Method for preparing mulberry leaf instant powder and mulberry leaf feed

Abstract

The invention provides a method for preparing mulberry leaf instant powder and a mulberry leaf feed, and belongs to the technical field of mulberry leaf processing. The preparation method comprises the following steps: blanching mulberry leaves, mixing the blanched mulberry leaves with water, and grinding into mulberry leaf homogenate; performing enzymolysis on the mulberry leaf homogenate by using compound enzyme to obtain mulberry leaf enzymatic hydrolysate; homogenizing the mulberry leaf enzymatic hydrolysate for 3-4 times, sieving after homogenizing, and respectively collecting filter residues and filtrate; and performing vacuum concentration on the filtrate, mixing the concentrated filtrate with maltodextrin, whey protein isolate and lecithin, performing homogenization twice, performing spray drying, and collecting powder to obtain the mulberry leaf instant powder. The mulberry leaf instant powder prepared by the preparation method disclosed by the invention can retain more mulberry leaf nutritional ingredients, is better in solubility, is not layered after being brewed, and is better in mouth feel. The mulberry leaf feed is prepared from the filter residues for preparing the mulberry leaf powder, and the tannin content of the mulberry leaf feed is remarkably reduced.

Description

Technical Field

[0001] The invention relates to the technical field of mulberry leaf processing, in particular to a method for preparing instant mulberry leaf powder and mulberry leaf feed. Background Art

[0002] Mulberry leaves are a dual-purpose resource for medicine and food, with the effects of dispersing wind-heat, clearing the liver and improving eyesight, and clearing the lungs and moistening dryness. Mulberry leaves are not only rich in nutrients such as protein, carbohydrates, cellulose, vitamins and minerals, but also rich in alkaloids, flavonoids, polysaccharides and other bioactive substances, and have multiple pharmacological effects such as lowering blood sugar, lowering blood lipids, anti-oxidation, anti-inflammatory, anti-tumor, and regulating the body's immunity. In addition, mulberry leaves have comprehensive and balanced nutritional components, and are suitable as high-quality feed raw materials for use in the production of chickens, cattle, sheep, pigs, fish and other animals.

[0003] At present, in the process of food processing, mulberry leaf powder is mainly made by drying first and then crushing. The nutrients of mulberry leaves are easily lost during the processing, and the particles of mulberry leaf powder are large, and the bioavailability of its active ingredients is low. Studies have found that mulberry leaf powder made by adding water to fresh mulberry leaves for homogenization, homogenization and spray drying can retain the nutrients in mulberry leaves to the greatest extent. The prepared mulberry leaf powder is rich in nutrition and has a good taste. However, mulberry leaves have a high fiber content. After being made into mulberry leaf powder, it is easy to agglomerate, easy to stratify after being dissolved in water, and has a granular feel, and the taste is not good; and it is easy to clog the pipeline during the homogenization, homogenization and spray drying process, and the work efficiency is low.

[0004] The utilization of mulberry leaves as feed is mostly done by silage or whole leaf drying, crushing to make mulberry leaf powder and then adding it to animal feed. Although these utilization methods are simple and easy, some active ingredients in mulberry leaves that are beneficial to the human body (such as polyphenols) are anti-nutritional factors for animals, and their excessive content will affect the growth performance of animals. The use of physical methods, microbial fermentation and other processes can eliminate some anti-nutritional factors in mulberry leaves and improve their nutritional value. Therefore, how to make full use of mulberry leaves to produce high-quality and high-value-added products has important theoretical value and practical significance. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing instant mulberry leaf powder and mulberry leaf feed, so as to solve the problem that the mulberry leaf powder has a poor taste. The residue after preparing the mulberry leaf powder is used to prepare the mulberry leaf feed, and the content of anti-nutritional factors is reduced.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing mulberry leaf instant powder, comprising the following steps:

[0008] S1. After blanching the mulberry leaves, mix them with water and grind them into a mulberry leaf homogenate;

[0009] S2. hydrolyzing the mulberry leaf homogenate with a composite enzyme to obtain a mulberry leaf hydrolyzate;

[0010] S3. homogenize the mulberry leaf enzymatic hydrolysate at 25-30 MPa for 3-4 times, each time for 8-15 min, sieve after homogenization, and collect the residue and filtrate respectively;

[0011] S4. The filtrate is vacuum concentrated to a solid content of 10-15%, mixed with maltodextrin, whey protein isolate and lecithin, homogenized at 25-30 MPa for 8-15 min, and then homogenized at 150-180 MPa for 5-10 min. The powder is collected after spray drying to obtain mulberry leaf instant powder.

