JPH08114586A - Taste evaluating method for skimmilk - Google Patents

Abstract

PURPOSE: To objectively evaluate an offensive odor component by determining a specified offensive odor component by means of gas chromatography-mass spectrometry (GC-MS) by single ion monitoring method (SIM method). CONSTITUTION: The aroma component in skimmilk was first concentrated, the resulting aroma concentration was fractionated by thin-layer chromatography, and a fine fractionation is further performed for a functionally recognized fraction by sampling GC-smelling method to evaluate the smell. At a result, tetradecanal, β-ionone, and benzothiazole were judged as offensive odor related components. As an easy determination method for offensive odor component, SIM method by GC-MS was adapted, the fragment to be monitored was further examined for mass number, quantitative property, and reproducibility to set the standard areas of tetradecanal and β-ionone in skimmilk to 24-27ppb and 0.25-0.35ppb, respectively, and when these components are present beyond these areas, the presence of an offensive odor is recognized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for evaluating the flavor of skim milk powder, and more specifically, in the flavor evaluation of foods which are difficult to objectively evaluate, the odor components are analyzed by instrumental analysis of skim milk powder. The present invention relates to a method for quantifying and objectively and accurately evaluating the flavor.

[0002]

2. Description of the Related Art Food quality judgment has changed greatly from nutritional value to palatability and soundness. Among them, fragrance is becoming more and more important as the first criterion for food selection. Although skimmed milk powder is often used as a raw material for dairy products, it is often a problem that products with deteriorated flavor, especially products with off-flavor, are mixed.

Naturally, skim milk powder having an offensive odor has a remarkably poor commercial value, but is particularly unsuitable as a raw material for high-quality dairy products. Therefore, there is a strong demand in the art for elucidating the offensive odor of skim milk powder and for establishing an objective flavor and quality evaluation method in place of sensory evaluation, which has a strong subjective aspect and is not nearly efficient.

[0004]

In order to meet such a strong demand of the industry, an attempt was made to separate off-flavor components of skim milk powder, but the off-flavor components are in trace amounts, and peak separation cannot be performed completely. Therefore, FID that gives a non-selective response
Direct quantification of off-flavor components by the GC method (gas chromatography) using (flame ionization detector) was not successful.

Moreover, even if the amount of the offensive odor component is extremely small, the human sense of smell can fully sense it, and if the intensity of the sensory offensive odor and the type and concentration of the offensive odor component match. However, it was extremely difficult to objectively evaluate the offensive odor.

As described above, according to the present invention, not only the odor, which has been unsuccessful in the prior art, can be easily quantified as a subjective component, that is, a subjective component that is sensitive to perception even in a very small amount. This was done for the purpose of establishing and establishing a new recognizable objective evaluation standard.

[0007]

The present invention has been made in order to achieve the above-mentioned object, and sets a simple quantification method for an offensive odor component, and at the same time, sets the intensity of the offensive odor and the concentration of the offensive odor component. This was done to clarify the relationship between the two and to construct an objective evaluation method for offensive odors.

Therefore, the offensive odor component was identified. Therefore, first, the aroma components in skim milk powder were concentrated, and the resulting aroma concentrate was fractionated by TLC (thin layer chromatography). Fractions with a sensory odor were collected by GC.
-As a result of further fractionation by an odor sniffing method to evaluate odor, it was determined that tetradecanal, β-ionone and benzothiazole were components related to off-flavor.

[0009] Then, as a result of examining from various directions in order to set up a simple quantitative method for the offensive odor component, GC-MS (Gas C
chromatograph-Mass Spectro
Single ion monitoring method (S)
IM method), and further examined the mass number, quantification, reproducibility, etc. of the fragments to be monitored, and as a result, this method has high sensitivity and is capable of quantifying offensive odor components over a wide concentration range. It was confirmed that the reproducibility of the measurement was good, and it was found that it was the most suitable method for the quantitative determination of off-flavor components in skim milk powder.

Further, as a result of the sensory evaluation by the three-point discrimination method, the number of panels for which correct answers were obtained, the significance of discrimination, and the concentration of tetradecanal and β-ionone in each skimmed milk powder,
The standard area for offensive odor certification is 24 for tetradecanal.
~ 27 ppb, 0.25-0.3 for β-ionone
It was set to 5 ppb, and it was confirmed that a strange odor was recognized when these components were present above this region. Thus, for example, the former is 25 ppb and / or the latter is 0.3 ppb
If the above is present, it is certified that an offensive odor is clearly recognized.

