D. Narasimha Rao

Efficacy of intermittent decontamination treatments during processing in reducing the microbial load on broiler chicken carcass.

Abstract Investigations were carried out to assess the efficacy of microbial decontamination treatment at each step during processing of broiler chickens. Treatments with acetic or lactic acid by dipping or spray washing with water containing acid were the decontaminating techniques adopted. Addition of lactic acid to scald water reduced the build up of the microbial load in scald water thus minimising the chances of cross contamination from scald water, as was evident from the lower microbial load on birds scalded in scald water with lactic acid. Acid treatment of carcasses by dipping after each step of processing reduced the microbial load on carcass surfaces. Spray washing of carcasses with water containing acetic or lactic acid after every step of processing reduced the microbial load considerably, compared to spray washing with water alone. Acid treatment at low concentrations did not affect the appearance of carcasses. It is concluded from the study that decontamination by acid treatment either by dipping or spray washing with water containing acetic or lactic acid at every step of processing could minimise the cross contamination and thus improve the microbial quality of broiler carcasses.

Microbial profiles during lactic fermentation of meat by combined starter cultures at high temperatures

Abstract Studies were conducted to stabilize minced meat and meat cubes with added salt and glucose by fermentation using mixed lactic cultures of Lactobacillus plantarum, Lactobacillus casei and Lactococci lactis. Microbial profiles were recorded. The study revealed that a desired pH of 4.0–4.2 can be achieved (within 24–36 h at 37 °C and 30–42 h at 30 °C), with a substantial reduction in coliforms, Escherichia coli, Staphylococcus aureus and Salmonella spp. The study demonstrated that the use of combined lactic cultures would enhance the fermentation process and preserve fresh meat for extended periods at high temperatures for further use in the development of specific products.

Microbial profiles of minced meat

Minced meat was examined for microbiological quality and for shelf-life at higher temperatures. Total plate counts, coliforms, Staphylococcus aureus, Enterococci and psychrotrophs were estimated. Types of bacteria associated with meat spoilage were isolated and identified. It was observed that minced meat obtained from local retail shops showed significantly higher microbial counts and shorter shelf-life than that processed under hygienic conditions. The predominant bacteria associated with fresh meat were S. aureus, Micrococcus and Escherichia. The results revealed that microbial spoilage of meat at higher temperatures was mainly due to the growth of mesophilic microorganisms such as Escherichia and S. aureus.

The microbiology of sheep carcasses processed in a modern Indian abattoir

A study has been conducted on the microbiology of sheep carcasses processed in a modern abattoir. The data revealed that careful handling at the different stages of processing of sheep reduced the level of microbial contamination of carcasses. Processing steps such as evisceration and washing did not increase the microbial counts on the carcass surface. Sources of microbial contamination in the abattoir were examined. It was observed that skin, floor washings, intestinal contents and gambrels were the major sources of microbial contamination. Seasonality did not have any effect on the microbial contamination of carcasses. The study revealed that total plate counts in 86·6% of the carcasses ranged between 3·0-4·9log/cm(2). The counts of coliforms, staphylococci, enterococci and psychrotrophs were low. Pathogens such as Salmonella were not detected. The microbial counts were well within the generally acceptable levels. These findings demonstrated hygienic handling of carcasses. Shoulder and neck are the critical points for microbiological sampling as these sites showed higher microbial counts. Micrococcus and Staphylococcus predominated among microorganisms associated with carcasses. It was noted that differences occurred in microbial types of carcasses processed in tropical and temperate climates. The data generated in a model facility procided useful information for improving meat handling practices.

