Cleaning milk - Use of separator and decanter in dairies
As a basic food, milk is subject to National and international laws. The aim of these laws is to ensure that milk and dairy products are brought into circulation only in perfect condition which will not harm health. Milk should be clarified by separators to improve milk quality.
Cleaning of Raw Milk
The raw milk delivered to dairies by agricultural businesses still contains unwanted foreign substances – such as somatic cells and blood from the udders, contaminants from the air and dirt from contact with the milking machines, the milk lines and the transport vehicles.
Clarifiers are equally suitable for cleaning cold and warm milk. Compared to milk filters which are used as an alternative, self-cleaning separators are clearly superior, as in filtration the filtrate cake remains in the milk flow for several hours. A growing bacterial flora can thus reinfect the milk flowing through the filter. Furthermore, cracking in the filter cloth is virtually impossible to check. Even the smallest cracks can cause severe problems and risk-free operation of relatively large banks of filters requires a high degree of automation. Compared to this, the clarifier is simple to integrate. Clarifier sludge can be routed straight to neutralization or to the waste water treatment plant which is present in any case. Last but not least, almost no product is lost as a result of treatment with clarifiers. The removal of milk sludge reduces valuable constituents of milk, such as protein, by only a barely measurable thousandth of a percentage point.
After a marked rise in cheese production increased the amount of whey first, more stringent water industry demands and associated disposal costs led to the desire for an economic use of this by-product. The development for the continued processing of whey into products such as whey concentrate, whey protein concentrate, whey powder or lactose are possible. Whey is defined as the liquid which forms in cheese-making after the casein have been separated when the milk clots. Depending on the type of casein separation, three kinds of whey may form: rennet whey (sweet whey), sour whey and technical whey. In order to achieve the greatest level of process technological and economical processing, whey must first be separated from cheese fines by clarifiers. In a second step the fat has to be removed. Separators not only fulfill their separation duties, but also make a considerable contribution to the overall profitability of processing companies by recovering and conditioning valuable constituents such as cheese dust or lactalbumin. Lactalbumin is a mixture of various whey proteins. It is traditionally recovered by heat denaturation of wheys from various origins, primarily from cheese wheys. Once the lactalbumin has become insoluble, it can be centrifuged by separators and dried in a spray-drying tower to form a powder. Lactalbumin has a high nutritional value.
Clarified Cheese Dust
The obtaining and further processing of unwanted products from whey can also be demonstrated by the example of cheese dust: cheese dust is defined as very fine cheese particles which are formed during the cutting, agitating and pumping of curd. These protein particles get into the whey during the separation of curd and whey or when draining the cheese molds and pressing them. For a higher level of defatting dairies separate the cheese dust from the whey with clarifiers and then use decanters to remove more moisture from the concentrate thus obtained to form a free-flowing cheese mass. This mass can then be made into processed cheese.