An online method for prompting the impending color change of raw salmon during HPP treatment

Abstract

The present invention discloses a method for online prompting that the color of raw salmon meat is about to change during HPP treatment, including: S1, taking multiple samples of salmon meat to obtain salmon meat samples; S2, mixing the salmon meat samples with water, fully homogenizing and centrifuging, and discarding the supernatant to obtain salmon meat precipitates; S3, setting up a device for carrying an indicator, and putting the sampled salmon meat to be HPP-treated into a high-pressure processing equipment after vacuumizing; S4, before treatment, adding an enzyme preparation to the salmon meat precipitates to obtain an indicator, quickly mixing the indicator evenly, filling it into a packaging bag, vacuumizing and sealing it, and then putting it into the device for carrying the indicator, and immediately performing HPP treatment on the salmon meat; S5, using an instrument to reflect the color change of the indicator in real time through a window, and when a signal of drastic color change occurs, the HPP treatment needs to be ended immediately. This method can maximize the retention of the color of the salmon meat in the fresh state after HPP treatment.

Description

Technical Field

[0001] The present invention relates to the technical fields of raw aquatic product processing and ultra-high pressure application, and particularly relates to a method for online prompting that the color of raw salmon meat is about to change during HPP treatment. Background Art

[0002] In many regions of the world, there is a habit of eating raw salmon. The fresh flavor and taste are the main reasons attracting people to eat raw. Using the non-thermal processing technology of high pressure processing (HPP) can play a bactericidal role at normal temperature or even low temperature, improve the safety of raw salmon, and maintain the fresh quality.

[0003] At present, the technical research on the safety of salmon after HPP treatment has been mature, but there are bottlenecks in the appearance impact. The primary factor for consumers to select the quality of fresh fish is the appearance of the product, and the quality of the appearance will have a great impact on consumers' purchase desire and eating desire. Currently, it is generally believed that salmon has low pressure resistance, and lower pressure will not have too much impact on the fish appearance. However, as the pressure increases to more than 200 MPa and the treatment pressure reaches a certain critical range, the appearance of salmon will mutate, the transparency of the fish meat will decrease, the color will turn white, the redness will decrease, and it will be similar to the cooked appearance after heat treatment.

[0004] This phenomenon is related to the denaturation of myofibrils in fish meat under high pressure, and the structural changes of apolipoprotein combined with astaxanthin and the astaxanthin-actinin embedding matrix caused by pressure. Under the induction of pressure, the quaternary and tertiary structures of proteins will change, the hydrophobic region with the lowest stability will be exposed, the surface hydrophobicity of proteins will increase, and the water holding capacity will decrease. The decrease in redness is related to the treatment time, pressure magnitude, and treatment temperature.

[0005] Moreover, due to the short-term or even instantaneous denaturation of the protein structure or denaturation, and the different qualities, sources, colors, and protein properties of each batch of salmon meat, it is difficult to accurately judge the critical value of pressure, and it is impossible to conduct refined process exploration for each batch in industrial production. Summary of the Invention

[0006] In order to overcome the deficiencies or defects in the above-mentioned existing HPP treatment of salmon meat, where as the pressure increases above 200 MPa and reaches a certain critical range during the treatment, the appearance of the salmon changes, the transparency of the fish meat decreases, the color turns white, the redness decreases, and it shows a cooked appearance similar to heat treatment. The purpose of the present invention is to provide a method for online prompting the impending color change of raw salmon meat during HPP treatment; this method can online monitor, provide real-time feedback, and prompt the time when the color of different batches of salmon meat treated by HPP is about to change by observing the color change of the indicator during the HPP treatment of salmon meat, and it is necessary to immediately end the HPP treatment to ensure that the color of the salmon meat treated by HPP does not turn white due to overpressure. On the basis of ensuring the sterilization effect, it can maximize the preservation of the original fresh color of the salmon meat treated by HPP.