As described above, an objective evaluation method and evaluation standard for the odor of skim milk powder by instrumental analysis could be set. Hereinafter, the present invention will be described in more detail with reference to Examples.

[0012]

Example 1 (1) Five kinds of domestic skim milk powder (normal products) (n1 to n5) having a normal flavor and seven kinds of imported skim milk powder (abnormal products) (o1 to o7) having a strange odor The off-flavor components therein were quantified. That is, 300 g of skim milk powder and 900 m of deionized water
After adding 1 and homogenizing, the aroma component was extracted by the vacuum continuous distillation extraction method. The sample temperature is 60 ° C for distillation,
It was performed under 150 mmHg for 1 hour, and 80 ml of diethyl ether was used as an extraction solvent. Next, naphthalene was added to the resulting extract as an internal standard for skim milk powder at 10 ppb.
And dehydrated with anhydrous sodium sulfate,
It was concentrated to about 0.2 ml and used as it was as a sample for SIM method.

(2) Mass spectrometry of naphthalene and three kinds of offensive odor components (tetradecanal, β-ionone, benzothiazole) were carried out. These standard mass spectra are shown in FIG. Considering the background noise, the mass spectrum of the components that elute before and after the offensive odor component, and the intensity of each fragment peak of the offensive odor component, naphthalene has m / z
Value 128, tetradecanal 82, β-ionone 17
7. Benzothiazole was determined to be suitable for monitoring 108 and 135 fragment ions.

(3) A calibration curve for quantifying these offensive odor components was prepared. As a result, as shown in FIG. 2, tetradecanal was 1.6 to 50 ppb and β-ionone was 0.02 to 0.02.
0.75 ppb, benzothiazole 0.08-2.5
A good linear relationship with a correlation coefficient of 0.99 or more was obtained between the concentration and the peak area ratio with respect to the internal standard in the ppb range. According to this method, the offensive odor component in skim milk powder was actually quantified and the reproducibility was examined. As a result, the relative standard deviation of 5 repetitions was 4.8 to 5.7%.

(4) Twelve kinds of skimmed milk powder (n1 to n5 and o1 to o7) produced in different production lots were quantified for the offensive odor components, and the results shown in Table 1 below were obtained.

[0016]

[Table 1]

As is clear from the above results, a significant difference in the offensive odor component concentration was found between the normal product and the abnormal product. That is, the concentration of tetradecanal in the normal product is 17.0.
22.0 ppb, whereas 29.6 in abnormal products
.About.49.1 ppb, and there was a difference of two times or more in average value between the two. As for β-ionone, the normal product had a range of 0.11 to 0.19 ppb, while the abnormal product had a concentration difference of 0.41 to 1.12, which is more than double, and the average value is close to five times. It became clear that there is.

In addition, no significant difference was observed in the concentrations of these compounds between normal products,
In the abnormal product, the difference in concentration was extremely large. This strongly suggests that these components are the causative components of the off-flavor of skim milk powder.

On the other hand, regarding benzothiazole, 0.17 to 0.58 ppb for the normal product and 0.47 to 1.8 for the abnormal product.
The concentration range was 22 ppb and both concentration ranges partially overlapped, but n4, n5, o5 and o6 in this range were found.
Except for, the abnormal product had higher benzothiazole concentration, and the average value was 0.40 ppb and 0.8, respectively.
A 2-fold difference was observed with 0 ppb. Therefore, it was speculated that this compound does not directly cause an offensive odor, but contributes to the development of an offensive odor when tetradecanal or β-ionone is present to some extent.

(5) Furthermore, the relationship between the intensity of the sensory offensive odor and the concentrations of these offensive odor components was examined. First, arrange each skim milk powder in order of concentration based on the concentration of tetradecanal,
It was classified into 6 groups of A to F shown in FIG. From the 6 groups, n5 was used as a control, and each one type of nonfat dry milk, that is, n2, o6, o7, o4 and o2 was selected from each of the B to F groups. It was evaluated sensually.