[0012] Preferably, the complex enzyme comprises cellulase, pectinase and neutral protease.

[0013] Preferably, the amount of cellulase is 200-400 U / g mulberry leaf, the amount of pectinase is 100-200 U / g mulberry leaf, and the amount of neutral protease is 200-400 U / g mulberry leaf.

[0014] Preferably, the enzymatic hydrolysis temperature is 38-42° C., and the enzymatic hydrolysis time is 2-6 h.

[0015] Preferably, the amount of maltodextrin added is 20-40% of the solid content of the filtrate, the amount of whey protein isolate added is 10-30% of the solid content of the filtrate, and the amount of lecithin added is 2-5% of the solid content of the filtrate.

[0016] Preferably, the inlet air temperature of the spray drying is 180-200°C, and the outlet air temperature is 80-90°C.

[0017] Preferably, the mass volume ratio of the mixture of mulberry leaves and water is 1kg:3-7L.

[0018] The present invention also provides a method for preparing mulberry leaf feed, the steps are as follows: mixing the filter residue obtained in step S3 with fermentation agent activation liquid, fermenting for 3 to 7 days, drying to a water content of less than 10%, and obtaining mulberry leaf feed.

[0019] Preferably, the mass of the fermentation bacteria activation liquid is 2-4% of the mass of the filter residue.

[0020] Preferably, the drying temperature is 55-65°C.

[0021] By adopting the above technical solution, the present invention has the following beneficial effects:

[0022] 1. Adding an enzymatic hydrolysis step before the homogenization step can increase the dissolution rate of active ingredients such as polyphenols in mulberry leaves, increase the content of active ingredients beneficial to the human body in mulberry leaf instant powder, and reduce the content of anti-nutritional factors in feed.

[0023] 2. After homogenization, the 100-mesh sieve treatment can ensure smooth production during the subsequent spraying, and can ensure that the obtained product has better solubility and better taste. Compared with filtration and centrifugation, it can retain more mulberry leaf nutrients in the filtrate.

[0024] 3. Adding soy protein isolate can effectively cover the green and astringent taste of mulberry leaves and increase the bioavailability of mulberry leaf phenolic substances. Adding lecithin can improve the wettability and dispersibility of mulberry leaf powder and enhance its solubility. After homogenization, the mulberry leaf slurry is treated with micro-jet high-pressure homogenization equipment to make the mulberry leaf powder more soluble, without stratification after brewing, and with a better taste.

[0025] 4. The "waste" remaining from the preparation of mulberry leaf instant powder is used to prepare mulberry leaf feed, making full use of mulberry leaf resources to achieve the effect of making the best use of them. Moreover, compared with directly using fresh mulberry leaves as feed, the anti-nutritional factor (tannin) content of the mulberry leaf feed prepared by the method of the present invention is significantly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the appearance of the mulberry leaf instant powder of Examples 1 to 3 and Comparative Examples 1 and 2 after brewing. DETAILED DESCRIPTION

[0027] The present invention provides a method for preparing mulberry leaf instant powder, comprising the following steps:

[0028] S1. After blanching the mulberry leaves, mix them with water and grind them into a mulberry leaf homogenate;

[0029] S2. hydrolyzing the mulberry leaf homogenate with a composite enzyme to obtain a mulberry leaf hydrolyzate;

[0030] S3. homogenize the mulberry leaf enzymatic hydrolysate at 25-30 MPa for 3-4 times, each time for 8-15 min, sieve after homogenization, and collect the residue and filtrate respectively;

[0031] S4. The filtrate is vacuum concentrated to a solid content of 10-15%, mixed with maltodextrin, whey protein isolate and lecithin, homogenized at 25-30 MPa for 8-15 min, and then homogenized at 150-180 MPa for 5-10 min. The powder is collected after spray drying to obtain mulberry leaf instant powder.

