Low glycemic index sweet potato fermented juice and preparation method thereof

Abstract

The invention belongs to the field of fermented food, and particularly relates to low glycemic index sweet potato fermented juice and a preparation method thereof. Sweet potato starch is converted into glucose through enzymolysis, then lactobacillus plantarum is utilized for fermentation metabolism of glucose, and finally the sweet potato fermented beverage which is good in taste, low in glycemic index and rich in probiotics and functional components is obtained.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of fermented food, and particularly relates to a low glycemic index sweet potato fermented juice and a preparation method thereof. BACKGROUND

[0002] Sweet potato (Ipomoea batatas), also known as red potato or batata, is one of the most important food crops in the world, and is widely cultivated in tropical, subtropical and temperate regions. According to the statistics of the Food and Agriculture Organization (FAO) of the United Nations, the global annual output of sweet potato is about 110 million tons, and China, as the largest producer, accounts for more than 60% of the global output, about 70 million tons. In China, sweet potato is not only an important food crop, but also an important economic crop, and is widely cultivated in Zhejiang, Sichuan, Hunan, Henan and other places. For example, the sweet potato planting area in Zhejiang Province in 2024 reached 53.15 thousand mu, with a yield of 423.38 kg per mu, and an annual output of 337,500 tons, which has played a positive role in increasing farmers' income and food security in the region.

[0003] The sweet potato tuber is rich in nutrients, containing not only starch (10%-30%), but also dietary fiber (2%-3%), β-carotene, vitamin C, potassium, iron and other nutrients. Among them, the content of β-carotene is particularly outstanding, which can meet 120% of the daily human requirement per 100 grams of sweet potato. In addition, sweet potato also contains polyphenols, flavonoids, anthocyanins (especially in purple sweet potato varieties) and other active ingredients, and has many physiological functions such as antioxidant, anti-inflammatory, immune enhancement, anti-aging and reduction of cardiovascular disease risk, and is widely regarded as one of the representatives of healthy food.

[0004] However, the current processing and utilization of sweet potato is still mainly primary processing, such as starch extraction, whole powder preparation, and potato chip production, and the types of deep processing products are limited, with only a small amount of sweet potato wine and sweet potato vinegar on the market. In the processing process, the functional components such as dietary fiber, polyphenols and anthocyanins in sweet potato are often discarded as by-products or not effectively utilized, resulting in resource waste. With the improvement of health consciousness and the upgrading of consumption structure of Chinese residents, traditional high-starch and high-sugar sweet potato processing products have been difficult to meet the market demand for healthy and functional food.

[0005] With the increasing incidence of obesity, high blood lipids, diabetes and other metabolic diseases in China, consumers are increasingly concerned about the glycemic index (Glycemic Index, GI) of food. Low GI food can slowly release blood glucose, which helps to control weight, improve insulin sensitivity, and reduce the risk of diabetes and cardiovascular disease, and thus is favored by more and more consumers.

[0006] Sweet potato is rich in nutrients, but its starch content is high, and direct consumption or processing may still cause rapid blood sugar rise. How to reduce the GI value of sweet potato products without losing their nutritional functions has become a major challenge in the field of food processing. Traditional processing methods such as baking, steaming, frying, etc. can change the texture and flavor of sweet potato, but have limited effect on its GI value, and may even lead to increased blood sugar response due to gelatinization. Therefore, developing a processing technology that can not only retain the nutritional active ingredients of sweet potato but also effectively reduce its GI value has important market significance and health value.

[0007] Lactic acid bacteria are an important group of probiotics, widely used in fermented foods such as yogurt, pickles, and soy products. Lactic acid bacteria produce lactic acid and other organic acids by metabolizing sugars, reducing the pH of the system, and inhibiting the growth of harmful bacteria. They can also synthesize a variety of bioactive substances, such as short-chain fatty acids, gamma-aminobutyric acid, bacteriocins, vitamins, and exopolysaccharides. These metabolites confer lactic acid bacteria with various probiotic functions, including promoting mineral absorption, enhancing intestinal barrier function, regulating immunity, and antioxidant activity.

