JP6301628B2 - Milk and production method thereof - Google Patents

Description

  The present invention relates to heat-sterilized milk with good flavor and a method for producing the same.

  Milk is manufactured through heat sterilization from the viewpoint of hygiene, but it is known that these foods are susceptible to chemical changes in various components due to heat sterilization, and the flavor deteriorates due to these changes. Yes. On the other hand, it is known that various flavors change due to heat sterilization, thereby providing a desirable flavor.

  In general, heat sterilization of milk is carried out according to the “Ministerial Ordinance on Component Standards of Milk and Dairy Products” based on the Food Sanitation Law. In addition to LTLT sterilization (low-temperature sterilization method: 63 ° C. to 65 ° C., 30 minutes or more), HTST sterilization (high temperature short time sterilization method: 72 ° C. to 72 ° C.) 78 ° C. for 15 seconds or more) or UHT sterilization (ultra-high temperature sterilization method: 120 ° C. to 150 ° C., 1 to 3 seconds).

  One of the causes of flavor deterioration due to heat sterilization of milk is the generation of sulfides. It is known that HTST sterilization, which has a lower heating temperature than UHT sterilization, is more suitable for suppressing the formation of sulfides by heat sterilization. The special milk-derived richness cannot be imparted. Therefore, as a method for improving the flavor of heat-sterilized milk, efforts have been made exclusively to suppress the formation of sulfides in UHT sterilization.

  For example, when producing milk, the raw milk is replaced with an inert gas such as nitrogen gas before heat sterilization, thereby reducing the dissolved oxygen in the solution, thereby generating sulfides by UHT sterilization. There exists a method of suppressing (patent document 1). In addition, there is a method of suppressing the growth of harmful microorganisms by reducing the dissolved oxygen in the raw milk by aeration and stirring of nitrogen gas when storing the raw milk (Patent Document 2).

Patent No. 3083798 JP-A-5-49395

  Although it is possible to suppress the formation of sulfides by lowering the dissolved oxygen in the raw milk before and after heat sterilization by UHT sterilization, the content of sulfides in the milk obtained is compared with the case of HTST sterilization. It could not be lowered.

  The present invention solves the problems as described above, and has a good flavor derived from milk equivalent to that of UHT-sterilized milk even though the content of sulfides is lower than that of HTST-sterilized milk. The issue is to provide milk.

The milk of the present invention is characterized in that, as sulfides, the content of dimethyl sulfide (DMS) is 7 ppm or less, the content of dimethylsulfone (DMSO ₂ ) is 1100 ppm or less, and the content of lactones is 35 ppm or more. And
Furthermore, in the method for producing milk of the present invention, raw milk as raw material milk is homogenized and then separated into cream and skim milk by centrifugation, and the resulting cream is UHT sterilized. And after heat-sterilized cream and skim milk are mixed and homogenized, HTST sterilization is performed.

  ADVANTAGE OF THE INVENTION According to this invention, milk with favorable flavor to which the richness derived from milk equivalent to the milk content which has a low sulfide content compared with the milk which UHT sterilized is provided is obtained.

The graph which shows the relationship between the median diameter of the fat globule of the milk of the Example and comparative example of this invention, and the casein / whey protein amount ratio in a fat globule membrane.

Hereinafter, the present invention will be described in more detail.
In the present invention, milk refers to milk, processed milk, milk beverages and the like obtained from raw milk as a raw material through a heat sterilization process.
The sulfides contained in milk are components that cause odors generally expressed as heated odors, and examples thereof include dimethyl sulfide and dimethyl sulfone. Lactones are components relating to the richness of milk derived from UHT pasteurized milk, and examples include deltadecalactone and deltadodecalactone.

  The milk of the present invention can impart high emulsification stability to the cream after the cream separation step by going through the step of homogenizing the raw milk, and even if the cream is subjected to UHT sterilization treatment, sulfides are generated. The richness derived from the milk peculiar to UHT pasteurized milk can be provided, suppressing this. And after mixing the pasteurized cream with skim milk, HTST pasteurization can suppress the production | generation of sulfides, providing the richness derived from milk equivalent to UHT pasteurized milk. Here, when the cream is separated without homogenizing the raw milk, the generation of sulfides cannot be suppressed even if the cream is sterilized by UHT. Therefore, when HTST pasteurization is performed after mixing such pasteurized cream and skim milk, the content of sulfides in the resulting milk can be equivalent to HTST pasteurized milk, but lower than that. It is not possible.

