Optimization of drying techniques for extraction of bioactive compounds from guava (Psidium guajava L.) leaves.
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Date
2021
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Punjab Agricultural University, Ludhiana
Abstract
Guava is known to have high nutritive value. Several health benefits of guava leaves have
also been reported. However, the information on drying, modelling parameters and effect of
drying on bioactive compounds is limited. The leaves of guava varieties Shweta and Purple
Guava were dried using shade drying, tray drying (50°C, 60°C and 70°C) and microwave
drying (360 W, 540 W and 720 W) approaches. To explain the drying data 19 models were
evaluated. The drying data was best explained by Page model and Verma model in shade
drying; Midilli and Kuck model, Jena and Das model at 70˚C tray drying; Midilli and Kuck
and Logarthmic model for 360 W microwave drying in Purple Guava and Shweta,
respectively. In both the guava varieties L*, a*, b* values were higher in fresh leaves in
comparison to shade, tray drying and microwave drying methods. In Purple Guava, the
rehydration capacity was highest (1.89) at 500C in tray drying, while in Shweta, it was highest
(1.75) at 720 W in microwave drying. The total phenol content in fresh Purple Guava leaves
was highest i.e 580.18 mg GAE/ mg dry weight among all drying conditions, while in Shweta
the highest phenol content i.e 646.81 GAE/ mg dry weight was attained by 600 tray drying. In
case of Purple Guava leaves powder, the highest (208.62 mg QE/ mg dry weight) flavonoid
content was noted for 500C tray drying. The total flavonoid content decreased during the
storage period irrespective of the guava variety.
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Citation
Ishwinder Kaur (2021). Optimization of drying techniques for extraction of bioactive compounds from guava (Psidium guajava L.) leaves. (Unpublished M.Tech. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.