Preparation method of flavored low-fat milk

Abstract

The invention discloses a preparation method of flavored low-fat milk, and belongs to the technical field of food processing. The flavored milk fat prepared by the method is free of any additional components, has natural aroma-enhanced milk product characteristic aroma, standardizes sensory characteristics of products in different production batches, and is high in applicability. The flavored milk fat prepared by the method can be widely applied to milk-flavored, butter-flavored, cream-flavored and other related frankincense-flavored dairy products, baked foods and other foods.

Description

Technical Field

[0001] The present invention belongs to the technical field of food processing, and particularly relates to a method for preparing flavored low-fat milk. Background Art

[0002] Milk is deeply loved by consumers worldwide due to its rich nutritional value (such as protein, calcium, vitamins, etc.), mild and smooth taste, and wide range of application scenarios (such as direct drinking or used in the production of dairy products and foods).

[0003] The market development shows a healthy trend, and innovative products such as low-fat, lactose-free, and plant-based milk are emerging continuously to meet the health needs of consumers. As an innovative product that meets the health needs of consumers, the market scale of low-fat flavored milk is expanding rapidly, showing a broad and bright future.

[0004] The technology for enhancing the flavor of low-fat milk is an important research direction in the dairy industry, aiming to improve the aroma and taste of milk through physical, chemical, or biological methods. Today, with increasing attention to food health, consumers focus on the natural properties of foods, and flavored milk prepared by chemically synthesizing milk flavor essence is gradually withdrawn from the market. Currently, foreign research focuses on the application of advanced technologies such as ultra-high pressure treatment, microencapsulation technology, and molecular distillation to retain and enhance the natural aroma of milk, but these technologies face challenges of high cost and complex operation and are difficult to industrialize. Domestic research mainly focuses on enzymatic hydrolysis technology, fermentation process, and heat treatment optimization. Enzymatic hydrolysis technology uses lipase, protease, etc. to hydrolyze the fat and protein in milk, releasing more flavor substances in milk, which can enhance the natural aroma of dairy products without adding, but has the disadvantage that the enzymatic hydrolysis process is difficult to precisely control. Fermentation technology produces natural aroma components through the fermentation of lactic acid bacteria, etc., with diverse aromas and potential health benefits such as probiotics, but its application in enhancing the flavor of milk is likely to produce a slightly sour taste unacceptable to consumers, and the production cost is high and the operation difficulty is large. Heat treatment optimization enriches the milk flavor type by optimizing the heat treatment conditions, with simple operation and low cost, but is prone to caramelization or the generation of off-flavors. Based on the current research trend of naturalization, high efficiency, and precision in milk flavor enhancement, the technology of combined double enzymatic hydrolysis of lipase and protease and heat treatment optimization has become a new strategy for preparing natural flavored milk fat, but the precise control of the process and the stable control of the enzymatic hydrolysis flavor are still problems to be solved. Summary of the Invention

[0005] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this part, the abstract, and the title, and such simplifications or omissions shall not be used to limit the scope of the present invention.

[0006] In view of the above problems and / or those existing in the prior art, the present invention is proposed.

[0007] Therefore, an object of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing a flavored low-fat milk.

[0008] To solve the above technical problems, the present invention provides the following technical solution: A method for preparing a flavored low-fat milk, characterized in that it includes:

[0009] Fully mix milk fat and water, emulsify and sterilize, add lipase and mix evenly, stir to carry out lipase hydrolysis reaction. After the hydrolysis ends, heat to inactivate and centrifuge to obtain lipase-hydrolyzed milk fat.

[0010] Prepare a whey protein solution, adjust the pH, add protease and mix evenly, stir to carry out protease hydrolysis reaction. After the hydrolysis ends, heat to inactivate to obtain a protease hydrolysate.

[0011] Add the protease hydrolysate to the heat-treated lipase-hydrolyzed milk fat, mix evenly, emulsify and then centrifuge to remove the aqueous phase. The obtained oil phase is the flavored milk fat.

[0012] Mix the flavored milk fat with skim milk, with the addition amount less than 1.5 g / 100 g, and homogenize to obtain a flavored low-fat milk with stable quality.

