Biomedical Engineering Reference
In-Depth Information
other phytochemicals such as carotenoids and vitamin C, which exhibit antioxidant
potential, and improve the nutritional status of the products (González-Aguilar et al.
2007a
,
b
). However, in addition to the above physiological effects produced by
UV-C irradiation, there is also damage to the microbial DNA.
Several studies have been published on UV-C as a method to preserve the quality
of different FCFV. Pre-storage application of UV-C reduced chilling injury in pep-
per (Vicente et al.
2005
), delayed senescence yellowing, chlorophyll degradation,
and pheophytin accumulation in broccoli (Costa et al.
2006
). Likewise, its applica-
tion can control the storage rot in strawberry, reduced pathogen growth and induced
disease resistance in other fresh produce (Rivera-Pastrana et al.
2013
; Bu et al.
2013
; Bonomelli et al.
2004
). Chilling injury symptoms and deterioration of
“Tommy Atkins” mangoes were reduced by UV-C irradiation during storage at 5 °C
(González-Aguilar et al.
2007b
). In addition, the effect of short UV-C doses
(0.4-8.14 kJ m
−2
) over the shelf life of the processed lettuce was studied (Allende
et al.
2006a
). UV-C effectively delays the senescence and deterioration of fresh-
processed lettuce during storage (Allende et al.
2004
,
2006a
).
5.4.2
Controlled/Modifi ed Atmospheres
Some of the technologies used to preserve the quality of the FCFV are the con-
trolled and modifi ed atmospheres (CA/MA), and their benefi cial effects have been
well documented (Yahia
2010
). CA/MA is a passive or active dynamic process that
consists in altering the gases surrounding a commodity to produce a composition
different from that of air. This is achieved by the interaction between two processes;
the respiration rate of the fresh-cut product and the transfer of gases through the
packing material (Caleb et al.
2012
). Low levels of O
2
and high levels of CO
2
reduce
respiration rates and help to delay senescence, thus extends the storage life and
maintain nutritional and sensory quality of the fresh-cut produce (Yahia
2010
;
González-Aguilar et al.
2010b
).
Passive CA/MA can be generated inside a package by relying on the natural
respiration of produce and fi lm permeability to attain the desired gas composition
over time (Charles et al.
2003
). While, active CA/MA implies a rapid process of
gas replacement or displacement, or the use of gas scavengers or absorbers to
establish a desired gas mixture within a package. This involves the addition of
active agents into a packaged food product, such as O
2
, CO
2
and ethylene scaven-
gers (Kader et al.
1989
). Once the package is closed, no further control on the gas
composition is required, and the composition will inevitably change due to FCFV
respiration and fi lm gas permeability. However, the positive effects of CA/MA
depend on several factors such as type of FCFV, concentrations of gases, tempera-
ture, and duration of storage (González-Aguilar et al.
2010b
). Extremely low levels
of O
2
and high CO
2
favors fermentative processes, which might cause the forma-
tion of acetaldehyde and the occurrence of off-fl avor compounds (Thompson
2010
).
