Recent Developments in Non-thermal Processess - Food and Industrial Bioproducts and Bioprocessing - page 305

13 Recent Developments in
Non-thermal Processess
Fernando Sampedro and Howard Q. Zhang
13.1 INTRODUCTION
The need for “fresh”, safe and convenient foods with more health benefits is supported by
demographic and socioeconomic changes that are occurring in the population. The industry
is conscious about the changes in consumer trends. A significant fact is the introduction of a
great variety of minimally processed foods that need chilled chain of storage and distribution
systems (fruit juices, vegetable-based soups and sauces and “ready to eat” (RTE) products,
among others) in the market. Through the years, thermal treatment has been used for
producing microbiologically safe food with low enzyme activity and this continues to be the
best processing method for mass production of foods. Nevertheless, in certain products
containing health beneficial thermolabile bioactive compounds, quality and nutritional
content (vitamins, color and flavor, among others) are compromised after thermal processing,
even at mild temperatures.
Taking into account the limitations of traditional thermal processes and the trends in
consumer demand, scientists have searched for alternative technologies that could
ensure the microbial safety while retaining the fresh-like or fresh-prepared quality.
These technologies have been called “emerging preservation technologies” and
particularly, the ones based on processing parameters other than temperature,
“nonthermal technologies” (Barbosa-Cánovas et al ., 1998 ). These technologies include
pressure-based processing (high pressure processing, high pressure homogenization
and high pressure carbon dioxide), electric fields (pulsed and radiofrequency), radiation-
based technologies (UV light and irradiation) and high intensity ultrasounds. Some of
these technologies are more suitable for solid food processing, such as high pressure
processing (HPP), ionizing irradiation and static-UV processes, whereas pulsed electric
fields (PEF), high pressur e homogenization (UHPH), high pressure carbon dioxide
(HPCD), ultrasounds and flow-through UV treatment are continuous processes used for
liquid food pasteurization. In some cases, HPP and irradiation technologies can also be
used for processing packaged liquid foods and PEF static devices for extraction of
bioactive compounds in solid foods.