[0013] As a preferred embodiment of the preparation method of the present invention, wherein: the lipase is derived from a variety of microorganisms, including Candida rugosa, Aspergilus oryzae, Aspergilus niger, Penicilium expansum, Pseudomonas fluorescens, Bacillus subtilis, Rhizomucor miehei, Candida antarctica.

[0014] As a preferred embodiment of the preparation method of the present invention, the lipase includes Lipase AY “Amano” 30SD, Newlase F3G, Lipase DF “Amano” 15, Lipase MER “Amano”, Lipase MHA “Amano” 10SD, Lipase A “Amano” 12, Lipase G “Amano” 50, Lipozyme RM IM, Lipase PS “Amano” SD, Lipase AY400 “Amano” SD-K, Lipase AK “Amano”, Lipozyme Patalase 2000L, NovoCor ADL.

[0015] As a preferred embodiment of the preparation method of the present invention, stirring is carried out for lipase hydrolysis reaction, wherein the hydrolysis time is 1 - 4 h, the hydrolysis temperature is 25 - 45 °C, the enzyme addition amount is 0.02% - 0.2%, the oil-water ratio is (0.25 - 4):1, the pH is 5.0 - 8.0, and the mechanical emulsification condition is shearing at 9000 - 12000 rpm for 2 - 5 min.

[0016] As a preferred embodiment of the preparation method of the present invention, the protease includes alkaline protease, neutral protease and flavor protease.

[0017] As a preferred embodiment of the preparation method of the present invention, for the protease hydrolysate, based on whey protein, the concentration of the protein solution is 15% - 25%, the enzyme addition amount is 0.1% - 0.5%, the hydrolysis temperature is 40 - 55 °C, and the hydrolysis time is 1 - 4 h.

[0018] As a preferred embodiment of the preparation method of the present invention, adding the protease hydrolysate to the heat-treated lipase-hydrolyzed milk fat, wherein the heat treatment is dry heat treatment in an oven at 95 - 105 °C for 0.5 - 1.5 h.

[0019] As a preferred embodiment of the preparation method of the present invention, the addition amount of the protease hydrolysate is 1% - 7% of the hydrolyzed milk fat.

[0020] As a preferred embodiment of the preparation method of the present invention, mixing the flavored milk fat with skim milk, wherein the addition amount of the flavored milk fat is 0.5% - 1.5%, the homogenization temperature is 50 - 55 °C, and the homogenization pressure is 22 - 26 MPa.

[0021] Another object of the present invention is to overcome the deficiencies in the prior art and provide a natural flavored milk fat and low-fat flavored milk.

[0022] Advantages of the present invention:

[0023] (1) The double-enzyme method combined with dry heat treatment technology described in the present invention for preparing flavored milk fat can significantly increase the content and variety of its flavor substances, and the obtained flavored milk fat has a strong milk fragrance and no abnormal smell.

[0024] (2) Compared with the chemically synthesized milk flavor, the flavored milk fat prepared by the present invention is naturally free of added chemical reagents, completely uses food raw materials, reduces environmental pollution, and is a more environmentally friendly processing method. The lipase and protease used in the process are harmless and easy to remove, ensuring the safety of the processing process, retaining the natural properties of the flavored milk fat, and at the same time having a very obvious effect on enhancing the flavor of the milk fat. The milk fragrance is rich, mellow, harmonious, soft and has no abnormal smell.

[0025] (3) Compared with the milk flavor prepared by lipase-hydrolyzed milk fat, the flavored milk fat prepared by the present invention has no abnormal sour smell, stench, putrid smell or other pungent smells and other bad flavors. The present invention uses the synergistic effect between the taste peptides in the protease hydrolysate and the off-flavor substances to mask the off-flavors, which can more quickly and effectively eliminate the off-flavors, reduce the control difficulty of the lipase hydrolysis process, make the process simpler and more efficient, and at the same time ensure the purity of the milk fragrance.

