Preservation of Meat and Meat Products From Microbial Spoilage

Table of Contents

• Introduction to Preservation of meat
• A. Asepsis
• B. Thermal method
• C. Non-thermal method
• D. Curing
• E. Spices
• F. Fermentation and pickling
• G. Use of preservatives agents
• H. Irradiation
• I. Hydrostatic pressure processing
• J. Hydrodynamic pressure processing
• K. Packaging
• References

Introduction to Preservation of meat

• Meat and its products contain a wide range of nutrient contents.
• Due to their rich nutrient composition, meat and meat products serve as an excellent growth medium for various microorganisms.
• To prevent microbial activity, different preservation methods are applied to eliminate the growth of spoilage-causing microorganisms.
• These preservation methods also play an important role in maintaining the nutritional properties of meat.
• Over time, several techniques have been developed and utilized to limit the growth of organisms in meat and meat products.

A. Asepsis

• Aseptic conditions must be maintained during the slaughtering and handling of meat to prevent microbial contamination.
• Spraying water on animals before slaughter helps in removing gross dirt, which contributes to maintaining asepsis.
• The use of sterile knives, utensils, clothes, and other equipment is essential to avoid microbial contamination of meat.

B. Thermal method

1. Heat processing

• Sterilization involves heating meat at temperatures above 100 °C, which kills spoilage-causing microorganisms present in meat.
• During heat processing, factors such as water content, fat levels, and consistency of various meat products are carefully considered.

2. Dehydration

• Dehydration reduces water activity in meat, thereby preventing the growth of spoilage-causing microbes.
• Meat dehydration is mainly achieved in two ways:
• Sun drying: Practiced in ancient times, where meat chunks were dried under the sun as a preservation method.
• Mechanical drying: Involves passing hot air with controlled humidity over the meat.
• Dehydrated meat can be stored for a few months to up to a year in air-tight containers without requiring refrigeration.

3. Canning

• Canning is a preservation method achieved by thermal sterilization of meat sealed in hermetically closed containers.
• The canning process includes several steps: preparation of meat, precooking, filling, exhausting, seaming, thermal processing, cooling, and storage.
• Properly canned meat products have a shelf life of at least two years at ambient temperature.

4. Smoking

• Smoking is an ancient preservation technique in which meat is subjected to smoke, enhancing both sensory and nutritional qualities of meat products.
• Meat is exposed to smoke from burning wood or other plant materials, either with or without curing, as curing and smoking are closely related.
• Smoke preserves meat by:
• Dehydrating the meat surface.
• Lowering the surface pH.
• Providing antioxidant effects from smoke constituents.
• Smoking extends the shelf life of meat up to a year or even longer without the need for refrigeration.
• It is effective against pathogenic microorganisms such as Staphylococcus aureus, Escherichia coli, Listeria monocytogenes, and Salmonella spp., while also reducing lipid oxidation.
• Common smoking methods include:
• Hot smoking: Meat is hot smoked with mild salt addition to inhibit bacterial growth. The temperature range is 60 °C to 93 °C.
• Smoke roasting: Meat, often with curing, is hot smoked at around 300 °C. Spices are added both to enhance flavor and inhibit bacterial growth.
• Cold smoking: Meat, either partially or fully cured, is hung or placed on racks and smoked for several days at temperatures ranging from 23 °C to 48 °C.

C. Non-thermal method

1. Freezing method

• Freezing is considered the best method for preserving fresh meat while maintaining the original characteristics of the meat.
• It works by slowing down enzymatic reactions and microbial growth.
• An ideal temperature of –55 °C completely prevents quality changes and reduces microbial spoilage.
• Microbial growth is arrested at freezing temperatures but the microbes are not killed, which slows down the spoilage process.
• Storage times:
• Uncooked meat (such as steaks or chops) can be frozen for 4–12 months.
• Cooked meat can be stored for 2–3 months.

2. Chilling:

• Chilling is the most widely used method for short-term preservation of fresh meat.
• Fresh meat is stored at refrigeration temperatures between 0 °C and 8 °C.
• At 4 ± 1 °C, fresh meat usually remains in good condition for 5–7 days.
• Chilling inhibits multiplication and metabolic activities of pathogenic bacteria, viruses, and toxins.
• Certain parasites can also be destroyed through chilling:
• Taenia cysts and all stages of Trichinella spiralis may be destroyed when infected meat is stored at –18 °C for 20–30 days.

