Pasteurisation and food safety, then and now

this is an excerpt from the Briefing Pack v2:

Pasteurisation was one approach to a milk hygiene crisis that peaked as the industrial revolution gathered pace.

The 1800s brought rapid industrialisation across Europe and the mass movement of populations to cities. Overcrowding and poor nutrition, without understanding of the need for sanitation, or infrastructure to prevent pathogen spread, were a public health disaster. These were the days of slops buckets; open sewers; rodent infestations; open privies shared between multiple families; and sealing the dead in walls. These factors increased susceptibility to disease and allowed easier spread of pathogens. Engineering works separating sewage and drinking water greatly reduced disease transmission from around 1900.

Food adulteration was a constant public health issue. The most common method of adulterating retail milk was (and still is) the addition of water. Most of the infectious human pathogens (Salmonella, E. coli Shigella, and Campylobacter) are water-borne. Pasteurisation resolved this problem and allowed dairy factories to sell diluted product while minimising public health dangers.

Inevitably, population movement also resulted in the loss of the ‘house cow,’ and the need for transportation of milk—the beginnings of industrial dairying. Few farms had milking machines, which were in any case technically crude. Often there was no running or clean water for cleaning equipment, and milk vessels were cleaned (if at all) by hand. There was no refrigeration.

These were dark times for dairying, which abandoned traditional methods of dairy cow and milking hygiene that have been validated by science and form the basis of the farming principles followed today by suppliers of certified raw milk in other countries—and by some Australian producers.

Poor nutrition of cows

Many cows suffered from poor feeding practises, which were bad for their health and their milk. In the early 19th century, the alcohol distillery business in the Unites States began to grow. Large amounts of swill (spent grains) were produced as a by-product of whisky and other alchohol production. Many distilleries opened dairies and began feeding their dairy cows with the waste swill. The low nutritional content of the swill led to sickness in the cows and in the humans who drank their milk.

A historian of milk at this time writes:

During the industrial revolution in the first half of the 19th century, the European population doubled, and the proportion of city dwellers rose to 50 per cent. Industrialisation and urbanisation jeopardised infant nutrition during the 19th century. Cow's milk was produced in the cities or transported long distances under suspect conditions. Milk was contaminated with bacteria or adulterated with water, flour, chalk and other substances. When distilleries proliferated in the metropoles, their waste slop was fed to cows which then produced thin and contaminated swill milk. This was exacerbated by the prohibition because 'milk shakes' became the next legitimate business of the distilleries and they paid little attention to hygiene. These were the first generation of 'industrial' dairy farmers.

Grain diets cause acid toxicity in ruminants, grain feeding must be strickly controlled to produce hygienic milk.

Confined to filthy, manure-filled pens, the unfortunate cows gave a pale, bluish milk so poor in quality, it couldn't even be used for making butter or cheese.

The same poor quality milk has been observed in Victorian dairies feeing vegetable waste and cotton seed waste, when traditional feeds are too expensive. Milk composition changed. The poor quality milk couldn't even be used for cheese.

Sickness and disease

The consumption of poor quality milk led to sickness and disease. During 1800s, the death rate was as high as 50 per cent among urban children drinking ‘swill milk,’ that is, milk produced in inner city confinement dairies, from cows fed brewery swill and raised in unimaginable filth. Water (usually from a well or dam) was often added to milk to make it go further; chalk was sometimes added. Such milk spread diseases like typhoid and tuberculosis.

Satisfactory sanitation could not be achieved in the milking procedures and equipment. Dairy inspectors were most concerned about unsanitary milking machines. Bacterial contamination was common, because water around the dairies was often contaminated by nearby outhouses.

US physicians launched the milk certification movement

In 1893 Dr Henry Coit of Newark, New Jersey, enlisted several other physicians and together they formed the Essex County Medical Milk Commission. Thus was born the first Medical Milk Commission and the certified milk movement.

Coit's plan included three general requirements. First, physicians in the local medical society selected members of a Medical Milk Commission and supported their efforts to bring to the city in which they lived a supply of milk produced under conditions that would assure purity. Second, "approved and trustworthy dairymen possessing honor" would be induced, by reason of promised medical support and an increased price of their milk, to produce and handle their milk in accord with the requirements imposed by legal contract with the Medical Milk Commission. Third, the Commission would set standards of purity for the milk and ensure that physicians made periodic inspections of the dairies, the animals and the employees. The Commission would conduct periodic chemical analyses and bacterial counts of the milk, so that it could be certified entirely free of pathogenic organisms. Coit coined the term ‘Certified Milk’ to distinguish milk produced through the operation of his distinctive plan.

Dr Coit and his colleagues understood the importance of having the best quality raw milk available for the ill—infants, children and adults alike. Other cities throughout the United States began forming Commissions, and in 1906 the Commissions were federated into the American Association of Medical Milk Commissions.

Certified raw milk, endorsed by a significant percentage of the medical profession and enjoying strong from legislators and the public, was thus established as the standard to which all other milk was compared. Though more and more milk was being pasteurized, many saw pasteurization as a stopgap measure that would no longer be necessary once more careful regulation of the production and distribution of milk was in place. Certified milk became the model for the production of better milk everywhere. In writings about milk throughout the first half of the 1900s, time and again one finds references to the essential role the certified milk movement played in raising the standards of the entire dairy industry. This is reflected in the rules and regulations governing dairy production that have been codified in every state's laws, for both raw and pasteurized milk.

Dr Ted Beals described how the county Medical Milk Commissions became controversial over subsequent decades because pasteurisation was not part of their standards.

