Method for removing livestock and poultry by-product nitrofuran metabolite

Abstract

The invention belongs to the technical field of food processing, and discloses a method for removing livestock and poultry by-product nitrofuran metabolites. The method comprises the following steps: soaking the livestock and poultry by-products in light salt brine, then transferring the livestock and poultry by-products into pickle liquid with the total amount of lactic acid bacteria higher than 108-109 cfu / mL, carrying out staged variable-temperature soaking, and then carrying out two-stage spin-drying treatment. According to the method, the removal effect on the livestock and poultry by-product nitrofuran metabolite is remarkably improved, the removal rate reaches 100%, meanwhile, the quality of the livestock and poultry by-product is kept to the maximum extent, the pickle processing waste liquid is reused, and the cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of food processing, and particularly to a method for removing nitrofurans metabolites from livestock and poultry by-products. Background Art

[0002] Livestock and poultry by-products are the by-products, scraps and wastes generated during the slaughter and processing of livestock and poultry, mainly including bones, blood, internal organs, feathers, etc. Traditionally, most livestock and poultry by-products are used as feed or fertilizers, with low utilization rate and low added value. With the rapid development of the livestock industry and the continuous expansion of the slaughter and processing scale, the production of livestock and poultry by-products has been increasing year by year, and their resource utilization and high-value development have been increasingly emphasized. However, livestock and poultry are vulnerable to environmental pollution during the breeding process, veterinary drugs are inevitably used when treating diseases, and some processing aids are used during the pre-cooking treatment process, such as using sodium hypochlorite as a disinfectant for some livestock and poultry by-products, which may lead to the residue of nitrofurans metabolites in livestock and poultry by-products. According to the food hygiene standard, the residue of nitrofurans metabolites in meat and its by-products should be less than 0.5 μg / kg. According to the applicant's detection, the residue of nitrofurans metabolites in existing meat and its by-products generally does not exceed this limit, but there may occasionally be cases of exceeding the standard. Nitrofurans metabolites are harmful substances with risks such as carcinogenicity, teratogenicity, and mutagenicity, and cannot be decomposed during cooking. Long-term consumption of foods with residual nitrofurans metabolites will have an adverse impact on human health. Reducing or even completely removing its residue as much as possible is beneficial to ensuring product safety.

[0003] Existing technologies usually use physical or chemical methods to degrade or remove nitrofurans metabolites from livestock and poultry by-products. For example, using ethanol, hydrochloric acid, etc. for multiple washings and centrifugations, which not only have complicated steps and high costs, but may also cause other safety problems. There are research reports that specific strains such as lactic acid bacteria can decompose nitrofurans metabolites, but the degradation effect is not ideal and industrial application has not been realized yet. Finding a natural, safe, low-cost, efficient, convenient and practical method for removing nitrofurans metabolites is of great significance for promoting the sustainable development of livestock and poultry by-products resources.

[0004] In view of this, the present invention is specifically proposed. Summary of the Invention

[0005] The present invention aims to provide a method for removing nitrofurans metabolites from livestock and poultry by-products, which can significantly improve the removal effect of nitrofurans metabolites from livestock and poultry by-products, and the removal rate reaches 100%.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows: A method for removing nitrofurans metabolites from livestock and poultry by-products, comprising: After soaking the livestock and poultry by-products in light salt water, transfer them to a total amount of lactic acid bacteria higher than 108 -10 9 It is soaked in pickled vegetable liquid at 8 cfu / mL by staged variable-temperature soaking, and then undergoes two-stage centrifugal dehydration treatment.

[0007] Preferably, the concentration of the light brine is 0.8-1%, and the dosage is 2-3 times the mass of the livestock and poultry by-products.

[0008] Preferably, the temperature for soaking the livestock and poultry by-products in the light brine is 18-20 °C, and the time is 6-8 h.

[0009] Preferably, the staged variable-temperature soaking includes soaking at a lower temperature first and then at a higher temperature.

[0010] Preferably, the temperature for soaking at a lower temperature is 2-4 °C, and the time is 40-48 h; the temperature for soaking at a higher temperature is 15-20 °C, and the time is 20-24 h.