[0032] The invention first picks fresh mulberry leaves, washes impurities on the surface of the mulberry leaves with clean water, blanchs the leaves in boiling water, drains the water, adds water to mix, grinds, and obtains mulberry leaf homogenate; the blanching time is 30 to 60 seconds, more preferably 40 to 50 seconds, and more preferably 45 seconds; the mass volume ratio of mulberry leaves to water is 1kg:3 to 7L, more preferably 1kg:4 to 6L, and more preferably 1kg:5L; after the blanched mulberry leaves are mixed with water, they are put into a colloid mill for grinding, and the grinding time is 10 to 15 minutes, more preferably 12 to 14 minutes, and more preferably 13 minutes; and the mulberry leaf homogenate is obtained.

[0033] The present invention adds a composite enzyme to a mulberry leaf homogenate for enzymolysis, wherein the composite enzyme comprises cellulase, pectinase and neutral protease; the amount of the cellulase is 200-400 U / g mulberry leaf, more preferably 250-350 U / g mulberry leaf, more preferably 300 U / g mulberry leaf; the amount of the pectinase is 100-200 U / g mulberry leaf, more preferably 120-180 U / g mulberry leaf, more preferably 150 U / g mulberry leaf; the amount of the neutral protease is 200-400 U / g mulberry leaf, more preferably 250-350 U / g mulberry leaf, more preferably 300 U / g mulberry leaf; the temperature of the enzymolysis is 38-42°C, more preferably 39-41°C, more preferably 40°C; the time of the enzymolysis is 2-6 hours, more preferably 3-5 hours, more preferably 4 hours, to obtain a mulberry leaf enzymolysis solution. The mulberry leaf enzymatic hydrolysate is homogenized and passed through a 100-mesh sieve, and the filtrate and the filter residue are collected separately; the homogenization pressure is 25-30 MPa, the number of homogenizations is 3-4 times, the homogenization time for each time is 8-15 minutes, more preferably 10-13 minutes, and more preferably 12 minutes. After homogenization, the filtrate is passed through a 100-mesh sieve, and the filtrate and the filter residue are collected separately.

[0034] In the present invention, the filtrate is vacuum concentrated to a solid content of 10-15%, preferably 11-14%, and more preferably 13%; then maltodextrin, whey protein isolate and lecithin are added to the concentrated filtrate, mixed evenly, homogenized twice, and then spray-dried, and the powder is collected to obtain mulberry leaf instant powder. The amount of maltodextrin added is 20-40% of the solid content of the concentrated filtrate, more preferably 25-35%, and more preferably 30%; the amount of whey protein isolate added is 10-30% of the solid content of the concentrated filtrate, more preferably 15-25%, and more preferably 20%; the amount of lecithin added is 2-5% of the solid content of the concentrated filtrate, more preferably 3-4%, and more preferably 3.5%; after uniform mixing, homogenization is performed twice, the pressure of the first homogenization is 25-30MPa, the time of the first homogenization is 8-15min, more preferably 10-13min, and more preferably 12min; the pressure of the second homogenization is 150-180MPa, the time of the second homogenization is 5-10min, more preferably 6-9min, and more preferably 8min, and the second homogenization is preferably performed in a microfluidizer. After two homogenizations, the mixture is spray-dried, wherein the inlet air temperature of the spray-drying is 180-200°C, more preferably 185-195°C, and more preferably 190°C; the outlet air temperature of the spray-drying is 80-90°C, more preferably 82-88°C, and more preferably 85°C. The powder is collected to obtain mulberry leaf instant powder.

