Historical Development of UHT Milk

The birth of high heat treatment and canning as a means of preserving food began in France in the early 1800s. By 1839, tin-coated steel containers were widely in use.

UHT processing was developed as early as 1938, aseptic processing, which enabled the distribution of milk without refrigeration, commenced only in 1961.

The various types of heating systems such as steam injection and infusion, were developed for UHT heating to achieve a better sterile product, however, the difficulty of packaging the sterile milk without recontamination into suitable containers for transport hindered the commercialization of UHT products until 1953.

The first system consisting of indirect heating which milk was indirectly heated at 125ºC with a holding time of 6 minutes was manufactured in 1893, only 11 years after the first commercial pasteurizer was used.

Patented in 1912, the continuous flow direct heating method mixed steam with milk to achieve temperatures of 130 to 140ºC. Development was hindered due to contamination potential without commercial aseptic systems. This process avoided the burn on encountered in the indirect heating.

The development of aseptic processing in the United States started through the efforts of C. Olin Ball, and hot-cool-fill process was commercialized in 1938 for a chocolate milk beverage.

UHT processed milk produced in an innovative heater known as Uperiser, and aseptically packed in cans, was first developed in Switzerland in 1953, through the collaborative efforts of a dairy company and a machinery manufacturing firm.

A similar heating technique has employed for long-shelf-life milk but this has aseptically packaged into a tetrahedral paperboard carton for sale in Switzerland in 1961. Tetra Pak pioneered its own continuous UHT process and aseptic packaging systems, and so kick started the growth of the UHT milk segment.

In 1964, ice cream mix and concentrated milk formulations UHT heat treated with direct heat and packaged in four-liter cans. This represented the first commercial aseptic production in Australia.
Historical Development of UHT Milk

Thermal sterilization of food in history

Thermal sterilization has been used to achieve long-term shelf stability for canned foods and is now used for a broad range of products. The majority of shelf-stable foods are thermally processed after being placed in the final containers.

The beginnings of preservation and sterilization techniques go back to ancient years. Aristotle recommended to Alexander the Great , his troops should boil the water before they drank it.

It is known that Hippocrates attempted to send the plague away from Athens by lighting fires in the streets and burning aromatic woods to disappear the plague-spots.

The use of high temperature to produce safe food products dates to the 1790s in France. Napoleon Bonaparte offered a prize to scientist to develop preserved foods for the armies of France. A man named Nicholas Appert won the prize for successfully preserving, for the first time, a variety of perishable food products by heat-processing foods in glass jars and bottles.

The technology is receiving increasing attention from thermal processing specialists to improve both the economy and quality of some canned foods.
Thermal sterilization of food in history

Radio frequency heaters

Radio frequency energy is used in many ways aside from communication. It had been discovered as early as 1890 that high-frequency energy was capable of heating human tissue without much discomfort.

The origin of radio frequency (RF) identification technology is generally traced back to the 1940s during World War II when British developed the first radar system that could actively identify friend or foe. The early efforts attempted to apply RF energy to cook various processed meat products, to heat bread and to dehydrate and blanch vegetables.

The desired energy transferred rate enhancement led to an increased frequency: the microwaves. The first patent, describing an industrial conveyor belt microwave system was issued in 1952, however it first application started 10 years later.

By the 1960s, studies on the application of RF energy in foods focused mainly on thawing frozen products, which resulted in several commercial production lines.

The next generation of commercial applications of RF energy in the food industry was postbake drying of cookies and snack foods, starting in the late 1980s.
Radio frequency heaters

Infrared heating of food

Sir William Herschel discovered infrared or heat radiation in the 1800s when he was attempting to determine the part of the visible spectrum with the minimum heat in connection with the astronomical observations he was making.

His experiment Herschel shows that red light had the highest degree of temperature change in the light spectrum; however, infrared heating was not commonly used until World War II.

In 1847 AHL Fizeu and JBL Foucalt showed that infrared radiation has the same properties as visible light.

During World War II infrared heating became more widely used and recognized. Infrared heating was first used in the 1930s for automotive curing applications and rapidly became a widely applied technology in the manufacturing industry.

The used of this technology in the food industry was first reported in the 1950s for drying processes. During the early 1970s there were many discussion about finding new methods for industrial frying/cooking of meat products and the use of near infrared technique started to be discussed.

Infrared heating can be used to inactivate bacteria, spores, yeasts and mold in both liquid and solid foods.

Efficacy of microbial inactivation by infrared heating depends on the following parameters: infrared power level, temperature of food samples, peak wavelength and bandwidth of infrared heating source, sample depth, types of microorganisms, physiso9logical phase of microorganism and types of food materials.
Infrared heating of food

Ohmic heating

Both irradiation and microwave heating employ radiant energies which affect foods when their energy is absorbed whereas ohmic heating raises the temperature of foods by passing an electrical current through the food.

