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Titel

Der Limulus-Test zur Hygienekontrolle von "frischer Mettwurst"

Titel(englisch)

The Limulus test for monitoring the hygienic condition of German fresh "Mettwurst"

Name:

Gleumes, Heinz-Willi

Ort und Jahr der Promotion

Berlin, Freie Univ., Diss., 1997

Abstract

Fresh "Mettwurst" is a hygienically critical product. Gram negative bacteria play an Importantrole in spoiling the product, high numbers of these being indicative for a possible health hazard.Identifying lipopolysaccharides, which are almost unique to Gram negative bacteria, the Limulustest can detect this type of bacteria and allows a rough estimate of their count Moreover, theLimulus test is a rapid, simple and inexpensive method.The present study intended to validate the Limulus test as a rapid method to assess thehygienic conditions of German fresh "Mettwurst" From preliminary experiments could bedrawn the following conclusions:- There are no factors that affect the results of the Limulus test in German fresh "Mettwurst"- Based on the results of the present study the Limulus test should be carried out without heatingthe sample as recommended by a few investigators Heating the sample can result inunderestimation of lipopolysaccharides hereby affecting the accuracy of the method.- To estimate the lipopolysaccharide content with adequate accuracy samples of at least 200 gshould be drawn These samples should be taken from different sites (3-5) of the batch beforestuffing into casingsIn a further series of experiments 20 batches of German fresh "Mettwurst" of two butcheries inBerlin as well as 10 batches were examined, which had been made of highly contaminated rawmaterial Samples were taken at different times during processing and storage The content oflipopolysaccharides was determined (Limulus test) as well as the total aerobic count (drop-plating)and the count of different groups of bacteria (among others Enterobacteriaceae andPseudomonaceae drop-plating). Analysis of the data led to the following conclusions:- The Limulus test has demonstrated the growth of the microflora during the process of production.- The level of contamination of the raw material as well as the hygiene during the productiondetermine the Gram negative bacteria count of the final product- Testing for lipopolysaccharides with the Limulus-Test in the batter before filling as well as in"Mettwurst" during storage cannot exactly determine the number of viable Gram negative bacteriaHowever an estimation can be made- The Limulus test allows to distinguish an inacceptable bacterial load from a level of contamination,which can be expected if the German fresh "Mettwurst" is produced under conditions of GoodManufacturing Practice.From supermarkets and butcheries 51 retail samples of German fresh ""Mettw?rste" were drawn tosurvey the content of lipopolysaccharides and the bacterial contamination. Results indicated thatEnterobacteriaceae counts of log 4,0 KbE/g and Pseudomonaceae counts of log 6,0 KbE/g canbe expected in "Mettwurst", which is produced under conditions of Good Manufacturing Practice76,5 % of the samples contained less than log 3,0 EU/g lipopolysaccharides, 96 % less than log4,0 EU/g.As a guideline a value of log 3,0 EU/g is recommended to differentiate between lower and highercontamination levels with Gram negative bacteria of the filling of the fresh "Mettwurst". If the"Mettwurst" is produced under conditions of Good Manufacturing Practice the product should notcontain more than log 4,0 EU/g, higher values indicate an inacceptable level of contamination.The Limulus test could be used as a simple inexpensive and apid screening method to monitor thehygiene of the process of production. Further studies should confirm the feasibility of the testunder conditions of practice of in plant control and official food control.