[0007] The present invention is realized through the following technical solutions:

[0008] A method for online prompting the impending color change of raw salmon meat during HPP treatment, comprising the following steps:

[0009] S1. Take multiple samples from the salmon meat to be treated by HPP to obtain salmon meat samples;

[0010] S2. Mix the salmon meat samples with water, homogenize thoroughly, and centrifuge. After discarding the supernatant, obtain salmon meat precipitates;

[0011] S3. Install a device for carrying the indicator near the window in the ultra-high pressure treatment equipment with a window, and put the sampled salmon meat to be treated by HPP into a vacuum packaging bag for vacuum packaging and then put it into the ultra-high pressure treatment equipment;

[0012] S4. Before the start of the HPP treatment of the salmon meat, add an enzyme preparation to the salmon meat precipitates, quickly mix well, load it into a colorless, transparent, and matte vacuum packaging bag, evacuate and seal it, and then put it into the device for carrying the indicator, and immediately carry out the HPP treatment of the salmon meat;

[0013] S5. Use an instrument to reflect the color change of the indicator in real time through the window. When a signal of a drastic color change of the indicator is obtained, determine that this time is the time when the color of the salmon meat is about to change during the HPP treatment, and it is necessary to immediately end the HPP treatment.

[0014] In some embodiments, in step S1, the multiple sampling is to select 1 cm of the surface of different parts of the same batch of salmon meat to be treated by HPP 2 and longitudinally cut the salmon meat.

[0015] In some embodiments, in step S2, the mass ratio of the salmon meat sample to water for mixing is 1:5 - 1:10; the homogenization equipment for sufficient homogenization is selected from a high-speed tissue homogenizer.

[0016] In some embodiments, in step S2, the centrifugation is carried out at a rotational speed of 1000 - 1000 rpm for 1 - 10 minutes.

[0017] In some embodiments, in step S3, the device for carrying the indicator is a bracket that can make the indicator closely adhere to the inner wall of the viewing window in the treatment chamber of the HPP equipment, and an external light source and an instrument for reflecting the color change of the indicator are arranged outside the viewing window, and the color of the indicator can be monitored through the outer wall of the viewing window.

[0018] In some embodiments, in step S3, the color of the salmon meat to be treated by HPP is bright orange, orange or pinkish red.

[0019] In some embodiments, in step S4, the indicator is an enzyme preparation whose enzyme activity needs to be maintained above 50% under the conditions of 360 MPa and 5 minutes; the enzyme preparation is selected from at least one of lipoxygenase, polyphenol oxidase, and peroxidase.

[0020] In some embodiments, in step S4, the mass of the salmon meat precipitate is taken as 10 - 100 g; the addition amount of the enzyme preparation is 0.1‰ - 1% of the mass of the fish meat precipitate.

[0021] In some embodiments, in step S5, the instrument for reflecting the color change of the indicator is an instrument that can convert the color into an electrical signal or data in real time, and can continuously measure the color of the indicator during the HPP treatment process. At the same time, through a certain computer program, the color difference between the color of the indicator and the color of the indicator measured in the previous measurement can be calculated in real time, and a device that gives a prompt when the color changes violently; specifically selected from a color difference meter, a colorimeter, a spectrophotometer or a hyperspectral imager.

[0022] In some embodiments, in step S5, when obtaining a signal that the indicator has a violent color change, it means that the color of the indicator changes from orange or pinkish red to light orange or light pink rapidly, and the color difference value increases in terms of the signal.

[0023] In some embodiments, in steps S3 and S4, the vacuum packaging bag material must have a certain flexibility, can transmit pressure and be pressure-resistant, has strong sealing and barrier properties, and can prevent the leakage of substances inside the package or the infiltration of pressure media outside the package.