As the commercial dairy industry pushed the requirement for pasteurisation, the local milk commission came under direct fire because they did not include pasteurisation. There were conflicts between the commissions, which wanted their standards adopted by the states, and the industry, which insisted that pasteurisation was necessary to ensure safe milk. The commissions were essentially focused on farm hygiene and hygienic handling of the milk. In their view pasteurisation was unnecessary.

Note that the Medical Milk Commissions were satisfied that raw milk was safe if farm hygiene was good. Dairy manufacturers, on the other hand, promoted pasteurisation for two important commercial reasons: they could take bulk milk from all farms (hygienic and unhygienic), pasteurise it to clean it up, and safely sell it; and pasteurisation machines were expensive—if made compulsory, competition from direct sales by farmers and small players would be eliminated.

New standards emerge

American standards for clean milk production did not appear until early 1900's. One significant accomplishment was a system of sanitation from which dependably clean milk could be produced on any farm. This included dairy farm inspections, laboratory milk tests, and statistical monitory. An official history of the dairy industry in the United States describes how:

[t]he pipeline milking system and bulk tanks replaced the bucket milkers and milk cans on dairy farms in the 1960s. In 1965 federal and state milk regulations established a maximum of somatic cells, which are a marker (measure) of mastitis, for grade A milk.

Pasteurisation arrives in Australia

After a slow start, pasteurisation became comon in Australia during the mid-1950s, a period when milk still carried a risk of infection with brucellosis (eradicated in 1989) and tuberculosis (eradicated in 1997). The introduction of pasteurisation in Australia was widely hailed as a major contribution to public health.

Dr Ron Hull’s praise is more muted. He says pasteurisation resolved problems of poor hygiene, and cows sickened by poor diets. It was a solution to the mixing (‘co-mingling) of good quality milk with poor quality milk from below-standard farmers—about 10 per cent Dr Hull says. Milk from ten or more farms is combined in road tankers. One farm with poor quality can contaminate the entire tanker load. This necessitates pasteurisation to produce a safe product. Commercial processors have responded to this problem by testing suppliers’ milk daily and applying penalties, resulting in three or more levels of payments, varying by 35 per cent. Moreover, large commercial processors collect some milk selectively from particular suppliers when high quality is demanded, as it is for some cheeses and milk powders.

Nevertheless, for bulk milk produced for the dairy factories, and manufactured for the extended shelf life required by the long supply chain, pasteurisation is essential. And it must be done before the milk is homogenised, to inactivate the natural fat-degrading enzyme (lipase). Otherwise the action of this enzyme leads to a rancid flavour. Homogenised milk spoils fast if it has not been pasteurised, because heating destroys the built-in safety factors (described earlier in this report).

Pasteurisation was seen by the industry as a ‘silver bullet’ to solve the health regulators’ problems. But sometimes the bullet misses its mark, as Dr Hull explains:

In the 1960s, deaths of infants and babies from Salmonella infections caused by contaminated milk powders led Australia, as well as New Zealand and South Africa, to seize an international marketing advantage by mandating pasteurisation of all milk (not just drinking milk), as this was seen as a watertight solution to the Salmonella problem—which was assumed to come from the cows. This required the Dairy Acts to assign legal ownership of milk, at the point when farmers removed it from their cows, to government-delegated authorities (Milk Boards). The Milk Boards assigned the milk to licensed dairy manufacturers (co-ops and companies) for processing. State Departments of Agriculture enforced this requirement for pasteurisation on all milk powder plants, though not on cheese producers until around 1985.

However, Salmonella was not eradicated from the milk powders, though subsequent investigations absolved the farms of blame. Contamination was occurring at the factories, after pasteurisation, from bird droppings and dirty plant. Nevertheless, faith in pasteurisation was maintained.

In the 1980s pasteurisation received another dent to its reputation. In Chicago a large number of people died or fell very sick from Salmonella-contaminated drinking milk. The milk was produced in a new ‘state of the art’ liquid processing milk plant owned by a supermarket chain. Despite all the experts’ attempts to resolve the problem, the plant never restarted. This incident and others led to significant revision of pasteuriser operation.

These problems do not discredit pasteurisation as a food processing technique. But they demonstrate that it is not a guarantee of safety. No food can receive such a guarantee. Today pasteurisation is a useful food safety tool in marketing bulk farm milk with a high probability of including milk from diseased or stressed cows.

The Australian Raw Milk Movement believes that both certified raw milk and pasteurised milk are safe foods, but should be considered as different products. We accept that under the present system, regular factory milk must be pasteurised, despite the changes that causes. Public safety is essential.

Laws compelling pasteurisation favour large, industrialised dairy operations and squeeze out small farmers. However, when farmers have the right to sell safe unprocessed milk directly to consumers, they can make a decent living, even with small herds.

Pasteurisation unnecessary for safety of certified raw milk

We have noticed much confusion about the risks posed by certified raw milk, compared with retail pasteurised milk. Both products are safe, low-risk foods. Our point is that milk produced to the highest standards of farming and hygiene is safe to drink in the raw form, as is obvious from the successful certified raw milk industries in New Zealand, the United Kingdom, and the United States.

Certified raw milk drinkers don’t seek extended shelf life. Homogenisation is unwanted and unnecessary. Certified raw milk reaches its consumers rapidly, often straight from the dairy. Properly refrigerated, it keeps for well over a week.

For more detailed information on how to increase food safety on the farm see the 11 categories of the Risk Identification and Risk Reduction program: