Agriculture Reference
In-Depth Information
treat mangoes to eliminate oriental fruit fl y eggs (Varith and others 2007). Changes
in physiochemical properties of mangoes, including color, titratable acid, soluble solid
content, and fi rmness of the treated mangoes were not signifi cantly different (P
0.05)
from untreated mangoes. The combined treatment resulted in less heat damage to
mangoes than conventional steam treatment and greater than 90% reduction in pre-
heating time. It would be interesting to study the combined effect of microwave
heating with steam on the reduction of microorganisms in produce.
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Infrared
There have been no publications about the use of infrared heating to inactivate food-
borne pathogens on fresh and fresh-cut fruits and vegetables. Gomez Galindo and
others (2005) treated carrot slices with far-infrared for 7 s (from a radiant surface
of 538 °C) and found that the far-infrared radiation damaged only the fi rst half-
millimeter of cells from the surface, and the carrot slices exhibited the texture
characteristics of the raw tissue.
Conclusion
There is no question that thermal treatment can reduce or even eliminate the popula-
tion of foodborne pathogens on or in fresh produce. However, such treatments may
cause damage to fresh produce if not optimized. The goal of any food safety interven-
tion technology is to decontaminate food products while maintaining or minimizing
the adverse effects to the treated product in terms of quality loss. Understanding the
fundamental mechanism of thermal treatment and application of mathematical calcu-
lations and modeling will help design better and more effective thermal processes to
inactivate the targeted pathogens and to minimize quality loss. In general, if the tem-
perature at the site of pathogen attachment to produce reaches 70 °C, vegetative bacte-
rial pathogens will defi nitely be inactivated. However, whether fresh produce can
tolerate such a high temperature even for a brief period depends on the type of fresh
fruit or vegetable and whether the produce will be further processed. For fresh produce
(such as lettuce leaves) that is rather tender and delicate, thermal treatment may have
a limited application because heat treatment can cause quality deterioration. For this
type of produce, warm-water treatment may be combined with other intervention
treatments (such as hydrogen peroxide and organic acids) to enhance microbial safety
and to maintain product quality. If the produce has a thick protective layer (such as
cantaloupe rind), damage caused by heating may be minimal. For products in which
the surface of a fruit or vegetable will be removed during fresh-cut processing,
damage to the surface may not be an issue, simply because the damaged surface layer
will be discarded. However, prolonged surface thermal treatment may cause the inter-
nal temperature to increase to a point high enough to induce internal tissue damage
in the product. Therefore, the commercial application of thermal processing to enhance
fresh produce safety needs to be evaluated on a case-by-case basis. Furthermore, more
studies are needed to evaluate the feasibility of microwave, RF, and infrared treat-
ments in inactivating foodborne pathogens on/in fresh and fresh-cut fruits and
vegetables.