[0026] (4) Compared with the milk flavor prepared by simple dry heat treatment, the flavored milk fat prepared by the present invention does not produce adverse reactions such as caramelization or bad flavors such as burnt smell and rancid smell. The heat treatment substrate in the technology described in the present invention is the milk fat treated by double enzyme hydrolysis, which contains many precursor substances such as acids and alcohols. After dry heat treatment, the produced milk fragrance is mellow, diverse, and has no abnormal smell or color.

[0027] (5) The double-enzyme method combined with dry heat treatment technology adopted by the present invention has the advantages of good flavor enhancement effect, simple operation, natural without addition, low energy consumption, etc., is suitable for industrial production, can realize high-efficiency and large-scale production of flavored milk fat, and provides strong support for the industrial development of low-fat dairy products.

[0028] (6) The low-fat flavored milk prepared by the technology described in the present invention is naturally free of addition, meets the health pursuit of consumers, and has a strong and diverse milk fragrance and no abnormal smell, which is superior to the existing low-fat milk in the market and has a bright market prospect. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. Among them:

[0030] Figure 1 and Figure 2For the JAR sensory evaluation comparison of different samples.

[0031] Figure 3 and Figure 4 are the PCA graphs obtained by the electronic nose analysis of different samples. Detailed implementation manners

[0032] To make the above objects, features and advantages of the present invention more obvious and understandable, the following will describe the detailed implementation manners of the present invention in conjunction with the embodiments of the specification.

[0033] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0034] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure or characteristic that may be included in at least one implementation manner of the present invention. The appearances of "in one embodiment" in different places in this specification do not all refer to the same embodiment, nor are they separate or alternative embodiments that exclude each other with other embodiments.

[0035] The raw materials used in the embodiments of the present invention: Lipase (EC 3.1.1.3) Lipase AY “Amano” 30SD, Newlase F3G, Lipase DF “Amano” 15, Lipase MER “Amano” and Lipase MHA “Amano” 10SD, Lipase A “Amano” 12, Lipase G “Amano” 50, Lipase PS “Amano” SD, Lipase AY400 “Amano” SD-K, Lipase AK “Amano” were purchased from Amano Enzyme Inc., Nagoya, Japan. Lipozyme RM IM, Lipozyme Patalase 2000L, NovoCor ADL were purchased from Novozymes, Denmark); Alkaline protease (EC 3.4.21.62) and acid protease (EC 3.4.23.18) were purchased from Angel Yeast Co., Ltd., Yichang, China; Neutral protease (EC 3.4.24.4) and flavor protease (EC 3.4.11.1) were purchased from Sunhy Biology Co., Ltd., Wuhan, China; anhydrous milk fat (fat content ≥ 99.8%) was purchased from Ningxia Saishang Dairy Co., Ltd., Yinchuan, China; 0.1 mol / L sodium hydroxide standard titration solution and 0.5 mol / L hydrochloric acid standard titration solution were purchased from Sinopharm Chemical Reagent Co., Ltd., Shanghai, China.

[0036] Instruments used in the embodiments of the present invention: Headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC / MS, Thermo Trace 1310-ISQ LT type, Thermo Fisher Scientific, USA); High-pressure homogenizer (AH-2010 type, jointly developed by ATS NanoTech Co., Ltd., Suzhou, China and Duning Biotech Co., Ltd., Suzhou, China); High-speed shear disperser (T18 brushless digital type, IKA Werke GmbH&Co.KG, Germany); Analytical balance (XS105DU type, Mettler Toledo International Inc., Switzerland); Refrigerated centrifuge (Centrifuge 5811R type, Eppendorf AG, Germany); Multi-channel magnetic stirrer (SN-MS-6D type, Shanghai Shangpu Instrument Equipment Co., Ltd., Shanghai, China); Super constant temperature water bath (HS-601A type, Shenzhen Dingxinyi Experimental Equipment Co., Ltd., Shenzhen, China). The operation specifications of all equipment refer to the manufacturer's technical manual, and the key steps are verified through blank control and repeatability tests.

[0037] In the embodiments of the present invention, the detection method for volatile components adopts headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC / MS), specifically as follows:

[0038] ① Sample preparation: Take 5 mL of the sample, add 10 μL of 2-methyl-3-heptanone at 50 mg / L as the internal standard, and place it in a 20 ml headspace vial.

