Sterilized dairy product and method for producing the same

Abstract

The present invention relates to a technique for stably providing a sterilized dairy product that excellently retains both a rich feeling and a refreshing feeling. More specifically, the present invention relates to a sterilized dairy product that satisfies (A) and at least one selected from (B) to (D).　(A) The concentration of dimethyl sulfide is 27-63 ppb. (B) The concentration of hexanal is 3.2 ppb or lower. (C) The concentration of δ-decalactone is 112-140 ppb. (D) The concentration of δ-dodecalactone is 1,290-2,300 ppb.

Description

Pasteurized dairy products and their manufacturing methods REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims priority based on Japanese Patent Application No. 2024-017437, filed on February 7, 2024, the entire disclosure of which is incorporated herein by reference.

[0002] The present invention relates to a pasteurized dairy product and a method for producing the same.

[0003] When foods are provided as final products for long-term storage, they are typically sterilized by heat. However, heat sterilization can affect the color and aroma of heat-sensitive food ingredients, reduce functional nutritional components, and even degrade the original flavor of the food ingredients. Therefore, new sterilization techniques that cause less thermal degradation than conventional methods are being investigated in order to provide higher quality products while maintaining food safety.

[0004] Common heating methods for sterilizing dairy raw materials include indirect heating methods (plate type, tube type, scraper type, etc.) and direct heating methods (steam injection type, steam infusion type, etc.).

[0005] It is generally known that with the indirect heating method, when using high-protein dairy ingredients (such as liquid foods and pre-spray dried formula), the heating time is long, the heating surface can burn, and long-term operation is difficult.

[0006] In addition, the direct heating method is less likely to burn, even with high-protein dairy ingredients, and can operate for long periods of time, but because water is added as steam, it cannot be used for milk, which is prohibited by law from being watered.Furthermore, with the direct heating method, the added steam is removed under reduced pressure, which also causes the loss of aroma components.

[0007] Furthermore, internal heating methods (Joule heating, AC high electric field, etc.) are commonly used to sterilize tomato puree, lemon juice, etc. Internal heating methods are less likely to burn than indirect heating methods because they do not have a heating surface, and they also have the advantage of not losing aroma components like direct heating methods, so in recent years their use for foods containing dairy proteins has been considered.

[0008] For example, Patent Document 1 discloses a sterilization method for suppressing or preventing the occurrence of precipitation in liquid foods containing dairy proteins, characterized in that the liquid food containing dairy proteins is continuously passed through an electricity-carrying unit having an electrode structure in which an insulator is sandwiched between metal flat electrodes, and to which a voltage is applied by an AC power source connected to the electrodes in a closed system, and is subjected to an AC high electric field treatment under conditions of a linear speed of 0.6 m / s or more and a temperature rise rate of 800 to 2000°C / s.

[0009] Furthermore, Patent Document 2 discloses a method for preventing scale formation on electrode surfaces during continuous electrical heating, in which power is supplied from a pair of output terminals of a power supply device that generates an AC voltage to at least a pair of electrodes exposed to a flow path through which a fluid food material such as milk is continuously transported, and the food material is continuously electrically heated in the flow path, wherein an electrical resistor having a predetermined electrical resistance is inserted between one of the pair of output terminals of the power supply device and one of the pair of electrodes, and electrical heating is performed by supplying power to the electrodes.

[0010] In addition, Patent Document 3 discloses a method for producing a heated milk-containing processed product by the present applicant, which comprises adjusting a milk raw material in a flow path to become a fluid selected from a turbulent fluid, a transition fluid, and a combination thereof, and subjecting the fluid to Joule heating treatment in the flow path.

[0011] JP 2010-268756 A JP 2010-023966 A JP 2019-054732 A

[0012] In dairy products such as pasteurized milk, it is desirable for them to have both a rich flavor (also called "fullness") and a refreshing beverage flavor (also called "refreshing flavor") even after the pasteurization process in order to stimulate consumer demand. However, the applicant's studies have revealed that it is difficult to maintain both the rich flavor and the refreshing flavor in pasteurized dairy products in a good and stable manner using any of the conventional heating methods. Therefore, the applicant has conducted further intensive studies and found that treating milk raw materials with a combination of heating methods under specific conditions can allow pasteurized dairy products to maintain both the rich flavor and the refreshing flavor in a good and stable manner.

[0013] Therefore, one object of the present invention is to stably provide a sterilized dairy product that maintains both a rich taste and a refreshing taste.

