Biomedical Engineering Reference
In-Depth Information
Soliva-Fortuny et al.
2002
). The softening process is mainly related to the activity
of pectin methylesterase (PME, EC 3.1.1.11) (Banjongsinsiri et al.
2004
; Guillemin
et al.
2008
) and polygalacturonase (PG, EC 3.2.1.15) (Rastogi et al.
2007
). The rate
of softening after processing depends on many factors related to the product, pro-
cessing, and storage conditions (Martın-Belloso et al.
2006
).
Another drawback of the fresh products or minimally processed packaged fruits
and vegetables is the fact that fl avor life is shorter than the postharvest life (Caleb
et al.
2013b
). Once the plant tissue is disrupted, enzymatic reactions allow the
formation of volatile compounds such as alcohols, aldehydes, terpenes, esters and
acids (Dávila-Aviña et al.
2011b
). Volatile compounds also contribute to the forma-
tion of off-odors, depending on their concentration; they can shorten the storage life
of the product as well (Poll et al.
2006
).
Very often, the development of off-odors is one of the factors limiting the shelf-
life of fresh-cut products, as has been observed in oranges (Rocha et al.
1995
),
melons (Bai et al.
2003
), baby spinach (Tudela et al.
2013a
), and iceberg lettuce
(Tudela et al.
2013b
). Cut fruit products rapidly lose their typical fl avor, even when
stored under refrigerated conditions (Voon et al.
2007
). Temperature control is
essential to maintain fl avor and quality of fresh products (Deza-Durand and
Petersen
2011
; Tietel et al.
2012
; Jacobsson et al.
2004
). Poll (
2006
) stated that
aldehydes in lower concentrations contribute to characteristic aromas in leeks but
at higher concentrations can cause off-odors. Deza-Durand and Petersen (
2011
)
investigated aroma compounds as a function of cutting direction and concluded
that transverse cutting is a more severe method of preparation than longitudinal
cutting, based on the increase in the levels of volatiles compounds produced
through the LOX Enzymes like lipooxidase, which catalyzes peroxidation reac-
tions, cause the formation of numerous bad-smelling aldehydes and ketones
(Varoquaux and Wiley
1994
).
12.3.3
Safety
New technologies to ensure quality, security, and availability of food are emerging.
They have profound effects on the capacity to produce food with appropriate man-
agement of natural resources and environment. A number of technologies have been
developed over the past century in the areas of molecular biology, nutritional sci-
ence and food science, among others. Fields, like biotechnology, in which the appli-
cation of molecular biology to a wide range of agricultural production problems
have allowed scientists to develop crops with specifi c benefi cial traits (Gregory
et al.
2009
; Taeymans
2000
).
The food quality is a major concern today. Determining when a food is fi t for
consumption, the diffi culty to detect the dangerous levels of contaminants and/or
decrease of quality, is one of the main reasons why sensors have been developed
(Avella et al.
2011
). In minimally processed foods, it is important to know if the food
