Standard Operating Procedure (SOP) for Meat Handling in Factory and Link to In-Store

From a Nigerian perspective with micro-compromised meat.

Important note: We write SOPs in English and German; See Earthworm Writing & Research Studio & Earthworm Schreib und Forschungsstudio

Carcass Receiving

  • Trim: trim all the dirt and scraps hanging off the carcass off
  • Wash: wash with 40% anolyte water, scrub, don’t only spray.

It is important to understand that good micro-control starts here.

Factory-Store Coordination

In-store team is to be identified.

To facilitate proper coordination between the factory and a store, set up a team in-store that will directly liaise with the factory team related to MAP orders and Bulk orders. Also in terms of off-shelves and freezer management. All off-shelves must initially be approved by someone from the factory team who will validate how it’s being handled. In terms of orders, ensure that the order is in line with SOH and projected sales for the store. Only then should the order be sent to the supply chain to place the actual order and formalise the LPO.

Production Planning

The production process will result in three types of stock being produced: The two actual orders being a bulk order and a MAP order per store and “excess stock” which is sent to the – 18 deg C long-term freezer. ALL Excess stock is packed in – 18 deg C bulk bags.

a. A Bulk Order: Produced in multiples of 5kgs
b: A MAP order: produced in MAP trays and packed into crates.

The bulk orders and the MAP are combined per store and sent to the 10 deg C holding/ dispatch freezer where they are kept together for dispatch the following day.

Production – Beef/ Pork

Create a -10 deg Freezer toi facilitate reduced crystal size formation during freezing.

Want to know more?

Lets evaluate the freezing options and what is happening. When freezing meat, the size of ice crystals and the extent of cellular damage depend on the temperature and speed of the freezing process. In a freezer set to -10°C, ice crystals will form more slowly and be smaller compared to a freezer set to -18°C, where the process is slower due to the lower temperature. In other words, the same freezer, set at -10 and -18 respectively -> it will take longer for the meat to reach – 18 which results in bigger ice crystals. The simple truth about ice is that smaller ice crystals cause less damage to muscle cells, preserving the bound water within the cells, resulting in less purge (water loss) upon thawing.

There are two options in getting to the targeted temperature points of – 10 and – 18 (for comparative reasons) One if to change the set point on the freezer and the second option is to use a blast freezer.

Freezer Set Points:

Here we change the set points on the same freezer and compare the effects.

-10°C Freezer: Leads to smaller ice crystals, reducing cellular damage, but doesn’t fully freeze all the free water, potentially leaving some microbial activity if not monitored carefully.

-18°C Freezer: Larger ice crystals form due to slower freezing, causing more cell damage and more water loss (syneresis) when the meat thaws.

Blast Freezer Option:

There is a way that we could use the blast freezer. For this we need a probe which we insert in one o piece of meat and we measure when we get to the required temperature.

Assuming the Blast Freezer is set at at -30°C with Probe Monitoring: A blast freezer rapidly reduces the temperature, creating very small ice crystals, which minimizes cellular damage and preserves meat quality. If you monitor the temperature with a probe and remove the meat when it reaches -10°C or -18°C, the freezing process can be carefully controlled to balance between freezing rate and final storage temperature.

Best Option:

The blast freezer at -30°C, with probe monitoring, is preferable. It allows for faster freezing, smaller ice crystals, and less cellular damage. Removing the meat when it reaches -10°C will be ideal if the goal is to minimize ice crystal size and preserve meat quality. However, if long-term storage is needed, freezing to -18°C might be necessary, albeit with more significant syneresis and potential quality loss.

Why is – 18 deg C better for long term Storage compared to – 10 deg C

At -18°C nearly all free water within the meat is frozen which effectively halts microbial activity. While microbes are inactivated at both -10°C and -18°C, some free water may remain unfrozen at -10°C, which could allow minimal microbial activity to persist over time, leading to spoilage. The time is however very long which means that it will not impact us for the factory – retail store scenario. It effectively removes the negative of freezing and thawing the meat. Two important additional points must be made. At -18°C enzymatic reactions are also prevented more thoroughly and slows down oxidation processes more effectively than -10°C, which further preserves meat quality during extended storage.

