reducing sugar content of the sample solution after volume determination was determined by DNS method. The starch digestibility of yam flour was analyzed by measuring the percentage of rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS), where G20 and G120 were the amounts of reducing sugar in the enzymatic hydrolysate after digestion for 20 min and 120 min (mg); FG was the amount of reducing sugar in the starch before enzymatic hydrolysis (mg); and TS was the amount of total starch in the sample (mg).

[0022] % Determination of reducing sugar content: Accurately weigh 2.0 g of sample, place it in a 100 mL centrifuge tube, add 30 mL of deionized water, shake at room temperature for 90 min (275 r / min), centrifuge at 4000 r / min for 10 min, take the supernatant and make up to 50 mL, and determine its reducing sugar content by DNS colorimetry.

[0023] Polysaccharide content determination: Enzymatic extraction method: weigh 2.5 g of pretreated yam powder, add 50 mL of water and 6.4 U of medium-temperature α-amylase, extract at 60 ℃ for 1 h, then add 3 U of saccharifying enzyme, extract at 60 ℃ for 1.5 h, centrifuge at 8000 r / min for 10 min, take the supernatant, add 8 U of medium-temperature α-amylase, extract at 60 ℃ for 45 min, add 1.25 U of saccharifying enzyme, extract at 60 ℃ for 45 min, take 5 mL of sample, add 4 times the volume of anhydrous ethanol and let stand overnight, centrifuge at 3500 r / min for 5 min, wash twice with anhydrous ethanol, make up to 20 mL, and determine by sulfuric acid phenol method.

[0024] Determination of polyphenol content: Preparation of extract: accurately weigh 2.0 g sample, add 50 mL of 80% acetone precooled to 4°C, homogenize at 10000 r / min for 5 min under ice bath protection, centrifuge at 4000 × g for 10 min, and take the supernatant. Add 50 mL of 80% acetone precooled to 4°C to the precipitate, homogenize and centrifuge again under the same conditions, combine the supernatants obtained from the two centrifugations, evaporate to dryness under reduced pressure at 45°C, and dilute the residue to 10 mL with methanol to obtain the free phenolic substance extract.

[0025] Take 0.125 mL of the extract, add 0.5 mL of deionized water and 0.125 mL of Folin phenol reagent, mix well, let stand for 6 min, add 1.25 mL of 7% (m / v) Na2CO3 and 1.0 mL of deionized water, mix well, let stand for 90 min in the dark, measure its absorbance at 760 nm, and use 0.125 mL of deionized water instead of the extract as a blank control. Prepare gallic acid standard solution with methanol, dilute to different concentrations, and make a standard curve.

[0026] Determination of total sugar content: Accurately weigh 1.00g of yam powder, put it into a 100mL conical flask, add 15mL of distilled water and 10mL of 6 mol / L HCl, and heat it in a boiling water bath for 30 minutes for hydrolysis (the complete hydrolysis can be checked with iodine-potassium iodide solution). After the hydrolyzate in the conical flask cools down, neutralize it to pH7 with 6 mol / L NaOH, make up to volume in a 100 mL volumetric flask with distilled water, and mix well. Filter the hydrolyzate after volume adjustment, take 1 mL of the filtrate, transfer it to another test tube with 9 mL of water, mix well, and dilute it 10 times as the total sugar test solution. The glucose content is determined by the DNS method.

[0027] Example 1 The method for preparing the fermented yam beverage provided in this embodiment comprises the following steps: Pretreatment: After the fresh yam is cleaned, it is sliced ​​into slices with a thickness of 2 to 4 mm, placed in a color protection solution containing 0.3% w / v ascorbic acid and 0.2% w / v citric acid, and treated under ultra-high pressure conditions of 600 MPa and 60 ℃ for 10 min. Then, the yam slices are spread flat in an oven, dried at 50 ℃ for 7.5 hours, and powdered to obtain yam powder.

