*2.2.1 High-pressure processing (HPP)*

A nonthermal method of food and dairy product preservation and sterilization in which a product is subjected to extremely high pressure, causing some microbes and enzymes in the food to be inactivated [33]. Research on raw milk treated with high pressure has shown that HPP treatment produces raw milk of comparable quality to pasteurized milk, as it is equally successful in eradicating pathogenic and spoilage microorganisms. When compared to foods with a higher pH, such as milk, HPP proved effective at inactivating bacteria in both high- and low-acid food systems. It may influence the qualities of treated milk by modifying the fundamental features of milk ingredients [34]. In the food and dairy sector, high-pressure processing is a unique alternative to thermal processing [33] that includes a treatment chamber, a pressure generating system, a pressure transmission medium, and a pressure intensifier [34]. HPP was performed at 680 MPa for 10 minutes at room temperature and the number of microorganisms was reduced by 5–6 log cycles.

### *2.2.2 Pulsed electric fields (PEF)*

The fundamental principle of PEF technology is the use of short pulses of high electric fields with durations ranging from microseconds to milliseconds and intensities ranging from 10 to 80 kV/cm. Short pulses (1–10 μs) generated by a high voltage (5–20 kV) pulse generator have been used to treat biological material or food placed between two electrodes installed 0.1–1.0 cm apart in a treatment chamber separated by an insulator [35].

The processing time is calculated by multiplying the number of pulse times with effective pulse duration. The applied high voltage results in an electric field that causes microbial inactivation. When an electrical field is applied, electrical current flows into the liquid food and is transferred to each point in the liquid because of the charged molecules present ([36]; as cited by [33]). PEF treatment has achieved a reduction in the microflora of milk with a shelf life similar to that of high temperature, short time (HTST) pasteurized milk.

The ability to control the amount of ohmic heating in food preservation (lowtemperature processing) is the main benefit of PEF technology in liquid food pasteurization. This avoids the Maillard reaction, which affects the functional properties of food such as color, taste, and smell [37]. PEF is also effective in the inactivation of microorganisms such as *Salmonella typhimurium*, *Listeria innocua*, and *E. coli* up to 5.0 log cycles [38].

The method is highly scalable and can be incorporated into existing food processing lines. In comparison to traditional heat pasteurization technology, it is more

energy-efficient [39]. Furthermore, PEF treatment chambers can be easily adapted to existing continuous-flow production lines for liquid food pasteurization [40]; however, achieving a homogeneous treatment may be an issue [41]. The main disadvantage of PEF technology is its effectiveness and efficiency, which are largely dependent on the liquid conductivity and viscosity [42].

#### *2.2.3 Ultra-sonication*

It refers to the application of sound waves at the frequency (˃ 16 kHz) greater than the upper limit of human hearing through liquid, solid, or gases, which causes the formation of small bubbles (known as cavitation). While droplets reach the required size range, they collapse under near-adiabatic conditions, resulting in significant conditions both within the droplets and in the surrounding liquid that include intense shear forces, turbulence, and micro streaming effects. These ultrasound-induced physical effects are increasingly being used in food and dairy processing industries, its application is used to enhance whey ultrafiltration, extraction of functional foods, reduction of product viscosity, homogenization of milk fat globules, crystallization of ice and lactose, and the cutting of cheese blocks [33].

The use of ultrasound in traditional dairy processes has the potential to bring significant cost savings and improved product qualities to the dairy sector. Furthermore, as compared to other new technologies, the use of ultrasound as a processing technique has been deemed safe [43]. These technologies include low- and high-intensity ultrasounds. Low-intensity ultrasounds have been used to determine, evaluate, and define the physical features of foods, whilst high-intensity ultrasounds have been utilized to speed up specific biological, physical, and chemical processes during the handling and transformation of food products [44].

## *2.2.4 Cold plasma (CP)*

Cold Plasma is an electrically powered gaseous state consisting of charged particles, free radicals, and some radiation that is known as the fourth state of matter. An electrical discharge [45] produces a partially or totally ionized plasma made up of photons (basically), ions, free electrons, and atoms in their fundamental or excited states. These species are classified as either "light" (photons and electrons) or "heavy" (remaining constituents) [46, 47].

Currently, CP undergoing extensive testing for the preservation of perishable commodities such as milk and milk products. The use of cold plasma (CP) techniques to preserve milk and milk products has been pushed as a revolutionary nonthermal technology. CP not only preserves the nutritional value of the food but also inactivates germs, eliminating the risk of resistance. Cold plasma was also discovered to disrupt enzymes involved in browning (color change) processes and the production of an off-flavor [48].

