Physicochemical, drying characteristics and rheological behaviour of foam mat-dried soursop (Annona muricata L.) powder
Soursop is also known as Annona muricata from Annonaceae family and the fruit has been described as a sour citrus flavor. Soursop have been located in tropical regions to treat various ailments such as pain, fever, skin illness, internal and external parasites, respiratory illness, bacterial infe...
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| Format: | Thesis |
| Language: | English |
| Published: |
2019
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| Online Access: | http://ethesis.upm.edu.my/id/eprint/15027/1/FSTM%202020%204%20t.pdf |
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| Summary: | Soursop is also known as Annona muricata from Annonaceae family and the fruit has
been described as a sour citrus flavor. Soursop have been located in tropical regions to
treat various ailments such as pain, fever, skin illness, internal and external parasites,
respiratory illness, bacterial infections, inflammation, hypertension, diabetes and
cancer. However, due to short shelf life of the fruit, drying process such as foam mat
drying process may be an alternate method to preserve the fruit. The foam mat drying is
a process in which the transformation of products from liquid to stable foam followed
by air drying. The foam mat drying process is suitable for drying viscous and high fiber
product at lower temperature for producing easily rehydrated juice powders. The aim of
this study is to evaluate the physicochemical properties, drying characteristics and
rheological behaviour of foam mat dried soursop powder. Foam mat drying was done
using different foaming agent (methycellulose (MC), fish gelatin (FG) and Arabic gum
(AG)) at various concentration (MC: 0.5, 10, 1.5, 2.0%; FG: 5, 10, 15, 20% and AG: 2,
4, 6, 8%). Physicochemical properties such as foam properties, bulk density, tap
density, pH, moisture content, water activity, phenolic content, color and flowability of
powder were analyzed. Foam mat dried powder which contains methylcellulose at
1.5% showed a better quality of soursop powder with total phenolic content
481.09±12.27 mg GAE/100g compared to other formulations; an equivalent of about
86.0% retention in its total phenolic content. The phenolic content for raw soursop fruit
was 560.21 mg GAE/ 100g. The drying kinetics for foam mat drying of soursop with
1.5% methylcellulose concentration foaming agent was found to exhibit only the falling
rate phase as no distinct constant rate phase was observed. Analysis on its drying rate
showed that Page model represented by MR=e-kt^N (where k= 0.0035, N = 1.04) best
described the drying kinetics of the foam mat drying of the soursop powder with an R2
= 0.97. The foam mat dried soursop powder with 0.5% methylcellulose was rehydrated
at brix 5°, 10° and 15° to determine rheological properties at 10, 25, 35, 45 and 60 °C.
The rheological modeling of rehydrated soursop foam-mat dried powder showed best
fit to Power Law model. |
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