[0008] Lactobacillus plantarum is one of the lactic acid bacteria with strong antibacterial activity and environmental adaptability, widely used in traditional fermented foods and modern probiotic preparations. Studies have shown that Lactobacillus plantarum can effectively decompose anti-nutritional factors (such as phytic acid and oxalic acid) in plant raw materials during fermentation, improving the bioavailability of calcium, iron, zinc, and other minerals, and also synthesizing B vitamins and digestive enzymes to enhance the nutritional function of foods.

[0009] In recent years, lactic acid bacteria fermentation technology has been increasingly applied in the development of medicinal and edible materials. Through enzyme pretreatment combined with lactic acid bacteria fermentation, not only the utilization rate of raw materials can be improved, but also the growth and metabolic activity of the bacteria can be enhanced, further optimizing the flavor and function of the product. Although lactic acid bacteria fermentation technology has been applied in fruit and vegetable processing, such as fermented fruit and vegetable juice and fermented soy milk, there are still few fermented products of sweet potato. The existing few fermented products of sweet potato are mostly focused on alcohol fermentation or acetic acid fermentation, such as sweet potato wine and sweet potato vinegar, which often contain high sugar content and have high GI value, and the probiotic activity is not effectively preserved.

[0010] In patents and academic literature, there are a few reports on lactic acid bacteria fermentation of sweet potato, but most of them have the following problems: (1) unstable fermentation process: prone to contamination by other bacteria during fermentation, short shelf life of the product; (2)

[0011] (1) Nutrient loss: the retention rate of active ingredients such as polyphenols and flavonoids is low during fermentation; (2) Poor taste and flavor: the product often has a bitter taste or excessive sour taste, and the consumer acceptance is low; (3) Insufficient activity of probiotics: the number of live bacteria after fermentation is low, and it is difficult to meet the standard of probiotic beverage; (4) Unclear GI value control: most products have not been systematically evaluated and optimized for GI value. Therefore, there is no fermented sweet potato beverage on the market that has low GI characteristics, is rich in active probiotics, has good taste and high stability. SUMMARY

[0012] To solve the above problems, the present application provides a low glycemic index sweet potato fermented juice, which comprises sweet potato, high peak alpha-amylase, glucoamylase, lactobacillus plantarum RHZB 68, sorbitol and mogroside.

[0013] The present application also provides a preparation method of the above-mentioned low glycemic index sweet potato fermented juice, comprising the following steps:

[0014] (1) Take fresh sweet potatoes, wash, peel, slice, add water and beat pulp, and then mature to obtain a fermentation substrate;

[0015] (2) Add high peak alpha-amylase and glucoamylase to the fermentation substrate, inactivate after enzymolysis, inoculate lactobacillus plantarum RHZB 68, and ferment to obtain a fermentation liquor;

[0016] (3) After pasteurizing the fermentation liquor, sorbitol and mogroside can be added for seasoning, and cold storage filling.

[0017] Further, the water-to-material ratio of the water added in step (1) is 1:3 to 1:6.

[0018] Further, the addition amount of high peak alpha-amylase in step (2) is 0.05 g / kg to 0.15 g / kg.

[0019] Further, the addition amount of glucoamylase in step (2) is 0.1% to 0.2% of the mass of the fermentation substrate.

[0020] Further, the enzymolysis time in step (2) is 2 hours to 4 hours, and the enzymolysis temperature is 60℃.

[0021] Further, the inoculation amount of lactobacillus plantarum RHZB 68 in step (2) is 3% to 6% of the mass of the fermentation substrate.

[0022] As a flavor correction of the product, 1.5% sorbitol and 1.5% mogroside can be added, as well as similar functional and taste sweeteners, to obtain similar sweetness without increasing the GI value of the product

[0023] The present application has the following beneficial effects:

[0024] 1. Low glycemic index: starch is converted into glucose by enzymatic hydrolysis, and most of the glucose is metabolized by lactic acid bacteria fermentation, significantly reducing the content of fermentable sugar in the product, thereby reducing the glycemic index;

[0025] 2. Retention of functional ingredients: the retention rate of active ingredients such as total phenols and total flavonoids is high during fermentation, and the product has health benefits such as antioxidant and immune enhancement;

[0026] 3. Excellent taste: the fermentation process and seasoning formula are optimized through orthogonal test, and the product has moderate sweetness, rich flavor and stable texture;

[0027] 4. High probiotic content: the viable count of the finished product is 5.0 x 10 7 CFU / mL, which meets the standard of probiotic beverage. DETAILED DESCRIPTION

[0028] The various exemplary embodiments of the present application will now be described in detail, and the methods in the examples are all conventional methods unless otherwise specified, and the reagents are all conventional commercially available reagents or reagents prepared by conventional methods unless otherwise specified. This detailed description should not be considered as limiting the present application, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present application.