[0039] ② HS-SPME conditions: 50 / 30 μm DVB / CAR / PDMS extraction head, incubate at 50 °C for 5 min, extract for 40 min, and desorb for 60 s.

[0040] ③ GC conditions: DB-wax chromatographic column; injection temperature 230 °C; splitless; temperature program: hold at 40 °C for 1 min, ramp at 3 °C / min to 180 °C, then ramp at 20 °C / min to 230 °C, hold for 15 min.

[0041] MS conditions: EI, ion source temperature 260 °C, acquisition delay 2 min, mass range 29 - 350 amu, transfer line temperature 230 °C.

[0042] In the examples of the present invention, the sensory evaluation was carried out by a sensory evaluation panel composed of 10 professional sensory evaluators. The JAR sensory evaluation of the aroma of low-fat flavored milk was carried out, with a full score of 10 points. The scoring criteria were as follows: 9 - 10 points, strong milk flavor, no off-flavor; 7 - 9 points, relatively strong milk flavor, slightly off-flavor; 5 - 7 points, relatively light milk flavor or obvious off-flavor; 1 - 5 points, extremely light milk flavor or intolerable off-flavor.

[0043] Example 1

[0044] This example provides a method for preparing flavored low-fat milk, which includes the following steps:

[0045] (1) Preparation of lipase-hydrolyzed milk fat: Mix milk fat and water in a ratio of 2:1, pH 5.85, mechanically emulsify at 10000 rpm for 2 min, sterilize in a 70 °C water bath for 15 min, then add 0.2% lipase Newlase F3G, and carry out enzymatic hydrolysis treatment in a 25 °C water bath for 2 h. After the enzymatic hydrolysis is completed, immediately inactivate the enzyme in a 90 °C water bath for 15 min to terminate the reaction. Then, remove water by centrifugation to obtain lipase-hydrolyzed milk fat;

[0046] (2) Preparation of protease hydrolysate: Prepare a whey protein solution with a concentration of 20%, adjust the pH to 9.5 with sodium hydroxide or hydrochloric acid, then add 0.2% (based on whey protein) alkaline protease and mix evenly. Carry out enzymatic hydrolysis in a 45 °C water bath for 2.5 h. After the enzymatic hydrolysis is completed, immediately inactivate the enzyme in an 80 °C water bath for 15 min to terminate the reaction, and obtain the protease hydrolysate;

[0047] (3) Preparation of flavored milk fat: Transfer the lipase-hydrolyzed milk fat into a stoppered bottle with good sealing performance, dry heat treat in a 100 °C hot air oven for 1 h, and cool it sufficiently. Add 5% protease hydrolysate to the heat-treated lipase-hydrolyzed milk fat, mix evenly, mechanically emulsify at 5000 rpm for 2 min, and then centrifuge to remove the aqueous phase. The obtained oil phase is the flavored milk fat;

[0048] (4) Preparation of low-fat flavored milk: Mix and homogenize the flavored milk fat and skim milk, with an addition amount of 1.5 g / 100 g, a homogenization temperature of 50 °C, and a homogenization pressure of 24 MPa. After homogenization, obtain the stable-quality flavored low-fat milk.

[0049] Example 2

[0050] The difference between this example and Example 1 is that adding lipase Newlase F3G is replaced by adding lipase LipaseAY “Amano” 30SD, and the remaining steps are the same as those in Example 1.

[0051] Example 3

[0052] The difference between this example and Example 1 is that adding 0.2% lipase Newlase F3G and subjecting it to enzymatic hydrolysis treatment for 2 h in a 25°C water bath is replaced by adding 0.02% lipase LipaseMHA “Amano” 10SD and subjecting it to enzymatic hydrolysis treatment for 2 h in a 45°C water bath, and pH 5.85 is replaced by pH 7.4, and the remaining steps are the same as those in Example 1.

[0053] Example 4

[0054] The difference between this example and Example 1 is that adding 0.2% lipase Newlase F3G and subjecting it to enzymatic hydrolysis treatment for 2 h in a 25°C water bath is replaced by adding 0.02% lipase Lipase MER “Amano” and subjecting it to enzymatic hydrolysis treatment for 2 h in a 45°C water bath, and pH5.85 is replaced by pH 7.4, and the remaining steps are the same as those in Example 1.