[0024] In some embodiments, in step S4, the HPP treatment conditions for the salmon meat are: 260 MPa ≤ pressure ≤ 360 MPa.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) In the present invention, multi-point sampling is performed on the salmon meat to be HPP-treated, and then it is mixed with water and fully homogenized. The precipitated salmon meat after centrifugation is added with enzyme preparations of specific types and specific contents as indicators. During the HPP treatment of the salmon meat, the color of the indicator is observed for real-time online monitoring. When the treatment reaches a certain pressure, the tertiary structure of the apolipoprotein or actin in the precipitated salmon meat is damaged, and the hydrophobic area astaxanthin embedded in the apolipoprotein or actin is exposed. This astaxanthin will contact the externally added enzyme preparation indicator and undergo a hydrogenation reaction, resulting in color degradation, quickly fading from orange or pinkish-red to light pink and then to white. At this time, the strong signal of the color change indicates that the HPP treatment of the salmon meat has reached the critical value of protein color change, and the HPP treatment of the salmon meat can be stopped, ensuring that the color of the salmon meat does not turn white due to overpressure. On the basis of ensuring the sterilization effect, the color of the salmon meat in its original fresh state can be maximally maintained after HPP treatment.

[0027] (2) The online indication method of the present invention is simple and easy to operate, accurate and reliable, has good repeatability, and is easy to realize industrial production. Specific embodiments

[0028] The present invention will be further described below through specific embodiments. The following embodiments are specific embodiments of the present invention, but the embodiments of the present invention are not limited by the following embodiments.

[0029] The test methods for each performance index are as follows:

[0030] Indication method for sterilization effect:

[0031] The total number of colonies is determined according to the method specified in GB 4789.2. During the determination, the salmon in the sealed bag / vacuum bag is opened in the sterile area, sampled, and the fish meat is evenly crushed. A certain mass of the fish meat is diluted with sterile physiological saline into a homogenate with a suitable gradient, and the total number of colonies is determined. The test plate is cultured in an environment of 30 ± 1 °C for 72 ± 3 h, and the total number of colonies is calculated. The result is expressed as CFU / g. According to GB 10136, the total number of colonies in ready-to-eat raw aquatic products shall not be higher than 5×10 4 CFU / g.

[0032] Indication method for the color change of the indicator:

[0033] The color change of the indicator was measured through the window of the HPP device using a CR-400 full-automatic color difference meter system, and the difference in the average color values at different times was calculated as the total color difference (ΔE). The CIELAB system is often used to evaluate the color change of different processed products and can better reflect the visual change of ultra-high pressure treatment of aquatic products.

[0034]

[0035] Among them, the L* value represents brightness, ranging from 0 (black) to 100 (bright color);

[0036] The a* value represents green-red, ranging from -60 (green) to 60 (red);

[0037] The b* value ranges from blue-yellow, ranging from -60 (blue) to 60 (yellow). It is set to be tested once every 10 s, and it is set to trigger a prompt signal when ∆E≥10.

[0038] The total color difference (ΔE) represents the change in the surface color of the sample before and after treatment. Generally, the smaller the total color difference, the closer the color of the treated sample and the control sample.

[0039] Example 1

[0040] A method for indicating the color change of raw salmon meat during HPP treatment includes the following steps:

[0041] S1. Take multiple samples of the salmon meat to be treated by HPP to obtain salmon meat samples; the mass of the salmon meat samples is 50 g of salmon meat samples / kg of salmon meat;

[0042] S2. Mix the salmon meat samples with water at a mass ratio of 1:8, fully homogenize them using a high-speed tissue homogenizer, and centrifuge at 400 rpm for 4 min; separate the free astaxanthin in the salmon meat by centrifugation, and obtain a salmon meat precipitate after discarding the supernatant;

[0043] S3. Set up a device for carrying the indicator near the window inside the ultra-high pressure treatment device with a window, and put the sampled salmon meat to be treated by HPP into a vacuum packaging bag, vacuum pack it, and then put it into the ultra-high pressure treatment device; the color of the salmon meat to be treated by HPP is bright orange;