3. Freeze-drying:

• Freeze-drying uses the principle of sublimation to preserve meat.
• The process involves freezing the meat at low temperatures between –10 °C and –25 °C, followed by sublimation to reduce moisture content to as low as 0.5%.
• This method ensures that chemical reactions occur very slowly.
• Microorganisms cannot survive under these low-temperature and low-moisture conditions.

D. Curing

• Curing of meat is an old-age preservation technique that not only extends the shelf life of meat but also imparts a desirable flavor to the food.
• The preservation effect is achieved by decreasing water activity and increasing osmotic pressure, both of which delay microbial growth.
• Sodium chloride, sodium nitrite, potassium nitrite, and sugar are the main ingredients commonly used in the curing process.
• Curing often involves preserving meat with different combinations of salt, nitrates, nitrites, or sugar.
• Salting can be done either by rubbing dry salt directly on the meat or by soaking the meat in brine containing at least 18% salt.
• Sugars play an important role in curing because they bind moisture and reduce water activity in meat; generally, a sugar concentration of 20–25% is used.
• Common sugar sources used include dextrose, sucrose, brown sugar, corn syrup, lactose, honey, molasses, maltodextrins, and starches, which also enhance flavor, reduce the harshness of salt, and lower water activity.
• Sodium nitrite and potassium nitrite are effective in controlling the growth of anaerobic bacteria, maintaining the color of meat, reducing lipid oxidation, and preventing undesirable odor development.

E. Spices

• Different types of spices are commonly used in meat not only to impart unique flavors but also to extend the shelf life of the product.
• Spices such as pepper, black pepper, cloves, allspice, cinnamon, garlic, onion, and anise are frequently utilized in meat preservation.
• These spices function as antioxidants by reducing the rate of oxidative rancidity development in meat.
• Spices are incorporated during processes such as curing, smoking, and cooking, which enhances both the flavor and the preservation of meat.

F. Fermentation and pickling

• Fermentation is an ancient process that has long been used in the meat industry as an effective method for preserving meat while also enhancing its flavor.
• It is considered a simple and inexpensive preservation technique for meat and meat products.
• Meat fermentation is a complex biological process in which desirable microorganisms are introduced, often along with the addition of spices.
• Lactobacillus species are most commonly used in meat fermentation.
• The preservation effect of fermentation is mainly due to acid production, hydrogen peroxide production, and antimicrobial agents produced by the starter cultures, which together prevent the growth of food-borne pathogens and spoilage-causing microorganisms.
• In pickling, meat products are immersed in brine-filled containers for storage.
• The high concentration of salt and spices used in pickling acts as a strong barrier against pathogens and undesirable bacteria.

G. Use of preservatives agents

• Preservatives are substances that have the ability to inhibit or slow down the growth of microorganisms in food, thereby extending its shelf life.
• In the context of meat and meat products, preservatives can generally be divided into three main types: 
• Natural preservatives
• Bio-preservatives
• Chemical preservatives

Types of Preservatives	Preservatives Used	Action
Natural preservatives	Salt, Sugar	Increase osmotic pressure, reduce water activity in meat
	Oregano, rosemary, thyme, clove, lemon balm, ginger, coriander, cumin, pepper, garlic, turmeric, mustard seed	Affect the enzymatic activity of microorganisms, increase permeability of microbial cells
	Lactoferrin	Antimicrobial activity against bacteria, fungi, viruses, and protozoa
Chemical preservatives	Benzoic acid, citric acid, propionic acid, sorbic acid	Effective mold inhibitors, exhibit antibacterial activity
	Sulfites	Antimicrobial agent, efficient against aerobic Gram-negative bacteria, molds, and yeasts
	Nitrites	Stabilize red meat color, cured meat flavor, retard rancidity, inhibit growth of anaerobic bacteria
	Acetic acid, lactic acid	Prevent bacterial growth by reducing pH, increase microbial cell permeability
	Sorbate, acetate	Arrest growth of yeasts in meat
	Ascorbic acid (Vitamin C), sodium ascorbate, erythorbate	Antioxidant properties, enhance antimicrobial effects of sulfites and nitrites
	BHA, BHT, TBHQ, Propyl Gallates (PG)	Delay, retard, or prevent lipid peroxidation, reduce oxidation of meat, exhibit antimicrobial properties against bacteria, fungi, viruses, and protozoa
	Phosphates	Exhibit antioxidant activity, retard rancidity, reduce oxidation in meat products
Bio preservatives	Bacteriocin (nisin)	Inhibit or kill unwanted microorganisms by pore formation in bacterial plasma membrane
	Lysozyme	Exhibits antimicrobial activity mainly against Gram-positive bacteria
	Chitosan	Exhibits antimicrobial activity by chelating ions from lipopolysaccharide, increases microbial cell permeability, acts as an oxygen barrier inhibiting aerobic bacteria