[0055] Example 5

[0056] The difference between this example and Example 1 is that adding 0.2% lipase Newlase F3G and subjecting it to enzymatic hydrolysis treatment for 2 h in a 25°C water bath is replaced by adding 0.02% lipase LipaseDF “Amano” 15 and subjecting it to enzymatic hydrolysis treatment for 2 h in a 40°C water bath, and pH5.85 is replaced by pH 7.4, and the remaining steps are the same as those in Example 1.

[0057] Comparative Example 1

[0058] Commercially available whole milk, brand: Causeway Golden River.

[0059] Comparative Example 2

[0060] Commercially available skim milk, brand: Causeway Golden River.

[0061] Comparative Example 3

[0062] The difference between this comparative example and Example 1 is that low-fat milk is formulated using anhydrous milk fat without double enzymatic hydrolysis and heat treatment.

[0063] Comparative Example 4

[0064] The difference between this comparative example and Example 1 is that the alkaline protease in step (2) is replaced by an acidic protease, and the enzymatic hydrolysis pH is 3.14, and the remaining steps are the same as those in Example 1.

[0065] Comparative Example 5

[0066] The difference between this comparative example and Example 1 is that the whey protein in step (2) is replaced with soy protein isolate, and the remaining steps are the same as those in Example 1.

[0067] Comparative Example 6

[0068] The difference between this comparative example and Example 1 is that the Newlase F3G lipase in step (1) is replaced with TLIM lipase, and the remaining steps are the same as those in Example 1.

[0069] Comparative Example 7

[0070] The difference between this comparative example and Example 1 is that the Newlase F3G lipase in step (1) is replaced with TL IM lipase, and the alkaline protease in step (2) is replaced with acidic protease, and the remaining steps are the same as those in Example 1.

[0071] Comparative Example 8

[0072] The difference between this comparative example and Example 1 is that the Newlase F3G lipase in step (1) is replaced with TL IM lipase, and the whey protein in step (2) is replaced with soy protein isolate, and the remaining steps are the same as those in Example 1.

[0073] Sensory evaluation and electronic nose analysis were carried out on Examples 1 to 5 and Comparative Examples 1 to 3, and the results are as Figure 1 and Figure 3 shown. It can be seen that the flavor of all low-fat flavored milks has been improved, which is significantly better than skim milk and low-fat milk, and is close to whole milk. Among them, the low-fat flavored milk flavored by Newlase F3G lipase is very close to whole milk in sensory evaluation, and some sensory evaluators even gave evaluations better than whole milk, indicating that the low-fat milk prepared by the technology described in the present invention has a mellow and rich aroma, a strong milk flavor, and no off-flavors such as sour and putrid smells.

[0074] Sensory evaluation and electronic nose analysis were carried out on Example 1 and Comparative Examples 1, 4 to 8, and the results are as Figure 2 and Figure 4 shown. It can be seen that the flavor of Example 1 is significantly better than that of Comparative Examples 4 to 8. The results of sensory evaluation and electronic nose both show that the lipase, protease and protein substrate in steps (1) and (2) are optimized. The 9 enzymes mentioned in the present invention can significantly enhance the milk fat flavor. Combined with the whey protein hydrolysate under the action of alkaline protease, the obtained low-fat milk is highly similar to whole milk in flavor.

[0075] Volatile analysis was carried out on Example 1, Comparative Example 1, and Comparative Example 2. The results are shown in Table 1. The results indicate that a total of 20 main volatile components were detected in the low-fat flavored milk, 21 main volatile components were detected in the whole milk, and 11 main volatile components were detected in the skim milk. The number of main volatile components is close, indicating that the low-fat flavored milk prepared by the present invention is similar to the whole milk in terms of flavor richness. The total volatile content of the low-fat flavored milk is 184.82 μg / L, the total volatile content of the whole milk is 326.94 μg / L, and the total volatile content of the low-fat milk is 72.94 μg / L, indicating that the low-fat flavored milk prepared by the present invention can greatly improve the flavor of the skim milk and make it close to the whole milk. At the same time, from Table 1, we can see that the low-fat flavored milk is rich in key milk flavor substances such as acids and ketones, providing a rich and strong milk flavor. The results show that the volatile content and variety of the low-fat flavored milk prepared by the method of the present invention increase, making the milk flavor rich and mellow.