#### **2.3 Membrane separation technology**

It is a method of separating a liquid into two streams using a semipermeable membrane. The two streams are called retentate and permeate, respectively. Specific components of milk and whey can be separated using membranes with

## *Recent Advances and Application of Biotechnology in the Dairy Processing Industry: A Review DOI: http://dx.doi.org/10.5772/intechopen.105859*

different pore sizes. Membrane filtering technology offers a variety of applications in the cheese industry, including boosting nutritional quality, improving compositional control and production by increasing total solid content, using whey during cheese manufacturing, and minimizing the need for rennet and starter culture. Concentrating milk before manufacturing cheese opens up a new market for the cheese industry, lowering costs and speeding up the entire process [49]. Membranes in the cheese industry concentrate the cheese milk, increasing yield and quality while controlling whey volume. It is now possible to recover growth factors from whey because of advancements in membrane technology [50]. Membrane filtration can basically be divided into four main technologies, which are as follows:

### *2.3.1 Microfiltration (MF)*

Microfiltration is a membrane filtration technique that uses a membrane with an open structure and is powered by low pressure. The membrane allows dissolved components to pass while rejecting the majority of non-dissolved components. Microfiltration is widely used in the dairy industry to reduce bacteria and spores, remove fat from milk and whey, and standardize protein and casein.

### *2.3.2 Ultrafiltration (UF)*

Ultrafiltration is a membrane filtration process that operates at medium pressure. Ultrafiltration works by passing most dissolved and non-dissolved components through a membrane with a medium open structure while rejecting larger components. UF is widely used in the dairy industry for whey protein concentration and milk protein concentration as well as standardization.

#### *2.3.3 Nano-filtration (NF)*

Nano-filtration is an intermediate step in the high-pressure membrane filtration process. In general, nano-filtration is a type of reverse osmosis in which the membrane has a slightly more open structure that allows primarily monovalent ions to pass through. The membrane rejects divalent ions to a large extent. Nanofiltration is primarily used in the dairy industry for specialized applications such as partial demineralization of whey, lactose-free milk, and whey volume reduction.

#### *2.3.4 Reverse osmosis (RO)*

Reverse osmosis is a high-pressure, membrane-based filtration process that uses a very dense membrane. In theory, only water passes through the membrane layer. Reverse osmosis is commonly used in the dairy industry for milk and whey concentration or volume reduction, milk solids recovery, and water reclamation.

#### **2.4 Application of biotechnology in dairy processing**

Recent biotechnological breakthroughs have emerged as a significant tool for developing quality features in livestock products, such as dairy and dairy-based

products. In most developing nations, biotechnology has been used to improve food processing by using microbial inoculants to improve qualities such as flavor, scent, shelf life, consistency, and nutritional content of meals and dairy products. Probiotic food products are a rapidly expanding segment of functional food that has been well received by consumers. The food sector, on the other hand, is striving to offer a variety of probiotic foods other than dairy products with potential health benefits [51].

Moreover, modern biotechnology has brought up new and exciting opportunities in the dairy industry, making milk and milk products more accessible to the poor and meeting the demands of a larger population. Since the dairy industry's primary responsibility is to provide consumers with high-quality, nutritional, and affordable dairy meals, biotechnological intervention at various stages of milk production and processing has become a foregone conclusion [52]. It has provided us with delicious, nutritious, wholesome, handy, shelf-stable, and safe foods. As long as research and development efforts continue, biotechnology will inevitably have a greater impact on the food we eat. It has enormous potential for expanding the variety and quality of food available to humans, especially more healthy and appealing foods. It also appears likely that it will continue to provide benefits to food processing and safety monitoring as new technologies develop at a faster rate. Furthermore, the biotechnological application has a remarkable role in dairy product bio-preservation, probiotics manipulation, and production; enzyme production; milk derived bioactive peptides and other functional ingredients; and starter cultures technology and genetic manipulation.

#### *2.4.1 Bio-preservation*

Although recent advances in innovative modern technologies implemented in food processing and more stringent microbiological food-safety standards have reduced the incidences of foodborne illnesses and product spoilage, they do not completely eliminate the possibility of health risks associated with such foods. As a result, the food industry is always exploring novel techniques and methods to produce minimally processed, ready-to-eat food that retains its nutritional value, taste, and flavor. Bio-preservation like bacteriocin is an ideal choice to preserve ready-to-eat processed foods without altering their nutritional and chemical properties.