[0014] According to one embodiment of the present invention, there is provided a pasteurized dairy product that satisfies the following (A) and at least one selected from (B) to (D): (A) the concentration of dimethyl sulfide is 27 to 63 ppb, (B) the concentration of hexanal is 3.2 ppb or less, (C) the concentration of δ-decalactone is 112 to 140 ppb, and (D) the concentration of δ-dodecalactone is 1,290 to 2,300 ppb.

[0015] According to another embodiment of the present invention, there is provided a method for producing a sterilized dairy product, comprising: a first heating step of heat-treating a dairy raw material at 95 to 125°C by indirect heating; and a second heating step of Joule-heating the heated dairy raw material obtained in the first heating step at 125 to 150°C.

[0016] According to another embodiment of the present invention, there is provided a method for maintaining a rich taste and a refreshing taste in a sterilized dairy product, the method comprising: a first heating step of heat-treating a dairy raw material at 95 to 125°C by an indirect heating method; and a second heating step of Joule-heating the heated dairy raw material obtained in the first heating step at 125 to 150°C.

[0017] According to the present invention, it is possible to stably provide pasteurized dairy products that maintain both a rich taste and a refreshing taste. The stable and efficient provision of pasteurized dairy products that meet consumer demand by combining specific methods without using new equipment, as in the present invention, is thought to lead to a reduction in environmental burden and also contribute to the achievement of the SDGs (Sustainable Development Goals).

[0018] The results of quantitative analysis of dimethyl sulfide (DMS) in pasteurized milk in Test Example 1 are shown. In Test Example 2, the cooling energy amounts per unit area were 412, 3,463, and 5,374 kcal / (m ２ 1 shows the results of quantitative analysis of dimethyl disulfide (DMDS) for pasteurized milk that has been cooled by the method (h). In Test Example 5, the results of quantitative analysis of DMS for pasteurized and cooled milk are shown. In Test Example 5, the results of quantitative analysis of DMDS for pasteurized and cooled milk are shown. In Test Example 5, the results of quantitative analysis of δ-decalactone for pasteurized and cooled milk are shown. In Test Example 5, the results of quantitative analysis of δ-dodecalactone for pasteurized and cooled milk are shown.

[0019] <Definition> In this specification, the term "sterilized dairy product" refers to a dairy product obtained by heat-treating a dairy raw material.

[0020] In this specification, "Joule heating" refers to one of the internal heating methods known as electrical heating, which means a method of heating an object by passing electricity directly through the object and using heat (Joule heat) generated by the object's electrical resistance.

[0021] <Pasteurized Dairy Product> According to one embodiment of the present invention, a pasteurized dairy product satisfies the following (A) and at least one selected from (B) to (D): (A) the concentration of dimethyl sulfide is 27 to 63 ppb, (B) the concentration of hexanal is 3.2 ppb or less, (C) the concentration of δ-decalactone is 112 to 140 ppb, and (D) the concentration of δ-dodecalactone is 1,290 to 2,300 ppb.

[0022] According to a preferred embodiment of the present invention, the sterilized dairy product has a concentration of (E) dimethyl disulfide of 0.56 to 0.72 ppb. Adjusting (A) to (E) in the sterilized dairy product to fall within the above range is preferable from the viewpoint of maintaining both the rich taste and refreshing taste characteristic of dairy products in the sterilized dairy product.

[0023] According to one embodiment of the present invention, (A) to (E) in the pasteurized dairy product are, respectively: (A) dimethyl sulfide concentration: usually 27 to 63 ppb, preferably 27 to 55 ppb, more preferably 30 to 55 ppb; (B) hexanal concentration: usually 3.2 ppb or less, preferably 0.1 to 3.2 ppb, more preferably 1.0 to 3.1 ppb, even more preferably 2.0 to 3.0 ppb; (C) δ-decalactone concentration: usually 111 to 140 ppb, preferably 112 to 140 ppb, more preferably 112 to 135 ppb, even more preferably 115 to 135 ppb; (D) Concentration of δ-dodecalactone: usually 1,290 to 2,300 ppb, preferably 1,300 to 2,000 ppb, more preferably 1,400 to 1,900 ppb, still more preferably 1,500 to 1,800 ppb, and even more preferably 1,550 to 1,750 ppb; (E) Concentration of dimethyl disulfide: usually 0.56 to 0.72 ppb, preferably 0.56 to 0.70 ppb, and more preferably 0.57 to 0.65 ppb.

[0024] According to one embodiment of the present invention, the sterilized dairy product satisfies (A) and one selected from (B) to (E). Also, according to one embodiment of the present invention, the sterilized dairy product satisfies (A) and two selected from (B) to (E). Also, according to one embodiment of the present invention, the sterilized dairy product satisfies (A) and three selected from (B) to (E). Also, according to one embodiment of the present invention, the sterilized dairy product satisfies (A) and four selected from (B) to (E). Also, according to one embodiment of the present invention, the sterilized dairy product satisfies all of (A) to (E).

