Biomedical Engineering Reference
In-Depth Information
4.
Reduction in some physiological disorders induced by C
2
H
4
, such as scald
of apples and pears and chilling injury of citrus fruits, avocado, chili
pepper, and okra.
5.
Reduction in microbial activity, especially molds.
The marketing and distribution advantages of CA or MA technologies include:
1.
Reduction in fresh food spoilage and quality loss through the distribution
at the retail level.
2.
Expanded radius of distribution systems and market area.
3.
Improved branding options and product differentiation.
4.
Potential for increased profitability in all fresh or chilled food operations.
In considering the above described benefits, a number of potential problems
associated with CA or MA storage must be recognized. Above all is the potential
health hazard associated with these technologies, especially modified atmosphere
packaging or MAP.
3,17
It has been pointed out that the same principles of atmosphere
modification responsible for all the benefits of CA or MA are also the main cause of
controversy surrounding the potential health hazards associated with these technolo-
gies.
3,18,19
Modification of the atmosphere and, in particular, the reduction or elimi-
nation of O
2
from the package head space will in many cases disturb the equilibrium
of the atmosphere in favor of anaerobic microorganisms. The aerobic bacteria that
normally spoil the product, and in so doing warn consumers of any potential health
hazard, may find themselves at an atmospheric disadvantage and their growth inhib-
ited. In the absence of competing aerobic organisms, anaerobic nonproteolytic toxin
producers, such as
Clostridium botulinum
, are likely to have the right conditions for
optimum growth, but their presence may not be obvious to the senses. The food may
appear to be acceptable long after it has become microbiologically unsafe. According
to Lioutas,
15
this issue probably represents the greatest vulnerability for the CA or
MA technology and could potentially inhibit any further application.
Other concerns associated with CA or MA technology include:
1.
Development of off-flavors due to accumulation of ethanol, acetaldehyde,
and other volatiles.
2.
Increased softening in products such as cucumbers, cauliflower, celery,
and onion.
3.
Development of physiological disorders, such as brown stain on lettuce,
internal browning and surface pitting of pome fruits, and blackheart of
potatoes induced by inappropriate modified atmospheres.
4.
Increased susceptibility of some products (celeriac, carrot, pepper, Chi-
nese cabbage, and citrus fruits) to post-harvest pathogens.
M
ETHODS FOR
C
REATING AND
M
AINTAINING
MA
The reduction of O
2
levels inside an enclosed space (storage room or polymeric film
package) can be achieved biologically through respiration of the food product, or it
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