Bacterium reducing method used in porphyra yezoensis production process

Abstract

The invention discloses a bacteria reducing method used in a process of producing dried porphyra yezoensis, which comprises the following steps: in production, according to temperature and porphyra conditions, carrying out extrusion cleaning on dehydrated sponge, blanching for 20-30 minutes, carrying out extrusion dehydration for later use, carrying out in-situ spraying blanching disinfection on a curtain sheet by using a high-pressure water pump of a primary vegetable processing unit, and carrying out sterilization on the curtain sheet by using a high-pressure water pump of the primary vegetable processing unit, so as to obtain the dried porphyra yezoensis. Performing composite quaternary ammonium salt soaking disinfection treatment on a seawater pool, a pipeline, a vegetable cutter, a blender, a blending pool and the like in the production line by using a material pump for 30-60 minutes, and then washing with tap water for 5-10 minutes for three times; according to the method, blanching and composite quaternary ammonium salt disinfection are adopted, a production line cannot be corroded, mass propagation of microorganisms on the contact surface of the production line and secondary pollution to laver materials can be effectively inhibited, and the microorganism content of wet materials after cake casting can be reduced, so that the microorganism content in the dried porphyra yezoensis is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of Porphyra sterilization, and in particular relates to a sterilization method used in the process of producing Porphyra yezoensis. Background Art

[0002] Laver is delicious and nutritious. It is known as a "treasure trove of nutrition". Its nutritional value is better than that of kelp. It contains high levels of essential amino acids, polysaccharides, taurine and B vitamins. Laver is the main cultivated species in my country, Japan and South Korea. It is mainly distributed in the Yellow Sea, Bohai Sea, the northern coast of the East China Sea, the Japanese archipelago and the Korean Peninsula. Dried laver is mainly used as a raw material for seaweed snacks. Typical products include sandwich seaweed, sushi or laver rice rolls and seaweed rolls. These are popular among children and young consumers and are characteristic aquatic products in coastal areas.

[0003] The general production process of Porphyra yezoensis is raw materials → initial washing (seawater washing, freshwater washing) → chopping, washing → blending → cake making (dehydrated sponge and curtain pieces are blanched) → dehydration → drying → peeling → selection and grading → secondary drying → selection and grading → packaging, which becomes the finished product of dried Porphyra yezoensis. Before the cake making step, the materials are transported by pumps and pipes.

[0004] In recent years, market supervision departments have found in random inspections of food quality and safety that many seaweed sandwich products have problems with excessive total colony counts and excessive coliform bacteria. Seaweed products have been reported to be contaminated with microorganisms and have caused some safety problems. Studies have shown that dried Porphyra yezoensis is one of the main sources of microbial contamination in nori rice rolls and sushi rolls. Preliminary laboratory studies have found that the microbial community in dried Porphyra yezoensis is the main source of microorganisms in baked seaweed sandwiches. Food safety control of the entire industry chain is an important guarantee for food safety. The seaweed food industry also recognizes the necessity of controlling the microbial level in the processing of raw dried Porphyra yezoensis. However, the microbial control of dried Porphyra yezoensis is currently an industry problem faced by major producing countries such as China and South Korea.

[0005] At present, the sterilization methods in laver processing are all targeted at laver materials, such as irradiation, low-temperature plasma, high-temperature baking, ultraviolet irradiation, and ozone fumigation for laver materials after drying, and electrolytic water immersion and ozone water immersion for laver before drying. No research has paid attention to the microbial contamination status of the contact surface of laver production line materials and carried out microbial control. During the cutting, cake pouring and dehydration and drying process of dried laver production, laver releases a large amount of nutrients such as protein and polysaccharides, which is conducive to the proliferation of microorganisms. The repeated use of dehydration sponges and curtains may colonize a large number of microorganisms and cause further contamination of laver materials, resulting in excessive total colony counts and coliform bacteria in the final product, and causing some safety problems. Therefore, it is necessary to control the level of microorganisms on the contact surface of equipment during the processing of dried laver. Summary of the invention

