Processing operation key points and quality control methods for mackerel and Spanish mackerel

Mackerel and Spanish mackerel are rich in nutritional value, with DHA and EPA content second only to tuna, and can enhance the body's immunity. They are also very low in price and are well received by consumers at home and abroad. However, mackerel and Spanish mackerel contain a relatively high amount of histidine. When the fish is not fresh or has spoiled, after the action of decarboxylase produced by bacteria, histidine is decarboxylated to produce histamine. When histamine accumulates to a certain amount, there is a risk of poisoning after human consumption. Therefore, process conditions must be strictly controlled during processing to ensure product quality.

1. Processing operation key points

1. Raw material receiving

The raw fish come from clean sea areas free of pollution and are purchased directly from fishermen's boats or purchased at sea by purchasing vessels. Before purchase, check the freshness retention state and storage temperature of the raw materials, take samples of the raw materials and carry out sensory inspection, and purchase only after the sensory inspection passes. After purchase, the raw materials are transported to the factory as quickly as possible in an ice-glazed state, or immediately put into production, or kept fresh by refrigeration.

2. Raw material refrigeration

Place the ice-fresh raw materials in clean containers, keep them fresh with flake ice and press down on top. The temperature of the freshness retention room is below 4°C, ensuring the fish body temperature is below 4.4°C. For raw materials not put into production immediately, send them directly to the warehouse for cold storage or frozen storage after arriving at the factory, and control the cold storage temperature below 4°C.

3. Thawing and washing

Before use, frozen-stored raw materials are naturally thawed in the thawing workshop until individual pieces are easy to separate. The temperature of the thawing workshop is controlled below 21°C, and the thawing time is preferably controlled at 8/hour (8 hours to 12 hours). Before processing, thawed raw materials and fresh raw materials are first washed with clean cold water to remove dirt and surface impurities.

4. Deheading and gutting

Trained workers use scissors or other knives to cut off the fish head and remove the internal organs, and take out adhesions and intestinal glands in the abdominal cavity.

5. Sorting and grading

Trained workers manually grade the raw materials according to the raw material grading requirements, and remove individual raw materials with poor freshness. Individuals with poor freshness are collected and discarded.

6. Washing

Wash the raw materials with flowing water at room temperature to remove surface impurities and congestion and intestinal glands in the abdominal cavity. If the product does not need to be sliced or cut into pieces, put it on trays and send it promptly to the quick-freezing process.

7. Cutting into pieces and slicing

Trained workers use knives to slice or cut Spanish mackerel into pieces (segments).

8. Trimming

Trained workers use knives to trim fish pieces, segments or slices, using scissors and other utensils.

9. Semi-finished product grading

According to the specification and grading requirements given by the customer, manually grade fish segments, pieces and slices, and put them separately into containers with specification labels.

10. Semi-finished product washing

Rinse the graded semi-finished products once with flowing water at room temperature. After rinsing, put them into clean containers and promptly transfer them to the quick-freezing process.

11. Quick freezing

Depending on the different products, the quick-freezing methods are:

(1) Deheaded and gutted products that are not cut into pieces or sliced are directly put on trays and then transferred to the quick-freezing warehouse for quick freezing;

(2) Products cut into pieces are put on trays and then transferred to the quick-freezing warehouse for quick freezing;

(3) Sliced products are quick-frozen with an individual quick freezer.

12. Ice glazing

Glaze the quick-frozen semi-finished products (individually quick-frozen products) with a layer of ice in clean ice water, preferably for 3 seconds to 5 seconds.

13. Inner packaging receiving

Purchase plastic bags that comply with food inner packaging from qualified suppliers, transport them with vehicles that meet the requirements, and confirm safety performance before receiving.

14. Outer packaging receiving

Purchase outer packaging cartons that meet high performance requirements from qualified suppliers, transport them with vehicles that meet the requirements, and confirm usability before receiving.

15. Packaging material storage

Store the accepted inner and outer packaging materials separately in dedicated inner and outer packaging material warehouses as required. Before use, transport them to the workshop with clean in-factory transport tools and keep them ready for use.

16. Packing and labeling

According to customer requirements, select suitable packaging materials, carry out inner and outer packaging of the product, and weigh to ensure the weight of each box meets the requirements. Check whether the outside of the packaging box has the statement "Fully heat before eating."

17. Metal detection

Each box of packaged products undergoes metal detection to prevent metal fragments from being mixed into the product.

18. Warehousing and refrigeration

Transfer the products to the finished product warehouse for cold storage, and control the cold storage temperature below -18°C.

19. Factory shipment

After packaging, send them into a freezer room below -18°C for low-temperature frozen storage. After passing inspection, they can be shipped at any time.

2. Quality control

1. Control of histamine

When raw materials are above 4.4°C and exposed for too long, histamine toxic to humans will be produced. Once histamine is formed in fish meat, even cooking cannot decompose it, and it is difficult to judge its histamine content based on the appearance or smell of the fish meat alone. Therefore, the following must be done:

(1) When receiving raw materials, the histamine content in the fish body shall not exceed 50 ppm, and among 118 sampled fish, no more than 3 spoiled fish shall be allowed.

(2) Strictly control time and temperature throughout the processing. Under normal circumstances, the time from completion of raw material thawing (or input of ice-fresh raw materials) to completion of quick freezing of the product is required to be controlled within 4 hours, and the workshop temperature is required to be controlled below 21°C. When arranging the progress of each process, attention should be paid to the word "timely," avoiding idling and backlog of raw materials and semi-finished products, and ensuring smooth handover between processes.

2. Requirements for inner packaging materials

Each batch of inner packaging materials comes from qualified suppliers, and suppliers are required to provide proof that the products comply with food packaging, ensure that the packaging materials do not contain harmful chemicals found in non-food-grade inner packaging materials, and confirm that they have not been contaminated during transport.

3. Packaging and labeling

Taking into account contamination or residues of pathogenic bacteria, each packaging carton is marked on the outside with "Fully heat before eating." If labels are missed or unclear, repackage.

4. Metal detection

Use a metal detector for continuous monitoring, verifying once every half hour, to ensure that the product does not contain iron fragments with a diameter greater than or equal to 2.5 mm and non-iron metal fragments greater than or equal to 1.6 g.

5. Other quality assurance measures

These include formulating personnel training plans, factory maintenance and repair plans, product recall plans, product identification code plans, corrective action plans for frozen mackerel/Spanish mackerel products, procedures for HACCP plan verification, etc.