CN115500428A - Low-temperature production method of white fish meal - Google Patents

Abstract

The invention provides a low-temperature production method of white fish meal, which is characterized in that raw materials for preparing the white fish meal are not steamed and/or squeezed, but dried under vacuum condition and crushed simultaneously. The white fish meal prepared by the method can meet the requirements of first-grade white fish meal in national standard; the average power consumption in the preparation process is only 178.3 kilowatt-hours/ton. And no odor pollutant is discharged in the preparation process.

Description

A kind of low-temperature production method of white fish meal

technical field

The invention belongs to the technical field of feed raw material processing, and in particular relates to a low-temperature production method of whitefish meal.

technical background

White fish meal is an irreplaceable raw material in the feed of larvae, shrimp fry, suckling pigs, eels, and soft-shelled turtles. White fish meal has low content of harmful substances such as histamine and malondialdehyde, good safety and adhesiveness. There is a large demand for white fishmeal in the market, but the quantity of whitefishmeal produced in China is very limited, mainly relying on imported whitefishmeal, which is expensive and the stability of supply cannot be guaranteed.

The raw materials for the production of white fish meal are mainly the by-products of processing fish fillets and fillets of white meat fish such as cod and flounder. The traditional white fishmeal production process is based on the whole fish of white muscular fish species such as cod and flounder or the remaining fish body parts after processing fish products (including fish bones, fish viscera, fish heads, fish tails, fish skins, fish eyes, etc.) , fish scales and fish fins) as raw materials, products obtained by cooking, pressing, drying and crushing.

But there is following problem in existing white fish meal production process:

1) Many processing steps and high energy consumption;

2) The cooking process causes damage to water-soluble nutrients, including water-soluble proteins, vitamins, minerals, etc.;

3) During the cooking and drying stages, the temperature of the material exceeds 90°C; high temperature treatment causes the decomposition and destruction of nutrients;

4) The waste gas with strong pungent smell is produced in the whole production process, which greatly pollutes the environment.

Contents of the invention

The purpose of the present invention is to provide a low-temperature production method of white fish meal, thereby reducing the loss of nutrients and reducing the side effects in the preparation process of white fish meal.

In the low-temperature production method of white fish meal provided by the present invention, the raw materials used for preparing white fish meal are not subjected to cooking and/or pressing treatment, but are dried under vacuum conditions and crushed while drying;

The raw material used to prepare white fish meal, as a specific record of the embodiment, is a by-product of cod steak or other cod processing;

The vacuum condition is that the absolute pressure in the container is not higher than 0.03Mpa;

The drying temperature is preferably not higher than 60°C;

Furthermore, the drying and crushing are carried out simultaneously in a vacuum oven

Furthermore, the steam generated in the drying process is recovered.

The white fish meal prepared by the white fish meal production method provided by the invention can meet the requirements of the first-grade white fish meal in the "National Standard"; the average power consumption in the preparation process is only 178.3 kWh/ton. And no odorous pollutants are discharged during the preparation process.

Description of drawings

Fig. 1: the flow chart of white fish meal production method of the present invention;

Figure 2: Photographic view of whitefish meal of the present invention.

detailed description

The invention does not cook and squeeze the white fishmeal material, but completes drying and crushing simultaneously under vacuum conditions during the preparation process. By preparing the white fish meal by the method, the nutrient components of the raw fish can be protected to the greatest extent, and the quality of the white fish meal meets the requirements of national standards. No odor pollutants, such as ammonia, trimethylamine, and hydrogen sulfide, are emitted during the preparation of white fish meal by the method, and the total power consumption is only 178.3 kWh/ton.

Vacuum drying is adopted in the method of the present invention, and the drying temperature is maintained at 60 ° C; the steam obtained by drying passes through the waste heat recovery device, on the one hand, it is condensed into a liquid, and the taste molecules are dissolved in it, so as to avoid the generation of peculiar smell; on the other hand, the waste heat recovery device will The heat released by condensation is recovered to maintain the drying temperature, thus greatly reducing energy consumption.

The method and standard of detection involved in the present invention are as follows:

1. Calculation method of energy consumption for white fishmeal production

Electricity consumption of white fish meal production = [electric meter reading after drying (kWh) - electric meter reading before drying (kWh)]/feeding amount (ton)

2. Quality testing method of white fish meal

According to "GB/T19164-2021 National Standard of the People's Republic of China Feed Raw Material Fish Meal", the quality index detection method of the produced white fish meal is as follows:

1. Microscopic inspection: In accordance with the "GB/T14698-2017 National Standard of the People's Republic of China Feed Raw Materials Microscopic Inspection Method", the appearance inspection of the white fish meal produced is carried out.

2. Crude protein: According to the Kjeldahl method in "GB/T6432-2018 Determination of Crude Protein in National Standard Feed of the People's Republic of China", the protein content of the white fish meal produced was tested.

