Physical and Chemical Methods of Decontamination of Carcasses

Introduction:

Meat is one of the most perishable foods, with a short shelf life and a higher risk of microbial contamination.  Contamination from various spoilage and harmful bacteria is generally unavoidable since corpses come into touch with trash during processing unhygienic surfaces, hide, human contact resulting in the visible presence of harmful bacteria in animal carcasses.

It enhances the chances of production of unhygienic meat by cross-contamination, microbe adhesion to the surface. For reducing the microbes on carcasses surfaces, initially washing and rinsing carcasses increases food safety by physically separating germs, boosting the efficacy of other interventions. It is recommended to use two or more technologies since their synergistic effect aids in the inhibition of germs at various phases such as meat harvesting and storage. As a result, reducing the growth of spoilage bacteria in carcasses is the top concern in harvesting quality and safe meat products with acceptable qualities. These are broadly classified into the following approaches based on the nature of the intervention's application technique.

1. Physical interventions

Carcass decontamination is achieved by using several physical hurdles to reduce or inactivate microorganisms without leaving any chemical residues or sensory changes.

• Water

• Steam

2.Chemical interventions:

This procedure entails the use of chemical elements during the slaughter of animals. To destroy or inactivate diverse heterogeneous microorganisms, a wide range of chemicals are used. These compounds are typically GRAS (Generally Recognized as Safe) by the USDA and FSIS-approved for usage in the meat industry. These compounds are far more efficient and have no effect on sensory or nutritional properties.

Some commonly used carcass decontamination treatments are as follows-

• Chlorine

• Organic acids

• Organic preservatives

• Inorganic phosphates

• Oxidizing agents

Water:

Water is routinely applied in meat processing plants with an objective to reduce microbial load of carcass by different modes of application such as rinsing, spraying, and immersing and steam treatment. Washing helps in removing visible contaminants such as soil, debris, faecal matter and feathers etc and become more effective with increase in water temperature due to increase in lag phase. Washing of carcass with high pressure cold water improved microbial quality by reducing significant reduction in microbial load. Several studies have been documented that application of hot water (more than 740C) has sanitizing effect on carcass by decreasing microbial load and its efficiency increases linearly with the increasing temperature of water.

Steam is much efficient than hot water due to higher heating potential and penetrating power even in deep cervices, follicles and cavities, leaving no residue, efficient removal of soils from surfaces, but steam should be applied for very short period otherwise it may damage the carcasses surface. However, Researchers did not notice any change in adhesion efficiency of bacteria on steam treated surfaces of carcasses. Scalding forms are the fundamental processing procedures used during pig and poultry slaughter. Scalding aids in hair removal by loosening hair follicles and eliminating soil from corpses. Scalding significantly reduces the number of Campylobacter jejuni and E. coli but does not improve further.

Organic acids:

Organic acids are most commonly used chemical decontaminants in meat industry. Application of organic acids solutions on carcasses resulted in reducing microbial load and prevalence of pathogens. The antimicrobial action of organic acid is due to their un-dissociated molecules as these molecules accumulated in the cytoplasm and dissociated into protons at higher pH leading to acidification of cytoplasm. Lactic acid and acetic acid are the two most commonly used organic acidshowever, use of other organic acids such as citric acid, succinic acid, sodium hypochlorite, peroxy-acetic acid etc have also been reported to decontaminate carcasses. Organic acids are more effective on hot carcasses.

Chlorine

In the food sector, chlorine is the most widely used sanitizer. By disrupting chemical bonds in microbes, chlorinated chemicals have a sanitising effect. Because of its ease of application, stability, quick effect, low cost, and inactivation of a wide spectrum of pathogens, chlorinated water is most widely used to disinfect beef and poultry carcasses and avoid cross-contamination in meat processing plants. Washing poultry carcasses with 20-50 ppm chlorinated water at various steps in slaughtering reduces total aerobic counts, total coliforms, Salmonella and E.coli.

Inorganic phosphates and other chemicals:

Trisodium phosphate (TSP) is water soluble alkaline saponifying agents, widely used as a surface cleaner, stain remover, and used as nonmeat additive during preparation of value added meat products with the for increasing yield, juiciness, sliceability and increasing antioxidant properties by combining with metal ions. However, indiscriminate use of phosphates causes water pollution by encouraging algal development, which reduces dissolved oxygen levels in water, damaging aquatic life and ecological balance (eutrophication). The use of trisodium phosphates (TSP) has no discernible effect on organoleptic qualities.

Hydrogen peroxide (H2O2) is also used to reduce microbial count by destroying as well as suppressing microbial growth. This action is related to free radicals produced by H2O2, which damage numerous biomolecules found in bacteria such as nucleic acids, protein, and lipids. However, its use resulted in excessive foaming in the chiller as a result of the excessive creation of oxygen from the skin and blood owing to catalase activity, as well as bleaching and bloating of carcasses. It is considered as an effective, economical and safe method for carcasses decontamination and has been used to decontaminate poultry carcasses by applying 0.5% w/v, sodium bicarbonate and beef carcasses.

Ozone (0.5%) has been used to enhance keeping quality of meat by inactivation of microbial growth such as E. coli O157:H7, S. typhimurium, Pseudomonas fluorescens, during storage by its oxidizing properties. Ozone use as an ozonized water washing agent has been shown to decrease microbial growth in beef and poultry without affecting sensory qualities significantly. However, the extremely reactive, unstable, and potentially lethal character of ozone, as well as the public hazards involved with its use, limit its application in corpse disinfection