[0025] Measurement of (A) to (E) can be carried out using a sterilized dairy product as a sample according to the method described in the Examples.

[0026] In one embodiment of the present invention, examples of dairy products include cow's milk, LL milk, low-fat milk, non-fat milk, processed milk, concentrated milk, low-fat milk, and dairy drinks, with cow's milk being preferred.

[0027] <Method for producing a sterilized dairy product> According to one embodiment of the present invention, there is provided a method for producing a sterilized dairy product, comprising: a first heating step of heat-treating a dairy raw material at 95 to 125°C by indirect heating; and a second heating step of Joule-heating the heated dairy raw material obtained in the first heating step at 125 to 150°C.

[0028] According to the method of the present invention, the sterilized dairy product can be produced efficiently and stably by adjusting the sterilization conditions by combining the first heating step using an indirect heating method and the second heating step using Joule heating. Therefore, according to a preferred embodiment of the present invention, the sterilized dairy product produced by the method satisfies (A) and at least one selected from (B) to (D).

[0029] As the dairy raw material of the present invention, raw materials containing "milk" can be used as long as they do not impair the effects of the present invention. Here, "milk" includes animal milk derived from mammals such as cow's milk, sheep's milk, goat's milk, and human milk, prepared powdered milk such as infant formula, compositions in which edible oils and fats are emulsified (artificial milk), and processed products thereof. A specific example of such a dairy raw material is raw milk.

[0030] The dairy raw material of the present invention may also contain secondary ingredients other than milk. The components of the secondary ingredients other than milk are not particularly limited, but may include, for example, amino acids, proteins, carbohydrates, lipids, vitamins, minerals, organic acids, organic bases, fruit juice, and flavors.

[0031] In the milk raw material of the present invention, the milk content is not particularly limited, but the amount of non-fat milk solids is preferably 0.1 to 100% by mass, more preferably 0.1 to 95% by mass, even more preferably 1 to 90% by mass, even more preferably 1 to 50% by mass, and particularly preferably 1 to 30% by mass. Here, the "non-fat milk solids" of the present invention corresponds to the milk solids excluding water and milk fat.

[0032] Furthermore, the viscosity of the dairy raw material of the present invention is not particularly limited, but is preferably 0.5 to 20 mPa s, more preferably 0.5 to 15 mPa s, even more preferably 0.5 to 10 mPa s, and particularly preferably 2 to 10 mPa s at 85° C. The viscosity of the dairy raw material of the present invention can be measured using a B-type viscometer.

[0033] The density of the dairy raw material of the present invention is not particularly limited as long as it can ensure fluidity, but is preferably 300 to 3,000 kg / m ３ , more preferably 300 to 2,500 kg / m ３ , more preferably 300 to 2,000 kg / m ３ , more preferably 300 to 1,500 kg / m ３ , particularly preferably 500 to 1,500 kg / m ３ The density of the dairy raw material of the present invention can be measured by a Coriolis mass flowmeter. A Coriolis mass flowmeter directly measures the mass flow rate by the Coriolis force generated in the flow. The density of the dairy raw material can be indirectly measured by the change in frequency caused by exciting a tube provided in the mass flowmeter.

[0034] The specific method of the indirect heating method is not particularly limited, and examples include a tube method and a scraper method, but it is preferable to use a plate method. These indirect heating methods can be performed alone or in combination before the Joule heating method.

[0035] In the first heating step, the temperature of the milk raw material before the heat treatment by the indirect heating method is usually 75 to 85°C, preferably 78 to 83°C.

[0036] The heat treatment temperature by the indirect heating method in the first heating step is usually 95 to 125°C, preferably 95 to 120°C, more preferably 95 to 115°C, and even more preferably 105 to 115°C.

[0037] In the first heating step, the heat treatment by the indirect heating method can be continued until the milk raw material reaches the desired temperature. The heat treatment time by the indirect heating method in the first heating step may be appropriately adjusted depending on the value obtained by dividing the retention volume of the heat exchanger of the indirect heating method by the treatment flow rate, etc., and is usually 10 to 120 seconds, preferably 15 to 70 seconds, and more preferably 20 to 45 seconds.

[0038] According to one embodiment of the present invention, as described above, after the first heating step, a second heating treatment is performed by Joule heating. A known Joule heating device can be used for the second heating treatment step. Examples of such Joule heating devices include a Joule heating device manufactured by Emmepiemme, a Joule heating device manufactured by Sanovo, and a Joule heating device manufactured by Frontier Engineering.

