Results (
Thai) 2:
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3. Results and Discussion
3.1. Effect of Chitosan Coating on Weight Loss
The changes in weight loss of chitosan coated bananas during one week storage were depicted in Fig. 1 and Fig.
2. As the banana fruits were easily perishable, the uncoated banana showed to be overripe at day four, thus in this
experiment, the storage time was limited to seven days. For the entire duration of the storage the percentage of
weight loss in the control sample (uncoated) was higher than in coated samples (p<0.05). The weight loss of control
sample was about 22%, whereas the coated banana showed a reduction of weight loss of about 30% during the same
period of storage. This confirmed the previous work demonstrating weight loss suppression to about 30% during the
same period of storage of chitosan coated banana
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. The primary mechanism of weight loss from fresh fruits and
vegetables is by vapour-phase diffusion driven by a gradient of water vapour pressure between inside and outside
the fruit leading to an enhanced transpiration process.
The varying DD of chitosan affected the weight loss profiles (Fig. 1 vs. Fig. 2). The weight loss of banana coated
with chitosan of 70% DD was higher compared to that of banana coated with 80% DD chitosan. The higher the DD
value of chitosan, the higher the purity the chitosan. This helped improve the homogeneity of chitosan solution, thus
improving the quality of the resulting edible coating. Within the same specified DD of chitosan, the increase of
chitosan concentration in the solution caused the decrease in weight loss (Fig. 1 and Fig. 2). The increased of
chitosan concentration in the edible coating could increase the barrier to the moisture loss. This seemed plausible
since the increase in chitosan concentration would increase the firmness
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. The addition of TEA emulsifier TEA to
the chitosan coating solution did not significantly affect the weight loss reduction. TEA was expected to improve the
wettability of chitosan and increase the chitosan emulsion stability. This might be due to the incompatibility of TEA
emulsifier with chitosan. Other additives were probably needed when combined with TEA emulsifier to improve the
quality of chitosan coating.
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