Non Thermal Technology in food Processing

What is Non thermal Processing?

Processing of foods without the application of heat is termed as the non-thermal processing. The most widely used non-thermal processing techniques are high pressure processing, pulsed electric field, ultrasound, pulsed light, ultraviolet light, irradiation, oscillating magnetic field (NIFTEM 2021).

As the foods are treated without heat, the foremost importance of the non-thermal processing is the maximum retention of colour, taste, appearance and nutrition content in food. The major facility in the centre is the unique equipment available for different non-thermal processing methods.

There are only few Non thermal Processing techniques that are capable of doing it which includes.

· Hight Pressure Processing (HPP)

· Pulsed electric Felid (PEF)

· Ultrasound processing (UF)

· Ozone

· Food irradiation

· Super critical fluid extraction (SCF)

· Cold Plasma.

Hight Pressure Processing (HPP)

High pressure processing (HPP) also described as high hydrostatic pressure (HHP, or ultra-high pressure (UHP) processing, subjects’ liquid, and solid foods, with or without packaging, to pressures between 100 and 800 Mpa. Process temperature during pressure treatment can be specified from below 0°C (to minimize any effects of adiabatic heat to above 100°C. Vessels are uniquely designed to safely withstand this pressure can range from a millisecond pulse (obtained by oscillating pumps to treatment time of over 1200 s (20 min).

HPP processed foods.

Fruits and vegetables, juices, shell fish, dairy products, jams, jellies and meat products.

source : https://www.foodnavigator-asia.com/Article/2018/08/29/Newly-launched-UAE-organic-food-e-commerce-site-seeks-to-become-region-s-biggest

Pulse Electric field

Pulsed electric field (PEF) processing is a novel, non-thermal preservation method that has the potential to produce foods with excellent sensory and nutritional quality and shelf-life. High intensity pulsed electric field (HIPEF) processing involves the application of pulses of high voltage (typically 20 - 80 kV/cm) to foods placed between 2 electrodes. PEF treatment is conducted at ambient, sub-ambient, or slightly above ambient temperature for less than 1 s, achieved by multiple short duration pulses typically less than 5 µs and energy loss due to heating of foods as well as undesirable changes in the sensory properties of the food is minimized. For food quality attributes, PEF technology is considered superior to traditional heat treatment of foods because it avoids or greatly reduces the detrimental changes of the sensory and physical properties of foods.

PEF processed foods.

Liquid eggs, juices, milk, yogurt.

source : https://helipack.en.made-in-china.com/product/sZUtiLSxsEYR/China-Water-Egg-Tart-Liquid-Emulsion-Pure-Milk-Cream-Cheese-Coffee-Spice-and-Soup-Whip-Topping-Lactobacillus-Beverage-Juice-Albumen-Yoghour-Catsup-Jam-Carton.html

Ultrasound processing (UF)

Ultrasound refers to sound waves beyond the audible frequency range (in general, >20 kHz). When ultrasound passes through a liquid medium, the interaction between the ultrasonic waves, liquid and dissolved gas leads to an exciting phenomenon known as acoustic cavitation (AC). In short, dissolved gas nuclei oscillate under the influence of the acoustic field due to the fluctuating pressure around them. During the oscillations, dissolved gas and solvent vapor diffuse in and out of the oscillating bubbles. Due to the ‘‘rectified diffusion’’ process, the amount of gas/vapor that diffuses into the bubbles during the expansion phase is greater than the amount that diffuses out of the bubble during the compression phase of the bubble oscillation. This leads to the growth of the bubbles towards a resonance size range. When bubbles reach the resonance size range, they grow to a maximum size within one acoustic cycle and violently collapse generating very high temperature conditions within the collapsing bubbles.

I know it is difficult to understand the above science let me break it down and help you.

In ultrasound food processing, these sound waves are directed towards the food. When the waves hit the food, they create tiny vibrations and waves within the food. These vibrations help in several ways:

Cleaning: The vibrations created by ultrasound can dislodge dirt, bacteria, and other particles from the surface of food. It's like giving the food a gentle scrubbing.

Mixing: The waves can also help mix ingredients more effectively. When ultrasound is used in mixing processes, it helps distribute flavors, colors, and other ingredients evenly throughout the food.

Preservation: Ultrasound can help preserve food by inactivating enzymes and bacteria that can cause spoilage. By applying ultrasound, the growth of microorganisms can be slowed down, helping to extend the shelf life of food.

