Method for producing purple sweet potato primary pulp through enzyme adding, extruding and liquefying

Abstract

The invention relates to the technical field of food processing, in particular to a preparation technology of enzymolysis purple sweet potato primary pulp. According to the preparation process provided by the invention, the difficulty in the existing process is overcome, an economical, practical and feasible production method is found, and limited enzymolysis can be carried out on the purple sweet potatoes. Purple sweet potatoes are bright in color and luster, rich in anthocyanin and selenium element and have a certain health-care function, so that the purple sweet potatoes are always a research and development hot spot in the food field. However, research on the aspect is started later in China, most research is still in a basic stage, leisure products mainly comprising purple sweet potato chips and purple sweet potato wine products mainly exist in the domestic market at present, and research and development reports about preparation of primary pulp from purple sweet potatoes are relatively few. Therefore, research and development of the enzymolysis purple sweet potato primary pulp can enrich the market in China and meet the nutritional and health-care requirements of consumers at the same time.

Description

Technical Field

[0001] The invention relates to the technical field of purple sweet potato puree preparation, in particular to a process for producing purple sweet potato puree by utilizing enzyme extrusion liquefaction technology and saccharification method. Background Art

[0002] Purple sweet potato, also known as black sweet potato, Sichuan purple sweet potato, etc., is a herbaceous tuberous plant belonging to the genus Ipomoea of ​​the Convolvulaceae family. It is a unique sweet potato variety introduced and successfully cultivated in my country from Japan. The potato is spindle-shaped, grows in a vine-like manner, has opposite leaves, and the flower is shaped like morning glory, purple and white. The plant can also be hydroponically cultivated for ornamental purposes; the tuber contains a large amount of anthocyanin, so the skin and potato flesh are bright purple, and it is a first-class natural food. At present, the foreign purple sweet potato varieties introduced and planted in my country mainly include Japanese mountain purple, American black potato, German black potato, etc., but their yield is low and cannot meet the development of agriculture well. Therefore, on this basis, Chinese scientific researchers have carried out a series of work such as evaluation and breeding on the introduced purple sweet potato germplasm resources, and improved the hybridization method of purple sweet potato, which not only improves the single plant fruiting rate of purple sweet potato, but also selects and breeds excellent purple sweet potato varieties suitable for development and utilization in China, such as Yan Zishu 653, 176, 323, 18, 20, 337, etc. One type is fresh-eating type, common types include violet and smoky purple; the other type is processed type. Purple sweet potatoes are often divided into two categories, mainly used for pigment extraction, such as Jingshu No. 6 and Lingzi. Purple sweet potatoes are suitable for planting in sandy loam and semi-sandy loam. They are widely planted in my country, especially in Sichuan and the southeastern coastal areas, which are the main production areas of purple sweet potatoes. Purple sweet potatoes have the characteristics of strong resistance to stress and high economic benefits. Therefore, in some mountainous areas with relatively poor natural conditions, planting and developing purple sweet potatoes has become an important way for local economic development.

[0003] Purple sweet potatoes are rich in various nutrients, such as starch, soluble sugar, dietary fiber, protein, inorganic salts, fat and various vitamins. Taking Sichuan purple sweet potatoes as an example, the water content is about 71.46%, the starch content is 57.33%, the crude protein content is 1.67%, the crude fat content is 0.26%, the Vc content is 17.30mg / 100g, and the selenium content is 0.016mg / kg. At the same time, the nutrient content of purple sweet potatoes is higher than that of ordinary sweet potatoes, and they have more significant health functions. Purple sweet potatoes are rich in dietary fiber, so they can better promote gastrointestinal motility and prevent constipation. Purple sweet potatoes contain high mineral content, such as copper, manganese, potassium, and zinc, which are 4 times higher than those of ordinary sweet potatoes, and iodine and selenium, which are more than 20 times higher than those of ordinary sweet potatoes. Therefore, purple sweet potatoes have certain effects in preventing cardiovascular diseases, anti-cancer, and anti-mutation. Purple sweet potatoes are also rich in a nutrient that ordinary sweet potatoes do not have - anthocyanins, which are mainly composed of paeoniflorin-3,5-glucoside and cyanidin-3,5-glucoside. This substance is known as the seventh essential nutrient. Relevant experiments have shown that anthocyanins have extremely strong antioxidant activity and can be used as free radical scavengers to effectively remove free radicals, delay animal aging, protect brain cells, improve memory, etc. They can also be used to treat diseases such as cancer. They are the safest, most direct and effective substance in maintaining human health, and have great market development potential.

