Cleaning and disinfection of knives in the meat industry.

The effect of disinfection of knives with water of 82 degrees C (180 degrees F) strongly depends on the amounts of protein and fat present on the tools. When fats or proteins are absent, even a high bacterial contamination on a stainless steel plate will be completely eliminated by immersion in water of 82 degrees C during 1 s, whereas even after 10 s immersion does not give satisfactory results if a high degree of fat and protein contamination is present. By adding lactic acid to hot water the bactericidal effect may be improved, although the results are far from optimal. Apparently, optimal disinfection of contaminated knives is extremely difficult to attain without the use of mechanical forces such as a high pressure water jet to remove the dirt. Therefore a special disinfection unit was designed in which apart from the factors cleaning time and temperature, the effects of mechanical forces could be determined. By increasing water pressure the cleaning effect was improved. Adding lactic acid to the spraying water made it possible to lower water temperature and water pressure, which, among other things, resulted in a lower climatological strain at the place of work. The thermodisinfector (a modified dish-washer) appear to be a good alternative for cleaning and disinfection of tools if the requirement is dropped that every worker had to have a disinfection facility within his immediate reach. The practical application of such equipment is discussed.

[Improvement in Hygiene of the slaughter line (author's transl)]. / Verbetering van de hygiëne in de varkensslachtlijn.

Those factors which are of importance in the contamination of carcases in modern slaughter lines are reviewed. Short-term measures (for instance, improving the technique of dressing carcases) and long-term procedures (for instance, developing other methods of slaughter) are suggested to improve hygiene on the slaughter line. Attention is paid to a number of methods to prevent contamination.

[Decontamination of hot beef carcases with organic acids (author's transl)]. / Decontaminatie van slachtwarme runderkarkassen met organische zuren.

The decontamination effect of spraying hot beef carcases with solutions of lactic acid and solutions of the commercial preparation of pH liquid was studied. Spraying a 0.5 per cent lactic acid solution only resulted in a significant reduction of aerobic, gram-negative and gram-positive bacterial counts on severely contaminated areas. Treatment with a 0.75 per cent solution of lactic acid caused a significant decrease of almost all bacterial counts, whereas a 1 per cent lactic solution produced a significant reduction of all bacterial counts at the sites sampled. The maximum reduction was 2 log units per sq.cm. and varied with the level of contamination. A 5 per cent pH Liquid solution was ineffective and a 20 per cent pH Liquid solution had an effect similar to that of a 0.5 per cent lactic acid solution. The reduced bacterial counts persisted during three days of storage in the chilling room. When the above concentrations are applied, this will not cause any permanent changes of colour of the treated carcases. These changes do occur when a 10 per cent solution of lactic acid is used. This treatment can only be used to spray severely contaminated superficial layers which are to be removed. Recommendations are made for the possible use of organic acids in the slaughter line. The legal aspects are discussed.

[Bone content in mechanically deboned pork (author's transl)]. / Botgehalte in mechanisch ontbeend varkensvlees.

The KOH method is a useful procedure to determine the bone content of pork. Samples containing a known quantity of added bone were tested by the KOH method. There were no significant differences between the results of the KOH method and the added bone content (P greater than 0.05). The correction for desiccation of clean bone is hard to determine because of the variations in loss of weight as a result of evaporation of water on preparing clean bone. The correction for conversion of hard bone residues into dry bone was determined from bones of fattening pigs, sows and male swine. Sex and age of the pigs were found to have little effect on this factor. It is suggested to base testing of mechanically deboned pork on the determination of hard bone residues. A content of 0.4 per cent is suggested as the maximum permissible residue of hard bone in mechanically deboned pork, which is equivalent to a clean bone residue of approximately 1 per cent.

[Assessment of bacterial counts in the meat-processing industry. III. The Stomacher method and the spiral plate method]. / Bepaling van kiemgetallen in de vleesindustrie. III. De Stomachermethode en de spiraalplaatmethode.

Two aids in the assessment of bacterial counts were evaluated. The Colworth-Stomacher technique is a reliable alternative to the relatively more expensive and more labour-intensive blendor method of homogenizing meat. In the suspensions obtained by the two methods, equally high bacterial counts were observed. The Spiral plate method provides equally high numbers of bacteria as does the pour-plate method, and reproducibility of the results is identical. In counting the total number of aerobic bacteria, the two methods show a very high correlation: r = 0.99.

[Assessment of bacterial counts in the meat-processing industry. II. The plate-loop method and the droplet method (author's transl)]. / Bepaling van kiemgetallen in de vleesindustrie. II. De öse-plaatmethode en de dropletmethode.

Two methods used in making bacterial counts of meat and surfaces are discussed. When the plate-loop method is used, dilutions are prepared with calibrated loops in spotting tiles. These loops are also used to swab droplets of these dilutions on quadrants of previously dried agar plates. A formula is presented, which may be used in calculating bacterial counts. When the droplet method is adopted, an apparatus is used to prepare dilutions in tubes containing liquid agar. Drops of agar then are transferred into empty Petri dishes by this apparatus. After incubation, the colonies which have grown in these droplets are counted by a viewer included in the apparatus. Both the plate-loop method and the droplet method (if slightly modified) were found to satisfy the criteria simplicity, reliability and saving time and material. This only holds good when accurate counts are made and when bacterial counts are more than 2,500 bacteria per gram or per sq. cm. When these conditions are complied with, the two methods are suited for routine studies of large numbers of samples.

[Assessment of bacterial counts in the meat-processing industry. I. A review of the literature (author's transl)]. / Bepaling van kiemgetallen in de vleesindustrie. I. Een literatuuroverzicht

Frequent examination of large numbers of samples of the surface of carcasses and apparatus is essential to gain a clear insight into the hygiene of the meat-processing line. To make this possible, efforts should be made te reduce the number of sampling sites of each carcass as well as the number of groups of bacteria to the studied, and to save time and material. Methods so far developed to the assessment of bacterial counts are reviewed in the present paper. It is concluded that the spray-pistol method, the Stomacher method, the drop method, the membrane filter method, microcolony counts and the spiral method are particularly eligible for closer examination. The methods referred to should be tested by the following criteria: (1) simplicity; (2) reliability and reproducibility and (3) saving of time and material.