Sampling of dairy products is necessary to ensure quality, safety, and specific attributes such as butterfat content. All types of dairy – cream, milk, whey, cheese – can be sampled in their various forms, whether liquid, slurry, solid or powder.
Dairy sampling and analysis is conducted to:
- Verify industry compliance to regulations
- Gather baseline information and perform assessments
- Set standards and guidelines
- Maintain consumer confidence in the safety of the food supply
- Prevent problems, health risks or fraudulent claims
Accurate analysis results require controlled, real-time data achieved through reliable, accurate and repeatable process monitoring and measuring. Producers must sample regularly to obtain representative samples, and government inspectors in many countries may take or request samples at any time.
If laboratory analysis of the samples is to be valid, it is essential to properly collect, transport and store perishable milk and milk product samples. The phrase, ‘garbage in, garbage out’ is relevant in relation to samples that have been compromised during collection, storage or transportation to a laboratory for analysis. Even under the best conditions, in dairy products microorganisms can survive and grow, and chemical and physical changes can occur. Professional training of sample collectors is critical so they can be continually aware of issues that can occur during sample collection and delivery.
Sample collection steps
Because samples must be representative of the entire process stream, it is important that liquid dairy be adequately mixed. During sample collection, the collector must ensure that microbial and chemical contamination is not introduced into the sample or process stream itself. After samples are collected, they must be protected from contamination and maintained under specified conditions, depending on the sample and the microbiological, chemical, and physical analysis to be performed, so they are the same when delivered to the laboratory as they were when collected.
Maintaining proper temperature is essential to preventing microbial growth and ensuring that there are no chemical or physical changes in the samples until they are analyzed. Under ideal conditions, analysis of the samples should begin within 24 hours of original collection. Collectors must ensure that all pertinent sample identification information is recorded and delivered to the laboratory as well, including the date, time and temperature of collection, and who collected the sample. Due to the legal nature of the process, when collecting samples for regulatory purposes, a chain of custody must be established to ensure only those with the proper authority handled the samples.
Because of the issues with transporting dairy within a timely period for analysis, sampling often takes place at transport trucks, receiving docks and/or transfer points using dairy samplers specifically designed for those applications.
Dairy sampling standards
The International Dairy Federation (IDF) currently is working on improving analytical standards for dairy sampling and analysis to:
- Detect veterinary medicinal drug residues and pesticides (insecticides, fungicides and herbicides) in milk and milk products;
- Standardize a method or methods for the determination of aflatoxin M1 and other mycotoxins in milk and milk products;
- Standardize methods of analysis for food additives in milk products, for determination of nitrate, nitrite, phosphorus and chloride in cheese and other dairy products, for elements with the exception of N, P, (PO4)3, polyphosphates, anions Cl and NO3 and radionuclides;
- Study the possibilities for a suitable routine determination of vitamins A and D in milk products and develop a method for the establishment of the strength of synthetic vitamin A and synthetic vitamin D standards of different manufacturers for the routine determinations;
- Describe, evaluate and standardize microbial inhibitor and preliminary confirmation tests for the detection of antimicrobials in milk and milk products and the development of detection concepts, integrated detection systems, based on the methods and residues found in the various countries;
- Collect information on elements other than those cited above and analytical information on normal trace element content in milk and milk products as well as an observed higher level (from contamination) and related problems and strategies to avoid them.
Key to meeting these standards are representative samples for analysis. Sentry sampling solutions empower customers around the globe to accurately monitor and measure processes for improved production efficiency, output and safety. Several Sentry ISOLOK® samplers designed for dairy sampling applications are conformant to 3-A Sanitary Standards (third-party verified) and offer reliable, sanitary, easy-to-clean designs with FDA-approved seals to sample liquid milk, powdered dairy products and higher viscosity products such as cream and butter.