H. Irradiation

• Ultraviolet (UV) radiation is a form of electromagnetic radiation with wavelengths ranging from approximately 10 to 400 nanometers.
• UV radiation is mostly bactericidal and is commonly used for the surface sterilization of meat.
• Gamma rays, X-rays, and accelerated electron beams serve as sources of ionizing radiation for the preservation of foods.
• Irradiation, also referred to as “cold sterilization,” preserves meat by affecting microbes through DNA damage and the ionization of water.

I. Hydrostatic pressure processing

• Hydrostatic pressure processing is a non-thermal pasteurization method in which food is subjected to high pressure ranging from 330 to 600 MPa for approximately 10 minutes.
• High pressure affects the cellular physiology of microorganisms and is often used as an additional final step during meat processing.
• This method inhibits microorganisms in meat by interfering with their regular cellular functions and inactivates certain food enzymes.

J. Hydrodynamic pressure processing

• Hydrodynamics refers to the study of fluid motion and the pressure exerted on solid bodies immersed in these fluids.
• Hydrodynamic pressure processing involves tenderizing meat using shock waves generated from underwater detonation.
• These shock waves create pressure on vacuum-packaged meat in the range of 70 to 100 MPa.
• This process also helps reduce the microbial load that may be present on the meat.

K. Packaging

• Packaging protects meat products from microbial spoilage and prevents defects such as discoloration, off-flavors, off-odors, nutrient loss, texture changes, and pathogenicity caused by microorganisms.
• Various types of packaging are used to preserve meat products without deteriorating their nutritional value or texture.
• Vacuum Packaging (VP) involves packaging meat in a high-barrier material from which air is removed to prevent the growth of aerobic spoilage organisms, shrinkage, oxidation, and color deterioration.
• In vacuum packaging, meats are commonly placed in materials such as ethyl vinyl acetate and polyvinylidene chloride.
• The absence of oxygen in vacuum packages reduces oxidative deterioration and inhibits the growth of aerobic bacteria.
• Modified Atmosphere Packaging (MAP) uses packaging materials that control moisture and gas permeation, creating a protective atmosphere around meat.
• The major gases used in MAP include nitrogen (78%), oxygen (20.99%), argon (0.94%), and carbon dioxide (0.03%).
• Active Packaging (AP) incorporates specific compounds into packaging systems to maintain or extend product quality and shelf life.
• Active packaging helps in moisture control, odor management, and flavor enhancement.
• Antimicrobial packaging, a type of active packaging, involves introducing bactericidal or bacteriostatic agents into the meat packaging to control microbial growth.