[0035] The multifunctional feed fermentation agent and the polysaccharide composite nutrient base are mixed and dissolved in warm water for activation to obtain a feed fermentation agent activation liquid; the mass of the polysaccharide composite nutrient base is 8 to 12 times, more preferably 9 to 11 times, more preferably 10 times, of the multifunctional feed fermentation agent; the mass of the warm water is 15 to 25 times, more preferably 18 to 22 times, more preferably 20 times, of the multifunctional feed fermentation agent; the activation time is 2 to 4 hours, more preferably 2.5 to 3.5 hours, more preferably 3 hours. The filter residue obtained when preparing the mulberry leaf instant powder is mixed with the feed fermentation agent activation liquid for fermentation, the amount of the feed fermentation agent activation liquid is 2 to 4% of the mass of the filter residue, more preferably 2.5 to 3.5%, more preferably 3%, the fermentation time is 3 to 7 days, and the mulberry leaf feed is obtained by drying after fermentation; the drying temperature is 55 to 65°C, more preferably 58 to 62°C, more preferably 60°C; the water content is dried to less than 10%.

[0036] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0037] Example 1

[0038] Take 1kg of fresh mulberry leaves, wash the surface impurities with clean water, blanch in boiling water for 30s, drain, add 5L of water to mix, homogenize for 2min, and then put it into a colloid mill for fine grinding for 10min to obtain mulberry leaf homogenate. Add 6g of cellulase (300U / g mulberry leaf), 3g of pectinase (150U / g mulberry leaf) and 6g of neutral protease (300U / g mulberry leaf) to the mulberry leaf homogenate and enzymolyze for 4h at 40℃ to obtain mulberry leaf enzymolyzate. Homogenize the mulberry leaf enzymolyzate 3 times at 30MPa, each time for 10min, pass through a 100-mesh sieve after homogenization, and collect the filtrate and residue separately.

[0039] The filtrate is vacuum concentrated to a solid content of 10%, 1 L of the concentrate is taken, 30 g of maltodextrin, 20 g of whey protein isolate and 3.5 g of lecithin are added, the mixture is fully mixed, homogenized at 30 MPa for 10 min, and the mixture is put into a micro-jet high-pressure homogenizer and homogenized at 160 MPa for 10 min; finally, the mixture is put into a spray dryer and spray-dried at an inlet air temperature of 190° C. and an outlet air temperature of 85° C., the powder in the collection cup is collected to obtain mulberry leaf instant powder.

[0040] 50g of commercially available multifunctional feed fermentation agent (Nanning Weirui Biotechnology Co., Ltd.) and 500g of polysaccharide composite nutrient medium (Nanning Weirui Biotechnology Co., Ltd.) were dissolved in 1kg of warm water and activated for 3h to obtain fermentation agent activation liquid. 400g of filter residue was added with 12g of feed fermentation agent activation liquid and stirred evenly, then put into fermentation bag, compacted and sealed, fermented for 5 days, and then taken out and dried at 60℃ to a water content of 8%, thus obtaining mulberry leaf feed.

[0041] Example 2

[0042] The difference from Example 1 is that 3g of cellulase, 2g of pectinase and 3g of neutral protease are added to the mulberry leaf homogenate, and the other steps and parameters are the same as those in Example 1.

[0043] Example 3

[0044] The difference from Example 1 is that 40 g of maltodextrin, 10 g of whey protein isolate and 3 g of lecithin are added to the filtrate, and the other steps and parameters are the same as those in Example 1.

[0045] Example 4

[0046] The difference from Example 1 is that the bags are packed, sealed and fermented for 3 days.

[0047] Comparative Example 1

[0048] Take 1kg of fresh mulberry leaves, wash the surface impurities with clean water, blanch in boiling water for 30s, drain, add 5L of water to mix, homogenize for 2min, then put it into a colloid mill for fine grinding for 10min to obtain mulberry leaf homogenate, put it into a colloid mill for fine grinding for 5min to obtain mulberry leaf homogenate; add 280g of maltodextrin to the obtained mulberry leaf homogenate, after fully dissolving, homogenize for 5min under 30MPa, then add 170g of whey protein isolate, after completely dissolving, put it into a homogenizer, continue homogenizing for 5min; put it into a spray dryer, spray dry it under the conditions of an inlet air temperature of 190℃ and an outlet air temperature of 85℃, collect the powder in the collection cup, and obtain mulberry leaf instant powder. This method often blocks the injection during the spray drying process, causing interruption of the processing process.