[0039] The heat treatment temperature by Joule heating in the second heating step is usually 125 to 150°C, preferably 125 to 145°C, and more preferably 125 to 140°C.

[0040] The heat treatment time by the Joule heating method in the second heating step may be appropriately adjusted depending on the value obtained by dividing the retention volume of the heat exchanger of the indirect heating method by the treatment flow rate, and is usually 0.1 to 10 seconds, preferably 0.1 to 5 seconds, and more preferably 0.2 to 5 seconds.

[0041] Furthermore, from the viewpoint of imparting an appropriate richness and a refreshing taste to the sterilized dairy product, it is preferable to perform a cooling treatment by adjusting the cooling conditions for the Joule-heated milk raw material after the second heating step. Therefore, according to a preferred embodiment of the present invention, the method of the present invention is to adjust the Joule-heated milk raw material obtained by the second heating step to a calorie content of 2,000 to 5,000 kcal / (m ２ - h) further includes a step of cooling with the amount of cooling energy per unit area.

[0042] In the cooling step, the amount of cooling energy per unit area is usually 2,000 to 5,000 kcal / (m ２ ·h), but preferably 3,000 to 5,000 kcal / (m ２ ·h), and more preferably 3,000 to 4,000 kcal / (m ２ ・h).

[0043] Here, the amount of cooling energy per unit area can be calculated by the following formula.

[0044] The specific method for the cooling treatment is not particularly limited, but it can usually be carried out using an indirect heating type heat exchanger.

[0045] The cooling time of the Joule-heated milk raw material in the cooling step may be adjusted appropriately depending on the value obtained by dividing the retention volume of the heat exchanger of the indirect heating method by the processing flow rate, and is usually 10 to 70 seconds, preferably 10 to 40 seconds, and more preferably 15 to 40 seconds.

[0046] <Method for maintaining a rich taste and a refreshing taste in a sterilized dairy product> According to another embodiment of the present invention, there is provided a method for maintaining a rich taste and a refreshing taste in a sterilized dairy product, the method comprising: a first heating step of heat-treating a milk raw material at 95 to 125°C by indirect heating; and a second heating step of Joule-heating the heated milk raw material obtained in the first heating step at 125 to 150°C. Furthermore, according to a preferred embodiment, the Joule-heated milk raw material obtained in the second heating step is heated to a calorie content of 2,000 to 5,000 kcal / (m ２ - h) further includes a step of cooling with the amount of cooling energy per unit area.

[0047] The above-described alternative embodiments of the present invention can be carried out in accordance with the description of the pasteurized dairy product and method for producing the same of the present invention.

[0048] According to one embodiment of the present invention, the following are provided. [1] A pasteurized dairy product satisfying the following (A) and at least one selected from (B) to (D): (A) a dimethyl sulfide concentration of 27 to 63 ppb, (B) a hexanal concentration of 3.2 ppb or less, (C) a δ-decalactone concentration of 111 to 140 ppb, (D) a δ-dodecalactone concentration of 1,290 to 2,300 ppb. [2] The pasteurized dairy product according to [1], wherein (A) the dimethyl sulfide concentration is 27 to 57 ppb. [3] The pasteurized dairy product according to [1] or [2], wherein (B) the hexanal concentration is less than 3.1 ppb. [4] The pasteurized dairy product according to any of [1] to [3], wherein (C) the δ-decalactone concentration is 112 to 140 ppb. [5] The sterilized dairy product according to any one of [1] to [4], wherein the concentration of (D) δ-dodecalactone is 1,300 to 2,300 ppb. [6] The sterilized dairy product according to any one of [1] to [5], which is cow's milk. [7] A method for producing a sterilized dairy product, comprising: a first heating step in which a milk raw material is heat-treated by indirect heating at 95 to 125°C; and a second heating step in which the heated milk raw material obtained by the first heating step is Joule-heated at 125 to 150°C. [8] The method according to [7], wherein the indirect heating method in the first heating step is a plate-type heating method. [9] The method according to [7] or [8], wherein the heat treatment temperature in the first heating step is 95 to 125°C.

[10] The method according to any one of [7] to [9], wherein the heat treatment temperature in the second heating step is 125 to 145°C.

[11] The Joule-heated milk raw material obtained by the second heating step is heated to a temperature of 2,000 to 5,000 kcal / (m ２

[12] The method according to any one of [7] to

[10] , further comprising a step of cooling the substrate with a cooling energy amount per unit area of ​​3000 to 5000 kcal / (m ２

[13] The method according to any one of [7] to

[12] , wherein the sterilized dairy product is the dairy product according to any one of [1] to [6].