[0076] Table 1 Comparison of volatile compositions of different samples (content: μg / L)

[0077]

[0078]

[0079]

[0080] Example 6

[0081] The difference between this example and Example 2 is that the enzymatic hydrolysis temperatures are replaced with 25°C, 30°C, 35°C, 40°C, 45°C, and 50°C respectively, and the remaining steps are the same as those in Example 2.

[0082] The effects of different enzymatic hydrolysis temperatures on the lipolysis rate of lipase are shown in Table 2. The results indicate that the optimal enzymatic hydrolysis temperatures of lipases Lipase MHA “Amano” 10SD, Lipase MER “Amano”, Lipase AY “Amano” 30SD, Lipase DF “Amano” 15, and Newlase F 3G are 45°C, 45°C, 30°C, 40°C, and 25°C respectively. At their respective optimal enzymatic hydrolysis temperatures, lipases can carry out enzymatic hydrolysis under the most suitable conditions, with high hydrolysis efficiency and good flavor enhancement effect of the hydrolyzed milk fat.

[0083] Table 2 Effects of different enzymatic hydrolysis temperatures on the lipolysis rate of lipase

[0084]

[0085]

[0086] Example 7

[0087] The difference between this example and Example 2 is that the enzymatic hydrolysis times are replaced with 1 h, 2 h, 3 h, 4 h, and 5 h respectively, and the remaining steps are the same as those in Example 2.

[0088] The effects of different enzymatic hydrolysis times on the lipolysis rate of lipase and the JAR sensory score are shown in Table 3. It can be seen that as the enzymatic hydrolysis progresses, the milk fragrance enhances, yet off-flavors also gradually emerge. The principle of flavor enhancement by lipase is to hydrolyze and release the bound fatty acid flavor substances. However, the hydrolysis by lipase does not only hydrolyze the desired acid aroma substances, but also the undesired long-chain fatty acids will be hydrolyzed, forming off-flavors that are either acidic or bitter. Since the desired aroma substances are short- and medium-chain even-carbon fatty acids that tend to be distributed at the sn-1,3 positions of triglycerides, we select lipases with sn-1,3 specificity or a preference for short- and medium-chain fatty acids, which greatly avoids the generation of off-flavors at the source. However, the characteristics of acidic substances are inevitable. If the hydrolysis time is too long and the milk fat is hydrolyzed excessively, a strong and unpleasant sour taste will be produced. Therefore, an appropriate enzymatic hydrolysis time needs to be controlled. The experimental results show that it is appropriate to control the time within 1 - 2 h and it should not exceed 4 h.

[0089] Table 3 Effects of different enzymatic hydrolysis times on the lipolysis rate of lipase and the JAR sensory score

[0090]

[0091] Example 8

[0092] The difference between this example and Example 2 is that the addition amounts of the protease hydrolysis solution are replaced with 1%, 3%, 5%, 7%, and 9% respectively, and the remaining steps are the same as those in Example 2.

[0093] The effects of different addition amounts of the protease hydrolysis solution on the JAR sensory score of low-fat milk are shown in Table 4. It can be seen that the lipolysis of milk fat by lipase makes the milk fragrance rich, but due to the characteristics of the key aroma substance acids, there is still a weak sour taste. Therefore, the protease hydrolysis solution is used to improve the flavor. The taste peptides in the protease hydrolysis solution will have a synergistic effect with acidic substances, especially long-chain fatty acids, to eliminate off-flavors. The results show that the appropriate addition amount of the protease hydrolysis solution is 1 - 5%, and there is no additional flavor improvement effect when it exceeds 7%.

