Method for confirming nutrient attenuation of frozen food

Abstract

This method for confirming nutrient attenuation of a frozen food is characterized by including a step for performing an acceleration test on a frozen food at a temperature of 0°C or higher and under a high-pressure condition of 90 MPa or greater, and a step for analyzing nutrients contained in the frozen food subjected to the acceleration test. The method is further characterized in that the nutrient to be confirmed is at least one of retinol, α-carotene, β-carotene, β-cryptoxanthin, vitamin D, α-tocopherol, vitamin K, vitamin B1, vitamin B2, niacin, vitamin B6, vitamin B12, folic acid, pantothenic acid, biotin, vitamin C, n-3-based polyunsaturated fatty acids, and n-6-based polyunsaturated fatty acids.

Description

How to check for nutrient loss in frozen foods

[0001] The present invention relates to a method for checking the nutrient decay of frozen foods.

[0002] In recent years, with the diversification of lifestyles, products called "optimized nutrition foods" that claim to allow easy intake of the daily required nutrients have been launched on the market. These products contain more than one-third of the daily required amount of essential nutrients as set out in the nutrient labeling standards established by the Ministry of Health, Labour and Welfare and the Dietary Reference Intakes for Japanese people, also established by the Ministry of Health, Labour and Welfare. In addition to these, there are also products such as semi-complete foods that are almost complete but lack only a few nutrients, and supplements that only supplement specific nutrients, and many foods have been launched on the market that allow easy supplementation of necessary nutrients that are lacking in daily diets.

[0003] Japanese Patent Application Publication No. 2003-274894

[0004] However, some nutrients contained in foods, not just optimized nutrition foods, decay over time. Therefore, products that claim to provide essential nutrients must have nutrients within the range of the Dietary Reference Intakes for Japanese (2020) established by the Ministry of Health, Labor and Welfare at the time of manufacture and within the expiration date.

[0005] The preferred method for measuring nutrient decay is to measure it sequentially over time. However, this method has the problem of taking a significantly long time to obtain the desired results. Therefore, accelerated testing is commonly used. Here, accelerated testing is a method of shortening the test period by changing the test environment. Specifically, it is performed by storing the product in an environment with higher temperature, humidity, etc. than the distribution, sales, and storage temperatures.

[0006] Accelerated testing is a very efficient method for foods stored at room temperature. However, it is not a practical method for chilled or frozen foods. Frozen foods, in particular, are required to be stored at temperatures below -15°C, so raising the temperature above -15°C could lead to bacterial growth, making the test itself unworkable. For this reason, there is currently no established accelerated testing method for frozen foods.

[0007] The present invention aims to provide a method for efficiently measuring the decay of nutrients in frozen foods without causing bacterial growth, even when the frozen foods are placed in a temperature environment higher than the distribution, sales, and storage temperatures.

[0008] The inventors of the present invention conducted extensive research to solve the above problems and discovered that by raising the temperature of frozen foods in a high-pressure environment, it is possible to prevent bacterial growth while also being able to check the decay of nutrients contained in frozen foods in a shorter time than conventional methods, which led to the completion of the present invention.

[0009] In order to solve the above problem, the method for confirming nutrient decay in frozen foods of the present invention is characterized by including a step of conducting an accelerated test on frozen foods under conditions of 0°C or higher and high pressure of 90 MPa or higher, and a step of analyzing the nutrients contained in the frozen foods that have undergone the accelerated test.

[0010] According to this configuration, the high pressure conditions prevent bacterial growth, while the heating allows the decay of nutrients to be examined in a short period of time.

[0011] In the above configuration, the accelerated test is preferably performed at a temperature of 10 to 60°C and under a high pressure of 90 to 600 MPa. Furthermore, the nutrients to be confirmed are preferably at least one of retinol, α-carotene, β-carotene, β-cryptoxanthin, vitamin D, α-tocopherol, vitamin K, vitamin B1, vitamin B2, niacin, vitamin B6, vitamin B12, folic acid, pantothenic acid, biotin, vitamin C, n-3 polyunsaturated fatty acids, and n-6 ​​polyunsaturated fatty acids.