3. 17 kinds of amino acids: cystine and methionine: According to "GB/T 15399-2018 Determination of Sulfur-Containing Amino Acids in National Standard Feed of the People's Republic of China", the contents of cystine and methionine in the produced white fish meal were tested. 15 other amino acids: including lysine, threonine, histidine, arginine, leucine, isoleucine, alanine, glycine, aspartic acid, serine, glutamic acid, valine Acid, tyrosine, phenylalanine and proline, according to "GB/T18246-2019 Determination of Amino Acids in National Standard Feed of the People's Republic of China" to detect the content of other 15 amino acids in the produced white fish meal.

4. The proportion of EPA and DHA in total fatty acids: According to "GB 5009.168-2016 Determination of Fatty Acids in Food Safety National Standard of the People's Republic of China", the proportion of EPA and DHA in total fatty acids in the produced white fish meal was tested.

5. Moisture: According to "GB/T 6435-2014 Determination of Moisture in National Standard of the People's Republic of China", the moisture content in the produced white fish meal is tested.

6. Crude ash content: According to "GB/T 6438-2007 Determination of Coarse Ash Content in National Standard Feed of the People's Republic of China", the crude ash content in the produced white fish meal was tested.

7. Sand content (hydrochloric acid insoluble ash): According to "GB/T 23742-2009 Determination of hydrochloric acid insoluble ash in national standard feed of the People's Republic of China", the sand content in the produced white fish meal was tested.

8. Salt content: According to "GB/T 6439-2007 Determination of Water-Soluble Chloride in National Standard Feed of the People's Republic of China", the salt content in the produced white fish meal was tested.

9. Histamine: According to "GB/T 23884-2021 National Standard of the People's Republic of China Determination of Biogenic Amines in Animal Feeds", the histamine content in the produced white fish meal was tested.

10. Malondialdehyde: According to "GB-T 28717-2012 Determination of Malondialdehyde in National Standard Feed of the People's Republic of China", the content of malondialdehyde in the produced white fish meal was tested.

The present invention will be described in detail below in conjunction with specific embodiments.

Embodiment 1: Preparation of white fish meal

In the preparation method of white fish meal provided by the present invention, the raw materials used for preparing white fish meal are not subjected to steaming and/or pressing treatment, but are dried under vacuum conditions, and are crushed while being dried.

Specific steps are as follows:

1) The remaining fish fillet after cod processing fish product is put into the device (publication number is the Chinese invention patent of CN109485466A) with crushing function and prepares; But other devices with similar functions can also be used to Prepare.

Adjust the vacuum so that the absolute pressure in the container is not higher than 0.03Mpa; the drying temperature does not exceed 60°C; and the fish fillets are continuously crushed by the crushing function of the dryer during the drying process.

First, the material enters the drying box through the feeding port, and the drying box is closed. Subsequently, the electric heater on the inner layer of the drying box was operated to raise the temperature in the drying box to 70°C. While the temperature is rising, the stirring shaft starts to work to drive the propeller blades; at the same time, the vacuum pump starts to work to gradually reduce the air pressure in the drying box. After the temperature meets the requirements, the electric heating will stop, and will not start again during the subsequent drying process. When the absolute pressure in the drying box is lower than 0.03Mpa, the boiling point of water drops below 68°C, and the liquid in the drying box begins to boil. The water vapor generated by boiling enters the waste heat recovery device, condenses again, and releases heat. On the one hand, the waste heat recovery device utilizes the heat released by condensation, on the other hand, it properly supplements electric energy to heat the heat transfer oil to above 62°C. To continuously reheat the material in the drying oven. During the whole drying process, the vacuum pump keeps the absolute pressure in the drying box always less than 0.02MPa, so that the boiling point of the water in the drying box is below 60°C. During the drying process, the waste heat recovery device always maintains the temperature in the drying box above 60°C to ensure that the liquid in the drying box is continuously in a boiling state. The above steps have realized the low-temperature drying of the white fish meal raw material.

During the drying process, the two stirring shafts drive the spiral cutter installed above to continue to rotate. In the early stage of drying, the cutter breaks and homogenizes the wet material. As the drying progresses, the cutter continuously crushes the dried and shaped materials, on the one hand to ensure that the materials are fully dried, on the other hand to achieve the effect of sufficient crushing. This design completes the crushing of the whitefish meal while drying.

The waste heat recovery device is equipped with a condenser, a compressor and a heat exchanger, wherein the heat exchanger is filled with Freon. The steam obtained by drying is first condensed into a liquid in the condenser, and the released heat vaporizes Freon. The temperature and pressure of the gasified freon are raised by the compressor, and then heat exchange is carried out with the heat transfer oil. When the heat transfer oil is heated to the required temperature, it liquefies itself (Figure 1).

2) During the drying process, the generated steam is recovered to avoid the emission of odorous pollutants.

The prepared white fish meal is detected, and the detection results are as follows:

1. Calculation of production yield of white fishmeal

A total of 10 batches of tests were carried out, a total of 300 tons of cod fillets were consumed, and 126.5 tons of white fish meal were produced. The yield was 42.2%.