[0049] Comparative Example 2

[0050] Take 1kg of fresh mulberry leaves, wash the surface impurities with clean water, add 5L of water, homogenize for 2min, water bath at 85℃ for 20min, filter and remove the residue, cool the extract at room temperature for 2.5h, then centrifuge at 4500r / min for 10min, take the supernatant, and vacuum concentrate to a solid content of 10%. Take 200mL of the concentrate, add 10.5g of maltodextrin, spray dry, set the inlet temperature to 190℃, the outlet temperature to 85℃, collect the powder in the collection cup, and obtain mulberry leaf instant powder.

[0051] Comparative Example 3

[0052] Take 1 kg of fresh mulberry leaves, chop them, add 30 g of feed fermentation bacteria activation liquid (the preparation method is consistent with Example 1), stir evenly and put them into fermentation bags, bag them, compact them, seal them and ferment them for 5 days, take them out and dry them at 60°C to a moisture content of 8% to obtain mulberry leaf feed.

[0053] Experimental Example 1

[0054] The mulberry leaf instant powder prepared in Examples 1 to 3 and Comparative Examples 1 to 2 was prepared. A sensory evaluation panel consisting of 10 professionals with sensory evaluation experience was formed to evaluate and score each sample in terms of product particle size, color, taste, and solubility using the fuzzy mathematical sensory evaluation method. The scoring criteria are shown in Table 1, and the average values ​​are statistically calculated. The particle size, color, taste, and solubility of the mulberry leaf instant powder accounted for 0.48, 0.12, 0.30, and 0.10, respectively, and the total weight was 1. The results are shown in Tables 2 and Figure 1 shown.

[0055] Table 1 Sensory evaluation standard of mulberry leaf instant powder

[0056]

[0057]

[0058] Table 2 Comparison of sensory qualities of different mulberry leaf powders

[0059]

[0060] From Table 1 and Figure 1 It can be seen that the mulberry leaf instant powder prepared by the method of the present invention has a more uniform solution after brewing, and has a good taste and color. Comparative Example 1 is easy to precipitate after brewing, and the color of Comparative Example 2 is yellower and the taste is not as good as the embodiment.

[0061] Experimental Example 2

[0062] Weigh 0.5 g of the mulberry leaf powder prepared in Examples 1 to 3 and Comparative Examples 1 to 2 respectively into a 50 mL centrifuge tube, add 30 mL of ethanol aqueous solution (concentration 70%, V / V), mix thoroughly, and then ultrasonically treat at a power of 300 W and a temperature of 40° C. for 30 min. Centrifuge at a speed of 4500 rpm for 10 min, collect the supernatant, repeat the above steps, combine the supernatants obtained twice, and make up to 100 mL to prepare a mulberry leaf instant powder extract, which is stored at 4° C. in the dark and the total phenol content in the extract is detected.

[0063] The determination method is as follows: take 1mL of mulberry leaf instant powder extract and add it to a 25mL volumetric flask, add 5mL of 0.1M Folin phenol reagent; after standing for 5 minutes, add 4mL of sodium carbonate solution (7.5%, w / v), and dilute to 25mL with distilled water; after fully mixing, react in the dark for 30 minutes. Use an enzyme marker to measure the absorbance at 760nm, and draw a standard curve with different concentrations of gallic acid (0, 0.02, 0.04, 0.08, 0.16, 0.32mg / mL) as the standard. The results are expressed in gallic acid equivalents and uniformly converted to relative content in the dry weight of mulberry leaf powder. The results are shown in Table 2.

