Hazards in the Meat Industry
Raw meat is material very susceptible to spoilage. This fact makes the manufacturers use preservatives in most of their products.
- Internal contaminants - infection from raw meat and blood
- External contaminants (cross-contaminations) - failure to personal or production hygiene
Appropriate selection of production methods and process control allows eliminating hazards causing the spoilage of meat and often be a threat to health, even life. An important problem in the meat industry is pathogenic Listeria monocytogenes.
An especially dangerous factor causing spoilage of food is external contamination. The cross-contaminations is a danger factor in particular for sliced meat products, such as sausages or hams. The infection often occurs due to failure to comply with the hygiene during the production process, when sausage are cutted. The equipment surface is contaminated with mircobies. Failure to observe the principles of the good hygiene practice and the good manufacturing practice results in exposition the product to spoilage microbes development in food
The cold chain disruption during distribution is the next importat dangerous factor threatening food safety. Temperature fluctuations during transport often occurs, particullary during the summer. The products being outside the safe temperature range poses a risk of microbial growth.
High Pressure Processing
The HPP technology is becoming an increasingly popular solution in the global meat industry. Innovative high pressure processing makes it possible to preserve meat products while maintaining their high quality. The result of the HPP process is extended shelf-life and exceptional taste qualities of treated products. High pressure, unlike high temperature, does not cause irreversible changes in the product. Meat retain their natural appearance and unchanged sensory characteristics. The HPP does not affect low molecular weight substances, such as aromatic compounds or amino acids. The innovative technology can be used in meat industry for processing the raw and treated meat products.
HPP meat products
- beef, pork, poultry and other raw meat
- marinated meat
- sliced cured meats
- sausages and salami
- RTE meals (ready to eat)
The most popular HPP products in the meat industry include sliced sausages and cured hams, ready-to-eat meals, burgers or marinated meat. The marinade strengthens the germicidal effect of the HPP process. High pressure tratment extend the shelf life without losing color and taste.
HPP is packaged food processing technology. The packaging should have appropriate flexibility and barrierity properties. These can be sliced products packaged in a modified atmosphere or vacuum packed pieces of meat. The packaging is an important factor in HPP. The packaged product is placed in a pressure chamber, which is then vented and filled with water. The hydrostatic pressure generated by the pump is transferred to the product, where it is evenly distributed in its entire volume. The water content protects it from destruction. After the process, the product leaves the chamber in a completely unchanged state.
High Pressure to High Safety
The HPP technology preserves the properties of meat products. The Innovative mechanism of high pressure processing causes changes only in compounds of high molecular weight. Smaller compounds such as vitamins, flavors or amino acids remain intact. The technology consists in limiting the use of high temperature of food processing, which is its biggest advantage. Treated product has much exteded shelf-life.
Pressure Levels in the Meat Industry
- Improvement of the organoleptic properties
- Texture improvement
- Losses limitation (eg increasing water absorption)
- Destruction of pathogens and spolage microobes
- Shelf-life extending
The HPP is the innovative treating method of the packed products in their final packaging. The meat products can be re-contaminated during slicing or portioning. As a result of inappropriate processing, cross-contamination or improper storage undesired microbes may growth in food. Pathogens such as Listeria or Salmonella are particularly dangerousIn in meat products. High pressure processing effectively eliminate the pathogens and ensure the safety of products during all storage period.
Marinating is widely used in the meat industry as a method of food preservation. It improves the taste values of meat and maintains its moisture, also improves the texture. In addition the low pH level and the chemical compounds present in the marinades spices effectively limit development of spoilage microbes.
The combination of the HPP and meat marinating is a popular practice in the industry. The result is elimination of possible color changes caused by the high pressure processing and the intensification of the germicidal effect. The HPP meat product has the extended shelf life due to the degradation of microorganisms. The ingredients of the marinade strengthens this effect.
