Page 42 - FoodFocusThailand No.163 October 2019

SMART PRODUCTI
SMART PRODUCTIONON

Advanced Food Processing Technology

Part I: Non-thermal Food Processing

Technology

Consumers’ demand is an important factor to change the concept of food processing technologies. Customer
tends to look for food products with high quality and nutritional value.

Traditional food processing dealing with conventional heat is applied to extend their shelf life. From the limitation of non-thermal
exchangers or retorts to heat foods to target temperatures becomes processing the use of thermal processing technology still exists. The
the cause of the loss of product quality and nutritional value due to reduction of heating time and/or temperature to maintain product
slow heat transfer and non-uniform heating. The replacement of quality is required.
thermal energy from steam and hot water with electricity, high
pressure, light and electromagnetic wave is an alternative method Examples of Non-thermal Processing Technology
to preserve foods. • Pulsed Electric Field (PEF)
A number of advanced food processing technology are currently Pulsed electric field (PEF) is a method which utilizes intensive
interested throughout the world including non-thermal processing electric field (EF) strength (15-80 kV/cm) in a very short time from
technology such as pulsed electric field (PEF), high pressure nanoseconds to microseconds. High-voltage power supply connects
processing (HPP), cold plasma; and thermal processing technology capacitor to store energy which discharges the electric field to food
such as pressure assisted temperature sterilization (PATS), ohmic products. Although product temperature increases, with a very short
heating (OH) and microwave heating. Both technologies are used processing time heat generation is not significant considered. High
to produce safe foods with high nutritional value and quality and to electric field can generate a transmembrane potential difference
extend their shelf life without the addition of food additives and high enough to produce pores in cell membrane (electroporation).
preservatives. If the pore formation is irreversible, the membrane was permanently
destroyed which allows free movement of cell contents and affects
Non-thermal Processing Technology the microbial metabolism causing microbial death (Jayaram, 2000;
Non-thermal processing technology can inactivate pathogenic and Ravishankar et al., 2008). PEF effectively affects yeasts, molds and
spoilage microorganisms in order to produce safe foods and prolong microorganisms. Large cells and rod-shaped microorganisms are
their shelf life with minimal negative impact on sensorial attributes. destroyed easier than small cells and cocci respectively. Yeasts are
However, the non-thermal processing technology (except irradiation) more sensitive to PEF than bacteria; and gram negative bacteria
cannot destroy spores. Therefore, low-acid foods should be kept in are more susceptible than gram positive bacteria. Spores of bacteria
refrigerated condition in order to prevent the germination and toxic are more resistant than those of yeasts and molds. Microorganisms
production of Clostridium botulinum. For acid foods, chilled storage in lag or stationary phases are stronger than those in exponential

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