In the step of homogenizing raw material milk, in order to make the median diameter of fat globules preferably 3.0 μm or less, more preferably 2.5 μm or less, the raw material milk is heated to a predetermined homogenization temperature, Homogenize using a homogenizer. A plate type heat exchanger, a batch type heating machine, etc. can be used for heating raw material milk. In view of the efficiency of heating raw material milk, it is preferable to use a plate heat exchanger. For homogenization, a homogenizer such as a homogenizer, a microfluidizer, a colloid mill, or the like can be used. A homogenizer is preferably used in terms of the homogenization efficiency of raw material milk and the ability of processing amount, and among them, a two-stage homogenizer is preferably used.
What is necessary is just to change a homogenization pressure suitably with the difference in manufacturing conditions, such as the kind of homogenizer, the processing flow rate of raw material milk, the shape of a homobubble, and the homogenization temperature. The higher the homogenization pressure at the time of the homogenization, the more the generation of sulfides in milk can be suppressed. However, the higher the homogenization pressure, the less the production of lactones, so the homogenization pressure should be 10 MPa or less. Is preferable, and 2 MPa to 5 MPa is more preferable.

  The technique for separating the cream and the technique for sterilizing the cream may be appropriately performed using known techniques. For example, a disk-type centrifuge or the like can be used in the cream separation step. Moreover, in a cream sterilization process, it is preferable to use the conditions for 120-150 degreeC and 1-3 seconds among the range of the conditions of UHT sterilization method.

  After sterilizing the cream separated from the raw milk, the method of mixing the cream and skim milk may be performed using a known method as appropriate, and the sterilized cream and skim milk may be fed into the tank at an arbitrary ratio. That's fine.

In the step of homogenizing the mixed solution of sterilized cream and skim milk, the mixed solution can be heated to a predetermined homogenization temperature and then homogenized using a homogenizer. For heating the mixed solution, a plate-type heat exchanger, batch-type heater, etc. can be used as in the case of heating raw material milk. In terms of heating efficiency of the mixed solution, a plate-type heat exchanger should be used. Is preferred. For homogenization, as in the case of raw milk, in addition to homogenizers such as homogenizers, microfluidizers, colloid mills, etc. can be used, and in terms of homogenization efficiency and throughput of raw milk It is preferable to use a homogenizer, and among these, it is preferable to use a two-stage homogenizer.
What is necessary is just to change a homogenization pressure suitably with the difference in manufacturing conditions, such as the kind of homogenizer, the processing flow rate of raw material milk, the shape of a homobubble, and the homogenization temperature.

  Examples of the present invention and test examples will be described below, but the present invention is not limited thereto.

  The raw milk heated to 60 ° C. was homogenized by passing it through a homogenizer without applying homogeneous pressure, and then a cream with a fat percentage of 45% was separated by a centrifuge. The obtained cream was passed through a plate type sterilizer and sterilized within the range of UHT sterilization (120 ° C., 3 seconds). And after plate-cooling to about 5 degreeC, the pasteurized cream was mixed with skim milk, and it heated to 60 degreeC, Then, it homogenized by the homogeneous pressure 15.0MPa. Then, the liquid mixture of cream and skim milk was passed through a plate type sterilizer and sterilized within the range of HTST sterilization (75 ° C., 15 seconds). The obtained milk was cooled to about 5 ° C. with a plate cooler and stored at 5 ° C. (Example product 1).

  The raw milk heated to 60 ° C. was homogenized at a homogeneous pressure of 1.0 MPa, and then a cream with a fat percentage of 45% was separated by a centrifuge. The obtained cream was passed through a plate type sterilizer and sterilized within the range of UHT sterilization (120 ° C., 3 seconds). And after plate-cooling to about 5 degreeC, the pasteurized cream was mixed with skim milk, and it heated to 60 degreeC, Then, it homogenized by the homogeneous pressure 15.0MPa. Then, the liquid mixture of cream and skim milk was passed through a plate type sterilizer and sterilized within the range of HTST sterilization (75 ° C., 15 seconds). The obtained milk was cooled to about 5 ° C. with a plate cooler and stored at 5 ° C. (Example product 2).