At my own factory in Cape Town I used the probe in blast freezer option for a ling time and it worked very well! Its less complicated than it sounds.

-> Equipment – Beef/ Pork

  • All scales have been checked for calibration daily before work starts by the maintenance team. A calibration spreadsheet must be drawn up and signed off by the various department managers.
  • Large white crates. It has to be properly washed with soap and sanitised with sanitiser and anolyte water. Is anolyte water available in the wash bay (maintenance plus new cleaning team)?
  • Bandsaw (washed and sanitised)
  • Soap, sanitisers and paper towels in the deboning hall for effective hand washing
  • Anolyte water for spraying on the tables after washing for sanitising them.
  • Buckets with 100% anolyte for dipping hands in to remove fat during processing.
  • Rubbish bins with no lidd and black bag liner inside.
  • Meat bags
  • Spay bottles to mist onto meat and packaging

-> Cutting Procedure – Beef/ Pork

  • Wash and sanitise hands every 40 minutes
  • Knives must be kept in a 40% anolyte solution. Every 40 minutes, change knives by placing the knives you are working on within the anolyte solution and taking a new set of sanitised knives. Wash and sanitise hands and resume work.
  • Before tea and before lunch, remove meat which is now in bags from the cutting tables and thoroughly rinse with anolyte water and dry the work area with squeegees.
  • A meat buggy with 40% anolyte water must be available. After cutting of the primal, they must be dipped in the anolyte solution and placed on a separate table to dry out. Pick from these to cut.
  • The buckets of 40% anolyte water for the butchers to rinse their hands in and the anolyte solution for knife sterilisation must be replaced with new anolyte while staff are on tea and on lunch break by the cleaning staff.
  • Meat for bulk supply is to be kept in the meat bag and mist-sprayed with a solution of anolyte water 40% and sodium metabisulfite, 0.5% before it’s packed in a meat bag – no more than 10kg per bag.
  • Mark the bag with a red cookie pen with a right tick as soon as the meat in the bag has been sprayed.
  • Bulk meet orders are produced directly in the 5kg meat bags as per the production plan for the day.
  • Meat for MAP packaging must be packed in a crate with a crate liner and sent to the packing department (Patrick to source crate liners – investigate )
  • All meat is waiting to be packed to be kept in the fresh meat WIP chiller.
  • Each crate is sent through to be properly tagged with a loop tag.
  • Deboners and trimming staff must cut directly into bags and not directly onto the table. When they leave their stations for tea or lunch, the bags must be placed in white crates so that cleaners can come and disinfect the tables with anolyte water (40%) and dry them with squeegees so that they dry again when the butchers return.

Production – Chicken

-> Equipment – Chicken

  • A scale that has been checked for calibration
  • Large white crates. These have to be properly washed with soap and sanitised with sanitiser and anolyte water.
  • Thawing batch equipped with compressed air for bubbling air through water to provide effective heat transfer in the water.
  • Soap, sanitisers and paper towels in the chicken thawing area for effective hand washing
  • Anolyte water for sparing on the tables after washing for sanitising them.
  • Buckets with 40% anolyte for dipping hands in to remove fat during processing.
  • Rubbish bins with the lid removed and a black bag liner inside.
  • Meat bags
  • Spay bottles to mist onto meat and packaging

-> Thawing Procedure – Chicken

Thaw the chicken for 36 hours and not just for 24 hours using the following procedure

  1. Remove large bags of chicken from the freezer (-18 degrees C) at 17:00 every day.
  2. Place in chiller at + 3 deg C overnight to break the hard freeze.
  3. Remove from large outer bag and place in water by 8:00 the next morning with bubbles and thaw for 3 hours.
  4. Remove the outer bag which is wrapped around each chicken and place it back in the chiller in large white crates.
  5. The next morning, at 8:00, remove from the chiller and cut or process further.
  6. Essential to tag all meat going into the WIP Chiller.