[0012] With this configuration, even for nutrients that do not show a tendency to decay easily, the tendency to decay can be observed in a short period of time.

[0013] The present invention makes it possible to check the nutrient decay of frozen foods using accelerated testing, which was previously impossible. This allows us to check the nutrient decay without the usual time lapse, allowing us to design products without being restricted by cooking methods.

[0014] This figure shows the attenuation of vitamin D, α-tocopherol, vitamin K, and vitamin B1 when a frozen food (dandan noodles) was subjected to accelerated testing according to the present invention and a conventional method. The vertical axis shows relative values ​​when the measured values ​​of nutrients before the storage test are set to 100, and the horizontal axis shows the number of days. This figure shows the attenuation of vitamin B2, vitamin B6, vitamin B12, and folic acid when a frozen food (dandan noodles) was subjected to accelerated testing according to the present invention and a conventional method. The vertical axis shows relative values ​​when the measured values ​​of nutrients before the storage test are set to 100, and the horizontal axis shows the number of days. This figure shows the attenuation of pantothenic acid, biotin, n-3 polyunsaturated fatty acids, and n-6 ​​polyunsaturated fatty acids when a frozen food (dandan noodles) was subjected to accelerated testing according to the present invention and a conventional method. The vertical axis shows relative values ​​when the measured values ​​of nutrients before the storage test are set to 100, and the horizontal axis shows the number of days. This figure shows the attenuation of vitamin C when a frozen food (dandan noodles) was subjected to accelerated testing according to the present invention and a conventional method. The vertical axis shows the relative values ​​when the measured values ​​of nutrients before the storage test are set to 100, and the horizontal axis shows the number of days. This figure shows the attenuation of vitamin D, vitamin K, vitamin B1, and vitamin B2 when a frozen food (beef bowl) was subjected to accelerated testing according to the present invention and a conventional method. The vertical axis shows the relative values ​​when the measured values ​​of nutrients before the storage test are set to 100, and the horizontal axis shows the number of days. This figure shows the attenuation of vitamin B6, vitamin B12, folic acid, and pantothenic acid when a frozen food (beef bowl) was subjected to accelerated testing according to the present invention and a conventional method. The vertical axis shows the relative values ​​when the measured values ​​of nutrients before the storage test are set to 100, and the horizontal axis shows the number of days. This figure shows the attenuation of biotin and vitamin C when a frozen food (beef bowl) was subjected to accelerated testing according to the present invention and a conventional method. The vertical axis shows the relative values ​​when the measured values ​​of nutrients before the storage test are set to 100, and the horizontal axis shows the number of days. This figure shows the attenuation of vitamin D, vitamin B1, vitamin B2, and vitamin B6 when a frozen food (curry) was subjected to accelerated testing according to the present invention and a conventional method. The vertical axis shows the relative value when the measured value of nutrients before the storage test is set to 100, and the horizontal axis shows the number of days. This figure shows the decay of vitamin B12, folic acid, pantothenic acid, and biotin when a frozen food (curry) was subjected to accelerated tests according to the present invention and the conventional method.The vertical axis shows relative values ​​when the measured values ​​of nutrients before the storage test are set to 100, and the horizontal axis shows the number of days. This is a diagram showing the attenuation of vitamin C when a frozen food (curry) was subjected to accelerated testing according to the present invention and a conventional method. The vertical axis shows relative values ​​when the measured values ​​of nutrients before the storage test are set to 100, and the horizontal axis shows the number of days. This is a diagram showing the attenuation of vitamin D, folic acid, and vitamin C when a frozen food (curry) was subjected to accelerated testing according to the present invention (400 MPa) and a conventional method. The vertical axis shows relative values ​​when the measured values ​​of nutrients before the storage test are set to 100, and the horizontal axis shows the number of days.

