Milk flavor evaluation method

Abstract

To provide an evaluation method of flavor degradation of container-packed milk at the time of being stored at a room temperature.SOLUTION: A milk flavor evaluation method includes a quantification step of quantifying (Z)-6-dodecene-4-olide. The milk may be milk stored at 15 to 40°C. The quantification step may be a step of quantifying a content of (Z)-6-dodecene-4-olide contained in the milk by a GC-MS method.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for evaluating the flavor of dairy products. [Background technology]

[0002] Packaged milk products are generally stored refrigerated, but products that can be stored at room temperature are also commercially available. One type of packaged milk that can be stored at room temperature is sterilized milk aseptically filled into aseptic containers, and can be stored at room temperature for several months.

[0003] In recent years, the importance of packaged milk products that can be stored at room temperature has increased, and there is a demand for further extension of their shelf life. However, it is known that the flavor deteriorates as the storage period increases. For example, Non-Patent Document 1 reports that commercially available aseptically packaged whole milk and skim milk were stored at 25°C for four months, and gas chromatography-mass spectrometry (hereinafter referred to as GC-MS analysis) of volatile compounds in the products was performed every 15 days, and sensory testing was performed every 30 days. GC-MS analysis detected 41 types of volatile substances, but the changes in each volatile substance were reported not to be related to changes in the intensity of each sensory attribute.

[0004] Gas chromatography-olfactometry (GC-O) analysis is useful for investigating odor substances that affect sensory evaluation. It has been reported that GC-O analysis was performed to investigate the characteristic aroma components of UHT (Ultra-High-Temperature) milk pasteurized at 130°C and 140°C for 2 seconds.

[0005] Furthermore, Patent Document 1 discloses a method for evaluating the deterioration of flavor of milk, which is characterized by determining γ-dodecalactone as a scientific indicator component for the deterioration of flavor of milks, and quantifying the amount of γ-dodecalactone. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent No. 5931452 [Non-Patent Document]

[0007] [Non-Patent Document 1] <0 / / Valero, E., Villamiel, M., Miralles, B., Sanz, J., and Martinez-Castro, I. (2001). Changes in flavor and volatile component during storage of whole and skimmed UHT milk. Food Chemistry, 72, 51-58, 2001 [Non-Patent Document 2] Iwatsuki, K., Mizota, Y., Kubota, T., Nishimura, O., Masuda, H., Sotoyama, K. and Tomita, M. (1999) Evaluation of Aroma of Pasteurized and UHT Processed Milk by Aroma Extract Dilution Analysis. J. Jpn. Soc. Food Sci. Technol. (Nippon Shokuhin Kagaku Kogaku Kaishi), 46(9), 587-597. [Non-Patent Document 3] Takagi, K., Yamazaki, K., Mizukami, Y., Hayakawa, F., He, F., Hiramitsu, M. (2020). Flavor Characteristics of low temperature long time (LTLT) and ultra high temperature (UHT) milk. J. Jpn. Soc. Food Sci. Technol. (Nippon Shokuhin Kagaku Kogaku Kaishi), 67(7), 230-235. [Summary of the Invention] [Problem to be solved by the invention]

[0008] As the demand for shelf-stable packaged milk increases, a method for evaluating the quality (flavor deterioration) of packaged milk when stored at room temperature is required. An object of the present invention is to provide a method for evaluating the deterioration of flavor of bottled milk when stored at room temperature. [Means for solving the problem]

[0009] The present invention includes the following aspects. [1] A method for evaluating the flavor of dairy products, comprising a quantitative step of quantifying (Z)-6-dodecen-4-olide. [2] The flavor evaluation method according to [1], wherein the milk is stored at 15 to 40°C. [3] The flavor evaluation method according to [1] or [2], wherein the quantification step is a step of quantifying the content of (Z)-6-dodecen-4-olide contained in the milk by GC-MS. [4] The flavor evaluation method according to any one of [1] to [3], further comprising a calculation step of calculating the increase rate of the (Z)-6-dodecen-4-olide by the following formula (1): Increase rate = (Z)-6-dodecen-4-olide content in the milk after any storage period (μg / 100g) / (Z)-6-dodecen-4-olide content in the milk after storage period 0 days (μg / 100g) (1) [5] The flavor evaluation method according to any one of [1] to [4], wherein the dairy product is one selected from cow's milk, special cow's milk, pasteurized goat's milk, adjusted milk, low-fat milk, non-fat milk, and processed milk and milk drinks. [Effects of the Invention]