Combination of HPP and Marinating
- Extended shelf-life
- Strengthening the degradation of microorganisms
- Facilitated distribution of the product to further regions
- Natural product without additives and flavor enhancers
- Clean label
- Masking color loss during meat processing
- Crating a new innovative products
Figure 1. The effect of high pressure processing on the different groups of microorganisms in marinated beef during 150 days refrigerated storage 
Garriga et al.  conducted storage tests for high pressure processed marinated beef tenderloin. The Figure 1 illustrate the potential of using HPP technology in the degradation of microorganisms in the marinated beef tenderloin. It was observed that level of microorganisms in the HPP product was below the detection level throughout the storage period (120 days). The shelf-life of product was extended.
Figure.2 The aerobic colony count (log10 CFU/g) of steak samples with different treatments and stored at refrigerated temperature at different days 
Wang et al.  investigated the possitive effect of HPP on the microbiological stability of marinated beef steaks during the storage period. Before the treatment the shelf life was 7 days. The analysis showed that the high pressure processing of marinated steaks extended their shelf life to over 80 days. The properties of meat proteins at higher pressures were identical to those for the fresh and the marinated meat without HPP. The numbers of pathogens, such as E. coli, Listeria and Salmonella have been marked below the limit of detection. It is also worth adding that the level of microbes was stable that throughout the period of storage .
Figure.3 The fresh or marinated beef steak treated with and without HPP. The first row left to right were fresh steak, marinated steak, marinated beef steak treated with 300 MPa and 350 MPa. The second row from left to right were marinated beef steaks treated with 400 MPa, 450 MPa, 500 MPa and 600 MPa, respectively 
The Figure 3 presents a comparison of the color of the beef steaks in teryaki sauce subjected to the HPP process. Wang et al.  has observed no visual difference between the control sample and the meat after high pressure treatment. Only instrumental analysis showed changes in L*a* b* parameters, but all samples gained acceptance because no significant changes in color were observed. High pressure processing used for the marinated meat treatment allows mask possible color changes caused by high pressure. Pork chops in garlic marinade treated with HPP  also showed a delicate color change, but no significant changes were observed between the marinated samples after high pressure processing. The treatment at 600 MPa also increased water absorption of the meat by 28.8% in comparison with the fresh meat (10.5%).
Biochemical processes occurring during meat spoiling cause adverse sensory changes. It is results of the activity of microorobes from the cross-contaminations. The sliced meat products, such as sliced cured ham are particularly exposed for this risk factor. Vacuum-packed meats are often infected with lactic acid bacteria or yeasts that can enter the product during slicing or packaging. The level of saprophytes results the visible symptoms of spoilage and shortening the shelf-life of meat products is at 106 CFU/g .
Table 1. Influence of high pressure on microbial quality of cooked and raw smoked pork loin 
The table 1 presents the results of research Hać-Szymańczuk et al.  on the effect of HPP on the number of individual groups of microrobes in sirloin and raw smoked sirloin during 8 weeks of storage. The meat products subjected to high pressure processing maintained very low levels of microorganisms as opposed to not treated meat that during all storage period. It was observed the high number of microbes in control samples, which was connected with the beginning of spolage processes.
Table 2. Microbial evoluation in sliced vacuum-packed dry cured ham after HPP treatment during storage at 4ºC 
Dried meat products are often exposed to the growth of yeast and gram-positive granulomas. HPP treatment of smoked and dried meats is the appropriate solution to control the level of these microorganisms. Garriga et al.  tested the vacuum-packed dried pork ham treated by HPP technology. The count level of all groups of spoilage microbes was very low throughout at 120 days of refrigeration storage.
The HPP method allows to reduction of microorganisms and more importantly maintains the microbiological stability of the product. Botsaris and Taki  investigated the impact of HPP processing on the quality and durability of the sliced ham and frankfurters. They did not record of significant microbial growth throughout the entire period of storage. The products was microbiological stable at period of 7 weeks. The minimal fluctuations in the total number of aerobic microorganisms, both in the ham and the vacuum-packed sausages was found. The shelf-life was extended from 7 to 49 days by using the high pressure process.