References

• Ağaoğlu, S., Dostbil, N., & Alemdar, S. (2007). Antimicrobial activity of some spices used in the meat industry. Bulletin of the Veterinary Institute in Pulawy, 51.
• Ahn, D. U., Mendonça, A. F., & Feng, X. (2017). The storage and preservation of meat: II – Nonthermal technologies. In Lawrie’s Meat Science: Eighth Edition. https://doi.org/10.1016/B978-0-08-100694-8.00008-X
• Aminzare, M., Hashemi, M., Hassanzadazar, H., & Hejazi, J. (2016). The use of herbal extracts and essential oils as potential antimicrobials in meat and meat products: A review. Retrieved from www.zums.ac.ir/jhehp
• Baltic, T., Ciric, J., Brankovic Lazic, I., Ljubojevic Pelic, D., Mitrovic, R., Djordjevic, V., & Parunovic, N. (2019). Packaging as a tool to improve the shelf life of poultry meat. IOP Conference Series: Earth and Environmental Science, 333(1). https://doi.org/10.1088/1755-1315/333/1/012044
• Chellaiah, R., Shanmugasundaram, M., & Kizhekkedath, J. (2018). Advances in meat preservation and safety. International Journal of Science and Research. https://doi.org/10.21275/SR20326194523
• Chellaiah, R., Shanmugasundaram, M., & Kizhekkedath, J. (2019). Advances in meat preservation and safety. International Journal of Science and Research (IJSR), 7(April), 1499–1502. https://doi.org/10.21275/SR20326194523
• El Sheikha, A. F., & Bakar, J. (2014). Fermented meat products. In Microorganisms and Fermentation of Traditional Foods (pp. 223–247). https://doi.org/10.1201/b17307
• Ghaly, A. E., Dave, D., & Ghaly, A. E. (2011). Meat spoilage mechanisms and preservation techniques: A critical review. American Journal of Agricultural and Biological Sciences, 6(4), 486–510.
• Gómez, I., Janardhanan, R., Ibañez, F. C., & Beriain, M. J. (2020). The effects of processing and preservation technologies on meat quality: Sensory and nutritional aspects. Foods, 9(10), 1–30. https://doi.org/10.3390/foods9101416
• Hassan, M. A., Amin, R. A., El-Taher, & Meslam, E. M. (2018). Chemical preservatives in some meat products. Retrieved from http://www.bvmj.bu.edu.eg
• Jay, J. M. (2000). Modern Food Microbiology (6th edition).
• Kerry, J. P., & Tyuftin, A. A. (2017). Storage and preservation of raw meat and muscle-based food products: IV Storage and packaging. In Lawrie’s Meat Science: Eighth Edition. https://doi.org/10.1016/B978-0-08-100694-8.00010-8
• Kharel, G. P., & H. F. (2010). Principle of Food Preservation.
• Laranjo, M., Talon, R., Lauková, A., Fraqueza, M. J., & Elias, M. (2017). Traditional meat products: Improvement of quality and safety. Journal of Food Quality, 2017. https://doi.org/10.1155/2017/2873793
• Lee, K. T. (2018). Shelf-life extension of fresh and processed meat products by various packaging applications. Korean Journal of Packaging Science and Technology, 24(2), 57–64. https://doi.org/10.20909/kopast.2018.24.2.57
• Mathew, R., & Jaganathan, D. (2017). Packaging and storage practices of meat. Global Journal of Biotechnology & Biochemistry, 6(1), 32–40. https://doi.org/10.24105/gjbahs.6.1.1707
• Nychas, G. J. E., & Skandamis, P. N. (2005). Fresh meat spoilage and modified atmosphere packaging (MAP). In Improving the Safety of Fresh Meat. https://doi.org/10.1533/9781845691028.2.461
• Olusegun, A. O., & Iniobong, G. N. (2011). Spoilage and preservation of meat: A general appraisal and potential of lactic acid bacteria as biological preservatives. International Research Journal of Biotechnology, 2(1), 33–46. Retrieved from http://interesjournals.org/IRJOB/Pdf/2011/February/Olaoye%20and%20Ntuen.pdf
• Pal, M., & Devrani, M. (2018). Application of various techniques for meat preservation. Journal of Experimental Food Chemistry, 4(1). https://doi.org/10.4172/2472-0542.1000134
• Romans, T., & Church, C. (2016). Fermented meat products. In Food Microbiology: Principles into Practice (pp. 288–312). https://doi.org/10.1002/9781119237860.ch41
• Sánchez-Ortega, I., García-Almendárez, B. E., Santos-López, E. M., Amaro-Reyes, A., Barboza-Corona, J. E., & Regalado, C. (2014). Antimicrobial edible films and coatings for meat and meat products preservation. https://doi.org/10.1155/2014/248935
• Soladoye, O. P., & Pietrasik, Z. (2018). Utilizing high-pressure processing for extended shelf life meat products. In Reference Module in Food Science. https://doi.org/10.1016/b978-0-08-100596-5.22332-9
• Ur Rahman, U., Sahar, A., Ishaq, A., Aadil, R. M., Zahoor, T., & Ahmad, M. H. (2018). Advanced meat preservation methods: A mini-review. Journal of Food Safety, 38(4). https://doi.org/10.1111/jfs.12467
• Frazier, W. C. (1995). Food Microbiology (4th edition).
• Xi, B., Gao, Y., Guo, T., Li, W., Yang, X., & Du, T. (2020). Study on preservation of chilled beef with natural essential oil nanocapsules. https://doi.org/10.1155/2020/8123254
• Zhang, H., Wu, J., & Guo, X. (2016). Effects of antimicrobial and antioxidant activities of spice extracts on raw chicken meat quality. Food Science and Human Wellness, 5(1), 39–48. https://doi.org/10.1016/j.fshw.2015.11.003
• Zhou, G. H., Xu, X. L., & Liu, Y. (2010). Preservation technologies for fresh meat – A review. Meat Science, 86, 119–128. https://doi.org/10.1016/j.meatsci.2010.04.033