-> Cutting Procedure – Chicken

  • Wash and sanitise hands every 40 minutes
  • Before tea and before lunch, remove chicken from the cutting tables and thoroughly rinse with anolyte water and dry the work area with squeegees.
  • A meat buggy with 40% anolyte water must be available. As chickens are removed from the white crates for cutting, first rinse them in the 40% anolyte solution and place them on an empty table to dry. Pick from these chickens to cut.
  • Knives must be kept in a 40% anolyte solution. Every 40 minutes, change knives by placing the knives you are working on within the anolyte solution and taking a new set of sanitised knives. Wash and sanitise hands and resume work.
  • The buckets of 40% anolyte water for the butchers to rinse their hands in and the anolyte solution for knife sterilisation must be replaced with new anolyte while staff are on tea and lunch break by the cleaning staff.
  • Anolyte for thawing chicken?

Packing in either MAP or for Bulk Orders

1. Bulk Stock (for HMR):

  • Place meat in bags, not exceeding 5kg per bag.
  • Fog spray with 0.5% sodium metabisulfite and 40% anolyte.
  • Seal bags without any exposed holes.
  • Ensure packers and deboners wash and sanitize hands every 40 minutes.
  • Change anolyte water in pales every 40 minutes.
  • During tea and lunch breaks, rinse tables with 100% anolyte and dry with squeegees.

2. MAP Packaging:

  • Meat awaiting packaging should be stored in the chiller.
  • Use crate liners for meat crates.
  • Wash hands every 40 minutes and sanitize them before packing.
  • Mist trays with anolyte before packing meat.
  • Mist meat cuts with 0.5% sodium metabisulfite and 40% anolyte before sealing trays.
  • Place packed trays in crates per variant and store in a -10 deg C freezer.
  • A QC function must be performed by the person taking the trays off the Polaris. If the seal is not `100% from a seal and a visual perspective, the packet must be sent back to be re-packed immediately.
For those who want to know more:

A. Efficacy of Mist Spray with 0.5% Sodium Metabisulfite and 40% Anolyte for Fresh Meat in Bulk Orders

Misting freshly cut meat with a 0.5% sodium metabisulfite and 40% anolyte solution after it has been placed in 5kg bags provides an additional layer of protection against microbial growth and oxidation. Sodium metabisulfite acts as an antioxidant and antimicrobial agent, helping to preserve the colour and freshness of the meat. Anolyte water, a powerful sanitiser, enhances this effect by neutralizing pathogens. This treatment ensures that the bulk meat remains safe and maintains its quality during transportation and storage.

B. Misting MAP Trays Before Meat Placement

Applying the same mist solution (40% anolyte and 0.5% sodium metabisulfite) to MAP (Modified Atmosphere Packaging) trays before placing the meat serves as a preemptive measure to sanitize the surface and reduce microbial contamination. This step is crucial in ensuring that the packaging environment does not introduce new contaminants to the meat, thereby extending its shelf life.

C. Misting After Meat is Placed on the Tray

Once the meat is placed in the tray, misting it with the solution adds an extra layer of protection, directly targeting the surface of the meat. This further reduces the microbial load and helps maintain the meat’s colour and texture by minimizing oxidative changes.

D. Value of Packing in MAP Trays with CO2, O2, and N2

Packing meat in MAP trays filled with specific gas mixtures—typically carbon dioxide (CO2), oxygen (O2), and nitrogen (N2)—creates an environment that significantly extends the shelf life of the product. CO2 inhibits the growth of spoilage bacteria, O2 maintains the meat’s colour by preventing oxidation, and N2 serves as a filler gas to maintain the package’s shape and prevent collapse.

Dispatch

  • Bulk Orders and Tray Ready (MAP): Send separately with two Local Purchase Orders (LPOs) per store.
  • Bulk Bags: Only 5kg per bag; bags over 5kg are not allowed. Pack bulk orders in crates, with each crate tagged separately, indicating total weight.
  • Crates: Ensure trays are packed in crates per cut/variant. Each crate must contain only the same variant and must be tagged with the total weight, the batch number and the variant.
  • Picked order is to be kept in the dispatch freezer set at 10 degrees C.