[0004] Purple sweet potato has been a hot research and development topic in the food industry because of its bright color, strong and special fragrance, rich content of anthocyanin and selenium, and certain health functions. In addition to daily fresh food, purple sweet potato has also been developed into various purple sweet potato foods. Existing purple sweet potato products include: purple sweet potato leisure food, such as purple sweet potato chips, purple sweet potato strips, purple sweet potato wine products, including purple sweet potato sake, purple sweet potato fruit and vegetable wine, purple sweet potato glutinous rice wine, etc. In the processing of health foods, purple sweet potato is also often used as a functional factor ingredient. In addition, because it has multiple pharmacological activities and has good health and therapeutic effects on people, it is also increasingly valued in the pharmaceutical industry. Summary of the invention

[0005] The purpose of the present invention is to overcome the following problems existing in the production and processing of purple sweet potato puree: it is easy to brown and affect the color of the beverage; there is a cooking smell that affects the flavor of the beverage; it contains substances such as starch, which can easily cause the beverage to stratify due to the aging of starch, resulting in a sense of gravel that affects the sensory quality of the beverage. The purple sweet potato beverage also has the problem of poor stability of anthocyanins during the production process (anthocyanins are unstable, easy to decompose, or easy to combine with proteins to produce precipitation). The applicant provides a method for producing purple sweet potato puree by extrusion liquefaction with a compound enzyme preparation. The present invention has high production intensity, economy, and environmental protection. The method is used to process purple sweet potatoes, with low energy consumption and shortened saccharification time, which greatly improves the industrial production efficiency of purple sweet potato puree. The specific technical scheme is as follows: A method for producing purple sweet potato puree by enzyme extrusion liquefaction, using purple sweet potato as raw material, adding water, adjusting the moisture, adding enzyme, extruding and steaming to achieve the purpose of liquefaction, and then sieving the extruded liquefied material and de-enzyme treatment to finally obtain the product. The method comprises the following steps:

[0006] S1. Select fresh purple sweet potatoes, wash, peel and cut into 2-3 cm cubes, and steam at 100°C for 10 min;

[0007] S2. Add water to make pulp: Mix purple sweet potato and water in a certain proportion and make pulp.

[0008] S3, enzyme saccharification: add high temperature-α amylase, cellulase, saccharifying enzyme, etc. to the purple sweet potato puree for enzymatic hydrolysis for 1-2 hours, the temperature of the enzymatic hydrolysis process is controlled at about 65°C, and the enzymatic hydrolysis time is 1-2 hours; The mass ratios of high temperature α-amylase, cellulase and saccharifying enzyme are 0.1%-0.5%, 0.05%-0.1% and 0.1%-0.3%.

[0009] S4, extrusion: the obtained enzymatic hydrolysate is subjected to twin-screw extrusion treatment, and the temperature of the extrusion sleeve is controlled at 60-70°C, 70-80°C, 80-90°C, 90-100°C.

[0010] S5. Insulation: After the enzymatic hydrolysis is completed, the enzymatic hydrolyzate is insulated for 1 hour.

[0011] S6. After the heat preservation is completed, the enzymatic solution is subjected to enzyme inactivation treatment.

[0012] S7, then the purple sweet potato puree after enzyme inactivation is passed through a colloid mill to make its colloid molecules reach the required level.

