Optimisation of microwave-assisted extraction and functional elucidation of bioactive compounds from Cola nitida pod.
INTRODUCTION
The quality characteristics and stability of phenolic by-products from Cola nitida wastes are critical factors for drug formulation and food nutraceutical applications.


OBJECTIVES
In this study, the effect of electromagnetic-based microwave-reflux extraction on the total phenolic content, antioxidant capacity, morphological characteristics, physisorption and chromatographic phenolic profiles were successfully investigated. These physicochemical analyses are often employed in the standardisation of dried herbal and food nutraceutical products.


MATERIAL AND METHODS
In this study, the electromagnetic-based extraction process was optimised using the Box-Behnken design. The oleoresin bio-products were subsequently characterised to determine the total phenolic content, morphological and microstructural degradation. These analyses were conducted to elucidate the effect of the microwave heating on the C. nitida pod powder.


RESULTS
From the predicted response, the optimal percentage yield was achieved at 26.20% under 5.39 min of irradiation time, 440 W microwave power and oven temperature of 55°C. Moreover, the rapid estimation of the phenolic content and antioxidant capacity were recorded at 124.84 ± 0.064 mg gallic acid equivalent (GAE)/g dry weight (d.w.) and 6.93 ± 0.34 μg/mL, respectively. The physicochemical characterisation results from the Fourier-transform infrared spectroscopy, field emission scanning electron microscopy and physisorption analyses showed remarkable changes in the micro-surface area (13.66%) characteristics.


CONCLUSION
The recorded optimal conditions established a basis for future scale-up of microwave extraction parameters with a potential for maximum yield. The physiochemical characterisation revealed the functional characteristics of C. nitida and their tolerance to microwave heating.
['Olalere|Olusegun Abayomi|OA|https://orcid.org/0000-0002-4382-7281', 'Gan|Chee-Yuen|CY|https://orcid.org/0000-0002-6509-1068', 'Akintomiwa|Olumide Esan|OE|', 'Adeyi|Oladayo|O|', 'Adeyi|Abiola|A|']
D000975:Antioxidants D030221:Cola D005707:Gallic Acid D008872:Microwaves D010636:Phenols
Cola nitida antioxidants microstructure microwave extraction total phenolic content (TPC)