[0010] According to the above aspect, a method for evaluating deterioration in flavor of container-packaged milk during storage at room temperature can be provided. DETAILED DESCRIPTION OF THE INVENTION

[0011] The method for evaluating the flavor of dairy products of this embodiment includes a quantitative determination step of quantifying (Z)-6-dodecen-4-olide.

[0012] (Z)-6-dodecen-4-olide is a compound represented by the following formula (2) (CAS registration number: 18679-18-0).

[0013] [ka]

[0014] As will be explained in the Examples below, it has been found that there is a correlation between the deterioration of milk flavor due to storage at room temperature and the amount of (Z)-6-dodecen-4-olide contained in the milk. By quantifying the amount of (Z)-6-dodecen-4-olide contained in bottled milk stored at room temperature, it is possible to evaluate the deterioration of milk flavor.

[0015] The quantitative determination of (Z)-6-dodecen-4-olide is not particularly limited, but may be performed by GC-MS, which allows for accurate quantitative determination of (Z)-6-dodecen-4-olide.

[0016] Storage at room temperature means storage at 15 to 40°C, and may be storage at 15 to 35°C or 20 to 30°C, for example. Examples of storage periods at room temperature include 1 month, 2 months, 4 months, and 6 months.

[0017] The deterioration of flavor of milk can be evaluated by the ratio of the content of (Z)-6-dodecen-4-olide contained in milk after storage to the content of (Z)-6-dodecen-4-olide contained in milk on storage day 0, for example, immediately after packaging. The milk after storage may be milk stored at room temperature. That is, the increase rate of (Z)-6-dodecen-4-olide may be calculated by the following formula (1).

[0018] Increase rate = (Z)-6-dodecen-4-olide content in milk after any storage period (μg / 100g) / (Z)-6-dodecen-4-olide content in milk after 0 days of storage (μg / 100g) (1)

[0019] The method for evaluating the flavor of dairy products in this embodiment may further include a calculation step of calculating the rate of increase in (Z)-6-dodecen-4-olide using the above formula (1).

[0020] The method for evaluating the flavor of dairy products in this embodiment may further include a step of determining the deterioration of flavor of dairy products after the calculation step. The flavor deterioration can be determined when the increase rate obtained in the calculation step exceeds 1. If the increase rate calculated by the above formula (1) exceeds 2, preferably 2.5 or more, more preferably 3.0 or more, more preferably 3.5 or more, and even more preferably 4.0 or more, it can be determined that the flavor of the dairy product has deteriorated.

[0021] Examples of dairy products in this embodiment include "milk" and "dairy products" as defined in the Order on Compositional Standards for Milk and Dairy Products (Ministry of Health and Welfare Ordinance No. 52 of December 27, 1951; hereinafter, also referred to as the "Milk Order"). Examples of milk include raw milk, cow's milk, special cow's milk, raw goat's milk, pasteurized goat's milk, raw ewe's milk, raw buffalo milk, adjusted milk, low-fat milk, non-fat milk, and processed milk. Examples of dairy products include cream, butter, butter oil, cheese, concentrated whey, ice cream, concentrated milk, concentrated skim milk, unsweetened evaporated milk, unsweetened evaporated skim milk, sweetened condensed milk, sweetened evaporated skim milk, whole milk powder, skim milk powder, cream powder, whey powder, protein-enriched whey powder, buttermilk powder, sweetened milk powder, modified milk powder, modified liquid milk, fermented milk, lactic acid bacteria drinks (limited to those containing 3.0% or more non-fat milk solids), and dairy drinks. The milk in this embodiment may be a "milk drink" as defined in Article 2, Paragraph 7 of the Fair Competition Code and Enforcement Regulations Concerning the Labeling of Drinking Milk. That is, the milk drink may be a milk drink as defined in Article 2, Paragraph 41 of the Milk and Other Products Order, and may contain 3.0% or more milk solids by weight.

