Thermization: A Gentle Heat Treatment for Preserving Raw Milk

Thermization is a mild heat treatment used in the dairy industry to improve the quality and storage life of raw milk before further processing. Unlike pasteurization, which is designed to eliminate harmful disease-causing bacteria, thermization applies a lower level of heat for a shorter period. The process typically heats raw milk to between 57°C and 68°C (135°F to 154°F) for 10 to 20 seconds, followed by immediate cooling to approximately 4°C (39°F). This gentle treatment reduces spoilage microorganisms while preserving the milk's natural flavor, nutritional qualities, and protein structure.

The thermization process is straightforward but carefully controlled. First, raw milk passes through a plate heat exchanger, where it is rapidly heated to approximately 63°C to 65°C. The milk is then held at this temperature for about 15 to 20 seconds, allowing sufficient time to reduce populations of spoilage bacteria. Immediately afterward, it is rapidly cooled to below 4°C, slowing any remaining microbial activity and preparing the milk for refrigerated storage or additional processing.

One of the primary purposes of thermization is to reduce the number of psychrotrophic bacteria, which are microorganisms capable of growing even under refrigeration. These bacteria produce enzymes that continue breaking down milk components during storage, causing undesirable flavors, odors, and texture changes. By lowering their numbers, thermization significantly slows milk deterioration and helps maintain freshness. Studies have shown that thermized milk can generally be stored below 8°C (46°F) for up to three days before further processing, provided proper refrigeration is maintained.

Another important advantage is the reduction of naturally occurring enzymes such as heat-sensitive lipases and proteases. These enzymes break down fats and proteins, leading to rancid flavors, bitterness, and reduced product quality over time. Thermization inactivates many of these heat-labile enzymes, helping preserve the milk's taste and extending its usable shelf life before pasteurization or manufacturing.

Because thermization uses lower temperatures than pasteurization, it causes minimal changes to the milk's natural composition. Valuable proteins, minerals, and much of the fresh flavor remain largely intact. This makes thermized milk especially suitable for specialty dairy products where maintaining raw or minimally processed characteristics is desirable.

Thermization is particularly valuable in cheesemaking. Many artisan and specialty cheeses require milk that retains much of its original protein structure and flavor profile. Thermized milk provides a practical compromise by reducing spoilage bacteria while preserving the characteristics needed for proper cheese ripening and flavor development. It also gives cheese producers greater flexibility by extending the storage time of raw milk before production begins.

It is important to note that thermization is not a substitute for pasteurization. While it effectively reduces spoilage microorganisms and improves storage stability, it does not eliminate all harmful pathogens. Consequently, thermized milk intended for drinking is usually pasteurized before reaching consumers. Instead, thermization serves as an intermediate preservation step that enhances milk quality, extends storage by approximately 24 to 72 hours, and supports efficient dairy processing while maintaining the fresh qualities of raw milk.
Thermization: A Gentle Heat Treatment for Preserving Raw Milk

Pilsner Brewing Process

Pilsner, a colorless lager beer originating from the Czech city of Pilsen, stands as a testament to the artistry and precision of brewing. Crafted with pilsner malt and bottom-fermenting lager yeast, it embodies a delicate balance of flavor and aroma, setting it apart from its ale counterparts.

The journey of brewing a fine pilsner begins with the selection of ingredients. Lightly kilned malted barley, along with spicy hops, defines its distinctive profile. Brewers also pay close attention to water composition, opting for harder water with elevated calcium and magnesium levels, essential for achieving the desired characteristics. Unlike other lagers, the color of pilsner remains notably lighter, reflecting its purity and clarity.

The meticulous production process unfolds in a series of meticulously orchestrated steps. It commences with malting, where barley grains undergo germination before being dried and heated to produce the essential malt. In the mash tun, a blend of cracked grain and hot water initiates enzymatic reactions, converting starches into fermentable sugars, resulting in a sweet liquid known as wort.

Following mashing, lautering separates the wort from the spent grains, a critical phase that demands precision to maximize efficiency. Hops make their entrance during boiling, releasing bitter essences that contribute to the beer's characteristic aroma. Subsequent cooling brings the wort to the optimal fermentation temperature, typically around 6-7°C.

The fermentation process unfolds in stainless steel cylindroconical tanks, where bottom-fermenting yeast works its magic over two distinct phases: fermentation and maturation. Unlike top-fermenting beers, pilsners require extended rest periods at cold temperatures, ensuring a crisp and clean finish.

Upon completion of fermentation, the beer undergoes maturation, allowing it to develop depth and complexity over a span of 3-4 weeks. Finally, the yeast is removed, leaving behind a refined brew ready for packaging and consumption.

In conclusion, pilsner stands as a shining example of brewing excellence, characterized by its light body, crisp taste, and refreshing finish. From the careful selection of ingredients to the precise execution of each brewing stage, it epitomizes the art and science of crafting a timeless classic. So, whether sipped on a sunny afternoon or savored with a hearty meal, pilsner remains a perennial favorite among beer aficionados worldwide.
Pilsner Brewing Process

Evaporated milk: Definition and processing

Evaporated milk is made by heating raw milk in a partial vacuum so that the boiling point is raised to 43 - 60°C/110–140°F until it has lost about half its water. The resulting creamy, mildly caramel flavored liquid is then homogenized and then canned and sterilized.

