Meat ageing

Preservation technique of meat

1. Unit IV- Processing & preservation of meat Meat aging Meat, poultry and fish Processing technology B. Tech. Final Year / Sem 7 (2021-22) Mrs. Snehal P. Khandekar

2. Meat Aging (Conditioning / Ripening ) Ageing is considered as very important aspect of meat processing as it imparts desirable flavours, textural and other sensory attributes to the finished product .

3. Mrs. S. P. Khandekar Fresh unpackaged carcass and meat can be stored providing it remains wholesome, as indicated by the absence of dryness, discoloration, visible mold growth, sliminess or odor. Meat stored for ageing purposes must be subjected to a controlled, documented and approved ageing procedure. Ageing is the process during which microbes and enzymes act upon the meat to help breakdown the connective tissue to tenderize the meat. There are two ways ageing can be accomplished: Wet ageing by placing beef in a plastic bag under vacuum; or Dry ageing by storing beef in a temperature and humidity controlled environment (room/chamber) The main difference is that wet ageing results in little or no moisture loss, whereas dry ageing can result in up to 50% moisture loss. Product labelling should indicate the ageing processes used.

4. Mrs . S. P. Khandekar 1. Dry ageing storage conditions: Temperature : between - 0.5°C to 1°C (2°C to 3°C may be used when only ageing for up to 3 weeks); Relative Humidity: between 75% to 85%; Air velocity: between 0.2 to 0.5 m/s. 2. Wet ageing storage conditions: Storage below 5°C; Validation testing than any mold is Thamnidium ; Shelf life testing for Enterobacteriaceae and E.coli at the end of the ageing period.

5. Factors & Changes during Ageing Flavor Dry ageing involves the degradation of connective tissue and muscle protein structure of the meat of carcasses or cuts of meat and must be managed to ensure growth of beneficial and non-harmful molds. Best practice is to reduce carcasses to smaller primals and sub-primals in preparation for the ageing process. Dry aged beef has an intense flavour when compared to wet aged meat that can have a sour blood/serum flavour . The reason for this is that the predominant bacteria on dry aged meat are the Pseudomonas that grow in the presence of oxygen.  This is different to wet aged packaged meat where Lactobacilli bacteria grow in the absence of oxygen. The Lactobacilli bacteria convert lactose to lactic acid therefore wet aged product may have a slightly sour taste or odor when compared to the Pseudomonas that do not produce any sour flavours on dry aged meat.

6. The flavor of dry aged beef can range from buttery to nutty. The flavor is also dependent on other factors such as the quality of the meat cut, storage temperature and relative humidity during ageing. Premium products can be dry aged for up to 6 weeks. It may be difficult to maintain the wholesomeness of meat after 8 weeks of dry ageing .

7. 2. Enzymatic action Endogenous proteolytic enzymes from the meat itself as well as from the specific beneficial molds weaken the structural Myofibrillar proteins in the meat. This takes 10 to 14 days and results in a more tender meat. At this stage the meat flavours can usually be described as buttery and smooth . 3. Evaporation Loss of water from the meat by evaporation causes increase in concentration of the proteins and increases flavour intensity to a nutty taste. Final water loss can be up to 50% and depends on the relative humidity used during drying.

8. 4. Relative humidity If the humidity is too high, it will result in the growth of spoilage bacteria, which would produce an off-flavor. If the humidity is too low, bacteria growth will be limited but evaporative weight loss will increase causing the meat to dry out quickly, resulting in a decrease in juiciness. The preferred range of relative humidity is 61%–85% and should be recorded and checked daily to maintain control.

9. 5. Tenderness Dry aging promotes the growth of beneficial mold on the surface of the meat like  Thamnidium . It has the appearance of a pale gray color and will form patches, called whiskers, on the fatty parts of the carcass or cut.  Thamnidium ’s enzymes are able to break down muscle and connective tissues by penetrating into the meat and emitting proteases and producing collagenolytic enzymes. Proper handling practices, aging time, temperature, relative humidity, and airflow are required to grow beneficial mold and limit other microbial contamination.

10. 6. Airflow It is crucial to have sufficient airflow in the refrigerated room to have adequate air circulation. The meat will not be able to release the required amount of moisture for the drying process without sufficient air circulation. However , if there is too much circulation, the meat could dry out too quickly. The recommended range of airflow is 0.5–2 m/s (1.6–6.6  ft /s) with a velocity of 0.2–1.6 m/s. It is important that airflow and velocity stay consistent through the entire dry aging process.

11. 7.Antibacterial Strategies The use of ultraviolet (UV) light for destruction of bacterial cells is well known for fresh meat. A more sophisticated approach to manage the dry ageing process is to install UV lighting entirely and leaving no other light source. Air can also be circulated through UV light chambers.

12. Testing wholesomeness of Aged Meat The quality and wholesomeness of meat for human consumption can be determined by basic observations of dryness, discoloration, visible mold growth, sliminess and odor.   Meat processing facilities are required to comply with the requirements of  Australian Standard for the Hygienic Production and Transportation of Meat and Meat Products for Human Consumption (AS 4696:2007)  with regards to the management of wholesomeness . The dry ageing of beef can be for up to eight weeks, depending on the product characteristics required. Dry aged meat products must be tested for mold to validate the procedure. Growth of Thamnidium mold can start from three weeks after commencing the ageing process. Testing involves removing a 100g portion of untrimmed aged meat that includes visible mold if it is present, and sending it for testing at laboratory .

13. If testing for mold shows that the results are positive, then confirmation that the mold is Thamnidium must be conducted. For wet aged meat products there will be no growth of mold due to the lack of oxygen in the bag therefore there is only a requirement to confirm the wholesomeness of the product. To confirm the wholesomeness of dry and wet aged products, the shelf life must be validated by testing for Enterobacteriaceae and E.coli. The critical limits for wholesomeness for these purposes are microbiological limits of Enterobacteriaceae of 1,000cfu/g and E.coli of 10cfu/g. Five 10 gram samples must be taken for testing of both Enterobacteriaceae and E.coli .

14. Testing Flow Chart

15. Thank You !!!