Abstract:
Myristica fragrans Houtt. produces two economically important spices, but
its fleshy outer pericarp is often discarded, leading to environmental pollution,
despite its potential as a rich source of bioactive compounds. These compounds
contribute to the antioxidant, antimicrobial, and many therapeutic properties.
Diversifying pericarp by extracting its compounds as essential oil and oleoresin
could enhance its economic value. Conventional extraction methods result in lower
extraction efficiency and quality. To circumvent these issues, eco-innovative
technologies such as Microwave Assisted Hydro-distillation (MAHD) for volatile
essential oil and Ultrasound Assisted Extraction (UAE) for non-volatile oleoresin
which offers sustainable results were exploited in this study to efficiently extract
the phytochemicals in pericarp and to optimise the process parameters thus
increasing its utilisation potential. For MAHD process, Box-Behnken design was
framed with the selected process variables of solid to water ratio (1:4 to 1:8 g/ml),
exposure time (1 to 2 h) and microwave power (320 to 640 W) and the responses
were essential oil yield, specific gravity, and energy consumption. For extracting
the oleoresin from the MAHD extracted samples UAE was employed, for which a
Central Composite experimental design was framed. The process variables such as
solid to solvent ratio (1:4 to 1:6 g/ml), sonication time (10 to 30 min) and types of
solvent (ethanol and ethyl acetate) were selected for optimising the response
variables of oleoresin yield, total phenolic content (TPC) and total flavonoid
content (TFC). The optimised conditions for essential oil yield were determined as
1:8 g/ml, 1.5 h with 320 W power for obtaining a maximum yield of 0.4% with
minimum energy consumption of 0.6 kWh and a specific gravity of 0.917.
Maximum oleoresin yield, TPC and TFC of 5.524%, 66.449 mg GAE/g and 4.284
mg QE/g respectively were observed for the process variables of 1:5.42 g/ml, 30
min in ethanol as the optimized condition for oleoresin. The optimised extracts
exhibited improved physicochemical and microstructural properties compared to
conventional extraction process. These findings suggests that the extraction of
bioactive compounds from nutmeg pericarp employing MAHD and UAE holds a
significant economic potential with high extraction efficiency and quality.