Ohmic heating is one of the newest methods of heating foods. Ohmic heating’s major advantage is that is simultaneously heats solid pieces and liquids in a food with minimal destruction. It has been shown that Ohmic heaters can provide an interesting alternative to heat exchanger for thermal processing applications.

Georg Simon Ohm (1789-1854)

In 1827, German physicist, Georg Ohm published his treatise: Dei galvanische Kette, mathematisch bearbeite where he described what is today known as Ohm’s law.

But recognition of the thermal effects of electricity within a conductor was first elucidated by James Prescott Joule in 1840.

This resulted in a number of patents on the heating of flowable materials in the latter part of the nineteenth century. The ‘electric pasteurization’ process was used for milk treatment in six states in the United States in the 1930s.

In the 1980s, Ohmic heating was introduced by APV, who licensed the technology from the Electricity Council of Great Britain.

During this time the technology has achieved some industrial applications that include pasteurization of liquid eggs and processing of fruit products. Ohmic heating has shown good potential for blanching, evaporation, dehydration, fermentation, extraction, sterilization and pasteurization of food products.
Ohmic heating

Tubular heat exchanger

Tubular heat exchanger ware more commonly used for thick liquids; do not need to acquire an aseptic homogenizer as they can withstand 200-300 bar pressure during homogenization.

In pursuit of more efficient aseptic processing systems, equipment manufacturers and design engineers have continued to improve in the design of tubular heat exchangers.

In some of the early systems when aseptic technology was first being developed, simple tubular heat exchangers were used in lieu of plate heat exchangers.

Although effective in reduced maintenance and able to handle much high pressures compared to plate heat exchangers, the first tubular heat exchangers were more expensive, tended to developed product building up on the walls of the heat exchangers due to burn-on, and were still limited to low-viscosity products.

Genrickh A. Dreitser is a well known specialist in heat and mass transfer and aerospace thermal techniques. He developed and investigated an effective method of heat transfer enhancement in tubular heat exchangers.

He for the first time found out the law of remarkable increase of heat transfer in channels with discrete turbulizers in comparison with similar smooth channels concerning increase of hydraulic resistance.

In the past, most heat exchangers in aseptic processing systems utilized either plate heat exchangers for very low viscosity beverages and scraped surface heat exchangers for all other products most of the newer aseptic processing systems utilize tubular heat exchangers or combination of tubular heat exchangers with steam infection or infusion.
Tubular heat exchanger

Steam infusion

Ever since the invention of thermal processing as a method for food preservation in the 19th century, there has been a relentless search to reduce the degree of thermal damage to the quality of food products.

Originally designed for boats, steam infusion was first used in pasteurization and has since been developed for further liquid heating applications.

There were literally hundreds of steam injection/infusion devises that were developed or investigated in the late 1950s and through the 1960s.

In the 1960s APV launched the first steam infusion system under the Palarisator brand name. Since then significant developments and progress have taken place which have led to one of the most sophisticated systems in the world.

This involves a 2-stage process for steam infusion whereby the liquid is cascaded into a large pressurized steam chamber and is sterilized when falling as film or droplets through the chamber.

Generally, steam injection and steam infusion heating systems are followed by flash cooling the product.
Steam infusion

History of heat treatment on food

In contrast to food irradiation processes, heat treatment has been used in the preparation of foods for millennia.

The original concept of in-container sterilization of foods has come a long way since Nicholas Appert first introduced ‘the art of canning’ in 1810.

He eventually received a prize of 12,000 French francs from the French government for inventing a method for safety preserving foods for long term storage.

Nicholas Appert showed that the application of thermal treatment to foods contained in tightly closed cans was able to preserve them from spoilage.

About 50 years later it was Pasteur who gave sense to this procedure by discovering that microbes were responsible for the deterioration of foods and heat acted killing them.

While at the same period, Nestlé started the production of condensed milk and powdered milk by concentrating milk through evaporation.

In 1819, William Underwood of the United States started the first canning factory in Baltimore.

To preserve foods in boiling water took too long, requiring about 6 hours, therefore salt was added to the water bath which increased the boiling temperature, thereby shortening the processing time.

This followed by the discovery of the pressure cooker and later the autoclave, which has gone through subsequent improvement to result in today’s still retorts.

In 1945, researchers studied the effect of heating the germ, at various moisture levels for different periods in a hot air oven, on the enzyme activities and its stability during storage at 37 degree C in laminated metal foil.

FMC Corporation introduced the continuous agitating cookers in the 1950s, and at about the same time, Steriflamme process was developed in France.

Steriflamme is a flame sterilization process in which rapidly rotating cans pass through live flames at temperatures of about 2000 ° F.
History of heat treatment on food