GENERAL AND FOOD MICROBIOLOGY PART II - L. V. Krasnikova - 2016

TOPIC 6. BACTERIOLOGICAL EXAMINATION OF POULTRY MEAT

Poultry Processing plants produce poultry meat as eviscerated carcasses, deboned (free of bones), and comminuted. Retail trade receives edible offal (necks, wings, heads, feet) as well as poultry giblets (Liver, hearts, gizzards). Poultry meat is contaminated with microorganisms ante-mortem, post-mortem, during scalding, defeathering, Evisceration, and chilling. Massive microbial contamination of carcasses can occur in chilling tanks, where Bacteria of the genera Salmonella and Campylobacter predominate. During storage, the surface microflora is found to contain coliforms, pseudomonads, Proteus species, clostridia, and others.

Poultry products are subject to Bacteriological examination in all cases provided for by current regulatory and technical documentation (RTD). Whenever there is the slightest doubt regarding the freshness of poultry meat based on even a single indicator, it is sent for bacteriological analysis. The examination is also performed if pathological changes are detected in specific Organs and Tissues of the poultry. Special attention is paid to examining poultry meat

when There is a suspicion of the presence of agents causing intestinal infections, food-borne intoxications, or toxicoinfections.

6.1. Sampling and Sample preparation

For bacteriological control, three samples of poultry carcasses, semi-finished poultry products, and edible offal are collected. Each sample is wrapped in parchment paper, cellophane, or polyethylene film, sealed, officially stamped, and recorded in a protocol in accordance with the RTD. Samples are stored for no more than 24 hours at a Temperature of 0-2 °С from the moment of collection until the beginning of the analysis.

To assess the quality of whole carcasses or half-carcasses, pieces are cut from the breast, drumstick, and thigh regions in equal amounts with a total mass of at least 150 g. The sample is comminuted in a homogenizer for 2.0-2.5 min (or in a porcelain mortar) to obtain a composite sample for a single carcass or half-carcass. A test portion (aliquot) with a mass of at least 10 g is taken from the composite sample.

To study microbial contamination of the carcass surface, samples are taken from a defined area using a sterile cotton swab with a template or by rinsing with a sterile liquid (saline solution).

Bacteriological analysis of poultry products includes determining Total Viable Count (TVC), Coliforms (coliform bacteria), the presence of sulfite-reducing clostridia (Clostridium perfringens), salmonellae, Staphylococcus aureus, and Proteus species (see sections 1.3.2-1.3.5).

6.2. Determination of Total Viable Count (TVC)

To determine TVC, an initial suspension and a series of subsequent tenfold dilutions are prepared from the prepared comminuted product sample or surface rinse of the carcass, to such a degree that the estimated number of microorganisms in 1 g of the tested product or on 1 cm³ of the carcass surface can be accurately enumerated. From the final dilutions (10^-5— 10^-6), 1 cm³ of the suspension is seeded simultaneously into two Petri dishes, after which they are poured with molten nutrient Agar (PCA) at a temperature not exceeding 45±1 °С. The nutrient medium is thoroughly mixed, and after the agar solidifies, the dishes are placed in an incubator at 37±1 °С. Following incubation, the number of colonies grown on the dishes is counted, and the TVC is calculated taking into account the dilutions used.

Topic Assignment:

1. Determine the microbial contamination of the poultry carcass surface.

2. Determine the presence of coliforms on the poultry carcass surface.

Control Questions

1. How are poultry meat samples collected and prepared for bacteriological control?

2. Which groups of microorganisms are enumerated during the MICROBIOLOGICAL EXAMINATION OF poultry meat?

3. How does microbial contamination of poultry carcasses occur?