Evaporated milk has a creamy consistence mildly caramel flavored liquid and it differs from ordinary milk in which containing slightly more than twice the number of solids.

It is then homogenized and then canned and sterilized. Evaporated milk is gaining popularity worldwide due to the long shelf life it enjoys. Evaporated milk does not require refrigeration if the can is not opened.

According to Codex Standard, evaporated milks are milk products which can be obtained by the partial removal of water from milk by heat, or by any other process which leads to a product of the same composition and characteristics.

It contains not less than 6.5 percent by weight of milk fat, not less than 16.5 percent by weight of milk solids not fat, and not less than 23 percent by weight of total milk solids.

Nicolas Appert was the first person to preserve milk in concentrated form in the early nineteenth century. First, he concentrated the milk by boiling it in a water bath over a fire, then poured it into glass bottles after cooling. Final process was sterilized the product by heating the bottles for 2 h in a boiling water bath.

The evaporation process involves evaporation, concentration, homogenization, and sterilization of whole milk. The process also concentrates the nutrients and the energy content of the evaporated milk.
Evaporated milk: Definition and processing

Food changes during Processing

Humans have learnt to cook, to broil, to steam, to bake, to roast, to fry, to smoke and to barbeque food on burning coal, wood or oil, transmitting heat through metal surface contact, by convection, by radiation, using steam or gas or fluids.

To these can be added in modern times, to pasteurize (UHT) treatments heating with infrared, microwave and ohmic heating.

Chemical changes that occur during food processing are numerous, and they can be desirable, undesirable, of questionable consequence or a combination thereof.

Thermal treatment lead to desirable changes, such as protein coagulation, starch swelling, textural softening and formation of aroma components and these changes can influence sensory properties, functional properties and/or nutritive value.

Changes induced by processing in food proteins relate mainly to their denaturation, binding of flavor-active and lipid oxidation products to them and modifications brought about intentionally by derivation and enzymatic treatment.

Among lipid constituents of foods, both polar and non-polar components are affected by processing. While many of the changes that occur in food lipids are experienced during their production, many of these effects are system-dependent.

Carbohydrates also undergo changes during milling, cooking, drying, freezing and storage. Carbohydrates present in food are either in the polymeric, oligomeric or simple form. Many of the characteristics of carbohydrates in foods and their physio-chemical changes during processing are dictated by structural characteristics. Complex carbohydrate constituent of foods and the source material from which they are derived also affect many of their properties.

However undesirable changes also occur, such as losses of vitamins and minerals, formation of thermal reaction components of biopolymers, and in minimal processing terms, losses of fresh appearance, flavor and texture.

Yet gradually some ill effects of processing on food compositions and wholesomeness started to come to light, for example the Maillard interaction between carbonyl and amino compounds and their subsequent cyclization and polymerization, caramelization reactions that lead to the formation of heterocyclic compounds, polycyclic aromatic molecules, nitrosamine and such other toxic, carcinogenic and mutagenic molecules during processing.

Although these are known to be produced in trace quantities the consumer has become aware of the lurking danger.

Food processing can result in several changes and advantages, some of which are substantial:
*Lessened hazards from microbial pathogens
*Lessened spoilage (microbial, enzymatic)
*Inactivation of heat-labile, anti-nutritional substance
*Increase a variety of foods, some with enhanced sensory properties - bakeries, confectionary, meat analogs, fermented foods.
Food changes during Processing

Introduction to food processing

A process may be thought of as a sequence of operations which take place in one or more pieces of equipment, giving rise to a series of physical, chemical or biological changes in the fed material and which results in a useful or desirable product.

Many of the traditional definitions stress the relationship of food processing to the preservation of food, and this dimension still represents the single most important reason for processing.

These processes may be relatively simple such as the milling of wheat to produce flour or highly complex such as creating a pizza that to be cooked in a toaster.

Some of the earliest forms food processing resulted in dry food products. These references to various types of commodities date to very early times and the use of thermal energy from the sun to evaporate water from the product and establish a stable and safe dry product. Developing new complex today involves a lot of research experimentation, testing, and trialing.

A small scale recipe for a chicken korma cannot simply be multiplied up and used on a production line to create tens of thousands of meals.

Large scale machinery may affect food in a different way to a domestic cooker, causing meat to become tough or a sauce to runny. In general, processing is used to improve one or more properties of the food, with the underlying reasons falling into one (or more) of four categories: safety, quality value and convenience.

Although foods are always liquid or solid in form, many foods are aerated (e.g. ice cream), many processes utilize gases or vapors and many storage produces require gases or a particular composition.
Introduction to food processing

Thermal processing of food

Thermal technologies have been at the core of food preservation and production for many years. It involves heating foods in hermetically sealed containers for specific time at a specific temperature to eliminate the microbial pathogens that endanger public health and microorganisms and enzymes that deteriorate food during storage.

