Ultrasound Assisted Extraction: A Review
on the Effects of Microenvironment
Variables on Polyphenols
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PRESENTATION OUTLINE
• INTRODUCTION
• AIM OF STUDY
• MICROENVIRONMENT PARAMETER EFFECTS
Temperature
Power
Frequency
Solvent / Material ratio
• FURTHER RESEARCH
• THE END
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INTRODUCTION
• A plethora of industrial applications employ high intensity
ultrasonication, known to be a relatively simple technique to use
in terms of methodology and instrumentation (Luo et al, 2019).
• Recently, ultrasonication has been extensively used in the
extraction of polyphenols and other functional phytochemicals
from different sources (Maran et al., 2017).
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AIM OF REVIEW
• This review seeks to gather literature on the subject of the effects
of ultrasonication parameters on the efficiency of polyphenol
extraction.
• The gap to be filled by this review is the lack of comprehensive
assessment of the subject matter regarding ultrasonic
parameters during extraction.
• Parameters to be considered in this review are temperature,
time, frequency, power, and solvent/material ratio.
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1. Temperature effects
• The yield of polyphenols increased when temperature was
increased from 30 to 50 oC, attributed to increased rates of
cavitation effect (Maran et al., 2017; Toma et al., 2018).
• This was confirmed by others who observed similar increments in
extraction yield as a result of increased extraction temperatures
(Altemimi et al., 2016; Li et al., 2016; D'Alessandro et al., 2013).
We can talk about other effects such as viscosity, density, and
inherent properties of material as related to temperature.
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1. Temperature effects
• Temperature sensitivity of polyphenols was demonstrated about
three decades ago by Havlikova & Mikova (1985).
• They showed that long extraction times and high temperature
increase the rate of phenol oxidation and decrease total phenol yield
in extracts.
• Temperatures above 70 °C especially have been shown to cause rapid
polyphenol degradation (Wizi et al., 2018; Mojzer et al., 2017;
Altemimi et al., 2016).
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2. Power effects
• As ultrasonic power is increased, the number of vacuum
bubbles also increases, hence greater cavitation effects,
hence higher yields.
• Yield increases in polyphenol contents of Nephelium lappaceum fruit
peel extract (Maran et al., 2017).
• Polyphenols from grape seeds-increase (50 to 150W) power resulted
in significant increases in polyphenols (Da Porto et al., 2018).
• Increasing power from 25 to 125 W increased polyphenol content by
16.63 % and polyphenol purity by 7.51 % (Van Man et al., 2017).
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3. Frequency effects
• Ultrasound frequency range (20 kHz – 100 kHz) has also been
reported to influence extraction yield of polyphenols (Guo et al.,
2017; Zhu et al., 2016).
• Low frequencies (20 kHz ~ 40 kHz)- invasive, effective (Carciochi et
al., 2015; Paini et al., 2015), unlike high frequencies known to be
noninvasive, less destructive, less efficient (Sharayei et al., 2019;
Juliano et al., 2017).
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4. Solvent / Material ratio
• The results showed that increasing the ratio from 15:1 to
40:1, increased polyphenol content by 33% (Xu et al., 2017).
Further decreases had no significant influence.
• This has bearing on density, viscosity, power attenuation,
propagation speed, etc (Dzah et al., 2019; Luo et al., 2019).
• The mechanism involved has not yet been fully studied.
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FURTHER RESEARCH
• Further work is needed to understand the mechanisms
underlying the effects impacted by these microenvironment
parameters so as to better manipulate them with higher
accuracy for efficiency in UAE.
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END
• THANKS
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