[0015] The present invention will be described in detail below, but the present invention is not limited to the following description.

[0016] <Frozen Foods> There are no particular limitations on the frozen foods that can be used in the present invention. All commercially available frozen foods can be used. The frozen foods can be in the form of processed foods such as rice dishes, noodles, fillings, pizza, gratin, side dishes, soups, and desserts, as well as uncooked foods such as cut vegetables and fruits. In addition, any cooking method (natural thawing, microwave heating, hot water bath, etc.) can be used when eating.

[0017] <Nutrients> The nutrients targeted in the present invention are preferably those known to decay over time as individual nutrients. Specific examples include retinol, α-carotene, β-carotene, β-cryptoxanthin, vitamin D, α-tocopherol, vitamin K, vitamin B1, vitamin B2, niacin, vitamin B6, vitamin B12, folic acid, pantothenic acid, biotin, vitamin C, n-3 polyunsaturated fatty acids, and n-6 ​​polyunsaturated fatty acids. In the present invention, a single nutrient can be examined, but multiple nutrients can also be examined.

[0018] <Pressure> The present invention is characterized by the use of high pressure. Here, high pressure refers to a pressure of 90 MPa or more, more preferably 100 MPa or more. Pressures below 90 MPa are undesirable because they may cause bacterial growth. On the other hand, pressures above 600 MPa significantly limit the products and volumes that can be measured, so a pressure of 600 MPa or less is preferable, and 400 MPa or less is more preferable.

[0019] <Accelerated Test> In the present invention, it is preferable to conduct an accelerated test at a temperature of 0°C or higher, which is higher than the -15°C temperature at which frozen foods are distributed, sold, and stored. Specifically, a temperature of room temperature (23°C) or higher is preferable, a temperature of 40°C or higher is more preferable, and a temperature of 50°C or higher is even more preferable. Of these, a temperature of 50°C or higher is preferable in order to examine the decay of nutrients over a short period of time. On the other hand, there is no particular upper limit to the temperature, but it is preferably 100°C or lower.

[0020] The humidification conditions in the present invention are not particularly limited.

[0021] In the present invention, an apparatus capable of heating while maintaining pressurized conditions is preferred. As an example, an apparatus manufactured by Toyo Koatsu Co., Ltd. can be used. By using such an apparatus, it is possible to change the temperature conditions while maintaining the pressurized conditions constant.

[0022] The accelerated testing method is similar to existing methods: multiple identical samples are prepared and heated under pressure. Over time (e.g., monthly), one sample is extracted from the multiple samples and the nutrient content is measured. Nutrient analysis can be performed using existing methods, such as high-performance liquid chromatography (HPLC), microbiological assays, liquid chromatography-tandem mass spectrometry (LC-MS / MS), and gas chromatography.

[0023] <Confirmation of Microbial Growth at Room Temperature Due to Pressurization> First, the effect of pressurization on microbial growth inhibition was confirmed. A commercially available frozen food (chicken in tomato sauce: manufactured by Nissin Food Products Co., Ltd.) was placed in a device manufactured by Toyo Koatsu Co., Ltd. and tested. The test conditions were a temperature of 25°C and a pressure of 100 MPa, 40 MPa, or 10 MPa, and the food was left for five days. After five days, the presence or absence of microorganisms was confirmed using a known test method. The results are shown in Table 1.

[0024]

[0025] As is clear from Table 1, the effect of inhibiting the growth of microorganisms was observed when a pressure of 40 MPa or more was applied.

[0026] <Confirmation of Nutrient Decay> Next, we confirmed the decay of nutrients. The confirmation test was carried out by measuring and comparing the amount of nutrients contained in products stored under different conditions. The test conditions were as follows.

[0027] <<Frozen Storage>> To check the loss of nutrients due to frozen storage, the samples were placed in an environment of −20° C. and normal pressure, and the loss of nutrients was checked after 6 months and 12 months.