[14] A method for maintaining a rich taste and a refreshing taste in a sterilized dairy product, comprising: a first heating step of heat-treating a milk raw material at 95 to 125°C by indirect heating; and a second heating step of Joule-heating the heated milk raw material obtained by the first heating step at 125 to 150°C.

[15] A method for maintaining a rich taste and a refreshing taste in a sterilized dairy product, comprising: a first heating step of heat-treating a milk raw material at 95 to 125°C by indirect heating; and a second heating step of Joule-heating the heated milk raw material obtained by the second heating step at 125 to 150°C.

[16] A method for maintaining a rich taste and a refreshing taste in a sterilized dairy product, comprising: a first heating step of heat-treating a milk raw material at 95 to 125°C by indirect heating; and a second heating step of Joule-heating the heated milk raw material obtained by the second heating step at 2,000 to 5,000 kcal / (m ２ The method according to

[14] , further comprising the step of cooling with a cooling energy amount per unit area of ​​(h).

[0049] The present invention will be described in detail below with reference to the following examples, but the present invention is not limited thereto. Furthermore, unless otherwise specified, the measurement methods and units described herein are in accordance with the provisions of JIS (Japanese Industrial Standards).

[0050] Method for Measuring Aroma Components In this example, the amount of aroma components was determined according to the method described below.

[0051] <Preparation of Measurement Sample> 10 g of sterilized milk was weighed into a 20 mL vial, and an internal standard (MIBK, cyclooctanol) was added to a liquid concentration of 20 ppb. The vial was then sealed to obtain a measurement sample.

[0052] <Preparation of calibration curve samples> (Highly volatile components: dimethyl sulfide (DMS), dimethyl disulfide (DMDS), and hexanal) For DMS and DMDS, the concentration of each substance was adjusted to 2000 ppm using methanol to obtain a stock solution. For hexanal, the concentration was adjusted to 1000 ppm using methanol to obtain a stock solution.

[0053] (Medium to Low Volatility Components: δ-Decalactone and δ-Dodecalactone) With regard to δ-decalactone and δ-dodecalactone, the concentration of each substance was adjusted to 5000 ppm using ethanol to obtain a stock solution.

[0054] Using the above stock solutions, aqueous solutions of each substance were prepared at the concentrations shown in Table 1 below. Next, for each substance, each aqueous solution was diluted 100-fold with milk to obtain calibration curve sample 1. Next, each calibration curve sample 1 was diluted with milk to obtain calibration curve samples 2 to 5. Calibration curves were prepared using calibration curve samples 1 to 5 thus obtained.

[0055]

[0056] <Analysis of Aroma Components> Aroma components in each sample were collected by the DHS (Down-flow Hanging Sponge) method using an autosampler MPS-robotic pro manufactured by GERSTEL according to the following procedure.

[0057] (Highly volatile components: DMS, DMDS, and hexanal) The measurement sample in the vial described above was preheated at 25°C for 15 minutes using an agitator, and then nitrogen was passed through the sample at a flow rate of 40 mL / min for 10 minutes, and the aroma components contained in the nitrogen were adsorbed onto a collector, TenaxTA (manufactured by GL Sciences, Inc.). A thermal desorption unit (TDU: Thermal Desorption Unit) was used for thermal desorption of the aroma components.

[0058] The details of the equipment and conditions used are shown in Table 2.

[0059]

[0060] Analysis was carried out by the above-mentioned method, and a calibration curve was prepared for the detected DMS, DMDS, and hexanal according to the internal standard method using MIBK (methyl isobutyl ketone), and the samples were quantified.

[0061] (Medium to low volatility components: δ-decalactone and δ-dodecalactone) The measurement sample in a vial prepared by the method described above was heated to 60°C, and a Supelco SPME fiber (DVB / CAR / PDMS 50 / 30 μm 2 cm, 57299-U) was inserted into the gas phase and collected for 40 minutes. This SPME fiber was injected into a GC / MS and heated for 300 seconds to desorb the collected volatile components. Details of the equipment and conditions used are shown in Table 3.

[0062]

[0063] Analysis was carried out by the above-mentioned method, and a calibration curve was prepared for the detected δ-decalactone and δ-dodecalactone according to the internal standard method using cyclooctanol, and the measurement samples were quantified.

[0064] Test Example 1: Investigation of temperature rise range by Joule sterilization According to the conditions shown in Table 4, raw milk was preheated by plate heating, and the resulting heated raw milk was sterilized by Joule heating (device name: WAVE, company name: SANOVO) and cooled to obtain sterilized milk.

[0065]

[0066] Here, the cooling method was plate cooling, and the amount of cooling energy per unit area was calculated using the following formula.

