Microwave drying characteristics of Mas Cotek (Ficus deltoidea) leaves and its effects on colour and antioxidant properties
Ficus deltoidea or locally known as Mas Cotek in Malaysia is one of the 10 prioritized herbs shortlisted by the government of Malaysia in its Economic Transformation Programme (ETP). The herb is rich in chemical constituents which are known to have diverse therapeutic potentials such as reducing le...
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| Format: | Thesis |
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| Language: | English |
| Subjects: | |
| Online Access: | http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/77996/1/Page%201-24.pdf http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/77996/2/Full%20text.pdf http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/77996/4/Hafizah.pdf |
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| Summary: | Ficus deltoidea or locally known as Mas Cotek in Malaysia is one of the 10 prioritized herbs shortlisted by the government of Malaysia in its Economic Transformation Programme (ETP). The herb is rich in chemical constituents which are known to have
diverse therapeutic potentials such as reducing level of sugar in blood, decreasing blood
pressure, contracting the vagina after delivery, delaying menopause and reducing the
risk of cancer. Ficus deltoidea is commonly consumed, stored and further processed in
its dried form. High quality dried Ficus deltoidea leaves are therefore sought after by
the end-users and drying is therefore the most effective method to remove moisture to
preserve and extent the shelf-life of the herb. In this study, the thin layer microwave
drying characteristics of Ficus deltoidea leaves were investigated and the corresponding
quality of the dehydrated leaves such as the colour, total phenolic content and
antioxidant properties, were evaluated with respect to the fresh leaves. Three microwave
power levels (300, 600 and 800 W) and three ventilation rates (0.00, 0.013 and 0.025
m3/s) were the combination of drying parameters used to examine the drying
characteristics and quality changes of dried Ficus deltoidea. A modified domestic
microwave heater was used in the study. Microwave power levels were found to
significantly (p < 0.05) affect the drying rate and the quality of the dehydrated Ficus
deltoidea leaves. The drying rate increased as the microwave power level increased. The
colour quality, total phenolic content and antioxidant properties were higher at the
microwave power level of 600 and 800 W as compared to 300 W (p < 0.05) irrespective
of ventilation rate. On the other hand, the effects of the ventilation rates on the drying
rate and quality of dehydrated Ficus deltoidea leaves were found to be insignificant (p >
0.05) at all drying treatments. The thin layer drying characteristics of Ficus deltoidea
leaves were evaluated and it was found that the drying took place in the falling rate
period only. Five established thin layer drying models were used to compare the
experimental and predicted drying kinetics by using statistical software analysis. Based
on the fitting criteria, Midili et al. model appeared to best fit the thin layer microwave
drying data. Finally, the assessment of sorption isotherm is crucial in order to ensure
stability of the dehydrated Ficus deltoidea leaves during storage. Static gravimetric
method was used to determine the moisture sorption isotherm (adsorption and
desorption) of Ficus deltoidea leaves at two temperatures (5 and 30 °C) and five relative
humidities ranged from 11.26 to 75.65 %. Five established isotherm models were used
to compare the experimental and predicted sorption isotherms by using statistical
software analysis. Based on the fitting criteria, Peleg model appeared to best fit the
sorption isotherms data. The characteristic of the shape of the sorption curves were
found to fall under the Type II category. As a conclusion, drying treatment of 600 W
and 0.013 m3/s is suggested as drying conditions of Ficus deltoidea leaves for optimum
dried leaves quality retention. |
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