[0028] <<Pressurized High-Temperature Storage>> To confirm the attenuation of nutrients due to pressurized high-temperature storage, the product was placed in an environment of 50° C. and 90 MPa, and the attenuation of nutrients was confirmed after 2 weeks and 4 weeks.

[0029] In this example, under each test condition, tests were conducted using samples from the same lot for three types of products (Complete Meal Dandan Noodles, Complete Meal Beef Bowl, Complete Meal European-Style Curry: all manufactured by Nissin Food Products Co., Ltd.).

[0030] The amount of nutrients contained in each sample was measured before and after the storage test. Vitamins B1, B2, C, α-tocopherol, and vitamin K were measured using HPLC. Vitamins B6, B12, biotin, pantothenic acid, and folic acid were measured using a microbiological assay. Vitamin D was measured using liquid chromatography-tandem mass spectrometry. n-3 unsaturated fatty acids and n-6 ​​unsaturated fatty acids were measured using gas chromatography. Based on the obtained measurements, an approximate equation was calculated, and the slope of the approximate equation for each nutrient was determined. The results are shown in Figures 1 to 10. The vertical axis shows the relative value when the measured value of the nutrient before the storage test is set to 100, and the horizontal axis shows the number of days.

[0031] As shown in Figures 1 to 10, differences in the slope of the approximation equations were observed for each sample and / or nutrient. Furthermore, although there were some exceptions, it was found that the slopes of almost all of the storage methods according to the present invention (pressurized at high temperature) were steeper than those of the conventional method (frozen storage). On the other hand, although not shown in the figures, there were also cases where the slopes were nearly the same as those of the conventional method, or where the slopes increased. Here, since food deteriorates over time, it is common for the nutrients contained in food to decrease. However, as described in various papers (e.g., "Interlaboratory Collaborative Study on Quantitative Analysis of Vitamin D in Foods Using the Official Method and Its Modifications," Vitamins, 85(12), 645-650 (2010) and "Analysis Method of Vitamins in Foods Recommended and Officially Used in Japan," Vitamins, 73(11), 649-657 (1999)), nutrients are also substances that are prone to measurement errors. Therefore, in this example, data was treated as valid unless the slope exceeded +1.1. The present invention can also be applied to nutrients not listed in Figures 1 to 10.

[0032] Next, comparing Figures 1 to 4, Figures 5 to 7, and Figures 8 to 10, it can be seen that there are differences in the decay of nutrients even for the same nutrients. This is thought to be due to differences in the decay of nutrients depending on the cooking method. In this way, it can be said that the present invention is very effective even when the decay of nutrients differs depending on the sample.

[0033] Next, we will further examine the decay of nutrients. Looking at Figures 1, 5, and 8 for Vitamin D, we can see that almost no decay was observed in any of the samples tested using the conventional frozen storage method (referred to as "conventional" in the figures, and the same applies below), and the values ​​were nearly flat. In contrast, in the test using pressurized high-temperature storage method (referred to as "present invention" in the figures, and the same applies below), nutrient decay was observed in all of the samples. Of these, the slopes of the dandan noodles (Figure 1) and curry (Figure 8) were nearly the same. On the other hand, the slope of the beef bowl (Figure 5) was gentler than the other two, but the decay-accelerating effect was easily confirmed in all of the samples.

[0034] α-Tocopherol Measurement errors are likely to occur in α-tocopherol, and the results were only obtained for dandan noodles (Figure 1). While the conventional method showed a nearly flat result, a decrease was observed with the pressurized high-temperature storage method.

[0035] "Vitamin K" Vitamin K was confirmed for dandan noodles (Figure 1) and beef bowls (Figure 5). With the conventional method, there was a slight upward trend in both foods, but this is thought to be within the margin of error. This suggests that vitamin K is less likely to decay. On the other hand, with the pressurized high-temperature storage method, it is clear that vitamin K decays. Of these, the slope for dandan noodles is steep, about twice that of beef bowls. Furthermore, the results showed that the decay-accelerating effect was easily confirmed in both samples.

