Conservación De Alimentos

Microbes and Infection 4 (2002) 433–440
www.elsevier.com/locate/micinf

Current focus

Alternative food-preservation technologies: efficacy and mechanisms
Beatrice H. Lado, Ahmed E. Yousef *
Department of Food Science and Technology, The Ohio State University, 2015 Fyffe Road, Parker Hall, Columbus, OH 43210, USA

Abstract
High-pressure processing, ionizing radiation, pulsed electricfield and ultraviolet radiation are emerging preservation technologies
designed to produce safe food, while maintaining its nutritional and sensory qualities. A sigmoid inactivation pattern is observed in most
kinetic studies. Damage to cell membranes, enzymes or DNA is the most commonly cited cause of death of microorganisms by alternative
preservation technologies. © 2002 Éditions scientifiques etmédicales Elsevier SAS. All rights reserved.
Keywords: High pressure; Injury; Irradiation; Kinetics; Non-thermal; Pulsed electric field; Resistance; Ultraviolet

1. Introduction
Consumers are increasingly aware of the health benefits
and risks associated with consumption of food. To meet
consumers’ expectations, the food industry is devoting
considerable resources and expertise to theproduction of
wholesome and safe products. Production of safe food
includes scrutinizing materials entering the food chain,
suppressing microbial growth (e.g. storage at chilling temperature), and reducing or eliminating the microbial load by
processing and preventing post-processing contamination.
The presence of a processing unit operation aiming at
microbial destruction is of primary importanceto ascertain
safety and stability of food. Heat treatments are traditionally
applied to pasteurize or sterilize food, generally at the
expense of its sensory and nutritional qualities. As consumers increasingly perceive fresh food as healthier than heattreated food, the industry is now seeking alternative technologies to maintain most of the fresh attributes, safety and
storage stability offood [1].
Satisfactory evaluation of a new preservation technology
depends on reliable estimation of its efficacy against pathogenic and spoilage food-borne microorganisms. Research
on alternative technologies was initially focused on process
design, product characteristics and kinetics of microbial
inactivation. The success of these new technologies, however, depends on progress inunderstanding microbial physiology and behavior of microbial cells during and after

* Corresponding author. Tel.: +1-614-292-7814; fax: +1-614-292-0218.
E-mail address: yousef.1@osu.edu (A.E. Yousef).
© 2002 Éditions scientifiques et médicales Elsevier SAS. All rights reserved.
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treatment. Consequently, this article reviews alternative
preservationtechnologies with emphasis on (i) comparing
their efficacy with conventional heat treatment, (ii) mechanisms of microbial inactivation, (iii) patterns of inactivation
kinetics, (iv) microbial resistance mechanisms and (v)
potential causes of underestimation of survivors during food
processing by alternative technologies.

2. Food-preservation technologies
Thermal pasteurization and sterilizationare predominantly used in the food industry for their efficacy and
product safety record. Excessive heat treatment may, however, cause undesirable protein denaturation, non-enzymatic
browning and loss of vitamins and volatile flavor compounds. Many US consumers, for example, consider the
‘cooked’ and caramelized flavors of sterilized milk as taste
defects [2]. Advances in technology allowedoptimization of
thermal processing for maximum efficacy against microbial
contaminants and minimum deterioration of food quality.
High-temperature short-time (HTST) pasteurization and
ultra-high temperature (UHT) sterilization, for example,
minimize vitamin losses in milk in comparison with batch
pasteurization and conventional commercial sterilization,
respectively [3]. Products processed...