[0006] The invention aims to design a method for reducing bacteria in the process of producing Porphyra yezoensis, so as to solve the problem that the total number of colonies of dried Porphyra yezoensis exceeds the standard.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A method for reducing bacteria in the process of producing Porphyra yezoensis. The production process of Porphyra yezoensis is specifically carried out in the following order, namely, raw materials, initial washing, chopping, cleaning, blending, cake pouring, dehydration, drying, peeling, selection and grading, secondary drying, selection and grading, and packaging. The method is characterized in that the production process also includes a sterilization treatment, and the treatment method is as follows: S1: According to the temperature and laver conditions, after the production line is emptied of materials, stop production and remove the dehydrated sponge; S2: The disassembled sponges are subjected to high-pressure washing and squeezing cleaning to remove foreign matter and impurities such as polysaccharide proteins, and then cleaned and disinfected by hot blanching. After disinfection, the sponges are placed in a sponge temporary storage room for use; S3: Use the high-pressure water pump of the primary vegetable processing unit to spray and scald the curtain pieces to achieve the purpose of disinfection; S4: Use a high-pressure water gun to clean the surface of the production line, empty the seawater pool of the production line and fill it with tap water, add a composite quaternary ammonium salt disinfectant, and immerse the equipment in the production line in the composite quaternary ammonium salt for disinfection; S5: Then, the equipment of the production line is soaked and rinsed with clean water to remove the residual composite quaternary ammonium salt, and the soaking and rinsing steps are repeated 3 times; S6: Replace the sterilized sponge and then resume normal production.

[0008] Furthermore, the equipment in the production line includes but is not limited to a seawater tank, a pipeline, a vegetable cutter, a blender, a blending tank, a sponge, and curtain pieces.

[0009] Furthermore, the dehydrated sponge was replaced and disinfected every 4-48 h, and the curtain pieces were sprayed and disinfected in situ.

[0010] Furthermore, the disassembled sponge is blanched at a temperature of 100°C for 20-30 min, and the curtain pieces are sprayed and disinfected using a high-pressure water pump of a primary processing unit, with a hot water temperature of 100°C and a spraying time of 60 - 120 min.

[0011] Furthermore, the disinfection frequency in S4 is once every 24-72 h, the concentration of the composite quaternary ammonium salt is 400-500 ppm, and the treatment time is 30-60 min.

[0012] Furthermore, in S5, the immersion time is 5-10 min, and the rinsing time is 3-5 min.

[0013] Furthermore, in S5, the production line is flushed with high pressure, and the clean water is tap water, which is injected into the seawater tank and then pumped into the production line and its flushing pipeline through the pump body.

[0014] The following beneficial effects can be obtained through the above technical solution: Based on the actual situation that the total colony count levels of sponges and curtain pieces used in the production of Porphyra yezoensis processing plants are generally high, the present invention specifically proposes a sterilization method, and the sponges and curtain pieces dehydrated by the wet material contact equipment in the production process are blanched at 100°C, which can reduce the microbial content of the wet material after cake pouring, thereby reducing the microbial content in the dried Porphyra yezoensis.

[0015] The present invention realizes in-situ spray disinfection, solves the problems of large workload and easy damage during dismantling, as well as incorrect installation of the front and back sides of the curtain sheet, which leads to differences in the quality of the laver. Therefore, a high-pressure water pump spray device provided by the unit for cleaning and removing laver fragments is used, and boiling water is connected to realize in-situ spray disinfection.

[0016] After the sponge and the curtain sheet are blanched by the method of the present invention, the total colony count of the laver is reduced by 1.02 Log CFU / g, and the coliform group is reduced by 1.35 Log CFU / g after the cake-making process; the total colony count of the laver is reduced by 0.93 Log CFU / g, and the coliform group is reduced by 0.39 Log CFU / g after the primary drying; after the secondary drying, the total colony count is reduced by 0.94 Log CFU / g, and the coliform group is reduced by 0.31 Log CFU / g. In combination with the cleaning and disinfection of the production line, the laver microbial level before cake-making can be controlled, and the microorganisms of dried laver yezoensis can be further reduced, thereby achieving the purpose of reducing bacteria in the process of producing laver yezoensis as a whole.

[0017] The present invention rationally applies low-cost, green, and residue-free sterilization technology to dried Porphyra yezoensis processing equipment, realizes the promotion and application of dried Porphyra yezoensis sterilization technology, significantly controls the total colony count level of seaweed food, achieves the stabilization of seaweed product quality, improves the quality and safety level of Porphyra yezoensis and seaweed products, and promotes the healthy development of Porphyra yezoensis and its processing industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the total colony count levels of dehydrated sponges during Porphyra processing.

