Application of Indicator Strips “NUK-1000 mg” for Monitoring the Technological Process of Reducing Microbial Contamination in Poultry Carcasses

CChilled poultry carcasses are perishable products. Research has shown that the main microflora causing spoilage is concentrated on the surface of the carcasses.

Before slaughter, the microbial content on the skin of live poultry is approximately 1×10³ CFU/cm². As a result of technological operations (scalding, washing, chilling, etc.), the total microbial contamination of the surface of chilled carcasses can increase to 1×10⁶ CFU/cm². To ensure the final product meets the requirements specified in regulatory documentation and can be stored for 5 days at temperatures between 0 and +4°C, the contamination at the start of storage should not exceed 5×10⁴ CFU/cm².

The most effective way to reduce microbial contamination is the technological process of chilling poultry in an ice-water bath containing peracetic acid. The optimal concentration of peracetic acid is determined individually, considering the specific conditions of each production facility. Peracetic acid improves the sanitary-hygienic quality of poultry meat, has strong bactericidal properties, and its breakdown products are harmless. In diluted solutions, peracetic acid is unstable and readily decomposes into acetic acid and hydrogen peroxide. The decomposition rate depends on factors such as temperature, solution pH, and heavy metal ion concentration. For example, at 4°C, the half-life of peracetic acid is several months, whereas at 40°C, it decreases to one week. At pH = 2.7, the half-life is several weeks, while at pH = 5.7, it is less than one day. Heavy metal ions catalyze the decomposition of peracetic acid, with the rate varying depending on the type and concentration of the ions. Half-lives can range from several hours to several days.

Given these factors, it is essential to continuously monitor the concentration of peracetic acid in working solutions. The simplest, most cost-effective, and efficient method is using indicator test strips. Delta-CT LLC manufactures and supplies “PAA-1000 mg” indicator strips designed to measure peracetic acid concentrations in the range of 0 to 1000 mg/L.

Below is the procedure for measuring peracetic acid concentration using “PAA-1000 mg” indicator strips: 1. Pour the test sample into a beaker or glass. 2. Remove a test strip from the packaging and immerse it in the solution for 1–2 seconds, ensuring the indicator zone is fully wetted. 3. Remove the strip and quickly wipe off excess liquid by dragging the edge of the strip along the rim of the glass. 4. Place the strip on white filter paper, paper towel, or gauze with the indicator zone facing up and wait for 10 seconds (timed with a stopwatch or clock with a second hand). 5. Within no more than 10 seconds, compare the color of the indicator zone to the reference scale to determine the peracetic acid concentration. The entire analysis takes less than one minute.

For convenience, the table below provides concentration equivalents in different units of measurement.

The concentration of peracetic acid in chilling baths should be checked twice per shift—before starting work (to verify correct solution preparation) and after the lunch break (to monitor depletion). Adjustments should be made if necessary.

Chilling eviscerated carcasses in an ice-cold peracetic acid solution is performed in accordance with the current Technological Guidelines for Poultry Meat Production. After chilling, the carcasses are sent for sorting, labeling, weighing, and packaging without rinsing.

Veterinary-sanitary assessment of carcasses chilled in peracetic acid is conducted following the current Rules for Veterinary Inspection of Animals and Veterinary-Sanitary Examination of Meat and Meat Products, as well as regulatory and technical documentation for poultry meat.

No residual peracetic acid is permitted in 1 cm³ of carcass rinses 4 hours after chilling. Residual peracetic acid is monitored using “PAA-100 mg” indicator strips: 1. Immerse a test strip in 1 cm³ of carcass rinse for 1–2 seconds. 2. Remove the strip and compare the indicator zone color to the reference scale after 10 seconds.

Microbiological monitoring of decontamination effectiveness is performed once a month.