Extraction: Some food processing involves extracting valuable compounds from raw materials. Ultrasound can help with this process by breaking down cell walls and releasing these compounds more efficiently.

Ultrasound processed foods.

Meat, milk, honey, food enzymes, fruits and vegetables

source : https://www.123rf.com/photo_120056274_assortment-of-healthy-protein-sources-and-body-building-food-meat-fish-fruits-vegetables-legumes-nut.html

Ozone

Ozone is a strong oxidant and potent disinfecting agent. Disinfecting agents have widespread applications to assure safety and quality in the food industry. However, some of these agents, such as chlorine, are inefficient against some organisms, particularly at high pH or against spore-forming microbes. Furthermore, chlorine can react to form trihalomethanes, which are of concern for both human dietary safety and as environmental pollutants.

Therefore, the food industry is in search of applications that are:

· Effective in inactivation of common and emerging pathogens, and removing toxic contaminants.

· Leading to less loss in product quality and ensure ‘freshness’.

· Adaptable to food processes and economically feasible.

· Environmentally friendly.

Ozone processed foods.

Fruits and vegetables.

source : https://www.holchem.co.uk/media-centre/choosing-the-right-disinfectant-for-fruit-and-vegetable-processing/

Food irradiation

Food irradiation is a process that involves using ionizing radiation to treat food products. Ionizing radiation, such as gamma rays, X-rays, or electron beams, is applied to the food to achieve specific outcomes, such as reducing harmful bacteria, controlling pests, or extending shelf life.

During the process, the food is exposed to a controlled dose of radiation for a predetermined period. This exposure disrupts the DNA or cellular structure of microorganisms, insects, and parasites present in the food, rendering them unable to reproduce or cause harm. It can also slow down the natural ripening and spoilage processes in certain fruits and vegetables.

Range of doses for food

Low-dose range: 0.1 kGy to 1 kGy.

Medium-dose range: 1 kGy to 10 kGy.

High-dose range: Above 10 kGy.

Irradiation processed foods.

Any food can be irradiated because it can help in destroy microorganisms.

source : https://en.wikipedia.org/wiki/Food_irradiation.

Super critical fluid

Supercritical fluid processing in food involves the use of substances, typically carbon dioxide, heated and pressurized beyond their critical point to exhibit properties of both a liquid and a gas. This supercritical fluid is then utilized to extract, separate, or modify various components of food. The supercritical CO2 has excellent solvent capabilities, allowing it to selectively dissolve desired compounds like essential oils or flavors from food matrices.

In processes with supercritical fluids (SCFs), the driving potential for mass and heat transfer is determined by the difference from the equilibrium state. The equilibrium state provides information about:

(i) the capacity of a supercritical (gaseous) solvent, which is the amount of a substance dissolved by the gaseous solvent at thermodynamic equilibrium;

(ii) the amount of solvent, which dissolves in the liquid or solid phase, and the equilibrium composition of these phases;

(iii) the selectivity of a solvent, which is the ability of a solvent to selectively dissolve one or more compounds, expressed by the separation factor a;

(iv) the dependence of these solvent properties on conditions of state (p,T)

(v) the extent of the two-phase area, as limiting condition for a two-phase process like gas extraction.

Super critical processed foods

Fruits and vegetables, oils, seeds

Cold Plasma

The change of phase from solid to liquid and further to gas occurs as we increase the energy input likewise increasing the energy input beyond a certain level in gas state causes ionization of molecules which yields the plasma state.

Cold plasma technology is also used to inactivate endogenous enzymes which are responsible for browning reactions particularly polyphenol oxidase and peroxidases. Several research investigations showed a reduced growth of microorganism via different mode of actions by etching phenomenon, cell disruption by electroporation etc. Plasma technology is considered as modern non-conventional technique which is used for the preparation of modified starches, altering its physical and chemical properties. Overall application of cold plasma for microbial destruction on different food substrates like fruits, meat products, cheese.

source : https://vinit.com.vn/en/cold-plasma-project-for-preserving-agricultural-food-products/.

Conclusion

Non-thermal processing techniques have the potential to revolutionize the food industry by providing safe and high-quality food products while preserving their natural attributes. Continued research and development in this field will likely lead to further advancements and the wider adoption of non-thermal processing methods, contributing to a more sustainable and efficient food processing industry.