[0019] Figure 2 Schematic diagram of coliform bacteria levels in curtain sheets during laver processing.

[0020] Figure 3 Schematic diagram of the effect of blanching temperature on the total colony count and coliform group of sponge.

[0021] Figure 4 Schematic diagram of the effect of blanching time on the total colony count and coliform group of sponge.

[0022] Figure 5 Schematic diagram of the effect of slightly acidic electrolyzed water concentration on the total colony count and coliform group of sponge.

[0023] Figure 6 Schematic diagram of the effect of composite quaternary ammonium salt concentration on the total colony count and coliform group of sponge.

[0024] Figure 7 Schematic diagram of the effect of sodium hypochlorite concentration on the total colony count and coliform group of sponge.

[0025] Figure 8 Schematic diagram of the effect of sponge blanching before and after on the total colony count of produced Porphyra yezoensis.

[0026] Fig. 9 Schematic diagram of the effect of sponge blanching treatment on the coliform flora of produced Porphyra yezoensis. DETAILED DESCRIPTION

[0027] The following is attached Figure 1-9 , examples and experimental data further illustrate the present invention: The present invention is based on the production process of Porphyra yezoensis: raw materials → initial washing (seawater washing, fresh water washing) → chopping, washing → blending → cake pouring (dehydrated sponge and curtain pieces are blanched) → dehydration → drying → peeling → selection and grading → secondary drying → selection and grading → packaging. In the above process, a sterilization treatment is performed, and the specific method is: according to the temperature and the condition of the Porphyra, every 4-48 hours is taken as a cycle, and the dehydrated sponge is replaced once in each cycle, the replaced sponge is cleaned and disinfected, the sponge is high-pressure rinsed and squeezed for cleaning, and then blanched at 100°C for 20-30 minutes, the cleaned and disinfected sponge is placed in a temporary storage room for disinfected sponges for standby use, and the curtain pieces are sprayed and disinfected in situ by a high-pressure water pump of a primary processing unit, and the spraying time is 60-120 minutes. Once every 24-72 hours, empty the seawater pool, first use a high-pressure water gun to rinse the seawater pool, vegetable cutter, blender, etc., then fill the seawater pool with tap water, add 400-500 ppm of compound quaternary ammonium salt, and use the production line material pump to immerse and disinfect the seawater pool, pipelines, vegetable cutter, blending tank, etc. in the production line with compound quaternary ammonium salt for 30-60 minutes. Then, pass tap water into the seawater tank, pump it into the production line, soak for 5-10 minutes, flush the pipeline for 3-5 minutes, repeat the soaking and flushing steps 3 times, and after drying, achieve sterilization in production.

[0028] The sterilization method is demonstrated by experiments: Sampling procedures for material contact surfaces in dried Porphyra yezoensis processing plants: Wipe samples of material contact surfaces in laver production, including seawater pools, pipes, vegetable cutters, blending tanks, sponges and curtains, were collected from three dried laver processing factories in Lianyungang City. The specific method is to use a sampling specification plate to swab the surface to be collected 10 times horizontally and vertically with a cotton swab soaked in sterile saline, and the collection area is 5 cm×5 cm. After the sampling is completed, it is placed in a sampling tube, stored in ice, and immediately brought back to the laboratory for microbial testing. Samples with higher contamination levels were selected for subsequent material contact surface disinfection method screening experiments. Figure 1 The middle is the total number of colonies in the dehydrated sponge during laver processing. Figure 2 It is the coliform level of curtain sheets in laver processing.

[0029] The present invention adopts blanching treatment to sterilize A total of six experiments were set up, using 60℃, 70℃, 80℃, 90℃, 100℃ and room temperature to scald the sponges and curtains for 30 min, and parallel experiments were carried out to test the microbial levels of the six groups of laver before and after blanching ( Figure 3 and 4 as shown).

[0030] Control group 1: Disinfection by immersion in slightly acidic electrolyzed water A total of six groups of experiments were set up, using 0 ppm, 50 ppm, 100 ppm, 200 ppm, 300 ppm, and 400 ppm slightly acidic electrolyzed water to soak the sponge and curtain for 30 min, and parallel experiments were performed at the same time. The microbial levels of the six groups of laver before and after soaking were tested ( Figure 5 as shown).