[0028] Enzymatic hydrolysis extrusion puffing: Weigh 50 kg of yam powder, spray a complex enzyme solution containing cellulase, pectinase and neutral endoproteinase (25 g each) and high-temperature α-amylase (75 g), adjust the moisture content of the whole powder to 15% w / w, stir evenly, let it stand for 30 min, and then extrude and puff at a temperature of 150 ° C and a screw speed of 180 rpm. Compared with yam powder, the resistant starch content increased by 12%, the reducing sugar content increased by 56%, and the free phenolic content increased by 2 times after enzymatic hydrolysis extrusion puffing.

[0029] Fermentation: Add 250 kg of pure water to the yam powder after enzymatic hydrolysis, extrusion and expansion, mix and slurry, sieve to 120 mesh, and sterilize at 100 ℃ for 10 min. After cooling to 40 ℃, add 1000 mL of composite bacterial solution composed of plant lactobacillus, fermented lactobacillus and bifidobacterium (the colony concentration ratio is 1:2:1) (the total colony concentration in the composite bacterial solution is 1*10 9 CFU / mL), the fermentation temperature was 28 ℃, and the fermentation was carried out for 50 h to obtain the fermentation liquid. Compared with before fermentation, the total sugar content after fermentation decreased by 60%, and the polysaccharide content increased by 20%.

[0030] Homogenization and sterilization: 0.05% w / v sucrose fatty acid ester and 0.3% w / v oat beta-glucan were added to the fermentation broth, and after high-pressure homogenization, the broth was sterilized at 125°C UHT for 15-20 s, and aseptically filled to obtain the yam fermented beverage.

[0031] Example 2 The method for preparing the fermented yam beverage provided in this embodiment comprises the following steps: Pretreatment: After the fresh yam is cleaned, it is sliced ​​into slices with a thickness of 2 to 4 mm, placed in a color protection solution containing 0.2% w / v ascorbic acid and 0.5% w / v citric acid, and treated under ultra-high pressure conditions of 300 MPa and 65 ℃ for 15 min. Then, the yam slices are spread flat in an oven, dried at 55 ℃ for 6 hours, and powdered to obtain yam powder.

[0032] Enzymatic hydrolysis extrusion puffing: Weigh 50 kg of yam powder, spray a complex enzyme solution containing cellulase, pectinase and neutral endoproteinase (30 g each) and high-temperature α-amylase (100 g), adjust the moisture content of the whole powder to 12% w / w, stir evenly, let it stand for 30 minutes, and then extrude and puff at a temperature of 165 ° C and a screw speed of 190 rpm. Compared with yam powder, the resistant starch content increased by 20%, the reducing sugar content increased by 35%, and the free phenolic content increased by 1.5 times after enzymatic hydrolysis extrusion puffing.

[0033] Fermentation: Add 250 kg of pure water to the yam powder after enzymatic hydrolysis, extrusion and expansion, mix and slurry, sieve to 150 mesh, and sterilize at 90 ℃ for 15 min. After cooling to 38 ℃, add 1200 mL of composite bacterial solution composed of plant lactobacillus, fermented lactobacillus and bifidobacterium (the colony concentration ratio is 1:2:1) (the total colony concentration in the composite bacterial solution is 1*10 9 CFU / mL), the fermentation temperature was 35 ℃, and the fermentation was carried out for 60 h to obtain the fermentation liquid. Compared with before fermentation, the total sugar content after fermentation decreased by 90%, and the polysaccharide content increased by 48%.

[0034] Homogenization and sterilization: 0.05% w / v sucrose fatty acid ester and 0.3% w / v oat beta-glucan were added to the fermentation broth, and after high-pressure homogenization, the broth was sterilized at 130°C UHT for 10-15 s, and aseptically filled to obtain the yam fermented beverage.

[0035] Comparative Example 1 Except that the spraying of the complex enzyme solution containing cellulase, pectinase, neutral endoproteinase and high-temperature α-amylase in the extrusion puffing step in Example 1 was replaced by spraying water, the other conditions were the same as those in Example 1.

[0036] Compared with the enzymatically hydrolyzed extruded yam powder prepared in Example 1, the free phenolic substances in the extruded yam powder prepared in this comparative example were reduced by 45%, and the reducing sugar content was reduced by 35%.