[0067] The pasteurized milk samples were subjected to a sensory evaluation by six expert panelists who were trained to the extent that they could assign the same score to the same sample. The sample was heated from 85°C to 130°C by the plate heating method, held for 2 seconds, and then cooled. The samples were used as a control and evaluated according to the following criteria.

[0068] Evaluation criteria 5: Strong 4: Slightly strong 3: Almost the same 2: Slightly weak 1: Weak

[0069] The results of the sensory evaluation are shown in Table 5. It was confirmed that in Test Group 3, the conventional milky aroma, richness (body), and sweetness were maintained while the refreshing feeling was enhanced.

[0070]

[0071] The amount of DMS in pasteurized milk was also measured. The results of the quantitative analysis of DMS in pasteurized milk are shown in Figure 1.

[0072] Test Example 2: Study of endothermic rate after Joule sterilization After heating under the conditions of Test Area 3, the amount of cooling energy per unit area was 412, 3,463, and 5,374 kcal / (m ２ - h) A cooled pasteurized milk was prepared. The test conditions are shown in Table 4.

[0073]

[0074] A sensory evaluation of pasteurized milk was conducted by four expert panelists who were trained to the extent that they could assign the same score to the same sample. A sample heated from 85°C to 130°C by plate heating, held for 2 seconds, and then cooled (conventional indirect heating method: plate heating only) was used as a control, and evaluated according to the following evaluation criteria. Evaluation was conducted on a 5-point scale (average of the evaluators). The control was given a score of 0.

[0075] Evaluation criteria 2: Strong or good 1: Slightly strong or slightly good 0: Average -1: Slightly weak or slightly bad -2: Weak or bad

[0076] The results of the sensory evaluation are shown in Table 7.

[0077] Cooling energy per unit area: 412 kcal / (m ２ The flavor of the product was the same as that of the control (conventional indirect heating method), and almost no improvement in flavor was observed. The cooling energy per unit area was 3,463 kcal / (m ２ ・h) showed a difference from the control (conventional indirect heating method), and an improvement in flavor was observed. Specifically, the "fresh milk aroma" and "smoothness in the mouth" improved, and the "egg-like smell (sulfur smell)" was reduced. The cooling energy amount per unit area was 5,374 kcal / (m ２- h) significantly improved the "fresh milk aroma," "smoothness," "refreshing feeling," and "good aftertaste," while reducing the "egg-like smell (sulfur smell)," "degree of sweetness," and "richness (body)." However, the "refreshing feeling" increased and the "richness (body)" of the milk decreased, resulting in an unsatisfactory flavor. From the above results, it can be seen that the flavor is improved compared to the conventional indirect heating method, and the flavor with the best balance of "richness (body)" and "refreshing feeling" is the one with the heat transfer rate per unit area of ​​the cooling water of 3,463 kcal / (m ２ - It was confirmed that it was h).

[0078] In addition, the cooling energy amount per unit area is 412, 3,463, and 5,374 kcal / (m ２ The results of quantitative analysis of DMDS in step h) are shown in Figure 2. In Figure 2, the quantitative value of DMDS decreases as the cooling rate increases. Since the characteristic aroma of DMDS is an "egg-like odor (sulfur odor)," Figure 2 provides data that supports the results of the sensory evaluation.

[0079] From the above results, the conditions of test area 3-2 using Joule sterilization were evaluated as optimal, and measurement samples prepared under these conditions were used in the subsequent test examples.

[0080] Test Example 3: Study on the Flavor of Chilled Milk by Joule Pasteurization (1) A sensory evaluation of the pasteurized milk in Test Group 3-2 was conducted by 22 expert panel members who were trained to the extent that they could assign the same score to the same sample. Note that a sample that was heated from 85°C to 130°C by plate heating, held for 2 seconds, and then cooled served as a control and was evaluated according to the following evaluation criteria. The evaluation was conducted on a 5-point scale (average of the evaluators) as follows. The control was given a score of 0.

[0081] Evaluation criteria 2: Strong or good 1: Slightly strong or slightly good 0: Average -1: Slightly weak or slightly bad -2: Weak or bad

[0082] The results of the sensory evaluation are shown in Table 8.

[0083] The above results revealed that the refreshing feeling in particular was significantly different at a risk level of 5%. In other words, Test Group 3-2 had a stronger refreshing feeling than the control milk, but other evaluation items related to the deliciousness of milk, such as the fresh milk aroma, were equivalent.