[0022] From the viewpoint of the accuracy of evaluation of flavor deterioration by quantification of (Z)-6-dodecen-4-olide, the milk is preferably one or more types of milk selected from, for example, cow's milk, special cow's milk, pasteurized goat's milk, ingredient-adjusted milk, low-fat milk, non-fat milk, and processed milk. The milk drink may be a milk drink containing a flavor component, such as coffee, black tea, matcha, fruit juice (strawberry, banana, etc.), cocoa, or a flavoring that imparts the aroma of these.

[0023] According to the method for evaluating flavor deterioration of dairy products of this embodiment, it is possible to evaluate flavor deterioration by quantifying only (Z)-6-dodecen-4-olide among the various components contained in dairy products, thereby enabling accurate and efficient quality control of dairy flavor. [Example]

[0024] <Test example> (1) Purpose This study was conducted to exploratory identify the components that characterize the flavor of dairy products stored at room temperature.

[0025] (2) Sample preparation Raw milk (non-fat milk solids 8.9%, milk fat 3.8%) was sterilized at 140°C for 2 seconds using a plate-type indirect heat sterilization method. The sterilized milk was aseptically filled into 1000 mL tetrabrik aseptic packages to obtain bottled milk (i.e., dairy products).

[0026] (3) Preservation test The bottled milk prepared in (2) above was stored at 5°C or 25°C for 0, 2, and 4 months, respectively.

[0027] (4) Gas chromatography-mass spectrometry (GC-MS analysis) 500 g of bottled milk after the storage test described in (3) above and 500 mL of deionized water were transferred to a 2000 mL conical flask, and 1 mL of 4-octanol (50 μg / mL methanol) was added as an internal standard. 500 mL of dichloromethane (hereinafter sometimes referred to as DCM) was slowly added, and the mixture was gently stirred at room temperature for 1 hour, after which the DCM was separated. This procedure was repeated twice, and the DCM phases were combined and dried over anhydrous sodium sulfate. The extract was concentrated in a rotary evaporator to obtain a final volume of approximately 1.5 mL.

[0028] GC-MS analysis was performed in triplicate using a 5975C mass-selective detector (Agilent Technologies) equipped with a DB-WAX fused silica capillary column (60 m × 0.25 mm, 0.25 μm film thickness; Agilent Technologies). The helium carrier gas flow rate was 1.6 mL / min. The oven temperature was programmed to 50 °C for 2 min, then increased to 220 °C at 3 °C / min and held at 220 °C for 75 min. The injection port was maintained at 250 °C. The inlet was operated in split mode (split ratio 10:1), and 4 μL of the above extract was injected.

[0029] (Z)-6-Dodecen-4-olide was analyzed by GC-MS using (Z) selected ion monitoring (SIM) mode, with m / z values ​​of 41, 85, and 96 for (Z)-6-dodecen-4-olide and 69, 73, and 87 for 4-octanol.

[0030] Semi-quantitative analysis was performed using the relative peak area of ​​each compound and an internal standard. Volatile compounds were identified by comparing their mass spectra or odor characteristics with those of standard compounds, and by comparing their linear retention indices using n-alkanes with carbon numbers of 6 to 32 with those of standard compounds. Standard compounds used for the identification of volatile compounds were purchased from Tokyo Chemical Industry Co., Ltd., Sigma-Aldrich Japan, NARD Institute, Ltd., Ambeed, Inc., or Soda Aromatic Co., Ltd. 2-Acetyl-1-pyrroline and (Z)-1,5-octadin-3-one were prepared as previously reported (De Kimpe, NG, Stevens, CV, and Keppens, MA (1993). Synthesis of 2-acetyl-1-pyrroline, the principal rice flavor component. J. Agric. Food Chem., 41, 1458-1461, and Delort, E., Jaquier, A., Chapuis, C., Rubin, M., and Starkenmann, C. (2012). Volatile composition of oyster leaf (Mertensia maritima (L.) Gray). J. Agric. Food Chem., 60, 11681-11690). When standard compounds were unavailable, compounds were tentatively identified by matching mass spectral data using the Wiley Registry 11th Edition / NIST 2017 Mass Spectral Library (John Wiley and Sons, Inc. Hoboken, NJ, USA).