[0044] S4. Before the HPP treatment of salmon meat begins, add lipoxygenase with an enzyme activity retention of over 50% (enzyme activity of 60%) under the conditions of 360 MPa and 5 min to 55 g of salmon meat precipitate. The addition amount of the lipoxygenase is 0.6% of the mass of the fish meat precipitate. Mix quickly and load it as an indicator into a colorless, transparent, matte vacuum packaging bag, evacuate and seal it, then put it into the device carrying the indicator, and immediately carry out the HPP treatment of salmon meat. The HPP treatment conditions for the salmon meat are: 300 MPa;

[0045] S5. In this experiment, a prompt signal was obtained at 260 s, and at this time, the HPP treatment was stopped.

[0046] The starting and ending indicator signals of this experiment are shown in Table 1 below: The color of the indicator faded from orange to light orange, and the color of the salmon after stopping the HPP treatment remained bright orange.

[0047] The data on the sterilization effect of the salmon meat after stopping the HPP treatment are shown in Table 5.

[0048] Table 1

[0049] ∆E L* a* b* 0s / 57.78 14.69 23.41 260s 11.53 68.9 11.92 22.17

[0050] Example 2

[0051] A method for indicating the color change of raw salmon meat during HPP treatment, including the following steps:

[0052] S1. Take multiple samples of the salmon meat to be subjected to HPP treatment to obtain salmon meat samples. The mass of the salmon meat samples is 10 g of salmon meat samples per kg of salmon meat;

[0053] S2. Mix the salmon meat samples and water in a mass ratio of 1:5, fully homogenize them using an ultrasonic cell disruptor, and centrifuge at a speed of 1000 rpm for 1 min. Free astaxanthin in the salmon meat is separated by centrifugation. The astaxanthin content in the supernatant of this batch is relatively high, presumably due to feeding a large amount of astaxanthin before its capture. After discarding the supernatant, salmon meat precipitate is obtained;

[0054] S3. Install a device carrying an indicator near the window inside the high-pressure processing equipment with a window, and put the sampled salmon meat to be subjected to HPP treatment into a vacuum packaging bag for vacuum packaging and then put it into the high-pressure processing equipment. The color of the salmon meat to be subjected to HPP treatment is bright orange;

[0055] S4. Before the start of HPP treatment of salmon meat, add polyphenol oxidase with an enzyme activity of more than 50% (enzyme activity 55%) under the conditions of 360 MPa and 5 min to 10 g of salmon meat precipitate. The addition amount of the polyphenol oxidase is 0.1‰ of the mass of the fish meat precipitate; quickly mix evenly, load it into a colorless, transparent and matte vacuum packaging bag as an indicator, evacuate and seal it, and then put it into the device carrying the indicator, and immediately carry out HPP treatment on the salmon meat; the HPP treatment conditions for the salmon meat are: 360 MPa;

[0056] S5. In this experiment, a prompt signal was obtained at 70 s, and at this time, the HPP treatment was stopped.

[0057] The initial and end indicator signals of this experiment are shown in Table 2 below: The color of the indicator faded from pink to light pink, and the color of the salmon after stopping the HPP treatment remained bright orange.

[0058] The data of the sterilization effect of the salmon meat after stopping the HPP treatment are shown in Table 5.

[0059] Table 2

[0060] ∆E L* a* b* 0s / 59.93 15.19 22.94 70s 10.79 70.59 13.52 22.81

[0061] Example 3

[0062] A method for indicating the color change of raw salmon meat during HPP treatment, comprising the following steps:

[0063] S1. Take multiple samples of the salmon meat to be treated by HPP to obtain salmon meat samples; the mass of the salmon meat samples is 100 g of salmon meat samples / kg of salmon meat;

[0064] S2. Mix the salmon meat samples with water at a mass ratio of 1:10, fully homogenize them using a high-speed tissue homogenizer, and centrifuge at a speed of 200 rpm for 8 min; separate the free astaxanthin in the salmon meat by centrifugation, and discard the supernatant to obtain salmon meat precipitate;