Figure 5. The effect of HPP on the TAC at 30ºC of vacuum-packed sliced ham. The log10 CFU/g of HPP-treated and non-treated product is plotted against the storage time at 4ºC in days 
Figure 5. The effect of HPP on the TAC at 30ºC of frankfurters. The log10 CFU/g of HPP-treated and nontreated product is plotted against the storage time at 4ºC in days 
Taste and smell - the main features affecting the consumer acceptance of products.
The mechanism of HPP treatment retain the sensory attributes of meat products. That allows to creating completely new products with different properties. Traditional thermal methods of food preserving do not guarantee this. The use of high pressure does not expose meat products to the loss of their sensory characteristics. Due to the limited effect of pressure on the chemical composition of food, features such as taste or smell are preserved after processing. This makes the product attractive throughout its shelf life.
The results of sensory analysis of high-processed sausage pork with different parameters are presented below. The product was overall acceptable due to the absence of significant changes in sensory parameters. The HPP had a positive influence of taste value and smell properties. According to the evaluators, the product had better taste and general appearance throughout the storage period, which made it more attractive. The shelf life of the sausage was additionally extended by 30% using high pressure processing.
Figure 5. Sensory evaluation of high-pressure treated pork sausage at different time and pressure levels 
HPP is an innovative method of non-thermal treatment of product. This is the last of production stage carried out immediately after food packaging. The product is placed in pressure chambers in its final package. The high pressure processing combined with refrigerated storage is an effective way to extend the shelf life of meat products, while minimizing the negative impact on product characteristics. The HPP eliminates the microbial hazard and treated meat products are microbiologically safe and stable, also does not lose the sensory attributes simultaneously.
The HPP advantages
- Extending the shelf life without adversely affecting the product
- Increased safety and elimination of cross-contaminations
- Preservation of natural flavors
- Creating products without artificial additives
- Clean label
- Innovative products with high quality
- Facilitated distribution and guaranteed market effect
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 Botsaris G., Taki A., 2014. Effect of high-pressure processing on the microbial quality throughout the shelf life of vacuum-packed sliced ham and frankfurters. Journal of Food Processing and Preservation, 39(6)
 Fuentes V., Ventanas J., Morcuende D., Estevez M., Ventanas S., 2010. Lipid and protein oxidation and sensoryproperties of vacuum-packaged dry-cured ham subjected to high hydrostatic pressure. Meat science, 85(3), 506–14
 Garriga M., Aymerich T., Hugas M., 2002. Effect of high pressure processing on the microbiology of skin vacuum packaged sliced meat products: cooked pork ham, dry cured pork ham and marinated beef loin. Profit Final Project Report
 Hać-Szymańczuk E., Mroczek J., Tworzydlak S., Stolpe B., 2005. Wpływ wysokiego ciśnienia na wybrane cechy jakościowe polędwicy sopockiej i surowej polędwicy wędzonej. Żywność. Nauk. Technologia. Jakość., 4(45): 42-51
 Pietrzak D., Trejda E., Ziarno M., 2011. Wpływ wysokiego ciśnienia na wybrane właściwości oraz trwałość kotlecików z mięsa drobiowego żywność. Nauka. Technologia. Jakość., 1 (74): 68-78
 Wang H., Yao J., Gerlat M., Ganzle M., 2017. Effect of High Pressure Processing on Quality, Sensory Acceptability and Microbial Stability of Marinated Beef Steaks and Pork Chops during Refrigerated Storage. Report 1., Affiliation: Albersta Agriculture and Forestry
 C. K. Yeung, S.C. Huang, 2016. Effects of High-pressure Processing Technique on the Quality and Shelf Life of Chinese Style Sausages. Journal of Food and Nutrition Research, 4(7): 442-447