Store Receiving

Store Receiving Infrastructure

  • A working scale. The scale is checked for calibration every morning along with all scales in the factory (by whom???).
  • It must be clean (walls, floors, drains) (who will inspect?)
  • Tables must be set up in the meat area to receive the crates (by whom?)
  • Two freezer options must be investigated. – 18 and -10 deg C freezers. Whichever freezer setting is used, there must be space to accommodate the full quantity of crates expected to be in the meat area at any point in time (by whom? by when?)
  • No wood on the floor
  • Soap and sanitiser in dispensers by the wash basin (who checks??)
  • Water in the wash basins should be between 38 deg C and 42 deg C. No warmer or colder. (who will do this??)
  • Hand paper towels must be available in proper roll holders with a dustbin next to it where the staff member will not have to touch a lid to dispose of the paper towel. (who will ensure??)
For those who want to know more:

Why do we freeze meat and what is the impact of freezing meat? Also, why will we even be bothered to see if – 10 deg C or – 18 deg C works better for us and how will we be able to tell which is better?

Storage at -10°C vs. -18°C

Optimizing Meat Storage Temperature to Minimize Syneresis

Storing meat at -10°C, rather than freezing it to -18°C, helps mitigate purge or syneresis, which is the process where water and soluble proteins leak out of muscle cells, leading to weight loss and reduced visual appeal. Muscle tissue contains approximately 75% water, divided into bound water (around 70-75%, held within cells), biological water (5-10%, tightly bound to proteins), and free water (15-20%, loosely held and most prone to loss during thawing).

When meat is frozen, the water inside forms ice crystals. The slower and longer the freezing process, the larger these ice crystals become. Freezing meat to -18°C results in larger ice crystals than at -10°C. Large ice crystals can damage cell membranes, causing bound water to escape from the cells and become free water. Upon thawing, this unbound water is lost from the meat, reducing juiciness and quality.

Microorganisms cannot easily access bound water inside cells, but they can use free water to proliferate. The presence of more free water increases the risk of microbial growth, which is why repeated freezing and thawing is undesirable. While freezing temporarily inactivates microorganisms, they become active again once the meat is thawed, leading to spoilage. Therefore, maintaining the meat at -10°C is a good compromise temperature as it reduces large ice crystal formation, which in turn again limits cell damage, and this minimizes both water loss and microbial risks, preserving meat quality.

Microbial Proliferation and Freezing:

Microorganisms primarily access free water in meat, as it is not bound within the cellular structure. They cannot use biological water, which is integral to protein structures, or bound water within the cells, which is less available for microbial activity. The presence of more free water creates an environment where microorganisms can proliferate more rapidly.

Freezing does not kill microorganisms but instead places them in suspension (inactivates them) while the water is frozen. As soon as the meat is thawed, microorganisms resume their activity, breaking down the meat, and leading to spoilage. This breakdown is often detected through gas production, leading to bloated MAP trays, and through changes in the smell and colour of the meat.

Impact on Meat Tenderness:

It is essential to reduce water loss during the thawing of the meat as much as possible, also because of the impact it has on the tenderness of the meat. Meat tenderness is influenced by three primary factors namely water content, connective tissue (collagen), and the contraction of muscle fibers during cooking. Of these, collagen content and the contraction of muscle fibres during cooking are the most significant contributors to tenderness. While water content affects juiciness, losing water due to syneresis can negatively impact both tenderness and the overall eating experience. Proper storage conditions, such as maintaining a -10°C temperature, help retain the meat’s water, thus preserving its tenderness and juiciness.

While collagen and muscle fibre contraction are the primary determinants of meat tenderness, minimizing water loss through proper storage significantly enhances meat quality, ensuring a tender and enjoyable product for consumers.