[0065] S3. At a position close to the window in the ultra-high pressure treatment equipment with a window, set up a device for carrying the indicator, and put the sampled salmon meat to be treated by HPP into a transparent vacuum packaging bag, evacuate and package it, and then put it into the ultra-high pressure treatment equipment; the color of the salmon meat to be treated by HPP is orange;

[0066] S4. Before the HPP treatment of salmon meat begins, add peroxidase with an enzyme activity of more than 50% (enzyme activity 65%) under the conditions of 360 MPa and 5 min to 100 g of salmon meat precipitate. The addition amount of the peroxidase is 1% of the mass of the fish meat precipitate; quickly mix evenly, load it into a colorless, transparent, matte vacuum packaging bag, evacuate and seal it, and then put it into the device carrying the indicator, and immediately carry out the HPP treatment of salmon meat; the HPP treatment conditions of the salmon meat are: 350 MPa;

[0067] S5. In this test, a prompt signal was obtained at 140 s, and at this time, the HPP treatment was stopped.

[0068] The initial and end indicator signals of this test are shown in Table 3 below: The color of the indicator fades from pink to light pink, and the color of the salmon after stopping the HPP treatment remains orange.

[0069] The data of the sterilization effect of the salmon meat after stopping the HPP treatment are shown in Table 5.

[0070] Table 3

[0071] ∆E L* a* b* 0s / 60.36 12.17 20.81 140s 12.52 72.79 11.4 19.52

[0072] Comparative Example 1:

[0073] S4. Before the HPP treatment of salmon meat begins, add lipoxygenase with an enzyme activity lower than 50% (enzyme activity 40%) under the conditions of 360 MPa and 5 min to 55 g of salmon meat precipitate, and the others are the same as in Example 2; at this time, because the enzyme activity of lipoxygenase is not resistant to high pressure, under the action of 360 MPa, the prompt signal will appear delayed. The initial and end indicator signals of this test can be compared with those of Example 2, as shown in Table 4: The prompt signal of the indicator color change appears at 250 s, and the color of the fish meat after stopping the HPP treatment has completely turned white at this time.

[0074] The data of the sterilization effect of the salmon meat after stopping the HPP treatment are shown in Table 5.

[0075] Table 4

[0076] ∆E L* a* b* 0s / 59.93 15.19 22.94 70s (Example 2) 10.79 70.59 13.52 22.81 250s (Comparative Example 1) 10.43 70.36 10.34 23.15 180s (Comparative Example 2) 14.63 74.28 8.87 23.89

[0077] Comparative Example 2:

[0078] For the existing raw salmon meat treated by HPP, the parameters are set empirically. For example, the HPP sterilization time is set to 360 MPa for 180 s, and the color difference of the salmon meat is detected by using the salmon meat instead of the indicator, and the others are the same as in Example 2. As shown in Table 4: The prompt signal of the indicator color change after 180 s reflects the color difference of the salmon meat, and the color of the fish meat after stopping the HPP treatment has completely turned white at this time.

[0079] The data on the bactericidal effect of the salmon meat with HPP treatment stopped are shown in Table 5, which can meet the safety requirements for ready-to-eat raw aquatic products.

[0080] Table 5

[0081] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Total number of colonies after sterilization <![CDATA[2.4×10 3 CFU / g]]> <![CDATA[8.1×10 3 CFU / g]]> <![CDATA[3.7×10 3 CFU / g]]> <![CDATA[6.6×10 3 CFU / g]]> <![CDATA[5.9×10 3 CFU / g]]>

