New analytical methods for the determination of ascorbic acid content in aqueous extracts of flesh, peel and seeds of pumpkin (Cucurbita maxima)

Abstract

ABSTRACT. The main objective of this research was to develop a simple, rapid, cost-effective, and environmentally friendly methods for determining ascorbic acid in flesh, peel, and seeds of pumpkin. Ascorbic acid was extracted from the different parts of the pumpkin in water. The content of ascorbic acid in three parts of the pumpkin was determined using ATR-FTIR and UV-VIS methods. The ATR-FTIR method was validated to determine ascorbic acid at 1046 cm^-1, and the results indicated a linear range of 5 to 50 g/L; R², 0.999; LOD, 1.7 g/L; LOQ, 5.2 g/L; RSD, 0.09% to 0.65%, and %recovery of 95.86%. Ascorbic acid was also determined at 265 nm by the UV-VIS method that revealed a linear range of 1 to 12 mg/L; R², 0.999; LOD, 0.25 mg/L; LOQ, 0.75 mg/L; RSD, 0.12% to 0.43%, and %recovery of 96.96%. Accordingly any of the two newly developed methods can easily be applied for quantitative determination of ascorbic acid in pumpkin flesh, peel, and seeds. Both methods yielded higher ascorbic acid content in pumpkin seeds than in pumpkin flesh and peel. Both ATR-FTIR and UV-VIS spectroscopic methods are green, low cost and rapid method. However, UV-VIS method showed higher sensitivity than the ATR-FTIR method.

KEY WORDS: Pumpkin, Cucurbita maxima, Ascorbic acid, ATR-FTIR spectroscopy, UV-VIS spectrophotometry

Bull. Chem. Soc. Ethiop. 2022, 36(2), 277-290.                                                            

DOI:https://dx.doi.org/10.4314/bcse.v36i2.3