IJERD – International Journal of Environmental and Rural Development (2014) 5-1

Research article
erd

Effect of Calcium Ascorbate Treatments on Juice Leakageof Fresh Cut Watermelon (Citrullus lanatus)
INTIRA LICHANPORN*
Faculty of Agricultural Technology, Rajamangala University of Technology Thanyaburi,
Phathum Thani, Thailand
Email: lintira@yahoo.com

NUNCHANOK NANTHACHAI
Faculty of Agricultural Technology, Rajamangala University of Technology Thanyaburi,
Phathum Thani, Thailand

PALIDA TANGANURAT
Faculty of Agricultural Technology, Rajamangala University of Technology Thanyaburi,
Phathum Thani, Thailand

UNCHALIN SINGKHUM
Faculty of Agricultural Technology, Rajamangala University of Technology Thanyaburi,
Phathum Thani, Thailand
Received 30 December 2013

Accepted 20 March 2014(*Corresponding Author)

Abstract Before cutting, melons were washed with sodium hypochlorite (100 ml/l activeingredient) and water rinsed. Melons were cut longitudinally into four parts, cut into
triangles 2 cm thick. A piece of watermelon was chosen from the center. Watermelon slice
were dipped in calcium ascorbate (CaAsc; 0, 1, 5, 10 and 20%, w/w) for 2 minutes anddrained. Fresh-cut watermelon was arranged in foam trays with 4 pieces per tray, coveredwith plastic polyethylene (LLDPE) film and stored at 10C with relative humidity of 9095%. At each storage interval, melon slices were evaluated for weight loss, changes incolor (L*, a* and b*), total soluble solids and juice leakage. Dipping fresh-cut watermelon
slices in 5, 10 and 20% CaAsc increased the weight loss up to 9.73 12.83 and 13.65%
respectively, compared with watermelon dipped in 0 and 1% CaAsc, which onlyexperienced 4.88 and 4.10% of weight loss after storage for 8 days. Percent juice leakagein fresh-cut watermelon dipped in 1 and 5% CaAsc was less than the other treatments. The
effect of calcium ascorbate on the changes of color and total soluble solids were notsignificantly different. However, fresh-cut melon dipped in 1% CaAsc tended to reducethe changes of weight loss and juice leakage better than other treatments.
Keywords watermelon, calcium ascorbate, juice leakage

INTRODUCTION
Fresh-cut watermelon is sold as quarters and halves with rind, or as cubes without rind. Quality
degradation of fresh-cut watermelon has been described as loss of texture, color, and sweetness(Rushing et al., 2001). Juice leakage in fresh cut watermelon can increase as a result of cube size,storage temperature, or modified atmosphere. Fonseca et al. (1999) found that cubes of length <1.9cm had more juice leakage due to cut surface injury, while cubes >4 cm in length had more juice
loss from compression. Water-soaked appearance of watermelon is an ethylene-induced
phenomenon characterized by softening and maceration of the endocarp and the placenta tissues(Risse and Hatton, 1982; Elkashif and Huber, 1988a, 1988b). Water-soaked tissue is characterized
by enhanced solute leakage, degradation of pectic polymers, cell separation, and loss of cell wallrigidity (Elkashif and Huber, 1988a, 1988b). The induction of water-soaking and the related
increases in softening and cell leakage by ethylene parallel the role of this growth regulator inⒸ ISERD

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IJERD – International Journal of Environmental and Rural Development (2014) 5-1

ripening; Calcium plays a pivotal role in cell signals related to AOS (Bhattacharjee, 2005). Calcium
dips have been implicated in enhancing membrane stability, slowing senescence, and improving theretention of membrane integrity (Picchioni et al., 1996). The softening rate is related to Ca levels in
the fruit tissue (Fallahi et al., 1997). For this reason, Ca dips have been used as firming agents toextend post harvest life of several products. Firmness and resistance to softening, resulting fromaddition of Ca, have been attributed to the stabilization of membrane systems and formation of Ca
pectate, which increases rigidity of the middle lamella and cell walls, leading to increased
resistance to polygalacturonase (PG) activity and to improved turgor pressure (Mignani et al.,1995). Ca ions form intermolecular bridges by interaction with free car- boxyl groups of pectic acidpolymers to form insoluble salts with ionic linkages between pectin molecules (McFeeters andFleming, 1991). Ca application often results in reduced incidence of physiological disorders anddecay (Garcํa et al., 1996). Therefore, in this study we determine the effects of calcium ascorbate(CaAsc) dips, subsequent storage time and a maintained modified atmosphere condition on juice
leakage of fresh-cut watermelon.
OBJECTIVE
The objective of this study was to determine effects of calcium ascorbate treatments on juice leakage
of fresh cut watermelon (Citrullus lanatus).
METHODOLOGY
Watermelon (Citrullus lanatus) fruit was purchased from a commercial market in Phathumtani
province in Thailand. Before cutting, melons were washed with sodium hypochlorite (100 ml-*l−1
active ingredient) and water rinse. Melons were cut longitudinally into four parts, and then cut into
triangles 2 cm thick. A piece of watermelon was chosen from the center. Watermelon slices weredipped in calcium ascorbate (CaAsc; 0, 1, 5, 10 and 20%, w/w) for 2 minutes then removed. Freshcut watermelon was arranged in foam trays with 4 pieces per tray and covered with plastic
polyethylene (LLDPE) film and stored at 10C with relative humidity of 90-95%. At each storage
interval, melon slices were evaluated for changes in color (L*, a* and b*), total soluble solids, juice
leakage and weight loss.
Watermelons from each treatment were weighed individually before and during the storage
period, and the percentage of weight loss was calculated using the equation by:
Totalweight loss(%) = [initial weight of fruit - initial weight of fruit] × 100
initial weight of fruit(1)