Ever since the invention of thermal processing as a method of preserving packaged foods by the Frenchman Nicolas Appert in the early 19th century, there has been a relentless search to reduce the amount of thermal damage to the quality of food products.

Today, however, the consumer demands much more than just safe and shelf stable food, including, primarily, higher quality food with greater convenience in the end use.

And food processors look for more energy-efficient, cost effective and high-speed processing technologies. Numerous methods exist for thermal processing of foods. Some of these techniques include the use of steam injection, stem infusion, tubular heat exchangers, shell and tube heat exchangers, plate heat exchangers, scraped surface heat exchangers extruders, ohmic heaters, infrared heaters, radio frequency heaters, microwave heaters and variations, combinations of these.

High temperature, short-time (HTST) techniques have primarily involved to minimize the severity of heat treatment and promote product quality.

Whatever the material and its shape or the food product it is necessary to apply a suitable process, i.e. given time at a specified temperature, to ensure that the products do not pose a public health problem, e.g. food poisoning.

Continuous aseptic processing, also called continues flow processing  and packing further minimize the heat severity by quick heating and cooling of the food, prior to packaging, under aseptic conditions.

Product must be heated to a set temperature for a set time in order to achieve a commercially sterile product.

This profile, thermostable, microwavable packages have been developed for promoting faster heat transfer rates, which minimizes the heat damage to product quality while adding the convenience of package microwavability.

Rotary and continuous cooker for canned food have been based on product agitation during processing to accelerate the rate of heat transfer in order to promote better quality in processed foods.
Thermal processing of food

Heating in food processing

Heating is one of the most essential methods for food preservation mechanism that applied by the food processor to render food products commercial sterile – that is free from pathogenic and spoilage microorganisms likely to grow during the normal distribution and shelf-life of the product.

Conventional heating methods sue external heat sources including hot water and steam. Heat may be transferred by one or more of the three mechanisms of conduction, convection and radiation.

Most industrial heat transfer operations involve a combination of these but it is often the case that one mechanism is dominant.

Heat sterilization of food in containers is an old technology largely attributed to the work of Nicholas’s Appert in the 1800s.

As introduced and developed in the initial stages, the primary focus of canning was safety and shelf stability. The application of heat processes to containers requires not only the ability to heat and cool the container contents efficiently but also the ability to do so while minimizing the stresses imposed upon the container.

Whether electrical or conventional, heating may be broadly classified as unit operations in blanching, cooking, drying, pasteurization, sterilization and thawing and involve raising the product to some final temperature that depends on the particular objective of the process.
Heating in food processing

Roquefort cheese

Roquefort cheese is a delicacy that has heretofore been manufactured only in parts of Europe where it was asserted the proper conditions for ripening existed. Also, to be labeled, Roquefort cheese must be made in France.

Roquefort is mentioned in literature as a far as 79 AD. In 1411 Charles VI of France gave sole rights to the ageing of Roquefort cheese to the village Roquefort-sur-Soulzon.

Roquefort is the original blue cheese. The designation ‘Roquefort’ is applicable only to cheese made from ewe’s milk in the Roquefort area of France.

And French law still dictates that only those chesses ripened in the natural caves of this village are allowed to use the name Roquefort.

A similar product made elsewhere in France is called bleu cheese.

The original Roquefort is produce from raw sheep milk, which after filtering is prepared with rennet. 

Penicillium roquefortii is primarily responsible for ripening the cheese. Proteolytic enzymes from the mild act to soften the curd and thus it produce the desired body in the cheese.

Roquefort is aged for three months in neat rows on oak benches in limestone caves in Combalou, in southwestern France.

The caves have a constant temperature, high humidity and optimal air circulation.
Roquefort cheese

Moisture content in fish

Water is the principle component (up to 80%) of the edible portions of seafood.

Among fish researchers there is no such accepted norm. Moisture content may be reported on a dry basis, a wet basis, a salt-free basis and often the basis is not specified.

However, mostly moisture content is expressed in a wet-weight basis – i.e., is the mass of water in a unit mass of the fish. Moisture contents range from 64.3 to 82.8 percent, with the exception of caviar; this range is very similar to that of mammalian species.

The moisture content of fish is usually determined by oven drying at 100 to 102° C for 16 to 18 hours; the loss of mass in that time being equated to the mass of water in the original sample.

The Karl Fisher method is probably suitable for material in which only a small percentage of moisture is present. But the method is hardly followed for fish and allied materials.

The method of storage as well as further processing, such as freezing determines the final moisture content of the fish flesh.

Considerable moisture, as well as soluble nutrients, may be lost in thaw drip. Water retention is highest in fresh fish. Finfish moisture contents generally show an inverse relationship to the lipid content.

Depth and latitude of fish catch also influence the moisture content of fish. Fish from deep water and from northern latitudes have higher moisture and lower fat content.

Raw shellfish moisture contents fall in the same range as finfish, but average is slightly higher, 80.1%. About one fourth of the moisture can be lost during cooking, which results in concentration of other components.
Moisture content in fish