Influence of direct and delayed chilling of excised female buffalo muscles on their textural quality

The excised muscles from the left half of 6 carcasses of old female buffaloes (4-5 years of age) were held, soon after slaughter, at the temperature of 2-3°C for 24 h (direct chilling) and those from the right half at ambient temperature (26±2°C) up to 6 h postmortem followed by chilling at 2-3°C for 18 h (delayed chilling) in order to study the improvement in the texture quality of muscles. During the delayed chilling, the muscle pH decreased to 6.0 (from the initial value of 6.5) in 3 h whereas it took 5-6 h in direct chilling. Reduction in Instron firmness values was 10.3-33.6% and that in cohesiveness values was 13.2-22.2% in delayed chilled muscles compared to direct chilled ones when cooked muscles were sheared along or across the muscle fibres. These observations were statistically significant (P⩽ 0.001) indicating a definite improvement in the texture quality of muscles subjected to delayed chilling. However, no definite trend was observed in the values of elasticity, cooking loss and water holding capacity of muscles due to direct or delayed chilling.

Reduction in microbial load on buffalo meat by hot water dip treatment.

Buffalo meat cuts from shoulder and leg portions were subjected to hot water treatment (70 and 80 °C for 30 and 60 s). Meat cuts dipped in water at ambient temperature served as control. The surface samples were analysed for microbial load, visual score for colour and numerical values of colour parameters (a(∗), b(∗), L(∗), W). Control samples of shoulder and leg meat had a mean total plate count (TPC) of 4.15 log CFU cm(-2) and 3.81 log CFU cm(-2) and enterobacteriaceae counts of 2.33 log CFU cm(-2) and 2.26 log CFU cm(-2), respectively. Treatment of meat cuts with hot water reduced the TPC significantly (p < 0.001)with a highest reduction of 1.60 log in leg meat and 1.80 log in shoulder meat at 80 °C. Hot water treatment of meat eliminated enterobacteriaceae. Although, there was discolouration of meat by hot water treatment, the colour regained during storage of meat at refrigerated temperature (4 ±1 °C). Hot water treatment of meat resulted in loss of redness (a(∗)), increase in lightness (L(∗)) and whiteness (W). After storage, a(∗) increased and L(∗) and W decreased. The results suggested that the dip treatment with hot water reduces the initial bacterial load substantially and improves the microbiological quality of buffalo meat without causing any permanent discolouration.

Microbiological quality of hygienically processed buffalo carcasses

Abstract Studies were conducted to assess the microbiological quality of buffalo carcasses processed hygienically in a modern abattoir as against those processed in traditional slaughter units of different sites. The hygienic measures followed include abattoir clean up operation, processing on overhead rail, careful removal of skin and viscera, closure of oesophagus and rectum and washing the carcasses with a spray of clean water. The carcasses, meat cuts and minced meat obtained from both the sources were examined for microbial load. A significant ( P ⩽0.001) difference in microbial load was seen in carcasses obtained from two sources, with carcass from traditional slaughter units showing 1.0–2.50 log higher microbial load. The reduction in microbial load in carcasses processed in a modern abattoir was attributed to the hygienic measures followed. The microbial load was high in shoulder portion and lower in leg portion and the data indicated that samples of shoulder, neck and rib surfaces provide a more realistic estimate of microbial load on buffalo carcasses. The meat cuts obtained from hygienically processed carcass had a shelf-life of six days as against three days for those obtained from traditional slaughter unit. The minced meat from hygienically prepared carcass had a shelf-life of four days as against one day for those obtained from local slaughter unit. The study indicated that by adopting proper hygienic and sanitary practices during processing of buffalo meat would yield meat with acceptable microbiological quality with extended shelf-life.

A preliminary study of the effect of urea in the preservation of meat

An investigation was undertaken on the effect of urea in the preservation of meat. It was observed that there was always a lag period in the early stages of microbial spoilage of meats at different temperatures, due to the non-availability of required nutrients, and subsequent rapid growth of microorganisms was attributed to the utilisation of amino acids released due to autolytic changes. Dry urea salt was employed in the present study to denature or retard the activity of enzymes of the meat in order to extend the shelflife of meat by preventing spoilage. Parameters such as ERV, pH and TPC were studied during meat spoilage. It appears from the present studies that autolytic changes were responsible for the ultimate spoilage of meat. When urea was applied in the meat, the microbial lag phase and the shelflife of meat were extended. It seems that urea checked the autolytic changes in meat and thereby microbial growth was delayed due to the non-availability of nutrients from the autolytic changes.