Storage at – 18 vs Storage at – 10 deg C -> The Retail Perspective

Storing the meat at a higher temperature such as – 10 instead of – 18 has a big impact in the retail environment where we don’t want to place solidly frozen meat on the shelf (-18 degrees C). Generally, the consumer wants to buy the meat thawed. If meat is kept at – 18 degrees C, a controlled thawing step is necessary in the back of the store before the meat is brought out for display on the shelves. This adds another layer of complexity to the operation with another step where close monitoring is required and where mistakes will happen by leaving the meat out too long in this area. This is why -10 freezers are considered:

-> The time to go from a frozen state to thawed products will be so short that pean can be placed directly on the shelve (validate how long and if this is more optimal compared to – 18 degrees C and chiller thawing before placement on shelves)

-> – 10 meat will have much smaller ice crystals which will reduce purge significantly in the MAP trays.

Receiving

  • Crate Handling: Upon receiving, the crates with tray-ready products will stay at the store and be picked up with the next delivery provided that the crates have been emptied.
  • Freezer Storage: Meat should remain in crates and be placed inside a -10°C freezer. Ensure that meat is not stored in the freezer for longer than 4 days.
  • Pricing and Shelving: Before moving the meat to the display fridge, price the meat with a 7-day shelf life.
  • FOFO Application: Write the receiving date on the tag for proper First Opened, First Out (FOFO) management.
  • Freezer Temperature Monitoring:
    • Check and record the -10°C freezer temperature at 8:00, 12:00, 16:00, and 20:00.
    • Do the same checks for the – 18 deg C freezer
    • Do the same checks for the display freezer

Management off-shelves

  • Freezer Preparation: Maintain an -18°C freezer and a -10°C freezer, keeping meat in crates with the production date, batch number, and freezing date tagged.
  • Stock Evaluation: Evaluate stock for colour and “blown” status at 8:00, 13:00, and 19:00 daily. Handle suspect meat as follows:
  • Removal and Inspection: Open the tray and smell for sourness. If sour, bag and freeze at -18°C.
  • Marination Option: If no smell, consider marinating for 24 hours, then assess for use or further processing.
  • Further Action: For meat that can’t be marinated, bag and store in the -18°C freezer until enough volume is available for transfer to HMR or bulk marination.

Handling Sour or Spoiled Meat

  • Inspection: Meat with a sour smell must be evaluated by factory support staff (Eben, Raja, Dapo) in-store. Perform an acetic acid (vinegar) or anolyte wash as required.
  • Utilization: If viable, use the meat in prepared dishes (HMR), not sold on its own. Complete proper documentation if the meat is deemed unfit for human consumption.
  • Corrective Actions: Review the entire process to identify and amend SOPs if necessary.

Off-Shelf Procedure

  • Daily Off-Shelf Register: Complete the off-shelf register daily and send a report to the factory support team, detailing reasons for off-shelving and actions taken.
  • Report Components:
    • Batch number, meat cuts, meat weight for every packet
    • Reason for off-shelving (e.g., smell)
    • Type of bag used (sour meat, HMR, or for future marination)
    • Freezer allocation (-10°C or -18°C)
    • Display cabinet temperature when offshelved
    • Seal-status of MAP tray (e.g., compromised or intact).

Consumables for Store and Tools to Evaluate Meat

  • Looptags to tag meat that is offs-helved.
  • Meatbags to “house meat that is offs-helved.
  • Temperature Probe
For those who want to know more:

When meat is exposed to air in a freezer or if there are holes in the packaging, freezer burn can occur. Freezer burn results from moisture in the meat evaporating into the dry freezer air, leading to dehydrated, discoloured, and tough areas on the meat. This not only impacts the texture but also diminishes the flavour, making the affected parts less palatable.

To prevent freezer burn, it is crucial to store meat in airtight packaging. The best option is to vacuum-seal the meat, which removes all air and prevents moisture loss. If vacuum sealing isn’t feasible, tightly wrap the meat in plastic wrap before placing it in a heavy-duty freezer bag, ensuring as much air as possible is squeezed out before sealing. Additionally, ensure there are no holes or gaps in the packaging, especially where the bag is tied.

For short-term storage (less than a month), placing the meat in a plastic bag with the air removed can be sufficient. However, for longer storage periods, vacuum sealing or using plastic wrap combined with a freezer bag is recommended. If plastic bags are unavailable, wrapping the meat tightly in aluminium foil can also offer protection. Properly sealed meat will retain its quality and flavour during freezing.