Milk quality for production of cottage cheese

This soft unripe cheese is made from skim milk (or reconstituted dry skim milk in some countries) using lactic acid bacteria and a small amount if any rennet.

High quality Grade A skim milk must be used to make cottage cheese curds because:
*It is the law
*High-quality cheese cannot be made from interior milk
*Fat softens the curd

The incoming raw milk must be of high quality with regard to aroma, flavor, titrable acidity (TA, between 0.12 and 0.16), total solids, microbial counts (ideally less than 50,000 per mL).

In addition to the microbial quality of the milk, its dry matter content is important on relation to product quality and yield.

For use in the production of cottage cheese, milk is usually pasteurized to inactivate pathogenic and spoilage bacteria that may be present.
Milk quality for production of cottage cheese

Raw milk associated with Campylobacter jejuni

Raw milk is a common source of infections. The bacterial are often carried by healthy cattle and by flies on farms. Non-chlorinated water may also be a source of infections. However, properly cooking chicken, pasteurising milk, and chlorinating drinking water will kill the bacteria.

Raw milk may become contaminated with C. jejuni in one of two ways. It may excreted directly by a mastitis udder or feces may contaminated the product. Contamination of milk from C. jejuni mastitis is thought to be rare, but direct milk excretion leading to human cases has been reported.

Milkborne campylobacteriossis outbreaks have even almost invariably associated with consumption of raw or inadequately pasteurised cow’s milk. However, a few cases of C. jejuni and C. coli enteritis have been trace to ingestion of raw goats milk in United States, Great Britain and Australia, with the epidemic strain identified in fecal samples from incriminated goats.
Raw milk associated with Campylobacter jejuni

Quality Characteristics of Raw Milk

Quality Characteristics of Raw Milk
Good raw milk quality is the basis for the production of high quality dairy products. The raw milk quality is controlled by the following characteristics:

Level of nutrient and reagents

Chemical physical characteristics

Level of total plate count and composition of the flora, e.g. level of spore formers, coliform, psychotrophs and thermosresistant microorganisms in the total plate count as well as level of somatic cells (cell count)

Presence or absence of pathogenic organisms such as those that cause tuberculosis, brucellosis or mastitis

Presence or absence of disease such as pus particles or toxins

Presence or absence of deleterious substances such as inhibitors or other foreign substances

Taste and flavor

Cleanliness of milk

Quality Characteristics of Raw Milk

Microorganisms in milk

Microorganisms in milk
As drawn from cow’s udder , milk seldom , if ever, is free from microorganisms; bacterial, molds, and yeasts are usually present in small numbers, among which the bacteria are most significant from stand point of quality and the transmission of food borne disease. The control of microbial activity in milk and milk products, especially the control of bacterial and bacterial growth, is the most important function in the handling and manufacturer of dairy products.

Raw milk, when improperly handled, may undergo any of several adverse changes. It may become sour due to the growth of bacteria that produce lactic acid , or it may become foamy due to the growth of gas producing coli form bacteria or yeasts. Raw milk may also be subject to peptonisation (digestion of casein), the formation of rope (viscous polymer of sugars), and sweet curding, when bacterial growth is not controlled.

Dairy herds are tested for tuberculosis and tested for and vaccination for brucellosis, and most milk is pasteurized to prevent the transmission of a variety of food –borne disease. However, some pathogens may be survive the pasteurization process, possibly because they may be protected by fat in which they may become encapsulated.

Most, but not all, certified milk is pasteurized. However, certified milk must be produced from herds that have been inspected, tested, and found to be free form disease, and the milk must be drawn and handled under the best condition of sanitation. There are bacterial standards certified milk that limits the number and types of bacteria that may be present.
Microorganisms in milk