[0011] Preferably, after soaking at a higher temperature, it further includes soaking at a lower temperature. The temperature for soaking at a lower temperature is 2-4 °C, and the time is 20-24 h.

[0012] Preferably, the mass ratio of the livestock and poultry by-products to the pickled vegetable liquid is 1:2-2.4.

[0013] Preferably, the two-stage centrifugal dehydration treatment is to dehydrate at a low speed first and then at a relatively high speed.

[0014] Preferably, the rotation speed for low-speed centrifugal dehydration is 550-600 rmp, and the time is 2-3 min.

[0015] Preferably, the rotation speed for relatively high-speed centrifugal dehydration is 900-1000 rmp, and the time is 2-3 min.

[0016] Compared with the prior art, the present invention has the following beneficial effects: Through soaking in light brine, staged variable-temperature soaking in pickled vegetable liquid and two-stage centrifugal dehydration treatment, the present invention significantly improves the removal effect of nitrofurans metabolites from livestock and poultry by-products, and realizes a 100% removal rate of nitrofurans metabolites.

[0017] The present invention controls the temperature for soaking the livestock and poultry by-products in the light brine at 18-20 °C, and the temperature for soaking in the pickled vegetable liquid at 2-4 °C and 15-20 °C. Combining with the two-stage centrifugal dehydration treatment, while avoiding the growth of harmful microorganisms during the soaking process and maximizing the preservation of the quality of the livestock and poultry by-products, the nitrofurans metabolites are completely removed.

[0018] The present invention first uses the discarded pickle juice in the treatment of livestock and poultry by-products. By utilizing the adsorption and metabolic degradation effects of microorganisms, ascorbic acid, lactic acid and other active substances contained in the pickle juice on nitrofurans metabolites, the residual nitrofurans metabolites in livestock and poultry by-products are completely removed in a natural way, and the waste liquid is reused.

[0019] The use of the discarded pickle juice in the present invention not only improves the production efficiency of pickles, but also reduces the treatment cost of livestock and poultry by-products. Compared with the degradation method of adding lactic acid bacteria and edible acid, taking the treatment of 10,000 tons of livestock and poultry by-products as an example, about 3 million yuan of treatment costs can be saved annually. Detailed implementation mode

[0020] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Those not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments not indicated by the manufacturer are all conventional products that can be obtained through commercial purchase.

[0021] The embodiment of the present invention provides a method for removing nitrofurans metabolites from livestock and poultry by-products, which includes: soaking the livestock and poultry by-products in light salt water and then transferring them to pickle juice with the total amount of lactic acid bacteria higher than 10 8 cfu / mL for staged variable-temperature soaking, and then performing two-stage centrifugal dehydration treatment.

[0022] After industrial production of pickles, the pickle juice is usually discarded as waste and discharged after environmental protection filtration treatment. The discarded pickle juice contains microorganisms such as Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus brevis, Leuconostoc, Lactobacillus, Weissella, Pediococcus, Lactococcus, Streptococcus, Enterococcus, Weissella, Pediococcus, Lactococcus, Enterococcus, etc., as well as active substances such as ascorbic acid and lactic acid. The applicant found in long-term experimental research that by soaking livestock and poultry by-products with pickle juice, the microorganisms and active substances in the pickle juice can play a synergistic role in efficiently adsorbing and metabolically degrading nitrofurans metabolites, effectively removing the residual nitrofurans metabolites in livestock and poultry by-products. It was also found that soaking at a relatively high temperature of 25-30 °C can effectively remove the nitrofurans metabolites inside the livestock and poultry by-products, but it is easy to breed harmful microorganisms and affect the quality of livestock and poultry by-products; reducing the soaking temperature will reduce the removal efficiency. When the soaking temperature is reduced to 2-4 °C, only the nitrofurans metabolites on the surface of the livestock and poultry by-products can be removed, but this temperature is the cold fresh-keeping temperature of meat products and can effectively maintain the quality of livestock and poultry by-products.

[0023] Therefore, in the embodiment of the present invention, the livestock and poultry by-products are first soaked in light brine to promote the adsorption and metabolic degradation of nitrofuran metabolites by the subsequent pickled vegetable liquid; then the pickled vegetable liquid is used for staged variable-temperature soaking of them to give full play to the adsorption and metabolic degradation of nitrofuran metabolites inside and on the surface of them, and finally two-stage centrifugal dehydration treatment is carried out to fully remove the liquid adsorbed with nitrofuran metabolites remaining in the livestock and poultry by-products. Thus, under the condition of maximizing the quality of the livestock and poultry by-products, the nitrofuran metabolites inside and on the surface of the livestock and poultry by-products are effectively removed, and the removal rate of nitrofuran metabolites reaches 100%.

[0024] The pickled vegetable liquid used in the embodiment of the present invention is obtained by clarifying and filtering the waste pickled vegetable liquid to remove impurities such as small pickled vegetables and precipitates that have formed. The waste pickled vegetable liquid is the pickled vegetable liquid discharged after large-scale processing of Sichuan pickles. The total amount of lactic acid bacteria is roughly in the range of 10 6 -10 9 cfu / mL, and the pH value is between 3.4 and 4.0. The processing of Sichuan pickles adopts traditional processes and formulas. For example, the formula is: fresh vegetables (such as Chinese cabbages, radishes, peppers, gingers, etc.) 1000 kg, salt 24 - 29 kg, sugar (brown sugar, rock sugar or white granulated sugar) 4 - 5 kg, Sichuan-style compound spices (star anises, cinnamon, cinnamon leaves, Chinese prickly ash, dried chili peppers) 150 - 200 g, white liquor 2 - 2.5 L, pickled vegetable special bacterial agent (such as Lactobacillus plantarum, Lactobacillus brevis, etc.) 100 - 150 g; the processing process is: raw material pretreatment, brine preparation, inoculation of bacteria and loading into the altar, fermentation control, flavoring and post-fermentation, sterilization and packaging, waste liquid discharge.

[0025] The total amount of lactic acid bacteria in the pickled vegetable liquid is the key to determining the removal rate of nitrofuran metabolites. Only when the total amount of lactic acid bacteria is higher than 10 8 cfu / mL can the removal rate of nitrofuran reach 100%. For the waste pickled vegetable liquid with insufficient total amount of lactic acid bacteria, after clarifying and filtering it, it is heated to 25 - 30 °C and kept warm for fermentation until the total amount of lactic acid bacteria is higher than 10 8 cfu / mL, and the effect of the present invention can also be achieved.

[0026] The concentration of the light brine is 0.8% - 1%. If the concentration is lower than 0.8%, the adsorption and metabolic degradation of nitrofuran metabolites by the pickled vegetable liquid will be reduced. If it is higher than 1%, the quality of the livestock and poultry by-products will be affected. The dosage of the pickled vegetable liquid is 2 - 2.4 times the mass of the livestock and poultry by-products. The temperature for soaking the livestock and poultry by-products in this light brine is 18 - 20 °C, and the time is 6 - 8 h. If the soaking time is too short, the removal efficiency of nitrofuran metabolites will also be affected. If the time is too long, it will have an adverse effect on the sensory quality of the livestock and poultry by-products. It can be understood that after soaking in the light brine, it also includes rinsing with clear water and draining the water.

[0027] The staged temperature-variable soaking includes soaking at a lower temperature first and then at a higher temperature. Among them, the temperature for soaking at a lower temperature is 2-4 °C, and the time is 40-48 h; the temperature for soaking at a higher temperature is 15-20 °C, and the time is 20-24 h. For livestock and poultry by-products with a relatively small residue amount of nitrofurans metabolites, such as the residue amount ≤ 0.15 μg / kg, the nitrofurans metabolites can be completely removed by using the two-stage temperature-variable soaking method of first low temperature and then higher temperature. For livestock and poultry by-products with a relatively high residue amount of nitrofurans metabolites, such as the residue amount > 0.15 μg / kg, after soaking at a higher temperature, it also includes soaking treatment at 2-4 °C for 20-24 h to completely remove the nitrofurans metabolites. Stirring treatment can be supplemented during the soaking process to facilitate the removal of nitrofurans metabolites, and after soaking, it also includes cleaning treatment with flowing clear water. If soaking at a higher temperature first and then at a lower temperature, it will affect the removal effect of nitrofurans metabolites.