[0037] Comparative Example 2 Except that the composite bacterial solution in the fermentation process of Example 1 was replaced with sterile water, other conditions were the same as Example 1. Compared with the fermentation solution prepared in Example 1, the total sugar content of the yam juice prepared in this comparative example increased by 1.5 times, the polysaccharide content decreased by 13%, and the flavor was relatively simple.

[0038] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing a fermented yam beverage, characterized in that: The steps include: (1) Pretreatment: The yam is cleaned and sliced, then placed in a color-protecting liquid, subjected to ultra-high pressure color protection, dried and crushed to obtain yam powder; (2) Enzymatic hydrolysis and extrusion: adding compound enzyme solution and extrusion; (3) Fermentation: After enzymatic hydrolysis, extrusion and puffing, water is added to the mixture for slurry mixing and sieving. After sterilization and cooling, the mixture is inoculated with a composite bacterial liquid for fermentation to obtain a fermentation liquid. (4) Homogenization and sterilization: Emulsifiers and thickeners are added to the fermentation liquid, and the fermented yam beverage is obtained by high-pressure homogenization, sterilization, and aseptic filling.

2. The method for preparing the fermented yam beverage according to claim 1, characterized in that: In step (2), the complex enzyme solution is composed of cellulase, pectinase, neutral endoproteinase and α-amylase, wherein the mass ratio of the cellulase, pectinase, neutral endoproteinase and α-amylase is (25-50): (25-50): (25-50): (50-300); further (25-30): (25-30): (25-30): (75-100).

3. The method for preparing the fermented yam beverage according to claim 1, characterized in that: In step (2), the complex enzyme solution is composed of cellulase, pectinase, neutral endoprotease and α-amylase, wherein the amount of cellulase, pectinase and neutral endoprotease is 0.05-0.1% w / w of the total mass of yam powder, and the amount of α-amylase added is 0.1-0.6% w / w of the total mass of yam powder; further, the amount of cellulase, pectinase and neutral endoprotease is 0.05-0.06% w / w of the total mass of yam powder, and the amount of α-amylase added is 0.15-0.2% w / w of the total mass of yam powder.

4. The method for preparing the fermented yam beverage according to claim 1, characterized in that: In step (2), before extrusion, the moisture content is adjusted to 12-40% w / w, the extrusion temperature is 150-165° C., and the screw speed is 180-200 rpm.

5. The method for preparing a fermented yam beverage according to any one of claims 1 to 4, characterized in that: In step (3), the amount of water used is 5 to 9 times the weight of the raw material; the composite bacterial solution is inoculated with 1 to 3% v / w of the raw material, and the total colony concentration in the composite bacterial solution is 1*10 9 CFU / mL or above; the composite bacterial solution is composed of the bacterial solutions of Lactobacillus plantarum, Lactobacillus fermentum and Bifidobacterium, and the colony concentration ratio is 1:2:

1.

6. The method for preparing the fermented yam beverage according to claim 5, characterized in that: In step (3), the sieving is through a 100-200 mesh sieve; sterilization: temperature is 90-100°C, time is 5-15 min; cooling to a temperature of 38-42°C; fermentation temperature is 25-35°C, and fermentation time is 24 h to 72 h.

7. The method for preparing a fermented yam beverage according to any one of claims 1 to 4, characterized in that: In step (1), the slice has a thickness of 2 mm to 4 mm and is quickly placed in a color protection solution, wherein the ascorbic acid concentration in the color protection solution is 0.1% to 0.3% w / v and the citric acid concentration is 0.1% to 0.5% w / v; the ultrahigh pressure pressure is 300 MPa to 600 MPa, the temperature is 60 to 70°C, and the processing time is 10 to 15 min; the drying condition is 45 to 55°C, and the time is 6 to 8 h.

8. The method for preparing a fermented yam beverage according to any one of claims 1 to 4, characterized in that: In step (4), the emulsifier is sucrose fatty acid ester and the thickener is oat beta glucan.

9. The method for preparing the fermented yam beverage according to claim 8, characterized in that: The amount of sucrose fatty acid ester added to the fermentation broth is 0.04-0.06% w / v, and the amount of oat beta-glucan added to the fermentation broth is 0.2-0.4% w / v.

10. A fermented yam beverage, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 9.

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