  The raw milk heated to 60 ° C. was homogenized at a homogeneous pressure of 2.0 MPa, and then a cream with a fat percentage of 45% was separated by a centrifuge. The obtained cream was passed through a plate type sterilizer and sterilized within the range of UHT sterilization (120 ° C., 3 seconds). And after plate-cooling to about 5 degreeC, the pasteurized cream was mixed with skim milk, and it heated to 60 degreeC, Then, it homogenized by the homogeneous pressure 15.0MPa. Then, the liquid mixture of cream and skim milk was passed through a plate type sterilizer and sterilized within the range of HTST sterilization (75 ° C., 15 seconds). The obtained milk was cooled to about 5 ° C. with a plate cooler and stored at 5 ° C. (Example product 3).

  The raw milk heated to 60 ° C. was homogenized at a homogeneous pressure of 5.0 MPa, and then a cream with a fat percentage of 45% was separated by a centrifuge. The obtained cream was passed through a plate type sterilizer and sterilized within the range of UHT sterilization (120 ° C., 3 seconds). And after plate-cooling to about 5 degreeC, the pasteurized cream was mixed with skim milk, and it heated to 60 degreeC, Then, it homogenized by the homogeneous pressure 15.0MPa. Then, the liquid mixture of cream and skim milk was passed through a plate type sterilizer and sterilized within the range of HTST sterilization (75 ° C., 15 seconds). The obtained milk was cooled to 5 ° C. with a plate cooler and stored at 5 ° C. (Example product 4).

  The raw milk heated to 60 ° C. was homogenized at a homogeneous pressure of 10.0 MPa, and then a cream with a fat percentage of 45% was separated by a centrifuge. The obtained cream was passed through a plate type sterilizer and sterilized within the range of UHT sterilization (120 ° C., 3 seconds). And after plate-cooling to about 5 degreeC, the pasteurized cream was mixed with skim milk, and it heated to 60 degreeC, Then, it homogenized by the homogeneous pressure 15.0MPa. Then, the liquid mixture of cream and skim milk was passed through a plate type sterilizer and sterilized within the range of HTST sterilization (75 ° C., 15 seconds). The obtained milk was cooled to 5 ° C. with a plate cooler and stored at 5 ° C. (Example product 5).

[Comparative Example 1]
In order to confirm the effect of homogenization before separating the cream from the raw milk, the milk with a fat percentage of 45% is separated by a centrifuge without homogenizing the raw milk heated to 60 ° C. did. Subsequent steps are the same as those in Examples 1 to 5. First, the obtained cream was passed through a plate sterilizer and sterilized within the range of UHT sterilization (120 ° C., 3 seconds). And after plate-cooling to about 5 degreeC, the pasteurized cream was mixed with skim milk, and it heated to 60 degreeC, Then, it homogenized by the homogeneous pressure 15.0MPa. Then, the liquid mixture of cream and skim milk was passed through a plate type sterilizer and sterilized within the range of HTST sterilization (75 ° C., 15 seconds). The obtained milk was cooled to 5 ° C. with a plate cooler and stored at 5 ° C. (Comparative Product 1).

[Comparative Example 2]
In order to confirm the effect of homogenization before separating the cream from the raw milk, the milk with a fat percentage of 45% is separated by a centrifuge without homogenizing the raw milk heated to 60 ° C. did. The separated cream was homogenized at a uniform pressure of 1.0 MPa, passed through a plate sterilizer, and sterilized within the range of UHT sterilization (120 ° C., 3 seconds). And after plate-cooling to about 5 degreeC, the pasteurized cream was mixed with skim milk, and it heated to 60 degreeC, Then, it homogenized by the homogeneous pressure 15.0MPa. Then, the liquid mixture of cream and skim milk was passed through a plate type sterilizer and sterilized within the range of HTST sterilization (75 ° C., 15 seconds). The obtained milk was cooled to 5 ° C. with a plate cooler and stored at 5 ° C. (Comparative Example Product 2).

