Physicochemical and antioxidant properties of pomelo residues using different drying methods and kinetic models of naringin degradation
Tambun Pomelo (PO52) also known as Limau Bali in Malaysia is a native citrus fruit recognized as the largest citrus fruit in the world. Pomelo is commonly eaten fresh while the pomelo residues (~50%) consist of flavedo, albedo, lamella and pulp waste discarded without acknowledging its potential....
Saved in:
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | English |
| Published: |
2020
|
| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/89920/1/FK%202020%2074%20ir.pdf |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | Tambun Pomelo (PO52) also known as Limau Bali in Malaysia is a native citrus
fruit recognized as the largest citrus fruit in the world. Pomelo is commonly eaten
fresh while the pomelo residues (~50%) consist of flavedo, albedo, lamella and
pulp waste discarded without acknowledging its potential. A significant amount
(p < 0.05) of antioxidant compounds was found in the pomelo residues compared
to the pomelo flesh. One of the major antioxidant compounds namely naringin in
pomelo peel was stated as a health-promoting compound with the ability to lower
the risk of heart disease. However, high levels of moisture from fresh pomelo
residues cause it to deteriorate over time, because of the microorganism
reactions. Thus, the drying process was recommended as a method of
preservation. Conventional hot air oven drying (CD) is known using hot air as a
heat source for drying a product while the mechanism of vacuum oven drying
(VD) utilized the removal of water molecules by evaporation due to the reduced
pressure. However, optimum drying methods or conditions have yet to be
investigated. Furthermore, the determination of drying kinetics of conventional
drying (CD) and vacuum drying (VD) which, explain the drying behavior of
pomelo residues at different drying temperatures has not yet been established.
Information on the degradation of the kinetic constant of naringin and its
antioxidant capacities in pomelo residue during storage is also limited.
Therefore, the overall aims of this research were to investigate the impact of
different drying methods (CD and VD) on the quality of pomelo residues. The
selection of optimum drying parameters was based on the capability to retain
high total phenolic content (TPC) and contribute to antioxidant capacity (DPPH
scavenging activity), where high desirability index (D ≥ 0.80) were obtained from
statistical analysis. Furthermore, kinetic modeling was analyzed for both drying
methods and degradation of naringin in dried pomelo residues during storage
were also identified. Selection of best drying models was referred to the highest value of determination of coefficient (R2) and the lowest value of standard error
of estimates (SEE) between drying models. The effects of storage time (12th
week at 8̂ °C) for both drying methods applied were also compared and the
fitness of kinetic degradation of naringin and antioxidant capacities to zero, first
and second order was evaluated. The results showed that both drying methods
(CD and VD) at different drying temperature significantly affected (p < 0.05) the
quality of the pomelo residues. Pomelo albedo was found to contain the highest
total phenolic content when compared to other pomelo residues. The current
findings also showed that VD at 90 °C (VD90) was indicated as the best drying
process for pomelo albedo (D ≥ 0.80). The diffusion approach model showed the
best fit for CD whereas the two-term exponential model showed the best fit for
VD method of pomelo albedo at 50 - 90 °C of drying temperatures. The effective
moisture diffusivity (Deff) was shown to decrease linearly over the stated
temperature range - from 5.00 x 10-7 to 6.98 x 10-7 m2/s for CD whereas Deff for
VD was shown to increase -within the range of 9.86 x 10-7 - 1.30 x 10-6 m2/s. The
absence of oxygen was shown to be correlated with the rate of moisture that
evaporated from samples to the environment under vacuum condition in VD
drying process (p < 0.05). During storage, vacuum dried crude extract (VC)
attributed to a higher concentration of naringin when compared to freeze-dried
crude extract (FC) at the initial week (0th week)(p < 0.05), however, as storage
time increases, the rate of naringin degradation kinetic were found to be lower in
FC (p < 0.05), indicating higher stability of FC than VC. Naringin degradation can
be described in zero, first and second order with the highest value (R2 > 0.89)
and lowest value of SEE (value less than 0.05). The present study provides
insightful information for the post-harvest research, food, nutraceutical, and
pharmaceutical industry as a guideline to produce a new alternative source of
higher bioactive compounds from pomelo’s albedo. |
|---|