That is, among the three kinds of offensive odor components, tetradecanal is found to be the most important offensive odor component because of its high concentration and strong odor.
Two kinds of skim milk powder were arranged in order of concentration and classified. From each of these groups, one kind was selected, and the strength of the offensive odor was sensory evaluated by a three-point discrimination method. In addition, skim milk powder is 14%
The product reduced to (w / v) was heated to 55 ° C. and then given to each panelist for sensory evaluation.

Similar results were obtained when the classification was performed based on the β-ionone concentration, and therefore the relationship between the tetradecanal and β-ionone concentrations and the offensive odor intensity was examined below. FIG. 4 shows the results. The bar graph in the figure shows the number of panels that got the correct answer, and the line graph shows the probability (P value) of getting the correct answer by chance. As is clear from the figure, the difference between the contents of tetradecanal and β-ionone was the smallest, and the control and n2 could not be distinguished at a risk rate of 5%, whereas the other four skim milk powders were all controls. It was judged that the odors of the normal product group and the abnormal product group were sensory different.

However, although a sensory difference was observed between the normal product group and the abnormal product group, the number of panels that gave a correct answer and the concentration of tetradecanal or β-ionone (Table 1). Has no correlation,
It was also considered that the panel responded to differences in aroma characteristics other than off-flavor.

Therefore, in order to reduce the difference in aroma composition other than the offensive odor component, a mixture of a normal product and an abnormal product in a fixed ratio was used as a comparative sample, and a sensory evaluation was similarly performed by the three-point discrimination method. That is, the comparative samples were samples A to D and o6 in which n5 and o6 having the lowest tetradecanal and β-ionone contents in the normal product group and the abnormal product group were mixed at the ratio shown in FIG. 5 (A). Used as control n
5 was used. Note that (B) and (C) in the figure show the concentrations of tetradecanal and β-ionone in these comparative samples and controls. FIG. 6 shows the results.

As is clear from the figure, as the contents of tetradecanal and β-ionone increased, the number of panels that gave correct answers also increased. As a result of the significance test, it was revealed that neither the control nor the mixed samples A to C could be distinguished at the risk rate of 5%, whereas D and o6 could be significantly distinguished from the control.

From the above results, the reference area for the offensive odor recognition is:
Considering that a synergistic effect may be exerted depending on the mixing ratio of the offensive odor components, 24-27 ppb for tetradecanal and 0.25-0.25 for β-ionone.
It was confirmed that 0.35 ppb was preferable. In addition, when tetradecanal and β-ionone are present at 25 ppb and 0.3 ppb or more, respectively,
An offensive odor was felt in all cases.

[0027]

Industrial Applicability According to the present invention, a simple method for quantifying off-flavor components in skim milk powder and an objective evaluation method and evaluation standard for the odor of skim milk powder by instrumental analysis can be set.

[Brief description of drawings]

FIG. 1 shows standard mass spectra of naphthalene and three off-flavor components.

FIG. 2 shows a calibration curve for quantifying offensive odor components.

FIG. 3 shows the grouping of each skim milk powder based on the concentration of tetradecanal.

FIG. 4 shows a sensory evaluation of various skim milk powders by a three-point discrimination method.

FIG. 5 shows the preparation of mixed skim milk powder in which various samples n5 and n6 are mixed.

FIG. 6 shows a sensory evaluation of mixed skim milk powder by a three-point identification method.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuya Shimoda 6-10-1 Hakozaki, Higashi-ku, Fukuoka City Faculty of Agriculture, Kyushu University (10) Hideki Shirato 6-10-1 Hakozaki, Higashi-ku, Fukuoka Kyushu University Agriculture Department of Food and Chemical Engineering

Claims (4)

[Claims] 1. A method for evaluating the flavor of skim milk powder, which comprises quantifying tetradecanal and / or β-ionone. 2. A flavor evaluation method for skimmed milk powder, which comprises quantifying one or more of tetradecanal and β-ionone and benzothiazole. 3. Non-fat dry milk is dissolved in water, off-flavor components are extracted by reduced pressure continuous distillation, and the off-flavor components are gas chromatograph by a single ion monitoring method (SIM method).
It quantifies by mass spectrometry (GC-MS), The flavor evaluation method of the skim milk powder of Claim 1 or Claim 2 characterized by the above-mentioned. 4. The flavor of skimmed milk powder according to claim 3, wherein the reference range for the offensive odor certification is 24-27 ppb for tetradecanal and 0.25-0.35 ppb for β-ionone. Evaluation method.