[0031] Control group 2: Compound quaternary ammonium salt immersion treatment and disinfection Six groups of experiments were set up, using 0 ppm, 100 ppm, 200 ppm, 300 ppm, 400 ppm, and 500 ppm of compound quaternary ammonium salt to soak the sponge and curtain for 30 min, and parallel experiments were carried out at the same time. The microbial levels of the six groups of laver before and after soaking were tested ( Figure 6 as shown).

[0032] Control group 3: Sodium hypochlorite solution immersion disinfection Six groups of experiments were set up, using 0 ppm, 100 ppm, 200 ppm, 300 ppm, 400 ppm, and 500 ppm sodium hypochlorite solutions to soak the sponge and curtain for 30 min, and parallel experiments were performed at the same time. The microbial levels of the six groups of laver before and after soaking were tested ( Figure 7 as shown).

[0033] Experimental verification of the effect of material contact surface disinfection on the reduction of bacteria in the production of dried Porphyra yezoensis 1) Wash and chop the laver with fresh water and prepare the laver blending liquid before pouring into the pancake at a ratio of 1:9.

[0034] 2) Casting the cake: Place the mold on the curtain piece and add 300 mL of seaweed blending liquid. The size of the curtain piece used for casting the cake is 19 cm × 21 cm.

[0035] 3) Dehydration: Use a dehydrated sponge to repeatedly press the laver cake to absorb moisture and set the shape. First, conduct a control group experiment (the sponge curtain has not been treated), and then conduct an experimental group, that is, the sponge curtain has been treated with the optimal sterilization method.

[0036] 4) Primary drying: the temperature is 45°C and the drying time is 2.5 h. After drying, some samples are taken for microbial determination.

[0037] 5) Secondary drying: 35-70°C, gradient drying (33°C 60 min; 38°C 60 min; 45°C 50 min; 50°C 40 min; 65°C 20 min; 70°C 10 min). After drying, take some samples for microbiological testing.

[0038] Microbiological testing The total colony count and coliform count were determined according to the national standard (GB19643-2016). The specific process was as follows: 25 g of sample was weighed and transferred into a sterile homogenizing bag containing 225 mL of sterile 0.85% saline and homogenized in a homogenizer for 1 min (HX-4GM, Huxi Industrial Co., Ltd., Shanghai). The sample slurry was then diluted and plate counted by pouring method. Plate count agar (PCA) and purple red bile agar (VRBA) were used to count the total colony count and coliform, respectively. After each sample was diluted, 1 mL of liquid sample was first added to a blank plate, and then about 20 mL of liquid PCA or VRBA agar was added to the plate. The plate was gently shaken horizontally to mix the sample and liquid agar. After the agar solidified (about 30 min), the PCA plate was inverted and incubated at 37 °C for 48 h. For the coliform test, 3-4 mL of VRBA medium was poured on the plate to form a double layer to inhibit the spread of colonies and mold growth. The VRBA plates were incubated upside down at 37°C for 48 hours.

[0039] In the production of Porphyra yezoensis, there were significant differences in the total number of colonies and coliform bacteria on the surfaces of different materials in the three Porphyra yezoensis factories (P<0.05). The overall change was that the microbial levels of the material contact samples of the three factories were high, including the inner surface of the vegetable cutter, the inner surface of the blender, the inner surface of the dilution blending tank, and the sponge. The total number of colonies on the curtain sheet was 6-8 Log CFU / g. Except for the curtain sheet, the coliform bacteria were not detected, and the coliform bacteria levels of the other samples were 3-5 Log CFU / g. This shows that the pollution of the environmental contact surfaces during the production of Porphyra yezoensis is serious and there is a lack of cleaning and disinfection measures.

[0040] Under room temperature, the blanching temperature, slightly acidic electrolyzed water concentration, compound quaternary ammonium salt disinfectant concentration, and sodium hypochlorite concentration were compared to reduce the bacteria of dehydrated sponges and curtains through single factor experiments. Under the optimal conditions, the four disinfectants could reduce the total number of sponge colonies to undetectable levels when the soaking time was 30 min. The optimal temperature for boiling treatment was 100℃, and the optimal concentrations for slightly acidic electrolyzed water, compound quaternary ammonium salt, and sodium hypochlorite solution treatment were 400 ppm, 400 ppm, and 500 ppm, respectively. After comprehensive consideration of the bacteria reduction effect, cost, and convenience, blanching treatment was selected, and the three treatment times of 10 min, 20 min, and 30 min were optimized. It was found that the total number of colonies and coliform group were not detected after 20 min of treatment, so blanching at 100℃ for 20 min was selected as the optimal solution.