[0031] (5) Gas chromatography-olfactometry (GC-O) analysis The GC-O analysis samples were prepared by mixing three equal amounts of the extracts obtained by solvent extraction in the above (4) and then serially diluting them three-fold (1:3 to 1:81) with DCM.

[0032] GC-O analyses of the extracts and their DCM dilutions were performed in triplicate using CharmAnalysis® and an Agilent 6890GC (modified by DATU, Inc., Geneva, NY, USA) (Acree, TE, Barnard, J., and Cunningham, DG (1984). A procedure for the sensory analysis of gas chromatographic effluents. Food Chem., 14, 273-286). A DB-WAX fused silica capillary column (15 m x 0.32 mm, 0.25 μm film thickness; Agilent Technologies) was used with a helium carrier gas flow rate of 3.2 mL / min. The oven temperature was programmed to start at 40 °C, increased at 6 °C / min to 230 °C, and then held at 230 °C for 30 min. The injection port and detector were maintained at 225 °C, and 1 μL of sample was injected in splitless mode.

[0033] The GC exhaust gas of each sample was smelled in humidified air by a skilled panelist with over 20 years of experience. The number of milky odor components detected by this panelist and their RI were confirmed by a panelist with over 10 years of experience.

[0034] The odor activity of volatile compounds obtained by GC-O dilution analysis was expressed as charm value (CMV) and aroma descriptors (Acree, TE, Barnard, J., and Cunningham, DG (1984). A procedure for the sensory analysis of gas chromatographic effluents. Food Chem., 14, 273-286). CMV is an index of odor intensity and is calculated by integrating the time length and dilution degree using the following equation (3):

[0035]

number

[0036] In equation (3), F is the dilution ratio, n is the number of dilutions, and di is the length of time.

[0037] The relative intensity of odor components is expressed as the odor spectral value (OSV). OSV is the normalized charm value corrected by an approximate Stevens law exponent (0.5 for example) for the odor component with the strongest detected odor intensity (Acree, TE (1997), GC / olfactometry, Anal. Chem. News Features, 69, 170A-175A). OSV is calculated using the following equation (4) and is used to approximate the relative intensity of odors by taking into account the exponential nature of olfactory psychophysics. OSV = {(charm value) / (charm value) max} 1 / 2 ×100 (4)

[0038] (6) Statistical analysis Analysis of variance (ANOVA) and Tukey-Kramer honestly significant difference test (TK HSD) were performed on GC-MS and GC-O data using the JMP14 software package (SAS Institute Inc., Cary, NC, USA).

[0039] (7)GC-MS analysis results The results of the GC-MS analysis are shown in Tables 1 and 2. A total of 43 compounds were detected and 39 were identified in the samples stored at 5°C and 25°C. The mean concentration and relative standard deviation (RSD) of each compound, as well as the results of a one-way analysis of variance followed by a multiple comparison test (TK HSD) for all samples, are shown in Table 1. Significant changes (increases or decreases) in each compound during storage at 5°C and 25°C are shown in the rightmost column of Table 2.

[0040] In Tables 1 and 2, "Concentration" is a semi-quantitative value calculated from the relative peak area of ​​each compound and the internal standard. "RSD" indicates relative standard deviation. "TK HSD" indicates the results of the Tukey-Kramer HSD test, and there was a significant (p<0.05) difference between samples marked with different letters (A>B>C>D). No. 6 and No. 7 2,3-butanediol are diastereomers. Tentative identification of No. 25 alpha-cadinol was made by comparing the mass spectrum with the Wiley Registry 11th Edition / NIST 2017 Mass Spectral Library. No. 32 (Z)-6-dodecen-4-olide was analyzed in selected ion monitoring (SIM) mode. The relative peak areas were (Z)-6-dodecen-4-olide (m / z 85) and 4-octanol (m / z 69). "-" indicates not detected.