Bacteriocins are antimicrobial peptides that are deemed harmless since they are easily destroyed by mammalian gastrointestinal proteolytic enzymes. Furthermore, the majority of bacteriocin producers belong to lactic acid bacteria (LAB). Bacteriocins, whether purified or secreted by bacteriocin-producing bacteria, are a wonderful alternative to chemical preservatives in dairy products because they pose no health risks. Bacteriocins can be added to dairy products in purified/raw form, as a bacteriocin-producing LAB in the fermentation process, or as an adjuvant culture. Bacteriocins and bacteriocin-producing LAB have been used to control pathogens successfully in milk, yogurt, and cheeses in a number of cases. One of the most recent development is the inclusion of bacteriocins, whether directly as purified or semipurified form, or as bacteriocin-producing LAB, into bioactive films and coatings that are directly applied to food surfaces and packaging [53].

#### *2.4.2 Probiotics*

Probiotic is a relatively recent term that means "for life," and it refers to bacteria that have been connected to beneficial effects in humans and animals. The probiotic

#### *Recent Advances and Application of Biotechnology in the Dairy Processing Industry: A Review DOI: http://dx.doi.org/10.5772/intechopen.105859*

microorganisms are primarily *Lactobacillus* and *Bifidobacterium* strains, but *Bacillus, Pediococcus*, and several yeast strains have also been identified as suitable possibilities [54]. Sour/fermented milk, yogurt, cheese, butter/cream, ice cream, and infant formula all contain probiotic bacteria. These probiotics are either used as a starter culture alone or in combination with traditional starters, or incorporated into dairy products after fermentation, where their presence confers many functional characteristics to the product (such as improved aroma, taste, and textural characteristics), as well as many health-promoting properties [55].

Milk and milk products, particularly fermented dairy foods, are thought to be excellent carriers of probiotic strains, which allows to express their health-promoting functions to the greatest extent possible. Probiotic microorganisms can be concentrated and added in small amounts directly to food or a milk product, where they can grow. Yogurt is a well-known example of probiotic-rich functional dairy food. Probiotic yogurt, also known as bio-yogurt, should contain living bacterial cultures. Probiotics have been used to treat intestinal disorders as dietary supplements and oral agents. Probiotics have appeared recently as among the most precious bugs due to their ability to express a plethora of novel health-promoting functions that are strainspecific. Immunomodulation, restoring the balance of disturbed gut flora, strengthening the mucosal barrier function, and preventing lactose intolerance are the most notable probiotic functions. However, the focus at the moment is on researching probiotics as potential biotherapeutics for chronic inflammatory metabolic disorders such as diabetes, CVD, obesity, irritable bowel disease (IBD) and syndrome (IBS), Ulcerative Colitis (UC), Crohn's disease (CD), acute diarrhea, serum cholesterol reduction, shortening the duration of respiratory infections, blood pressure control, colon cancer, and urinary tract infection (UTI), among others.

#### *2.4.3 Biotechnology and enzyme production*

Enzyme production is a new field that answers the needs of the food processing industry by drastically lowering investment and processing costs. Enzymes are a biotechnological processing tool whose action in the food matrix may be manipulated to produce high-quality products. Moreover, the application of biotechnology has a significant role to produce enzymes used in the food and dairy industries, microbial protease, lipase, and galactosidase are enzymes that come from beneficial microorganisms. Their thermoresistance, thermostability, and thermoacidophilic qualities brought a particular interest to food producers [56].

The industrial production of enzymes for use in food processing dates back to 1874 when Danish scientist Christian Hansen extracted rennin (chymosin) from calves' stomachs for use in cheese manufacturing. Bovine chymosin was the first enzyme to be produced through biotechnological approaches in *E. coli*. Since then, genetic manipulation has been used to make tailor-made enzymes for specific consumer requirements. Now enzymes can be produced through recombinant DNA technology in large quantities for their subsequent application in the food industry (**Table 1**).

Some microorganism strains have been genetically modified to boost their capacity for enzyme synthesis under ideal conditions. In most situations, changed genes from other kingdoms of microorganisms can be found in GM microorganisms that generate enzymes. Bio-based compounds such as glucoamylase, lipase, −amylase, pectinase, antibiotics, amino acids, lactic acid, nucleic acid, and polysaccharides are created utilizing GM starting cultures. For example, one of the DNA codes for chymosin, which causes milk to curdle or coagulate during cheese fermentation, was cloned


#### **Table 1.**

*Enzymes produced from genetically modified microorganisms using gene technology used in the dairy industry.*

into bacteria (*Escherichia coli*), yeast (*Kluyveromyces lactis*), and mold (*Bacillus niger*) (*Aspergillus niger*). In Thailand, modified *E. coli* is being utilized to produce lysine, with the goal of increasing yield in less time [58].