[0041] Figure 8 and 9As shown in the figure, the blanching treatment has a bactericidal effect on the material and contact surface samples of Porphyra yezoensis. The total colony count and coliform group of the untreated sponge reached 6.25 Log CFU / g, the total colony count and coliform group of the untreated curtain sheet were 2.08 Log CFU / g and undetectable, respectively. After blanching, the total colony count and coliform group of the sponge and curtain sheet were undetectable. The total colony count and coliform group of Porphyra yezoensis after washing were 4.73 Log CFU / g and 3.33 Log CFU / g, respectively. Compared with the non-blanched group, the total colony count and coliform group of laver in the blanching group after pancake making decreased by 1.02 Log CFU / g and 1.35 Log CFU / g, respectively; the total colony count and coliform group of laver in the blanching group after primary drying decreased by 1.08 Log CFU / g and 0.4 Log CFU / g, respectively; the total colony count and coliform group of laver in the blanching group after secondary drying decreased by 0.93 Log CFU / g and 0.32 Log CFU / g, respectively.

[0042] The above embodiments of the present invention are merely examples for clearly illustrating the invention, and are not intended to limit the embodiments of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention. The above are all preferred embodiments of the present invention. For those of ordinary skill in the art, without departing from the principle of the present invention, modifications to various equivalent forms of the present invention are within the scope of protection of the claims attached to this application.

Claims

1. A method for reducing bacteria in the process of producing Porphyra yezoensis, wherein the production process of Porphyra yezoensis is carried out in the following order, namely, raw materials, initial washing, chopping, cleaning, blending, cake pouring, dehydration, drying, peeling, selection and grading, secondary drying, selection and grading, and packaging. Features: The production process also includes sterilization treatment, the treatment method is as follows: S1: According to the temperature and laver conditions, after the production line is emptied of materials, stop production and remove the dehydrated sponge; S2: The disassembled sponges are subjected to high-pressure washing and squeezing cleaning to remove foreign matter and impurities such as polysaccharide proteins, and then cleaned and disinfected by hot blanching. After disinfection, the sponges are placed in a sponge temporary storage room for use; S3: Use the high-pressure water pump of the primary vegetable processing unit to spray and scald the curtain pieces to achieve the purpose of disinfection; S4: Use a high-pressure water gun to clean the surface of the production line, empty the seawater pool of the production line and fill it with tap water, add a composite quaternary ammonium salt disinfectant, and immerse the equipment in the production line in the composite quaternary ammonium salt for disinfection; S5: Then, the equipment of the production line is soaked and rinsed with clean water to remove the residual composite quaternary ammonium salt, and the soaking and rinsing steps are repeated 3 times; S6: Replace the sterilized sponge and then resume normal production.

2. The method for reducing bacteria in the process of producing Porphyra yezoensis according to claim 1, Features: The equipment in the production line includes but is not limited to a seawater tank, a pipeline, a vegetable cutter, a blender, a blending tank, a sponge, and curtain pieces.

3. The method for reducing bacteria in the process of producing Porphyra yezoensis according to claim 1, Features: Replace and disinfect the dehydrated sponge every 4-48 hours, and spray the curtain pieces in situ for disinfection.

4. A method for reducing bacteria in the process of producing Porphyra yezoensis according to claim 1 or 3, Features: The dismantled sponge is blanched at 100°C for 20-30 min. The curtain pieces are sprayed and disinfected using a high-pressure water pump of a primary processing unit. The hot water temperature is 100°C and the spraying time is 60 - 120 min.

5. The method for reducing bacteria in the process of producing Porphyra yezoensis according to claim 1, Features: The disinfection frequency in S4 is once every 24-72 hours, the concentration of compound quaternary ammonium salt is 400-500 ppm, and the treatment time is 30-60 minutes.

6. The method for reducing bacteria in the process of producing Porphyra yezoensis according to claim 1, Features: The immersion time in S5 is 5-10 min, and the rinsing time is 3-5 min.

7. The method for reducing bacteria in the process of producing Porphyra yezoensis according to claim 1, Features: In S5, the production line is flushed under high pressure, and the clean water is tap water. The tap water is injected into the seawater tank and then pumped into the production line and its flushing pipeline through the pump body.

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