[0041] In Table 2, an upward arrow indicates a significant increase from the time of packaging (0M) after 4 months of storage at 5°C or 25°C (5°C-4M or 25°C-4M). A downward arrow indicates a significant decrease from the time of packaging (0M) after 4 months of storage at 5°C or 25°C (5°C-4M or 25°C-4M). A combination of an upward and downward arrow indicates a significant increase from the time of packaging (0M) after 2 months of storage at 5°C or 25°C (5°C-2M or 25°C-2M) and a significant decrease from 2 months of storage at 5°C or 25°C (5°C-2M or 25°C-2M) to 4 months of storage at 5°C or 25°C (5°C-4M or 25°C-4M).

[0042] [Table 1]

[0043] [Table 2]

[0044] As shown in Tables 1 and 2, the compounds that increased significantly during storage only at 25°C were 2-heptanone (No. 2), 1-hydroxy-2-propanone (No. 4), furfuryl alcohol (No. 10), 2-buten-4-olide (No. 12), hexanoic acid (No. 14), heptanoic acid (No. 16), pyran-4-one (No. 17), octanoic acid (No. 21), nonanoic acid (No. 23), decanoic acid (No. 26), 9-decenoic acid (No. 27), 4-dodecanolide (No. 30), (Z)-6-dodecen-4-olide (No. 32), 11-dodecenoic acid (No. 36), myristic acid (No. 39), and tetradecenoic acid (No. 40). Furthermore, the compounds that decreased significantly only during storage at 25°C were 5-hexanolide (No. 13) and 5-octanolide (No. 18). The GC-MS analysis results allowed us to identify the compounds that increased significantly at a storage temperature of 25°C.

[0045] (8) GC-O evaluation results The volatile compounds detected by GC-MS as described in (6) above do not necessarily correspond to the odor intensity of the sample. Therefore, GC-O (CharmAnalysis®) was performed to clarify the odorants and their odor intensity that affect the changes in sensory characteristics during storage.

[0046] Tables 3 and 4 show the GC-O evaluation results. In Tables 3 and 4, "Charm value" indicates the average value of three measurements. "RSD" indicates the relative standard deviation of triplicate measurements.

[0047] Of the 15 compounds confirmed by GC-MS analysis to increase significantly at 25°C storage, (Z)-6-dodecen-4-olide (Nos. 1-7 in Tables 3 and 4) showed an OSV value of 100 (the strongest odor intensity) after both 2 and 4 months of storage at 25°C. Because (Z)-6-dodecen-4-olide showed a significant increase in odor intensity after storage at 25°C, it was revealed to be a component that characterizes the flavor of dairy products after storage at 25°C.

[0048] The increase rate of (Z)-6-dodecen-4-olide (No. 32) in Table 4 was calculated based on the following formula (1), and was 3.8 after storage at 25°C for 2 months and 4.3 after storage at 25°C for 4 months. Increase rate = (Z)-6-dodecen-4-olide content in milk after any storage period (μg / 100g) / (Z)-6-dodecen-4-olide content in milk after 0 days of storage (μg / 100g) (1)

[0049] [Table 3]

[0050] [Table 4]

Claims

1. A method for evaluating the flavor of dairy products, comprising a quantitative step of quantifying (Z)-6-dodecen-4-olide.

2. 2. The flavor evaluation method according to claim 1, wherein the milk is stored at 15 to 40°C.

3. 3. The flavor evaluation method according to claim 1, wherein the quantification step is a step of quantifying the content of the (Z)-6-dodecen-4-olide contained in the milk by a GC-MS method.

4. The flavor evaluation method according to claim 1 or 2, further comprising a calculation step of calculating an increase rate of the (Z)-6-dodecen-4-olide using the following formula (1): Increase rate = (Z)-6-dodecen-4-olide content (μg / 100 g) contained in the milk after an arbitrary storage period has elapsed / (Z)-6-dodecen-4-olide content (μg / 100 g) contained in the milk at 0 days of storage period (1)

5. 3. The flavor evaluation method according to claim 1, wherein the milk is one selected from cow's milk, special cow's milk, pasteurized goat's milk, adjusted milk, low-fat milk, non-fat milk, processed milk, and milk drinks.

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