2. Calculation results of energy consumption of white fishmeal production

A total of 10 batches of tests were carried out, a total of 300 tons of cod fillets were consumed, and 126.5 tons of white fish meal were produced. Its average power consumption is 178.3 degrees per ton fish fillet.

3. Test results and evaluation of white fish meal

The white fishmeal produced is yellowish white in appearance, and the powder, fish bones and fish eyes can be seen with the naked eye.

Fibrous fish flesh with many fish bones can be seen under the microscope. No insects, mildew, and agglomeration. It has the normal smell of white fish meal, without rancid and burnt smell. Crude protein content > 64%, lysine content > 5.0%, 17 kinds of amino acids total/crude protein > 90%, EPA and DHA accounted for > 18% of total fatty acids, moisture content < 10%, crude ash content < 28%, Sand content<0.4%, salt content (calculated as NaCl)<2.5%, volatile base nitrogen VBN<70.0mg/100g, histamine<25mg/kg, malondialdehyde (calculated based on crude fat contained in fishmeal)< 20mg/Kg.

Referring to "GB/T19164-2021 People's Republic of China National Standard Feed Raw Material Fish Meal", it is determined that the white fish meal produced is a first-class white fish meal (Figure 2).

Embodiment 2: the white fish meal prepared by the present invention compares with existing white fish meal

The white fish meal preparation method of the present invention is a low-temperature vacuum production method, which can reduce the loss of nutrients and the destruction of high-temperature sensitive nutrients in the traditional white fish meal production process, especially reduce the loss of water-soluble protein and reduce the structure of unsaturated fatty acids destruction and rancidity of fatty acids. Thereby improving the digestibility of animals.

Take the white fish meal prepared by the present invention as sample 1, the domestic white fish meal prepared by the existing traditional method as sample 2, and the imported white fish meal from Russia as sample 3. The protein content, the ratio of EPA and DHA to the total fatty acids, the content of malondialdehyde and the digestibility of pepsin in the three samples were compared. Three replicates were set up for each sample.

Among them, the domestic white fish meal prepared by the traditional method first chops the raw fish, sends it to the cooker for cooking through the screw conveyor, and sends it to the press for pressing by the conveyor, so that the oil and water are separated from the muscle, and the pressed cake is shredded After being shredded by the machine, it is sent to the dryer for drying. The dried coarse fish meal is removed by the magnetic separator to remove impurities such as metals, and then crushed by the crusher to the required particle size, and then passed through the sieving machine to the automatic scale for packaging according to the required quality. The squeeze liquid is separated by a decanter, and the coarse slag that precipitates in the form of mud is sent to the dryer to dry together with the shredded press cake. The liquid is separated from oil and water by an oil-water separator, and the obtained crude oil is separated by an essential oil separator to obtain a refined oil. The juice that comes out is concentrated to a certain concentration by a multi-effect evaporator, and then sent to a dryer to dry together with the pressed cake. The traditional domestic white fish meal obtained from this is

The protein content in the sample, the ratio of EPA and DHA to the total fatty acids, and the content of malondialdehyde refer to the method in Example 1. The detection method of pepsin digestibility is carried out according to the method stipulated in the standard "GB/T17811-1999 Determination of Pepsin Method for Digestibility of Animal Protein Feed".

After the original data was preliminarily sorted by Excel 2018, SPSS 20.0 was used to conduct one-way ANOVA (One-Way ANOVA), and Duncan's method was used to analyze the significance of the differences in the experimental data. The results were expressed as "mean ± standard deviation" (mean ± SD ) indicates that P<0.05 is considered a significant level of difference.

Table 1: white fish meal prepared by the present invention and existing white fish meal comparative index data table

From the results in Table 1, it can be seen that the crude protein content, the ratio of EPA and DNA to total fatty acids, and the pepsin digestibility of sample 1 were significantly higher than those of sample 2, while the content of malondialdehyde was significantly lower than that of sample 2. The ratio of EPA and DNA to total fatty acids in sample 1 was significantly higher than that in sample 3.

The above results show that the white fish meal prepared by the present invention can reduce the loss of protein and the destruction of polyunsaturated fatty acids, prevent rancidity and improve animal digestibility compared with domestic traditional white fish meal. Protection against polyunsaturated fatty acids was also shown compared to imported white fishmeal.

Claims (8)

1. The production process of white fish meal features that the material for preparing white fish meal is vacuum dried and crushed simultaneously.

2. The method of claim 1, wherein the raw material for the preparation of white fish meal is cod steaks or other by-products of cod processing.

3. The method of claim 1, wherein the vacuum condition is an absolute pressure in the vessel of not more than 0.03Mpa.

4. The method of claim 1, wherein the drying temperature is not greater than 60 ℃.

5. The method of claim 1, wherein the drying and comminuting are performed simultaneously in a vacuum oven.

6. The method of claim 1, wherein steam generated during said drying is recovered.

7. A white fish meal, prepared using the method of any one of claims 1 to 6.

8. Use of white fish meal according to claim 7 for the preparation of a feed.

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