Refurbishment of ante-mortem blood using pulsed electric fields (PEF) for germ reduction and sustainable use for food of animal origin
Initial situation:
Each year, approximately 150 million liters slaughter animal blood in Germany. Currently, only a small part of the production of food (20%) or in animal feed is used, although the blood contains technologically and physiologically valuable proteins. Especially the functional properties of the plasma proteins are from a technological perspective of interest.
Blood and blood plasma offer microorganisms favorable growth conditions, so that unacceptable total germ counts of over 106 colony-forming units (CFU)/ml can be exceeded even with products that have been stored in a cool place for an extremely short time and according to the regulations. The hygienic safety must be guaranteed during use. An application for the disinfection of blood has not been described in the scientific literature and in the patent literature.
The aim of the research project was therefore to develop a method for reducing the number of germs in blood and blood fractions. The functional properties desired and required for further processing into products, in particular of the valuable blood proteins, should be retained as far as possible. The implementation should take place using the example of meat products.
Research result:
It could be demonstrated that treatment using pulsed electric fields (PEF) reduced the total number of germs and various potentially pathogenic microorganisms by several powers of ten. The specific energy input was identified as a key influencing parameter.
The results show that with an energy input of 75 kJ/kg in gram-negative microorganisms, the number of germs is reduced by 3 powers of ten. From an energy input of 125 kJ/kg, an inactivation of at least 5 powers of ten is achieved for both gram-positive and gram-negative microorganisms. The intensity of the treatment affects the physical and technological-functional properties. The energy input of 75 kJ/kg causes a decrease in the denaturation enthalpy of 19% for whole blood and 14% for plasma. The strength of the gel formed by protein cross-linking is reduced by about 30% for whole blood and by about 11% for plasma. The effective viscosity increases with whole blood as a function of the treatment intensity, with plasma there are no significant changes in the flow properties.
In addition, the influence of the geometry of the treatment cells (colinear, coaxial, Ringpsalt) and the field strength (5 to 15 kV/cm) with an energy input of 35 to 166 kJ/kg was investigated. The use of a colinear electrode geometry led to the highest treatment efficiency. With regard to the field strength, a reduction in the energy requirement was observed with an increase in the field strength. The treatment parameters identified as suitable for whole blood could be transferred to the treatment of plasma. The storage time of plasma at a storage temperature of 4°C can be extended by at least 4 days, depending on the treatment intensity, without exceeding the total bacterial count of 106 CFU/ml.
The aim of the implementation was to produce a meat product from PEF-treated and thus germ-reduced and longer-lasting whole blood or blood plasma that is equivalent to the standard from native blood or native plasma in the most important product features.
The functional properties of the blood and blood plasma were partially impaired depending on the selected treatment intensity, but further processing of treated blood or plasma in meat products was possible without restricting the technological effect. Up to 7% of PEF-treated blood plasma (based on the total amount of the recipe) can be added to the boiled sausage meat without any sensory or technological deviations occurring.
The process developed within the project can therefore be used for the industrial processing of slaughtered animal blood.
Economical meaning:
The process parameters for whole blood and plasma developed and tested in the project make it possible to increase the product safety of slaughter animal blood and its fractions. The application of the method of pulsed electric fields enables a significant reduction in the total number of germs. The innovative concept of the sustainable use of animal raw materials, illustrated using the example of meat products, contributes to improved performance and competitiveness. In addition, other possible uses for the manufacture of convenience products or as a source of protein can be developed. Compared with a pig price in the range of approx. 1,30 €/kg (trade class E, January 2011) and a meat price in the range of 1,45 - 2,65 €/kg, the current value of the blood of the slaughter animal is approx. 5 ct/ l and that of blood plasma at 15 ct/l is significantly lower, even with additional costs of approx. 1,2 ct/l. With an input quantity in the range of 3 - 7%, this enables a significant reduction in the raw material costs and thus the added value, especially for small and medium-sized companies in the meat industry.
In Germany, around 7 million tons of meat are produced every year, from which around 1,4 million tons of meat products are made. The turnover of the meat industry amounts to approx. €30,5 billion, that of the 214 slaughterhouses €10,3 billion/pa. The meat processing companies, which are predominantly medium-sized (94% of the 1.014 companies have a turnover of < €50 million), account for this €17,7 billion with 83.230 employees.
Publications (selection):
- FEI Final Report 2011.
- Nowak, B., Boulaaba, A., v. Müffling, T. and Klein, G.: Blood - the protein supplier of the future. (Poster abstract) Proceedings 67th FEI Annual Meeting 2009, 103 (2010).
- Boulaaba, A., Nowak, B., Müffling, T. v., Hage, N. and Klein, G.: Effects of PEF (pulsed electric fields)-treated blood plasma on qualitative and technological parameters of boiled sausage. ALPHA information society, German veterinary medical society, federal association of official veterinarians (ed.): official veterinary service and food control (special edition) 51st workshop of the working area of food hygiene: three-country conference; Program and abstract volume, Garmisch-Partenkirchen, September 28.09-October 01.10.10, 0945; Lampertheim: ALPHA information society, ISSN 3296-124, 2010 (XNUMX).
- Nowak, B. and Boulaaba, A.: Blood - the protein supplier of the future. Longer durability through PEF application. (Report) Working group of the technology transfer offices of Lower Saxony universities (ed.): Technology information: Knowledge and innovations from Lower Saxony universities 3; Hanover: Uni Transfer, Gottfried Wilhelm Leibniz University, 6 (2009).
- Wiezorek, T., Heinz, V. and Toepfl, S.: Processing of slaughtered animal blood using pulsed electric fields (PEF) - A contribution to sustainability. circular meat hyg. Food Control 6 (2009).
- Heinz, V.: Non-thermal processes for sterilization and for influencing the structure of food. Proceedings of the 66th FEI Annual Meeting 2008, 89-96 (2009).
The final report can be accessed by the interested public at the research center. Further information material:
German Institute for Food Technology eV (DIL)
Prof. von Klitzing-Str. 7
49610 Quakenbrück
Tel: 05431 / 183 228-
Fax: 05431 / 183-200
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Foundation of the University of Veterinary Medicine Hanover
Center for Food Science
Institute for Food Quality and Safety
Bischofsholer Dam 15
30173 Hanover
Tel: 0511 / 856 7256-
Fax: 0511/856-82-7256
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Food Industry Research Group (FEI)
Godesberger Allee 142-148
53175 Bonn
Tel: 0228/372031
Fax: 0228 / 376150
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Source: Quakenbrück [DIL]