[0013] S8. The enzymatic hydrolysate treated by the colloid mill is then filtered.

[0014] S9. After the enzymatic hydrolysate is filtered, it is sent to a homogenizer for processing to obtain a homogenized enzymatic hydrolysate.

[0015] S10. The homogenized sample hydrolysate is sterilized by UHT and then aseptically packaged in an aseptic workshop.

[0016] The beneficial technical effects are: The processing method of producing purple potato pulp by adding enzymes to extrude and liquefy purple potato has obvious advantages over the prior art. When adding high temperature-α amylase to prepare purple potato pulp, the purple potato can solve the problems that it is difficult to filter after pulping, turbidity or stratified precipitation is easily generated when directly mixed, and the stability is poor after being made into a beverage, etc., because the purple potato contains a large amount of starch, sugars, cellulose and other substances.

[0017] The present invention realizes the liquefaction process of high-concentration materials through the enzyme extrusion liquefaction process. The extruded enzymatically hydrolyzed materials do not need to undergo a subsequent liquefaction process, and can be directly slurried for subsequent saccharification steps, thus saving liquefaction time. The extruded product is degraded, which is beneficial to subsequent enzymatic hydrolysis, shortens the saccharification time, and effectively improves production efficiency.

[0018] During the enzymatic hydrolysis process, the water-insoluble macromolecular nutrients in the fine powder are converted into water-soluble small molecular nutrients and dissolved as much as possible through enzymatic hydrolysis, making the fine powder particles smaller and softer. Combining the extrusion process with the enzymatic hydrolysis process can effectively improve the product absorption rate.

[0019] In the present invention, the limited enzymatic hydrolysis of soluble dietary fiber in purple sweet potato can increase the viscosity of purple sweet potato puree. Specific implementation methods

[0020] The present invention is described in detail through specific embodiments, which are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art. Embodiment 1

[0021] As shown below, the present invention provides a method for preparing a purple sweet potato puree beverage by extruding purple sweet potato puree with enzyme, and its technical measures include:

[0022] (1) Selection and processing of raw materials: Select high-quality fresh purple potatoes without mechanical damage, pests and diseases, and sprouts. Wash the surface sand and other impurities with running water, peel them manually, cut them into 2-3 cm pieces, and weigh them.

[0023] (2) Steaming: Place the cut purple sweet potato pieces in a steamer and steam for about 10 minutes until there is no hard core left.

[0024] (3) Beating: Beat the mixture in a ratio of purple sweet potato (g): water (g) -1:5.

[0025] (4) Enzymatic hydrolysis: Keep the prepared slurry in a constant temperature water bath, add high temperature α-amylase and saccharifying enzyme, and keep the temperature constant for 60 minutes.

[0026] (5) Extrusion liquefaction: The mixed purple sweet potato pulp is subjected to extrusion, cooking and liquefaction treatment using a twin-screw extruder. The barrel temperatures of the four zones of the twin-screw extruder are 60°C, 70°C, 80°C and 95°C, respectively, the screw speed is 200rpm, and the feed rate is 200kg / h. The extruded product is kept warm at high temperature and then the purple sweet potato pulp is treated with pulping and enzyme inactivation.

[0027] (6) Grinding and enzyme inactivation: After the heat preservation is completed, the enzyme is inactivated at 95°C for 5 minutes. The obtained purple sweet potato pulp product after enzyme addition and extrusion is further ground. A colloid mill is used for grinding.

[0028] (7) Filtration: Cool the purple sweet potato pulp after enzyme inactivation to room temperature and filter the purple sweet potato pulp.

[0029] (8) Preparation: Dissolve salt and citric acid into liquids and filter with gauze for later use. Mix all ingredients evenly according to the formula.

[0030] (9) Homogenization and degassing: Homogenize and degas the prepared purple sweet potato paste.

[0031] (10) Sterilization: The buckwheat puree obtained in step (9) is sterilized by UHT to obtain finished purple sweet potato puree.