[0094] Table 4 Effects of different addition amounts of the protease hydrolysis solution on the JAR sensory score of low-fat milk

[0095]

[0096] Example 9

[0097] This example explores the effect of heat treatment on the improvement of milk fat flavor. It includes two groups of experiments. Anhydrous milk fat sample 1 is treated in a 90°C water bath for 15 minutes, and anhydrous milk fat sample 2 is treated in a 100°C oven for 1 hour. Then, low-fat flavored milk is prepared by the same method as in Example 1. The results of volatile analysis are shown in Table 5. The results indicate that the content and variety of volatiles in the sample heat-treated in a 100°C oven are significantly increased. In particular, ketones are more abundant, and 2-heptanone with a cheesy flavor characteristic is greatly increased, ultimately making the milk fragrance of low-fat dairy products more rich and mellow.

[0098] Table 5 Effects of Different Heat Treatment Conditions on the Improvement of Milk Fat Flavor (Content: μg / L)

[0099]

[0100]

[0101] It should be noted that the above examples are only used to illustrate the technical solutions of the present invention and are not restrictive. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the present invention.

Claims

1. A method for preparing a flavored low-fat milk, characterized in that: including, fully mixing milk fat and water, emulsifying and sterilizing, adding lipase and mixing evenly, stirring for lipase hydrolysis reaction, after the hydrolysis ends, heating to inactivate and centrifuging to obtain lipase-hydrolyzed milk fat; preparing a whey protein solution, adjusting the pH, adding protease and mixing evenly, stirring for protease hydrolysis reaction, after the hydrolysis ends, heating to inactivate to obtain protease hydrolysate; adding the protease hydrolysate to the heat-treated lipase-hydrolyzed milk fat, mixing evenly, emulsifying and then centrifuging to remove the aqueous phase, and the obtained oil phase is the flavor milk fat; mixing the flavor milk fat with skim milk, with the addition amount less than 1.5 g / 100 g, and homogenizing to obtain the flavor low-fat milk with stable quality.

2. The preparation method according to claim 1, characterized in that: The lipase is derived from various microorganisms, including Candida rugosa, Aspergilus oryzae, Aspergilus niger, Penicilium expansum, Pseudomonas fluorescens, Bacillus subtilis, Rhizomucor miehei, Candida antarctica.

3. The preparation method according to claim 2, characterized in that: The lipase includes Lipase AY "Amano” 30SD, Newlase F3G, Lipase DF "Amano” 15, Lipase MER "Amano”, Lipase MHA "Amano” 10SD, Lipase A "Amano” 12, Lipase G "Amano” 50, Lipozyme RM IM, Lipase PS "Amano” SD, Lipase AY400 "Amano” SD-K, Lipase AK "Amano”, Lipozyme Patalase 2000L, NovoCor ADL.

4. The preparation method according to claim 1, wherein: For the stirring for lipase hydrolysis reaction, the hydrolysis time is 1 - 4 h, the hydrolysis temperature is 25 - 45 °C, the enzyme addition amount is 0.02% - 0.2%, the oil-water ratio is (0.25 - 4):1, and the pH is 5.0 - 8.

0.

5. The preparation method according to claim 1, wherein: The protease includes alkaline protease, neutral protease and flavor protease.

6. The preparation method according to claim 1, characterized in that: For the protease hydrolysate, based on whey protein, the concentration of the protein solution is 15% - 25%, the enzyme addition amount is 0.1% - 0.5%, the hydrolysis temperature is 40 - 55 °C, and the hydrolysis time is 1 - 4 h.

7. The preparation method according to claim 1, characterized in that: For adding the protease hydrolysate to the heat-treated lipase-hydrolyzed milk fat, the heat treatment is dry heat treatment in an oven at 95 - 105 °C for 0.5 - 1.5 h.

8. The preparation method according to claim 7, characterized in that: The addition amount of the protease hydrolysate is 1% - 7% of the hydrolyzed milk fat.

9. The preparation method according to claim 1, characterized in that: For mixing the flavor milk fat with skim milk, the addition amount of the flavor milk fat is 0.5% - 1.5%, the homogenization temperature is 50 - 55 °C, and the homogenization pressure is 22 - 26 MPa.

10. Natural flavor cream and low-fat flavored milk prepared by the preparation method according to any one of claims 1 to 9.

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