[0084] Test Example 4: Study on the flavor of chilled milk after Joule sterilization (2) A comparative sensory evaluation was conducted by 220 consumers (aged 25 to 74) on the sterilized milk in Test Group 3-2 (stored refrigerated at 10°C or below) and a control milk that had been heated from 85°C to 130°C using a plate heater, held for 2 seconds, and then cooled. The results are shown in Table 7.

[0085] The results are shown in Table 9. Test plot 3-2 received a higher rating for palatability than the control.

[0086] Test Example 5: Study on the flavor of chilled milk after Joule sterilization (3) Aroma analysis was performed using the sterilized milk from Test Plot 3-2 and four types of commercially available milk (Commercial Products 1 to 4). The results for DMS, hexanal, δ-decalactone, and δ-dodecalactone are shown in Figures 3, 4, 5, and 6, respectively.

[0087] The amount of DMS, an indicator of protein oxidation, in Test Plot 3-2 was reduced compared to the amounts in Commercial Products 1, 2, and 4. The amount of hexanal, an indicator of lipid oxidation, in Test Plot 3-2 was reduced compared to the amounts in Commercial Products 1, 2, 3, and 4. The amounts of δ-decalactone and δ-dodecalactone, indicators of the fresh aroma derived from raw milk, in Test Plot 3-2 were higher than the amounts in Commercial Products 1, 3, and 4, and the fresh aroma derived from raw milk was maintained.

[0088] Test Example 6: Study on the Flavor of Chilled Milk After Joule Pasteurization (4) A sensory evaluation was conducted by seven expert panelists who were trained to the extent that they could assign the same score to the same sample, using the pasteurized milk from Test Area 3-2 and four types of commercially available milk. Note that a sample that was heated from 85°C to 130°C by plate heating, held for 2 seconds, and then cooled served as a control and was evaluated according to the following evaluation criteria. The evaluation was conducted on a 5-point scale (average of the evaluators) as follows. The control was given a score of 0.

[0089] Evaluation criteria 2: Strong or good 1: Slightly strong or slightly good 0: Average -1: Slightly weak or slightly bad -2: Weak or bad

[0090] The results are shown in Table 10.

[0091] DMS is an aroma component corresponding to an "egg-like smell (sulfur smell)," and δ-decalactone and δ-dodecalactone are aroma components corresponding to a "fresh milk aroma." Test Plot 3-2 had a weak "egg-like smell (sulfur smell)" and a strong "fresh milk aroma," which confirmed the characteristics of the aroma components analyzed in Test Example 6 by the sensory evaluation.

[0092] Test Example 7: Study on the concentration of δ-decalactone and δ-dodecalactone in milk and its effect on flavor For commercial product 3, which had a low concentration of δ-decalactone and δ-dodecalactone, different concentrations of δ-decalactone or δ-dodecalactone were added to prepare test plots 4-1 to 4-6. In addition, for commercial product 3, δ-decalactone (Fujifilm Wako Pure Chemical Corporation) and δ-dodecalactone (Tokyo Chemical Industry Co., Ltd.) were added to prepare test plots 4-7, 4-8, and 4-10 so that the concentration was equivalent to that of commercial product 1, commercial product 2, and test plot 3-2. In addition, for commercial product 3, δ-decalactone (Fujifilm Wako Pure Chemical Corporation) and δ-dodecalactone (Tokyo Chemical Industry Co., Ltd.) were added to prepare test plot 4-9 so that the concentration was equivalent to that of the highest concentration sample among test plots 4-1 to 4-8 and 4-10.

[0093] Sensory evaluation was performed using test plots 4-1 to 4-10 by five expert panelists who were trained to the extent that they could assign the same score to the same sample. A sample heated from 85°C to 130°C by plate heating, held for 2 seconds, and then cooled was used as a control and evaluated according to the following evaluation criteria. Evaluation was performed on a 5-point scale (average of the evaluators) as follows. The control was given a score of 0.

[0094] Evaluation criteria 2: Good 1: Fairly good 0: Almost the same -1: Fairly bad -2: Bad

[0095] The concentrations of δ-decalactone and δ-dodecalactone and the results of the sensory evaluation are shown in Table 11.

[0096] When δ-decalactone was added alone, increasing the amount to 120 ppb (Test Area 4-1) added a creamy aroma and enhanced the flavor, resulting in an improved score. On the other hand, at 140 ppb or higher (Test Areas 4-2 and 4-3), the aroma became heavy and the aftertaste became cloying, resulting in a lower score. When δ-dodecalactone was added alone, at 1,300 ppb or higher (Test Areas 4-4, 4-5, and 4-6), a cheese and butyric acid aroma was detected, resulting in an undesirable milk flavor, resulting in a lower score. When δ-decalactone and δ-dodecalactone were added together, the combination of 120 ppb of δ-decalactone and 1,300 ppb of δ-dodecalactone (Test Area 4-7) imparted a creamy aroma, resulting in a richer and thicker flavor, resulting in an improved score. On the other hand, when δ-decalactone was 140 ppb or more and δ-dodecalactone was 1,600 ppb or more (test plots 4-8 and 4-9), cheese smell, oxidized smell and stickiness were perceived, and the evaluation score decreased.