[0036] "Vitamin B1" Figures 1, 5, and 8 show a slight upward trend in all samples using the conventional method, but this is thought to be within the margin of error. This suggests that vitamin B1 is less likely to decay. On the other hand, decay was observed in all samples using the pressurized high-temperature storage method. The magnitude of the slope was Dandan noodles (Figure 1) > Beef bowl (Figure 5) ≒ Curry (Figure 8). Furthermore, the decay-accelerating effect was easily confirmed in all samples.

[0037] "Vitamin B2" Figures 2, 5, and 8 show that vitamin B2 decayed in both the conventional method and the pressurized high-temperature storage method. With the conventional method, the results showed that the slope was greatest for dandan noodles > beef bowl > curry (the slope decreased by half for each step). On the other hand, with the pressurized high-temperature storage method, the results were that beef bowl > dandan noodles ≒ curry. Furthermore, the results showed that the decay-accelerating effect was easily confirmed in all samples. Taking dandan noodles as an example, it can be seen that one month's worth of the pressurized high-temperature storage method is equivalent to approximately seven months' worth of the conventional method.

[0038] "Vitamin B6" With the conventional method, a decrease in vitamin B6 was only observed in dandan noodles (Figure 2), but no decrease was observed in beef bowls (Figure 6) or curry (Figure 8), with the results remaining almost flat. In contrast, with the pressurized high-temperature storage method, a decrease was observed in all samples. With the conventional method, the results showed a greater slope in the order of dandan noodles > beef bowls > curry (the degree of slope decreased by half for each sample). On the other hand, with the pressurized high-temperature storage method, the results were that beef bowls > dandan noodles were approximately equal to curry. Taking dandan noodles as an example, we can see that one month's use of the pressurized high-temperature storage method is equivalent to approximately 12 months' use of the conventional method.

[0039] "Vitamin B12" With the conventional method, a slight decrease in vitamin B12 was observed only in dandan noodles (Figure 2), but no decrease was observed in beef bowls (Figure 6) and curry (Figure 9), and the results were almost flat. In contrast, with the pressurized high-temperature storage method, decrease was observed in all samples. Of these, the decrease effect was most easily observed in curry. The order of the slope was curry > dandan noodles > beef bowl. Using dandan noodles as an example, it can be seen that one month's use of the pressurized high-temperature storage method is equivalent to approximately 12 months' use of the conventional method.

[0040] "Folic Acid" Figures 2, 6, and 9 show that almost no decay was observed in any of the samples using the conventional method, and that the results are nearly flat. In contrast, with the pressurized high-temperature storage method, the order of the slope was Dandan noodles = curry > beef bowl, making it easy to confirm the decay-accelerating effect.

[0041] "Pantothenic acid" Figures 3, 6, and 9 show that in all samples using the conventional method, there was a slight upward trend, and no decay was observed. In contrast, in the case of the pressurized high-temperature storage method, the order of the slope was curry > beef bowl > dandan noodles, making it easy to confirm the decay-accelerating effect.

[0042] Biotin: Looking at Figures 3, 7, and 9, the results show that with the conventional method, the slope was larger for dandan noodles > beef bowl > curry. On the other hand, with the pressurized high-temperature storage method, the slope was larger for beef bowl > curry. However, no attenuation was observed with dandan noodles, and the results were almost flat. Taking beef bowls as an example, we can see that one month of pressurized high-temperature storage corresponds to approximately 12 months of the conventional method. Furthermore, in the case of curry, we can see that one month of pressurized high-temperature storage corresponds to approximately 290 days of the conventional method.

[0043] "n-3 polyunsaturated acids" and "n-6 polyunsaturated acids" For n-3 polyunsaturated acids and n-6 ​​polyunsaturated acids, results were only obtained for dandan noodles (Figure 3). While the conventional method showed a nearly flat result, the pressurized high-temperature storage method showed a decay, making it easy to confirm the decay-accelerating effect. Furthermore, between n-3 polyunsaturated acids and n-6 ​​polyunsaturated acids, n-3 polyunsaturated acids decayed faster.