[Comparative Example 3]
In order to confirm the effect of homogenization before separating the cream from the raw milk, the milk with a fat percentage of 45% is separated by a centrifuge without homogenizing the raw milk heated to 60 ° C. did. The separated cream was homogenized at a homogeneous pressure of 2.0 MPa, passed through a plate sterilizer, and sterilized within the range of UHT sterilization (120 ° C., 3 seconds). And after plate-cooling to about 5 degreeC, the pasteurized cream was mixed with skim milk, and it heated to 60 degreeC, Then, it homogenized by the homogeneous pressure 15.0MPa. Then, the liquid mixture of cream and skim milk was passed through a plate type sterilizer and sterilized within the range of HTST sterilization (75 ° C., 15 seconds). The obtained milk was cooled to 5 ° C. with a plate type cooler and stored at 5 ° C. (Comparative Product 3).

[Comparative Example 4]
In order to confirm the effect of homogenization before separating the cream from the raw milk, the milk with a fat percentage of 45% is separated by a centrifuge without homogenizing the raw milk heated to 60 ° C. did. The obtained cream was passed through a plate type sterilizer and sterilized within the range of UHT sterilization (120 ° C., 3 seconds). Thereafter, the UHT sterilized cream is homogenized at a uniform pressure of 1.0 MPa and then cooled to about 5 ° C., then the sterilized cream is mixed with skim milk, heated to 60 ° C., and then the homogeneous pressure of 15. Homogenized at 0 MPa. Then, the liquid mixture of cream and skim milk was passed through a plate type sterilizer and sterilized within the range of HTST sterilization (75 ° C., 15 seconds). The obtained milk was cooled to 5 ° C. with a plate cooler and stored at 5 ° C. (Comparative Product 4).

[Comparative Example 5]
In order to confirm the effect of homogenization before separating the cream from the raw milk, the milk with a fat percentage of 45% is separated by a centrifuge without homogenizing the raw milk heated to 60 ° C. did. The obtained cream was passed through a plate type sterilizer and sterilized within the range of UHT sterilization (120 ° C., 3 seconds). Thereafter, the UHT sterilized cream is homogenized at a homogeneous pressure of 2.0 MPa and then cooled to about 5 ° C., then the sterilized cream is mixed with skim milk, heated to 60 ° C., and then the homogeneous pressure of 15. Homogenized at 0 MPa. Then, the liquid mixture of cream and skim milk was passed through a plate type sterilizer and sterilized within the range of HTST sterilization (75 ° C., 15 seconds). The obtained milk was cooled to 5 ° C. with a plate cooler and stored at 5 ° C. (Comparative Product 5).

[Comparative Example 6]
In order to confirm the effect of homogenization before separating the cream from the raw milk, the milk with a fat percentage of 45% is separated by a centrifuge without homogenizing the raw milk heated to 60 ° C. did. The separated cream was homogenized at a homogeneous pressure of 1.0 MPa, then passed through a plate sterilizer, and sterilized within the range of UHT sterilization (120 ° C., 3 seconds). Thereafter, the UHT sterilized cream is homogenized again at a homogeneous pressure of 1.0 MPa and then cooled to about 5 ° C., then the sterilized cream is mixed with skim milk, heated to 60 ° C. and then heated to a homogeneous pressure of 15 Homogeneous treatment at 0.0 MPa. Then, the liquid mixture of cream and skim milk was passed through a plate type sterilizer and sterilized within the range of HTST sterilization (75 ° C., 15 seconds). The obtained milk was cooled to 5 ° C. with a plate cooler and stored at 5 ° C. (Comparative Product 6).

[Comparative Example 7]
In order to obtain general UHT pasteurized milk, raw milk heated to 60 ° C. is homogenized at a homogeneous pressure of 15.0 MPa, passed through a plate type sterilizer, and within the range of UHT sterilization (120 ° C., 3 ° C. For 2 seconds). After sterilization, the plate was cooled to about 5 ° C. and stored at 5 ° C. (Comparative Example Product 7).