[0029] It should be understood that the terms described in the present application are only for describing the specific embodiments, and are not intended to limit the present application. In addition, for the numerical range in the present application, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or intermediate value within the stated range, and any other stated value or intermediate value within the stated range, is also included in the present application. The upper limit and lower limit of these smaller ranges can be independently included or excluded from the range.

[0030] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as generally understood by those skilled in the art to which the present application relates. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present application. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of any conflict between the content of this specification and any incorporated document, the content of this specification shall prevail.

[0031] Many modifications and variations of the specific embodiments of the present application described in the specification can be made without departing from the scope or spirit of the present application, which will be apparent to those skilled in the art. Other embodiments resulting from the specification of the present application will be apparent to those skilled in the art. The specification and examples of the present application are only exemplary.

[0032] As used herein, the terms "comprises", "comprising", "includes", "including", "has", "having", "contains", "containing", or variations thereof, are intended to be open-ended terms that mean including, but not limited to.

[0033] Example 1:

[0034] Raw materials and proportions: sweet potato 1000 g, water 4000 g (material to water ratio 1:4), high peak alpha-amylase 0.1 g / kg (based on the mass of sweet potato), glucoamylase 0.15% (based on the mass of fermentation substrate), Lactobacillus plantarum RHZB68 inoculation amount 5% (based on the mass of fermentation substrate), sorbitol 1.5% (based on the total mass), mogroside 1.5% (based on the total mass).

[0035] Preparation steps:

[0036] (1) Wash the sweet potato, peel it, slice it, add water to pulp, and obtain the fermentation substrate by cooking;

[0037] (2) Add high peak alpha-amylase and glucoamylase to the fermentation substrate, and enzymatically hydrolyze at 60°C for 3 hours, and then inactivate;

[0038] (3) Cool to 37°C, inoculate Lactobacillus plantarum RHZB68, and ferment for 48 hours; (4) After the fermentation liquor is pasteurized (75°C, 15 minutes), add sorbitol and mogroside, stir evenly, and cold fill.

[0039] Product characteristics: viable bacterial count ≥5.2×10 7 CFU / mL, total phenol retention rate ≥86%, GI value 34.5, moderate sweet and sour taste, and good stability.

[0040] Example 2:

[0041] Difference from Example 1: high peak alpha-amylase addition amount is 0.05 g / kg, glucoamylase addition amount is 0.1%, and enzymatic hydrolysis time is 4 hours.

[0042] Product characteristics: viable bacterial count ≥4.9×10 7 CFU / mL, total phenol retention rate ≥84%, GI value 37.8, slightly light taste, and suitable for low sweet preference population.

[0043] Example 3:

[0044] Difference from Example 1: high peak alpha-amylase addition amount is 0.15 g / kg, glucoamylase addition amount is 0.2%, and enzymatic hydrolysis time is 2 hours.

[0045] Product characteristics: viable bacterial count ≥5.5×10 7CFU / mL, total phenol retention rate ≥ 83%, GI value 32.2, more obvious fermented flavor, suitable for people who prefer sour taste.

[0046] Example 4:

[0047] Difference from Example 1: Lactobacillus plantarum RHZB68 inoculation amount is 3%.

[0048] Product characteristics: viable bacteria ≥ 3.8 x 10 7 CFU / mL, total phenol retention rate ≥ 82%, GI value 39.5, mild sour taste, suitable for people who try fermented drinks for the first time.

[0049] Example 5:

[0050] Difference from Example 1: Lactobacillus plantarum RHZB68 inoculation amount is 8%.

[0051] Product characteristics: viable bacteria ≥ 6.5 x 10 7 CFU / mL, total phenol retention rate ≥ 85%, GI value 30.8, obvious sour taste, stronger probiotic activity.