[0044] "Vitamin C" With regard to vitamin C, decay was observed in dandan noodles (Figure 4) and curry (Figure 10) using the conventional method, but no decay was observed in beef bowl (Figure 7), and the results were almost flat. On the other hand, decay was observed in all samples using the pressurized high-temperature storage method. The magnitude of the slope was curry > beef bowl > dandan noodles. Taking curry as an example, it can be seen that one month's worth of the pressurized high-temperature storage method is equivalent to approximately 400 days' worth using the conventional method. Furthermore, the results showed that the decay-accelerating effect was easily confirmed in all samples.

[0045] Next, the samples were placed in an environment of 50 ° C and 400 MPa to check the decay of nutrients after 1 to 4 weeks. In this example, samples from the same lot were used and tested with Complete Meshi European-style Curry (manufactured by Nissin Food Products Co., Ltd.).

[0046] The amount of nutrients contained in each product was measured for each sample before and after the storage test. Vitamin D was measured using liquid chromatography-tandem mass spectrometry. Vitamin C was measured using HPLC. Folic acid was measured using a microbiological quantification method. Based on the obtained measurements, an approximate equation was calculated, and the slope of the approximate equation for each nutrient was determined. Here, Figure 11 shows nutrients that were found to have an even greater decay-accelerating effect than the above-mentioned 90 MPa.

[0047] "Vitamin D" Comparing Figure 8 and Figure 11, it can be seen that the slope of the approximation line at 400 MPa is approximately 23% higher than at 90 MPa. This suggests that vitamin D not only promotes damping through heating, but also has the effect of promoting damping through pressure when high pressure is applied.

[0048] 9 and 11, it can be seen that the slope of the approximation line at 400 MPa is approximately 36% higher than that at 90 MPa. This suggests that folic acid not only promotes damping by heating, but also has the effect of promoting damping by pressure when high pressure is applied.

[0049] "Vitamin C" Comparing Figures 10 and 11, we can see that the slope of the approximation line at 400 MPa is approximately 660% higher than at 90 MPa. This suggests that vitamin C not only accelerates decay through heating, but also accelerates decay through pressure by applying high pressure. In fact, it takes four weeks to achieve -20% decay at 90 MPa, while at 400 MPa, combined with the accelerated decay effect of pressure, it achieves -60% decay in one week.

[0050] Furthermore, no decay due to microbial growth was observed during any of the tests.

[0051] As explained above, according to the present invention, it is possible to check the nutrient decay of frozen foods in a short time, which was previously only possible under limited conditions to prevent bacterial growth. Furthermore, by applying high pressure, it is possible to combine not only heating but also the decay-accelerating effect of high pressure, so that nutrient decay can be checked even more quickly. This has the extremely advantageous effect of allowing product design without being limited by cooking methods.

Claims

1. A method for confirming nutrient decay in frozen foods, comprising the steps of: conducting an accelerated test on the frozen food; and analyzing the nutrients contained in the frozen food after the accelerated test, wherein the accelerated test is conducted at a temperature of 0°C or higher and under high pressure conditions of 90 MPa or higher.

2. The method for checking the nutrient decay of frozen foods according to claim 1, wherein the accelerated test is carried out under conditions of 10 to 60°C and high pressure of 90 to 600 MPa.

3. A method for confirming nutrient decay in frozen foods according to claim 1 or 2, wherein the nutrient is at least one of retinol, α-carotene, β-carotene, β-cryptoxanthin, vitamin D, α-tocopherol, vitamin K, vitamin B1, vitamin B2, niacin, vitamin B6, vitamin B12, folic acid, pantothenic acid, biotin, vitamin C, n-3 polyunsaturated fatty acids, and n-6 ​​polyunsaturated fatty acids.

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