[Comparative Example 8]
In order to obtain general HTST sterilized milk, raw milk heated to 60 ° C. is homogenized at a homogeneous pressure of 15.0 MPa, passed through a plate type sterilizer, and within the range of HTST sterilization (75 ° C., 15 For 2 seconds). After sterilization, the plate was cooled to about 5 ° C. and stored at 5 ° C. (Comparative Example Product 8).

(Test Example 1)
Sensory evaluation was implemented about Example goods 1-5, comparative example goods 1-7, and five commercial milk items (reference examples 1-5) prepared by various sterilization methods. The sensory evaluation was scored by a panel of 15 people, with a score of 10 out of 10 for hot odor and milk-derived body. High points were given to those with little heated odor (those with suppressed heating odor) and those with a strong feeling of milk-derived body, and the average value was calculated from the obtained points.
Table 1 shows the results of sensory evaluation on the suppression of heated odor and the imparting of a rich feeling to milk for Example Products 1 to 5, Comparative Product 1 to 7, and Reference Examples 1 to 5.

As shown in Table 1, Example products 1 to 5 have less heating odor than general HTST pasteurized milk (Comparative Example product 8), and general UHT pasteurized milk (Comparative Example product 7) In comparison, the richness of the milk was shown to be equivalent.
In milk (comparative product 1), the raw milk is separated into cream and skim milk without homogenization, HTST sterilized by mixing UHT sterilized cream and non-sterilized skim milk. The richness was equivalent to general UHT pasteurized milk (Comparative Example 7). On the other hand, although the suppression effect of a heating odor is comparable with general HTST pasteurized milk (comparative example product 8), the suppression effect is not enough compared with the example products 1-5.
Furthermore, the raw milk is separated into cream and skim milk without homogenization, and the cream is homogenized before or after UHT sterilization, and then UHT sterilized cream and non-sterilized skim milk are mixed. In milk (Comparative Examples 2 to 6) mixed and HTST-sterilized, the richness of milk was equivalent to that of general UHT pasteurized milk (Comparative Example Product 7). On the other hand, the effect of suppressing heated odor was inferior to that of general HTST pasteurized milk (Comparative Product 8).
As a result of similarly evaluating commercially available milk as Reference Examples 1 to 5, there was no milk that achieved both suppression of a heated odor and imparted a rich milk feeling as in Examples 1 to 5.

(Test Example 2)
About Example goods 1-5, comparative example goods 1-8, and reference examples 1-5, the aroma component was measured. The aroma component analysis was carried out by FEDHS (Full Evaporation Dynamic Headspace) -GC-MS method.
To 10 g of each sample, 0.2 mL of an aqueous 5-methyl-2-hexane solution diluted to 50 μg / mL as an internal standard sample was added. After mixing well, 0.1 g was taken in a 10 mL vial, sealed with nitrogen and set in a tray set at 4 ° C. Purging was performed with DHS (manufactured by Gester) at a flow rate of 100 mL / min and 3000 mL of nitrogen at 80 ° C., and the aromatic component was adsorbed to tenax as an adsorbent. For GC-MS, Agilent 6890 (GC) and 5973 (MS) (manufactured by Agilent Technologies) were used.
Table 2 shows the results of analyzing the aroma components of Example Products 1 to 4, Comparative Example Products 1 to 8, and Reference Examples 1 to 5.