[0097] In addition, in test plot 4-10, in which δ-decalactone and δ-dodecalactone were added to be equivalent to test plot 3-2, δ-decalactone 120 ppb and δ-dodecalactone 1,600 ppb, the aroma rose and the aftertaste was prolonged, and the richness was felt, so the score improved the most.

[0098] Comprehensive evaluation of the results in Table 11 confirmed that there are optimal contents for δ-decalactone and δ-dodecalactone, with the optimum conditions being more than 90 ppb but less than 140 ppb for δ-decalactone and more than 900 ppb but less than 2,300 ppb for δ-dodecalactone.

[0099] Test Example 8: Study on the flavor of long-life (LL) milk sterilized by Joule sterilization. Sterilized milk in test group 5 was prepared according to the method described in Test Example 1 under the heating conditions shown in Table 12.

[0100]

[0101] A sensory evaluation was conducted using Test Group 5 by seven expert panelists who were trained to the extent that they could assign the same score to the same sample. The sample was heated from 85°C to 140°C by plate heating, held for 2 seconds, and then cooled, and used as a control. Evaluation was performed using the following 5-point scale (average of the evaluators). The control was given a score of 0.

[0102] Evaluation criteria 5: Strong 4: Slightly strong 3: Almost the same 2: Slightly weak 1: Weak

[0103] The results of the sensory test are shown in Table 13.

[0104] The pasteurized milk from Test Plot 5 had a weaker "cooked smell" that was considered an undesirable flavor in conventional long-life milk, and a stronger "refreshing taste." These results confirmed that the manufacturing method of Test Plot 5 can produce conventional long-life milk with a good flavor that could not be achieved with conventional long-life milk manufacturing methods.

Claims

1. A pasteurized dairy product that satisfies the following (A) and at least one selected from (B) to (D): (A) the concentration of dimethyl sulfide is 27 to 63 ppb, (B) the concentration of hexanal is 3.2 ppb or less, (C) the concentration of δ-decalactone is 111 to 140 ppb, (D) the concentration of δ-dodecalactone is 1,290 to 2,300 ppb.

2. The pasteurized dairy product according to claim 1, wherein the concentration of (A) dimethyl sulfide is 27 to 57 ppb.

3. (B) A pasteurized dairy product according to claim 1 or 2, wherein the concentration of hexanal is less than 3.1 ppb.

4. A pasteurized dairy product according to claim 1 or 2, wherein the concentration of (C) delta-decalactone is 112 to 140 ppb.

5. A pasteurized dairy product according to claim 1 or 2, wherein the concentration of (D) δ-dodecalactone is 1,300 to 2,300 ppb.

6. The pasteurized dairy product according to claim 1 or 2, which is milk.

7. A method for producing a sterilized dairy product, comprising: a first heating step in which a dairy raw material is heat-treated at 95 to 125°C by indirect heating; and a second heating step in which the heated dairy raw material obtained in the first heating step is Joule-heated at 125 to 150°C.

8. The method according to claim 7, wherein the indirect heating method in the first heating step is a plate type.

9. The method according to claim 7 or 8, wherein the heat treatment temperature in the first heating step is 95 to 120°C.

10. The method according to claim 7 or 8, wherein the heat treatment temperature in the second heating step is 125 to 145°C.

11. The Joule-heated milk raw material obtained in the second heating step is heated to 2,000 to 5,000 kcal / (m ２ The method according to claim 7 or 8, further comprising the step of: h) cooling with an amount of cooling energy per unit area.

12. The amount of cooling energy per unit area is 3,000 to 5,000 kcal / (m ２ The method according to claim 11, wherein h).

13. The method according to claim 7 or 8, wherein the pasteurized dairy product is the dairy product according to claim 1.

14. A method for maintaining a rich and refreshing taste in a sterilized dairy product, comprising: a first heating step in which a dairy raw material is heat-treated at 95 to 125°C using an indirect heating method; and a second heating step in which the heated dairy raw material obtained in the first heating step is Joule-heated at 125 to 150°C.

15. The Joule-heated milk raw material obtained in the second heating step is heated to 2,000 to 5,000 kcal / (m ２ The method of claim 14, further comprising the step of: h) cooling with an amount of cooling energy per unit area.

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