[0064] Table 2 Comparison of total phenol content of mulberry leaf instant powder

[0065] sample Total phenol content (mg / g) Example 1 49.90 Example 2 42.45 Example 3 48.06 Comparative Example 1 23.08 Comparative Example 2 33.62

[0066] Total phenol content is the total amount of all phenolic compounds in mulberry leaf instant powder. Phenolic compounds are a class of compounds with extensive biological activity, and total phenol content has many effects on mulberry leaf instant powder, such as being related to sensory properties (such as fragrance, mouthfeel, color). In addition, phenolic compounds are important antioxidants, and products with high total phenol content may contain more antioxidants, and total phenol content can be used to evaluate the potential health benefits of products, such as anti-oxidation, anti-inflammatory, anti-tumor, etc. As shown in Table 2, the total phenol content of mulberry leaf instant powder prepared in the embodiment of the present application is higher than that of the comparative example, and has better health care performance.

[0067] Experimental Example 3

[0068] The tannin content of the mulberry leaf feed obtained in Examples 1 to 4 and Comparative Example 3 was measured. The tannin content was measured according to the national standard GB / T 27985-2011, and the results are shown in Table 3.

[0069] Table 3 Comparison of tannin content in mulberry leaf feed

[0070]

[0071]

[0072] It can be seen from Table 3 that compared with the control mulberry leaf feed, the tannin content of the mulberry leaf feed prepared by the method of the present invention is significantly reduced, indicating that preparing mulberry leaf feed using the mulberry leaf residue, a by-product of preparing mulberry leaf powder according to the present invention, can reduce the content of anti-nutritional factors in mulberry leaf feed.

[0073] It can be seen from the above embodiments that the present invention provides a method for preparing mulberry leaf instant powder and mulberry leaf feed. The mulberry leaf instant powder prepared by the present invention has good taste and high nutritional value, and the content of anti-nutritional components in the prepared mulberry leaf feed is low.

[0074] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing mulberry leaf instant powder, characterized in that: The following steps are involved: S1. After blanching the mulberry leaves, mix them with water and grind them into a mulberry leaf homogenate; S2. hydrolyzing the mulberry leaf homogenate with a composite enzyme to obtain a mulberry leaf hydrolyzate; S3. homogenize the mulberry leaf enzymatic hydrolyzate at 25-30 MPa for 3-4 times, each time for 8-15 min, sieve after homogenization, and collect the residue and filtrate respectively; S4. The filtrate is vacuum concentrated to a solid content of 10-15%, and then mixed with maltodextrin, whey protein isolate and lecithin, homogenized at 25-30 MPa for 8-15 min, and then homogenized at 150-180 MPa for 5-10 min. The powder is collected after spray drying to obtain mulberry leaf instant powder.

2. The preparation method according to claim 1, characterized in that: The complex enzyme comprises cellulase, pectinase and neutral protease.

3. The preparation method according to claim 2, characterized in that: The dosage of the cellulase is 200-400 U / g mulberry leaf, the dosage of the pectinase is 100-200 U / g mulberry leaf, and the dosage of the neutral protease is 200-400 U / g mulberry leaf.

4. The preparation method according to claim 1, characterized in that: The temperature of the enzymolysis is 38-42° C., and the time of the enzymolysis is 2-6 hours.

5. The preparation method according to claim 1, characterized in that: The added amount of maltodextrin is 20-40% of the solid content of the filtrate, the added amount of whey protein isolate is 10-30% of the solid content of the filtrate, and the added amount of lecithin is 2-5% of the solid content of the filtrate.

6. The preparation method according to claim 1, characterized in that: The inlet air temperature of the spray drying is 180-200°C, and the outlet air temperature is 80-90°C.

7. The preparation method according to claim 1, characterized in that: The mass volume ratio of mulberry leaves and water mixture is 1kg:3~7L.

8. A method for preparing mulberry leaf feed, characterized in that: The steps are as follows: mixing the filter residue obtained in step S3 of claim 1 with the fermentation agent activation liquid, fermenting for 3 to 7 days, and drying until the water content is below 10% to obtain mulberry leaf feed.

9. The preparation method according to claim 8, characterized in that: The mass of the fermentation bacteria activation liquid is 2-4% of the mass of the filter residue.

10. The preparation method according to claim 8, characterized in that: The drying temperature is 55-65°C.

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