The reception platform is the gate where you determine the quality that is fit for production purposes. Here, the quality you assign to the milk will determine the subsequent quality parameters determined at the quality assurance laboratory. These platform tests majorly serve two purposes.
First, you can use the tests to identify if the milk is fit for production.
Secondly, you can use the tests to monitor the quality of the milk during processing.
These tests will help you to ensure that the product is safe and of the right quality for human consumption.
Organoleptic tests rely on senses of touch, smell, sight, taste, etc #qualityassurance #dairy #milk Click To Tweet
Reception of Milk at the Platform
At the reception platform, the staff offloads the milk from the vehicles and onto the reception platform. They do this to facilitate ease of quality testing. The quality assurance officer in charge of reception must ensure that the milk is of right quality before receiving it for further processing.
Preliminary Platform Tests
The initial platform tests are majorly organoleptic (based on the senses) and simple chemical tests. The officer knows the product to be processed from the milk; therefore, he/she ensures adherence to strict quality parameters at the platform. He/she must reject any milk that does not meet the minimum quality standards. Accepting milk of substandard quality will ruin the quality of the finished product.
The officer looks at the color of the milk, feels the temperature of the milk, and smells for an offensive odour. Tasting of raw milk is generally discouraged as it may be a conduit for distribution of zoonotic/infectious diseases. The officer must reject any milk of questionable quality based on platform tests results.
Any mistake in accepting poor quality milk will compound the problem by spoiling the whole batch. Blending a small amount of bad milk with a large volume of good quality milk does not improve its quality; it spoils the milk instead. You can never improve the quality of milk by blending proper milk with a poor quality milk.
The officer must subject all the milk that pass platform tests (organoleptic) to additional confirmatory tests. These additional chemical tests further confirm that the milk is of exceptional quality.
Here, alcohol and specific gravity tests become very handy. You carry out alcohol tests by mixing equal amounts of 80% ethanol with milk using the alcohol gun. If the resultant mixture clots, the milk does not have stable proteins to withstand the heat treatment during pasteurization.
Such protein instability may be due to salt imbalance (colostrum in milk or late lactation) in the milk, or the milk is already aged (high acid). Accept only the milk that does not yield a positive alcohol test.
The lactometer test is necessary to determine milk adulteration by adding water (or any other foreign products). Adulteration alters the density of milk and you can detect the difference by the using a lactometer. Normal milk has a lactometer reading ranging from 1.028 to 1.032. Any reading below this range suggests less milk solids (more water than normal) and any reading above this range suggests higher amount of milk solids than normal.
All the milk that passes these tests indicate milk with proper chemical tests. Even though you can accept the milk at this stage, some manufacturers or milk vendors prefer to conduct resazurin test at this point just to be sure that the milk is of high quality.
At this stage, you can weigh the amount of milk received for pricing purposes. After weighing, release the milk into the dump tank. Interestingly, current dump tanks come fitted with the weighing scales to ease the work at the reception platform. Again, the dump tanks have muslin clothes, which filter off foreign particles that may be present in the milk.
Further Quality Assurance Tests
Once you have received the milk into the dump tank, you should take a sample of the composite to the lab for further quality assurance. Using this sample, conduct chemical tests such as titratable acidity, butter fat content, COB, etc.
Please note that some milk processors will conduct resazurin tests on the platform before accepting the milk into the batch to reduce the risk of accepting bad quality milk into the batch. Resazurin tests check the microbial load in milk; the lesser the load, the better the quality of milk. Poor resazurin results indicate the unsanitary storage conditions for the milk. It also suggests a very poor keeping quality of the milk.
Titratable acidity test determines the level of natural and developed acidity in the milk. Fresh milk should have near neutral pH with little native acidity attributed to the milk proteins.