[0052] Example 6:

[0053] Difference from Example 1: material to water ratio is 1:3.

[0054] Product characteristics: viable bacteria ≥ 4.5 x 10 7 CFU / mL, total phenol retention rate ≥ 80%, GI value 40.1, rich taste, suitable for dilution and drinking as concentrated fermented juice.

[0055] Example 7:

[0056] Difference from Example 1: material to water ratio is 1:6.

[0057] Product characteristics: viable bacteria ≥ 5.0 x 10 7 CFU / mL, total phenol retention rate ≥ 88%, GI value 36.2, refreshing taste, suitable for direct drinking.

[0058] Example 8:

[0059] Difference from Example 1: sorbitol and mogroside are not used, but erythritol 1.5% and stevioside 0.05% are added instead.

[0060] Product characteristics: viable bacteria ≥ 5.1 x 10 7 CFU / mL, total phenol retention rate ≥ 85%, GI value 31.5, sweet and fresh, suitable for diabetic population.

[0061] Example 9:

[0062] Difference from Example 1: No sweetener is added.

[0063] Product properties: viable bacterial count ≥5.0×10 7 CFU / mL, total phenol retention rate ≥87%, GI value ≤30.0, natural and slightly acidic taste, suitable for people with strict sugar control.

[0064] Example 10:

[0065] Difference from Example 1: 1000g of purple sweet potato is used instead of ordinary sweet potato.

[0066] Product properties: anthocyanin content ≥35 mg / 100 mL, antioxidant activity is significantly improved, viable bacterial count ≥5.0×10 7 CFU / mL, GI value 33.8, purple red color, visual and functional.

[0067] Example 11:

[0068] Difference from Example 1: Lactobacillus plantarum RHZB68 and Lactobacillus acidophilus are mixed at a mass ratio of 1:1, and the total inoculation amount is 6%.

[0069] Product properties: viable bacterial count ≥6.8×10 7 CFU / mL, total phenol retention rate ≥86%, GI value 32.5, more rich flavor levels, and more comprehensive probiotic functions.

[0070] Example 12:

[0071] Difference from Example 1: the enzymolysis time is 2 hours, and the fermentation time is extended to 60 hours.

[0072] Product properties: viable bacterial count ≥5.8×10 7 CFU / mL, total phenol retention rate ≥82%, GI value 29.5, suitable for functional products pursuing extremely low GI value.

[0073] The above-described examples only describe the preferred modes of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those of ordinary skill in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. A low glycemic index sweet potato fermented juice, characterized by, Ingredients include sweet potato, high peak alpha-amylase, glucoamylase, lactobacillus plantarum RHZB 68, sorbitol and mogroside.

2. The preparation method of the low glycemic index sweet potato fermented juice according to claim 1, characterized by, The method comprises the following steps: (1) Take fresh sweet potato, wash, peel, slice, add water to pulp, and mature to obtain fermentation substrate; (2) Add high peak alpha-amylase and glucoamylase to the fermentation substrate, inactivate after enzymolysis, inoculate lactobacillus plantarum RHZB 68, and ferment to obtain fermentation liquor; (3) After pasteurizing the fermentation liquor, add sorbitol and mogroside for seasoning, and cold storage filling.

3. The production method according to claim 2, characterized by, The water to material ratio in step (1) is 1:3~1:

6.

4. The production method according to claim 2, characterized by, The addition amount of high peak alpha-amylase in step (2) is 0.05 g / kg ~ 0.15 g / kg.

5. The preparation method according to claim 2, characterized in that, The addition amount of glucoamylase in step (2) is 0.1%~0.2% of the mass of the fermentation substrate.

6. The preparation method according to claim 2, characterized in that, The enzymolysis time in step (2) is 2 hours~4 hours, and the enzymolysis temperature is 60℃.

7. The preparation method according to claim 2, characterized in that, The inoculation amount of lactobacillus plantarum RHZB 68 in step (2) is 3%~6% of the mass of the fermentation substrate.

8. The method of claim 2, wherein, The addition amount of sorbitol in step (3) is 1.5% of the total mass.

9. The preparation method according to claim 2, characterized in that, The addition amount of mogroside in step (3) is 1.5% of the total mass.