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Originaltitel:
Mikrobiologische Sicherheit von Rohwurstprodukten 
Originaluntertitel:
Wirkung von Natriumnitrit auf Lebensmittelinfektionserreger 
Übersetzter Titel:
Effect of Sodium Nitrite on the Survival of Listeria monocytogenes, Shiga Toxin-Producing Escherichia coli (STEC), and Salmonella spp. in raw fermented sausages 
Jahr:
2014 
Dokumenttyp:
Dissertation 
Institution:
Fakultät Wissenschaftszentrum Weihenstephan 
Betreuer:
Scherer, Siegfried (Prof. Dr. ) 
Gutachter:
Scherer, Siegfried (Prof. Dr.); Gareis, Manfred (Prof. Dr. Dr.) 
Sprache:
de 
Fachgebiet:
BIO Biowissenschaften 
Stichworte:
Rohwurst, Natriumnitrit, Salmonella, STEC, EHEC, Listeria monocytogenes 
Übersetzte Stichworte:
raw fermented sausage, sodium nitrite, Salmonella, STEC, EHEC, Listeria monocytogenes 
Kurzfassung:
Die Verwendung von Natriumnitrit bzw. Kaliumnitrat (Salpeter) im Zusammenhang mit der Haltbarmachung von Fleischerzeugnissen hat eine lange Tradition. Trotz der vielfältigen positiven technologischen Wirkungen in Fleischprodukten ist Natriumnitrit nur zur Konservierung zugelassen. Eine antimikrobielle Wirkung ist vor allem in in vitro Versuchen für viele Mikroorganismen beschrieben. Im Vergleich zu den in vitro Versuchen liegen jedoch nur sehr wenige Daten mit zum Teil widersprüchlichen Ergebnis...    »
 
Übersetzte Kurzfassung:
Raw fermented sausages are meat products commonly spread in the European Union. They are made from raw meat without any heat treatment, so the growth of the most spoilage bacteria is inhibited in these products by low water activity (< 0.9) and low pH-values (ranging from 4.8 to 5.6). Pathogenic bacteria may, however, survive without being finally eliminated under these conditions. For a long time, curing has been the conservation technique widely used to prolong the shelf-life of fermented sausages. Nitrite (in the form of sodium nitrite) was added to fermented meat due to its contribution to organoleptic quality and its ability to inhibit the growth of Clostridium botulinum. Although the addition of nitrite or nitrate as curing agent to many meat products has been a common practice for preservation, there are no well-founded scientific data concerning the actual impact of different concentrations of sodium nitrite on relevant food borne bacteria. This study was conducted to investigate the effect of different sodium nitrite concentrations (0, 100, 150, 200 mg kg-1) on the survival of Listeria monocytogenes, shiga toxin-producing Escherichia coli (STEC) and Salmonella spp. in raw fermented sausages. For this purpose, several batches of different types of short fermented raw sausage (spreadable and sliceable) were therefore produced and artificially contaminated with the pathogenic bacteria mentioned above. Our investigations showed that in first order dynamic effects and an attentive control of the ripening programs reduce the bacterial count. But they also demonstrate clearly the positive effect of sodium nitrite as antimicrobial additive in raw fermented sausages. Only with sodium nitrite a growth of Salmonella spp. and Listeria monocytogenes in raw fermented sausage was avoided. However, the formation of carcinogenic nitrosamines from nitrate and nitrite is a major health issue. Consumers’ concerns about antibiotics, hormones and chemical additives connected with conventionally produced foods, lead to a raising popularity of organically produced foods. Based on the expending recruitments for natural products without any chemical preservatives, conventional curing agents like nitrite should replaced in organic or natural products by ingredients on an herbal basis. Indirect curing is a process that should utilizes ingredients with high amount of naturally occurring nitrate and a bacterial starter culture with a nitrate reductase activity to provide quality, sensory attributes and microbiological safety similar to conventionally cured meats. In the second part a commercial nitrate-containing plant extract was tested. For this purpose, the sausage batter was artificially contaminated with Salmonella spp., shigatoxin-producing Escherichia coli and Listeria monocytogenes. We found that the numbers of Salmonella spp. and Listeria monocytogenes increased rapidly between 1 to 2 log10 cfu g-1 in sausages produced with the nitrate containing plant extract. Our results showed that the tested extract could not avoid the outgrowth of the pathogens, hence leading to a microbiological hazard. The microbiological stability of the product and the dying off of the pathogens is enhanced by the exclusive combination of sodium nitrite and a sufficient decrease in water activity and pH-value. 
Mündliche Prüfung:
15.10.2014 
Dateigröße:
8425178 bytes 
Seiten:
296 
Letzte Änderung:
06.03.2015