Colorimeter measurements were made at days 0, 2, 4, 6 and 8 on eight random cubes percontainer replicate using a chromameter with an aperture of 8mm diameter, D65 illuminant, andCIE L*, a*, b* color scale, (Minolta CR200, Ramsey, NJ).
Percent juice leakage was determined by weight after each storage interval, using the formula
Percent juice leakage(%) = [(container + Juice wt.) - container wt.
] × 100 % (2)(container +fruit wt.) - container wt.

Total soluble solid (TSS) from fruit juice was measured by a digital refractometer (PAL-1,Atago, Tokyo, Japan). The units of TSS were expressed as a percentage.
RESULTS AND DISCUSSION
Watermelon treatment dipped in 0, 1, 5, 10 and 20% CaAsc were not significantly different inregards to brightness (L*) throughout storage (Fig. 1A). The lack of predictive power usingreflectance tristimulus colorimetry to determine lycopene content in watermelon flesh has beenpreviously reported and is thought to be due to the lack of instrument sensitivity (Perkins-Veazie etⒸ ISERD172

IJERD – International Journal of Environmental and Rural Development (2014) 5-1al., 2001). While, a* value is the redness, which was found to have decreased slightly duringstorage (Fig. 1B). The b* values, the blueness was reduced slightly as a result of the oxidation
process and deterioration (Perkins-Veazie and Collins, 2004) (Fig. 1C). Fresh cut watermelon
dipped in 0, 1, 5, 10 and 20% CaAsc showed a slight increase in the total soluble solid throughout
storage (Fig. 1D). The total soluble solids in the range from 7.33 to 10.33%, is consistent with theresearch of Perkins-Veazie and Collins (2004). They found that the total soluble solids ofwatermelons, cv Summer Flavor 800 and Sugar Shack, that were cut into 5 cm pieces were in therange of 11.4 to 12.2%. The juice leakage of fresh cut water melon increased rapidly in the first 2days (Fig. 1E), this may be a consequence of the increase of tissue decomposition.
4230AB2841

a*

L*264024392238200246
Days after storage

8100

16Total soluble solid (%)

C14b*46Days after storage

81016151312111014D1210864200246
Days after storage

8100246
Days after storage

8102010E

8Weight loss (%)

Juice leakage (%)

264F

161284

2000246
Days after storage

80102468

Days after storage

L* (A), a* (B), b* (C), Total soluble solid (D), Juice leakage (E), Weight loss (F)Fig. 1 Effects of calcium ascorbate on quality of fresh cut watermelonsⒸ ISERD17310IJERD – International Journal of Environmental and Rural Development (2014) 5-1

Juice leakage is not a desirable characteristic in fresh cut watermelons, as the juice gives thetissue a water-soaked appearance, and provides an excellent medium for microbial growth (Cartaxoand Sargent, 1997). Juice leakage in fresh cut watermelon can increase as a result of cube size,storage temperature, or modified atmosphere. Fonseca et al. (1999) found that cubes of length <1.9cm had more juice leakage due to cut surface injury, while cubes >4 cm in length had more juice
loss from compression. Sargent (1998) found that fresh cut watermelon cubes held at 1C had 50%
more leakage than those held at 3 C, and concluded that this difference was due to chilling injury.
Cartaxo and Sargent (1997) reported that juice leakage increased from 10 to 20% in fresh-cut
watermelon stored 5 days at 3 C under actively maintained atmospheres of O2, 3 kPa, plus CO2, 5–20 kPa, compared to that stored in an ambient environment. The percent leakage found in our study
was similar to that reported by Fonseca et al. (1999) for non-compartmentalized Sangria
watermelon cubes. Although the 5% CaAsc treatment slightly decreased the percent juice leakage
in fresh -cut watermelon, fresh-cut watermelon dipped in 1% CaAsc tended to reduce the changes
of weight loss and juice leakage better than other treatments. The weight loss of fresh cut
watermelon dipped in calcium ascorbate concentration of 1% was not significantly different fromthe control (Fig.1F). However, fresh cut watermelon dipped in 1 and 5% CaAsc had more weightloss than controls during the first 2 days of storage. The properties of calcium increased thefirmness. Dipping in calcium ascorbate will reduce the loss of firmness in apples stored byapproximately 13 % after 3 weeks at 10 ºC (Fan et al, 2005).
CONCLUSION
Calcium ascorbate affected the changes of color (L* a* b*) and total soluble solids in fresh cut
watermelon. Dipping with 1% calcium ascorbate decreased the weight loss and juice leakage. Adipping treatment in 5, 10 and 20% calcium ascorbate increased the weight loss and juice leakage
more than the control of fresh cut watermelon.
ACKNOWLEDGEMENTS
This work was supported by Faculty of Agricultural Technology, Rajamangala University ofTechnology Thanyaburi (RMUTT).
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