The results shown in Table 2 show the same tendency as the results of the sensory test shown in Table 1. When the contents of each DMS and DMSO ₂ are compared, the production of both compounds is suppressed in Examples 1 to 5 as compared with general HTST pasteurized milk (Comparative Example 8). In addition, compared with general UHT pasteurized milk (Comparative Example Product 7), the milks of Example Products 1 to 5 are equivalent to or higher in the production of lactones involved in the richness of milk and have a high content. Met.
In milk (comparative product 1), the raw milk is separated inhomogeneously and mixed with UHT sterilized cream and untreated skim milk, and HTST sterilized, so the content of lactones is generally UHT sterilized milk. Although the concentration was higher than that of (Comparative Example Product 7), both the contents of DMS and DMSO ₂ were higher than those of general HTST pasteurized milk (Comparative Example Product 8). It can be seen that the suppression effect is not sufficient.
Furthermore, the raw milk is separated into cream and skim milk without homogenization, and the cream is homogenized before or after UHT sterilization, and then UHT sterilized cream and non-sterilized skim milk are mixed. In milk mixed with HTST and sterilized with HTST (Comparative Examples 2 to 6), the production of lactones was equivalent to that of general UHT sterilized milk (Comparative Example Product 7). On the other hand, the effect of suppressing heated odor was inferior to that of general HTST pasteurized milk (Comparative Product 8).
As a result of similarly evaluating commercially available milk as Reference Examples 1 to 5, there was no milk that achieved both the suppression of DMS and DMSO ₂ and the generation of lactones as in Examples 1 to 5.
Moreover, when each Example product of Example products 1-5 is compared, there exists a tendency for the production | generation suppression effect of a sulfide to become high, so that the homogeneous pressure in the homogeneous process of raw material milk becomes high. On the other hand, the production of lactones tends to decrease as the homogeneous pressure increases. For this reason, the homogeneous pressure in the homogeneous treatment of raw material milk is preferably 2.0 to 5.0 MPa.

(Test Example 3)
In the production process of Examples 1 to 7 and Comparative Examples 1 to 6, the median diameter of fat globules was measured for the cream subjected to UHT sterilization before mixing with skim milk. Moreover, the protein composition analysis of the fat globule membrane was performed, and the casein / whey protein ratio in the fat globule membrane was calculated.
A laser diffraction particle size distribution analyzer (SALD-3100, Shimadzu Corporation) was used to measure the median diameter of fat globules. The cream was diluted to a measurable concentration with ion exchange water and measured at room temperature.
The protein composition analysis of the fat globule membrane was performed by the following method.
150g of cream of each level is diluted with 250g of ultrapure water, centrifuged at 2500rpm, 5 ° C for 20 minutes, and the lower aqueous layer is discarded. The remaining cream layer is diluted with 300 g of ultrapure water, centrifuged again, and the lower layer is discarded. This operation is further repeated twice to recover the cream layer. 15 g of hexane was added to 25 g of the recovered cream layer and mixed, and then centrifuged at 1000 rpm, 25 ° C. for 5 minutes, and the lipid in the cream layer was removed together with the upper hexane to prepare a sample.
10 g of the obtained sample was centrifuged and concentrated at 15000 rpm, 5 ° C. for 30 minutes using Amicon Ultra Ultrace-3K. 4 g of the concentrated sample was accurately weighed, and 5000 μl of 0.1 MBisTris buffer (pH 6.8) containing 5.37 mM Na citrate and 6 M guanidine hydrochloride and 300 μl of 1MDTT were added and mixed to solubilize the sample. After adjusting the pH to 8.2 with 1N-NaOH, distilled water was added to adjust the volume to 10 ml. Of this, 1 ml was collected in a 1.5 ml microtube, heated in boiling water for 3 minutes, and allowed to cool to room temperature. 300 μl of this was mixed with 900 μl of diluent and subjected to high performance liquid chromatography (HPLC). The diluted solution composition was used by dissolving guanidine hydrochloride in a mobile phase A described below to a final concentration of 4.5M. A high performance liquid chromatography apparatus was used by connecting a PDA detector (L7490, manufactured by Hitachi High-Technologies Corporation) to ELITE Lachrom (L2000, manufactured by Hitachi High-Technologies Corporation). As the column, an ODS-3 column (diameter: 4.6 mm × length: 250 mm, manufactured by GL Sciences Inc.) was used. Sample injection volume was 40 μl, column temperature was 25 ° C., flow rate was 1.2 ml / min, and detection was performed at 220 nm. The mobile phase was acetonitrile / water containing 0.1% TFA = 1/9 (mobile phase A), acetonitrile / water containing 0.1% TFA = 9/1 (mobile phase B), and the ratio of mobile phase B was started 27% To 4% after 32 minutes, 34% after 12 minutes, 36.5% after 17 minutes, 39% after 35 minutes, 43.5% after 50 minutes, and 80% after 52 minutes. It was.
Each eluted peak was identified from the elution position of the sample (Sigma Aldrich). For α-lactalbumin, β-lactoglobulin, and κ-casein, each mass was calculated from the peak area value using a calibration curve obtained from each sample. For α-casein and β-casein, the value obtained by subtracting the mass of the aforementioned α-lactalbumin, β-lactoglobulin, and κ-casein from the total protein amount of the sample subjected to HPLC is α-casein and β-casein. The total mass of From the ratio of the total mass of α-lactalbumin and β-lactoglobulin obtained and the total mass of αs ₁ -casein, αs ₂ -casein, β-casein, and κ-casein, the mass ratio of casein to whey protein (Casein / whey protein ratio) was calculated.
Table 3 shows the results of analyzing the fat globule diameter and the casein / whey protein ratio in the fat globule membrane for Examples 1 to 5 and Comparative Examples 1 to 6.