[0028] The two-stage centrifugal drying treatment is to first perform low-speed centrifugal drying and then relatively high-speed centrifugal drying to completely remove the liquid adsorbed with nitrofurans metabolites. The rotation speed of low-speed centrifugal drying is 550-600 rmp, and the time is 2-3 min; the rotation speed of relatively high-speed centrifugal drying is 900-1000 rmp, and the time is 2-3 min. After low-speed centrifugal drying, it also includes cleaning treatment with flowing clear water.

[0029] It should be noted that the nitrofurans metabolites described in the embodiments of the present invention refer to 3-amino-2-oxazolone, 5-morpholinomethyl-3-amino-2-oxazolidinone, 1-amino-hydantoin, and semicarbazide specified in the national standard GB / T 21311-2007 "Determination of Residues of Nitrofuran Drugs Metabolites in Animal-Derived Foods - High Performance Liquid Chromatography / Tandem Mass Spectrometry Method", and the residue amount of nitrofurans metabolites is the total content of the above 4 metabolites.

[0030] To make the present invention clearer, the following will disclose the examples for implementing the present invention and the corresponding comparative examples to prove the related technical effects of the present invention.

[0031] The waste pickle juice used in the following examples is the pickle juice discharged from the large-scale processing of Sichuan pickles; the tripe and chicken feet are provided by the enterprise production line of the applicant of the present invention.

[0032] The detection method for the residue amount of nitrofurans metabolites involved in the examples is: GB / T 21311-2007 "Determination of Residues of Nitrofuran Drugs Metabolites in Animal-Derived Foods - High Performance Liquid Chromatography / Tandem Mass Spectrometry Method", and the detection result is the total content of 4 metabolites, namely 3-amino-2-oxazolone, 5-morpholinomethyl-3-amino-2-oxazolidinone, 1-amino-hydantoin, and semicarbazide; The total amount determination method of lactic acid bacteria is: GB 4786.35-2023 "National Food Safety Standard Food Microbiology Examination Lactic Acid Bacteria Examination".

[0033] Example 1 Using the method of the present invention to remove the residual nitrofurazone metabolites in tripe, the residual amount of nitrofurazone metabolites in the tripe raw material is 0.4 μg / kg.

[0034] Experimental group: After clarifying and filtering the waste pickle juice, the total amount of lactic acid bacteria measured is 10 7 cfu / mL, so it is further heated to 28 °C and incubated for 12 h to obtain pickle juice with a total amount of lactic acid bacteria higher than 10 9 cfu / mL; The tripe is placed in light salt water with a concentration of 1%, soaked at 20 °C for 7 h, rinsed with clean water and drained, placed in pickle juice twice the mass of the tripe, soaked at 2 °C for 48 h, stirred 3 times during this period, then heated to 20 °C and incubated for 20 h, stirred once during this period, and then placed back in the pickle juice at 4 °C for 20 h. After the soaking is completed, it is washed clean with running water, centrifuged at 600 rmp for 2 min, washed clean with running water again, and centrifuged at 1000 rmp for 2 min to obtain the treated tripe.

[0035] Based on the above experimental group, the following control groups are set: Control group 1: Cancel the soaking in light salt water; Control group 2: The concentration of light salt water is 0.4%; Control group 3: The concentration of light salt water is 1.5%; Control group 4: The soaking temperature of the pickle juice is 20 °C; Control group 5: Exchange the soaking order of the first stage (2 °C) and the second stage (20 °C) during the pickle juice soaking process; Control group 6: The soaking temperature of the pickle juice is 4 °C; Control group 7: Cancel the third stage of soaking.

[0036] The treated tripe obtained from the above experimental group and control groups is subjected to nitrofurazone metabolite detection and treatment cost calculation. The treatment cost includes the consumption of lactic acid bacteria and organic acids, centrifugation electricity, etc. The results are shown in Table 1.

[0037] Table 1 Removal effect of different treatment methods on nitrofurazone metabolites in tripe .

[0038] Example 2 Using the method of the present invention to remove the residual nitrofurans metabolites in chicken feet, the content of nitrofurans metabolites in the chicken feet raw materials is 0.15 μg / kg.

[0039] Experimental group: The waste pickled vegetable liquid was clarified and filtered to obtain a pickled vegetable liquid with a total lactic acid bacteria content of 10 9 cfu / mL; The chicken feet were placed in light salt water with a concentration of 0.9%, soaked at 18 °C for 8 h, rinsed with clear water and drained, then placed in the pickled vegetable liquid with a mass 2 times that of the tripe, soaked at 4 °C for 40 h, stirred 3 times during this period, then heated to 22 °C and kept warm for 18 h, stirred 1 time during this period. After the soaking was completed, it was washed clean with running water, centrifuged at 550 rmp for 3 min, washed clean with running water again, and centrifuged at 900 rmp for 3 min to obtain the treated chicken feet.

[0040] On the basis of the above experimental group, the following control groups were set: Control group 1: Exchange the order of the two-stage centrifugation treatment during the centrifugation process; Control group 2: Cancel the centrifugation treatment; Control group 3: Only perform the first centrifugation treatment; Control group 4: Replace the pickled vegetable liquid with a lactic acid bacteria solution, which was prepared by adding 1 / 4 of Leuconostoc, Lactobacillus, Pediococcus, and Lactococcus respectively, and the total lactic acid bacteria content in the solution was 10 9 cfu / mL; Control group 5: Replace the pickled vegetable liquid with a lactic acid bacteria solution, which was prepared by adding 1 / 4 of Leuconostoc, Lactobacillus, Pediococcus, and Lactococcus respectively and adding 1 / 3 of lactic acid, acetic acid, and oxalic acid respectively, and the total lactic acid bacteria content in the solution was 10 9 cfu / mL; Control group 6: The total lactic acid bacteria content in the pickled vegetable liquid was 10 7 cfu / mL.

[0041] The treated chicken feet obtained from the above experimental group and control groups were subjected to nitrofurans metabolites detection and treatment cost calculation. The treatment costs included the consumption of lactic acid bacteria and organic acids, centrifugation electricity charges, etc. The results are shown in Table 2.

[0042] Table 2 Removal effects of different treatment methods on nitrofurans metabolites in chicken feet .

[0043] The embodiments described above are some, but not all, of the embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

Claims

1. A method for removing nitrofurazone metabolites from livestock and poultry by-products, characterized in that, Including: After soaking livestock and poultry by-products in light salt water, transfer them to pickled vegetable liquid with the total amount of lactic acid bacteria higher than 10 8 cfu / mL for staged soaking with variable temperature, and then perform two-stage centrifugal dehydration treatment.

2. The method according to claim 1, wherein The concentration of the light brine is 0.8 - 1%, and the dosage is 2 - 3 times the mass of the livestock and poultry by-products.

3. The preparation method according to claim 1, characterized in that, The temperature for soaking the livestock and poultry by-products in the light brine is 18 - 20 °C, and the time is 6 - 8 h.

4. The method according to claim 1, wherein The staged variable-temperature soaking includes soaking at a lower temperature first and then at a higher temperature.

5. The method according to claim 4, wherein The temperature for the lower-temperature soaking is 2 - 4 °C, and the time is 40 - 48 h. The temperature for the higher-temperature soaking is 15 - 20 °C, and the time is 20 - 24 h.

6. The method according to claim 4, wherein After the higher-temperature soaking, it also includes lower-temperature soaking. The temperature for the lower-temperature soaking is 2 - 4 °C, and the time is 20 - 24 h.

7. The method according to claim 1, wherein The mass ratio of the livestock and poultry by-products to the pickled vegetable liquid is 1:2 - 2.

4.

8. The method according to claim 1, characterized in that, The two-stage centrifugal dehydration treatment is centrifugal dehydration at a low speed first and then at a relatively high speed.

9. The method according to claim 8, characterized in that The rotation speed for the low-speed centrifugal dehydration is 550 - 600 rmp, and the time is 2 - 3 min.

10. The method according to claim 8, wherein The rotation speed for the relatively high-speed centrifugal dehydration is 900 - 1000 rmp, and the time is 2 - 3 min.