Claims

1. An online method for prompting that the color of raw salmon will change during HPP treatment, characterized in that, The steps include: S1. Sampling salmon meat to be processed by HPP at multiple points to obtain salmon meat samples; S2, mixing the salmon meat sample with water, fully homogenizing, centrifuging, and discarding the supernatant to obtain the salmon meat precipitate; S3. In the ultra-high pressure treatment equipment with a window, a device carrying an indicator is set up near a viewing window, and the sampled salmon meat to be treated with HPP is placed in a vacuum packaging bag, vacuum-packed, and then placed in the ultra-high pressure treatment equipment; S4. Before the start of the HPP treatment of salmon meat, the enzyme preparation is added to the salmon meat sediment and mixed quickly as an indicator, and the mixture is placed in a colorless, transparent, matte vacuum packaging bag, vacuum-sealed, and then placed in the device carrying the indicator, and the salmon meat is immediately subjected to HPP treatment; the enzyme preparation is an enzyme preparation whose enzyme activity must be maintained at more than 50% under the conditions of 360 MPa and 5 min; the enzyme preparation is selected from at least one of lipoxygenase, polyphenol oxidase, and peroxidase; S5. The color change of the indicator is reflected in real time by an instrument through a window. When a signal of a drastic color change of the indicator is obtained, it is determined that this is the time when the color of the salmon meat is about to change during the HPP treatment, and the HPP treatment needs to be terminated immediately.

2. The method according to claim 1 for online prompting the impending color change of raw salmon meat during HPP treatment, characterized in that, In step S1, the multi-point sampling is to select 1 cm2 of the surface from different parts of the same batch of salmon meat to be processed by HPP and cut the salmon meat longitudinally; the sampling ratio of the salmon meat sample is 10-100g salmon meat sample / kg salmon meat.

3. The method for online prompting the impending color change of raw salmon during HPP treatment according to claim 1, characterized in that In step S2, the mass ratio of the salmon meat sample to water is 1:5-1:10; the homogenization equipment for sufficient homogenization is selected from a high-speed tissue homogenizer; and the centrifugation is performed at a rotation speed of 100-1000 rpm for 1-10 min.

4. The method for online prompting the impending color change of raw salmon meat during the HPP treatment according to claim 1, characterized in that, In step S3, the device carrying the indicator is a bracket that enables the indicator to be close to the inner wall of the window in the HPP equipment processing chamber, and an external light source and an instrument that reflects the color change of the indicator are arranged outside the window, and the color of the indicator can be monitored through the outer wall of the window.

5. The method for online prompting the impending color change of raw salmon meat during the HPP treatment according to claim 1, characterized in that, In step S3, the color of the salmon meat to be HPP-treated is bright orange, orange or reddish pink.

6. The method for online prompting the impending color change of raw salmon meat during the HPP treatment according to claim 1, characterized in that, In step S4, the mass of the salmon meat sediment is 10-100 g; the added amount of the enzyme preparation is 0.1‰-1% of the mass of the fish meat sediment.

7. The method for online prompting the impending color change of raw salmon during HPP treatment according to claim 1, characterized in that, In step S5, the instrument reflecting the color change of the indicator is an instrument that can convert color into electrical signals or data in real time, and can continuously measure the color of the indicator during the HPP treatment process. At the same time, a certain computer program can be used to calculate the color difference between the indicator color and the last measured indicator color in real time, and a device that prompts when the color changes drastically; specifically, it is selected from a colorimeter, a colorimeter, a spectrophotometer or a hyperspectral imager.

8. The method for online prompting the impending color change of raw salmon meat during HPP treatment according to claim 1, characterized in that, In step S5, when the signal of the drastic color change of the indicator is obtained, the color of the indicator changes rapidly from orange or reddish pink to light orange or light pink, which is reflected in the signal as an increase in the color difference value.

9. The method for online prompting the impending color change of raw salmon during HPP treatment according to claim 1, characterized in that, In steps S3 and S4, the vacuum packaging bag material must have a certain flexibility, be able to transmit pressure and withstand pressure, have strong sealing and barrier properties, and can prevent the leakage of substances inside the package or the infiltration of pressure media outside the package.