Agriculture Reference
In-Depth Information
1727 μs applying 4 μs pulses at 188 Hz in bipolar mode).
A substantial loss of pectin methylesterase activity (
The total lycopene content of pomace were 80.26-114.35
μ g/g, depending on the juice extraction method used; the
heated (50 C) and pectinase enzyme-treated macerates pro-
duced higher amounts of total lycopene, beta-carotenes,
and total carotenoids. An added benefit of utilizing pomace
would be less solid waste thererby resulting in an environ-
mentally friendly processing venture.
The feasibility of producing dehydrated watermelon
flakes and their packing in laminate (LP) and low-density
polyethylene pouches (LDPE) was evaluated by Chawla
and Ranote (2009). The treatment containing 0.3% salt
and citric acid each, applied at 50% moisture content, and
drying at 55
50%)
was observed in all the HIPEF-treated juice samples; how-
ever, the loss of polygalacturonase activity was significantly
lower.
Microbial inactivation in watermelon juice by pulsed
electric field (PEF) treatment (100 or 250 Hz for 1250 or
2000 μ s), was reported by Mosqueda-Melgar et al. (2007).
Juice samples were inoculated with Salmonella enteritidis,
Listeria monocytogenes, and Escherichia coli to give a final
concentration of 10 7
>
10 8 CFU/ml. Among three micro-
organisms, L. monocytogenes was found to be more resis-
tant to PEF than S. enteritidis and E. coli in both juices
when treated at the same processing conditions. The use of
PEF or HIPEF for watermelon juice processing has been
reported in some other studies, too (Aguilo-Aguayo et al.,
2009; Oms-Oliu et al., 2009).
The use of UV-C and high-pressure processing (HPP) for
watermelon juice was investigated by Zhang et al. (2011).
The UV-C treatments were effective in inactivating the
pectin methylesterase in the watermelon juice. The HPP
at 600 MPa had better color retention and that at 600-900
MPa held the browning degree and dynamic viscosity of
the treated watermelon juice comparable to untreated sam-
ples. Moreover, the HPP treatment had minimal impact
on the all-trans-lycopene, total cis-lycopene, and total ly-
copene concentration in the watermelon juice compared to
the UV-C or heat treatments. Application of UV-C over 2.4
J decreased total lycopene content by 20-50%.
5 C was found optimum for getting de-
sired quality product. After 6-month storage, the dehy-
drated product packed in LP was superior, shelf stable,
and most acceptable.
±
Nutritional profile and health benefits
At first glance, watermelon does not appear to be a rich
source of many nutrients (Table 28.1). Table 28.3 shows the
composition of watermelons of different flesh colors. Vita-
mins C and A are the most outstanding; these nutrients are
needed for skin, nerve, and immune system health. In ad-
dition to vitamins C and A, watermelon contains lycopene,
beta-carotene, and citrulline (Fig. 28.3). Antioxidant tests
generally fail to yield a large value for watermelon, pos-
sibly because the total phenolic content of watermelon is
low, despite the high carotenoid content (Fig. 28.3).
Carotenoids are molecules with assorted functions in
plant cells. Some of the carotenoids, such as violaxanthin,
act as quenchers of excess photons in chloroplasts. Oth-
ers, such as lycopene, appear to provide attractive color to
fruits to entice herbivores and eventual perpetuation. Plants
provide much of the dietary carotenoids for animals and
humans. The phenolic components of watermelon have not
been studied in much detail. Reported modest amounts of
total phenolic compounds in flesh and rind of watermelon,
about 10% of that found in small fruit such as blueberry or
blackberry. Perkins-Veazie et al. (2002) reported that flesh,
rind, and seeds were similar in total phenolic content on a
fresh weight basis.
Watermelon is one of the best natural sources of lycopene
in fresh fruits and vegetables compared to tomato, red
grapefruit and guava (Perkins-Veazie, 2010). A study con-
ducted by Harvard researchers (Giovannucci et al., 2002)
found that men who ate lycopene-rich diets of tomatoes
and tomato products had much lower risk of developing
prostate cancer. Lycopene also appeared to slow prostate
tumor growth in clinical trials (Bowen et al., 2002). Re-
search has shown that lycopene in tomatoes can beabsorbed
By-products
The fresh-cut industry produces thousands of tons of waste
in nonedible portions that present an environmental and
management problem; these by-products could be reused,
in particular, to obtain bioactive compounds (Tarazona-
Diaz et al., 2011). The waste produced can range from
31.27% to 40.61%, depending on the watermelon cultivar
and rind thickness. The rind had a moderate total phenolic
content, higher than that of the flesh (458 vs. 389 mg/kg
chlorogenic acid equiv.), and a much higher content of the
citrulline (3.34 vs. 2.33 g/kg), which has potential bioac-
tive properties. More research is required on the efficient
extraction of citrulline from watermelon rind and its suit-
ability as an additive to drinks, juices, or other products
to produce new functional food products with valid health
claims (Tarazona-Diaz et al., 2011).
The pomace (residue left after juice extraction) has a po-
tential to be utilized as a value-added product. The pomace
was shown to have significant amounts of total lycopene,
beta-carotenes, and total carotenoids (Siddiq et al., 2005).
Search WWH ::




Custom Search