FIG. 1 shows a graph in which the data shown in the results of Table 3 are plotted.
As shown in the graph of FIG. 1, when the median diameter of fat globules is taken on the horizontal axis and the casein / whey protein amount ratio in the fat globule membrane is taken on the vertical axis, Examples 1 to 5 and Comparative Examples 1 to 5 are used. The cream after UHT sterilization before mixing with skim milk in the manufacturing process is distributed in different regions. In order to obtain milk such as Examples 1 to 5, in the graph of FIG. 1, the median diameter of fat globules is 3.0 μm and the casein / whey protein amount ratio in the fat globule membrane is 1.9. And the cream in the area below the straight line connecting the point where the median diameter of fat globule is 1.3 μm and the casein / whey protein ratio in the fat globule membrane is 5.4 are mixed with skim milk There is a need. Here, if the casein / whey protein amount ratio in the fat globule membrane is Y and the median diameter (μm) of the fat globule is X, the relationship between Y and X is approximated by the following formula (1) from the results of Table 3. Is done. Therefore, before mixing the cream after UHT sterilization with skim milk, by adjusting the relationship between Y and X in the cream so as to satisfy the formula (2), milk as in Examples 1 to 5 Can be obtained.
Y = -2X + 8 (Formula 1)
Y ≦ −2X + 8 (Formula 2)

  Like comparative example products 1-6, the cream prepared without homogenization with raw milk does not satisfy the condition of formula (2), and the dissociation from formula (1) is large. Compared to 5, sufficient heating odor control effect cannot be obtained.

Claims (7)

Milk having a dimethyl sulfide (DMS) content of 7 ppm or less, a dimethylsulfone (DMSO ₂ ) content of 1100 ppm or less, and a lactone content of 35 ppm or more. A first homogenization step for homogeneously processing raw milk;
Separating the homogenized raw milk into cream and skim milk;
A first sterilization step of sterilizing the separated cream by UHT sterilization method, a mixing step of mixing the sterilized cream and the separated skim milk,
A second homogenization step of homogenizing the mixed cream and skim milk;
A second sterilization step of sterilizing the mixed cream and skim milk by HTST sterilization after the second homogenization step ;
The produced milk has a dimethyl sulfide (DMS) content of 7 ppm or less, a dimethyl sulfone (DMSO ₂ ) content of 1100 ppm or less, and a lactone content of 35 ppm or more,
A method for producing milk characterized by the above.   The relationship between the median diameter of the fat globules in the cream after the first sterilization step and the casein / whey protein amount ratio Y in the fat globule membrane and the median diameter X (μm) of the fat globules satisfies Y ≦ −2X + 8. The manufacturing method according to claim 2, wherein the manufacturing method is characterized.   The manufacturing method according to claim 2, wherein the homogeneous pressure in the first homogenizing step is 10 MPa or less.   The manufacturing method according to claim 4, wherein the homogeneous pressure in the first homogenizing step is 2 MPa to 5 MPa.   The method according to any one of claims 2 to 5, wherein the sterilization conditions of the first sterilization step are 120 ° C to 135 ° C for 1 to 3 seconds.   The sterilization conditions in the second sterilization step are 72 ° C to 78 ° C for 15 seconds or longer, and the manufacturing method according to any one of claims 2 to 6.

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