[0032] Furthermore, when the buckwheat pulp is subjected to UHT sterilization, the sterilization temperature is 110° C. and the sterilization time is 4-15 seconds.

[0033] In this step, by sterilizing, the shelf life of the purple sweet potato pulp can be extended while retaining the nutritional components and stability of the purple sweet potato pulp. Embodiment 2

[0034] The difference between this embodiment and the first embodiment is that in this embodiment, when the material is enzymatically hydrolyzed in step (1), cellulase can also be added. The addition of cellulase can decompose the cell structure (i.e., the cellulose of the cell wall) into prebiotic active ingredients such as cellotriose (PD3), cellotetraose (PD4) and oligoxylose, thereby increasing the prebiotic content of the purple sweet potato puree, thereby achieving the purpose of improving the nutritional value of the purple sweet potato puree.

[0035] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them; any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A process technology developed based on the characteristics of purple sweet potatoes and applied to the production of purple sweet potato puree, thereby adding a compound enzyme preparation for enzyme extrusion, the process steps and conditions of the method are as follows: (1) Peel and cut purple sweet potatoes into pieces, and steam them; (2) Mix the purple sweet potato with water in equal proportions and beat into pulp; (3) Adding high temperature amylase and saccharifying enzyme to the purple sweet potato pulp for enzymatic hydrolysis, the mass ratio of high temperature α-amylase, cellulase, and saccharifying enzyme is 0.1%-0.5%, 0.05%-0.1%, and 0.1%-0.3%; (4) subjecting the premixed material obtained in (3) to twin-screw extrusion, with a liquid-to-material ratio of 1:3, 1:4, 1:5, or 1:6, and the extrusion sleeve temperature being controlled at 60-70°C, 70-80°C, 80-90°C, or 90-100°C; (5) The enzymatic hydrolysate obtained by extrusion is subjected to heat preservation treatment; (6) Inactivate the enzyme in the enzymatic solution after heat preservation at 90-95°C for 15 min; (7) The purple sweet potato pulp after enzyme inactivation treatment is filtered through a screen, and then processed by a colloid mill and a homogenizer: the slurry after saccharification is filtered, and then processed by a colloid mill and a homogenizer, so that the purple sweet potato particles after treatment reach the colloidal molecular level; (8) When the sample reaches the required molecular level, it is subjected to UHT sterilization and then aseptically packaged to complete the production of purple sweet potato puree; (9) Finally, add a certain proportion of edible oil, salt, stabilizer and other food additives to the slurry according to product requirements to make subsequent product improvements.

2. According to claim 1, a method for producing purple sweet potato puree by enzyme extrusion liquefaction, characterized in that: The enzymes required for enzymatic hydrolysis in step (3) are a mixture of one or more of high-temperature α-amylase, saccharifying enzyme, and flavor enzyme.

3. According to claim 1, the holding temperature of step (6) is 65°C-75°C and the holding time is as described above, a method for producing purple sweet potato puree by enzyme extrusion liquefaction, characterized in that: In step (7), the rotation speed of the colloid mill treatment is 1000-2000 r / min, and the treatment temperature is room temperature.

4. According to claim 1, a method for producing purple sweet potato puree by enzyme extrusion liquefaction, characterized in that: Step (7) filtration is performed using a 200-mesh sieve.

5. According to claim 1, a method for producing purple sweet potato puree by enzyme extrusion liquefaction, characterized in that: During the homogenization process in step (7), the homogenization temperature is 35°C-55°C, the first-level homogenization pressure is 60Mpa-100Mpa, and the second-level homogenization pressure is 40Mpa-60Mpa.

6. The method for producing purple sweet potato puree by enzyme extrusion liquefaction according to claim 1, characterized in that: In step (9), a certain proportion of edible oil, salt, stabilizer and other food additives are finally added to the slurry according to product requirements to carry out subsequent product improvements.