Sunday, January 10, 2010


Compared to plant foods, animal based foods are more difficult to preserve due to contamination by lethal pathogens like Salmonella, E.coli, Listeria, etc. Established processes like thermal treatment, irradiation, canning, dehydration etc have severe limitations when it comes to meat products. Modern preservation method for meat is freezing as most microorganisms do not grow under sub-zero temperatures. Though technologically freezing can preserve the original quality of the food processed, there is no way it can improve on the quality, if the raw material is already contaminated or cross contamination takes place from other contaminated products during storage and handling at various stages after the factory process. In other words freezing cannot destroy the microbes which are already present in the product or that which many contaminate it during storage. Food related food poisoning arise when the frozen products are brought to ambient conditions and consumed without any adequate cooking at the consumer's end.

There are strict guidelines that need to be followed by the abattoirs where animals are slaughtered and at manufacturing plants where the meat is further processed into finished products. In many countries surveillance authorities undertake plant inspection frequently to ensure strict compliance of safety guidelines. Still food poisoning due to E.coli and Salmonella occurs regularly though such episodes are not wide spread and causalities are minimal. Irradiation is a technically sound process which can achieve 100% kill but its industry-wide use is constrained by the labeling regulations calling for declaration regarding irradiation. As consumers do not accept irradiation process due to many reasons, industry is reluctant to use this technology. It is under such circumstances that Ammonia treatment of meat became an accepted process duly approved by FDA of the US and the USDA since 2007. Recent reports that even some of the Ammonia-treated meat products showed the presence of these pathogens are ringing alarm bells causing some concern.

Ammonia is a natural chemical found in human body and also in many foods at significant concentrations and it has not been declared as a toxic substance for use in foods. Products like peanut butter, cheese and a few other foods contain Ammonia at levels 400-800 ppm. Use of Ammonium Bicarbonate, Ammonium Carbonate, Gaseous Ammonia and Ammonium Hydroxide are permitted to be used 0.04 to 3.2%, at least in the US. Ammonium Hydroxide, a solution of Ammonia in water is allowed 0.6-0.8% in baked goods, cheese, relishes and puddings. Effectiveness of use of Ammonia for control of fungus in citrus fruits, storage of corn, in meat is known since 1976 and in 1988 scientists from Punjab University reported about the ability of Ammonia to kill aerobic bacteria and many anaerobic ones also. Use of Ammonia for preserving fish, dehydrated potato chips and broken eggs has also been reported without any apparent ill effect on human health.

Ammonia is used in gaseous form for killing pathogens in lean meat trimmings from the slaughter house after removing melted fat in centrifuges and the ground products were flash frozen and compressed for use in Hamburgers. The pH of the product is supposed to go up from 6 to more than 10 to get a 100% kill of pathogens. Ammonia brings about changes in extract release volume, water holding capacity, soluble protein nitrogen and cook out losses. It is somewhat intriguing why such specially treated products are not made to declare the same on the label since not much scientific information exists regarding the long term effect of consuming Ammonia treated meat. Besides many consumers are able to experience the pungent smell of Ammonia in the product, mistaking it for chemical contamination. At 50 ppm Ammonia can be detected by the nose while at 35 ppm it can impart undesirable tastes. As Ammonia treated meat is exempt from mandatory inspection and quality check, some of the samples were found to have pH of only 7.75, not considered safe, raising inconvenient questions regarding the reliability of the process under manufacturing conditions.

Any process if to be approved has to undergo strict evaluation for safety and ascertain the risk-benefit aspects based on which only valid conclusions can be drawn. It appears as if such an exercise has not been done in the case of "Ammoniacation" of meat, probably because of the anxiety to counter act increasing episodes of meat contamination and decreasing public confidence on the ability of the surveillance agencies to preempt such incidences. .


1 comment:

Anonymous said...

"At 50 ppm Ammonia can be detected by the nose while at 35 ppm it can impart undesirable tastes."
"Products like peanut butter, cheese and a few other foods contain Ammonia at levels 400-800 ppm."