Okra (Abelmoschus esculentus L.) pectin yield as influenced by particle size and extraction solvent

Abstract

Pectin extractable from okra (Abelmoschus esculentus L.) is known to have various food and non-food applications. The objective of this work was to investigate the effect of particle size of milled samples on okra pectin yield using two different extraction solvents. Phosphate buffer (PB) and citric acid solution (CAS) (at pH 6, temperature of 80°C and for 1 h) were used to extract pectin from 10 g of milled okra sample with varying particle sizes (0.5, 1 and 2 mm). Ethanol was added to the aqueous extract to precipitate the pectin. The crude pectin obtained was then freeze-dried and the % pectin yield was calculated. The average okra pectin yield when PB was used for extraction were 19.6±4.0%, 15.8±1.0% and 11.9±1.5% for 0.5 mm, 1 mm and 2 mm particle sizes, whereas that of the CAS counterparts were 32.7±8.1%, 25.6±0.8% and 35.6±5.5%, respectively. However, considering purity of the pectin extracts (PB > CAS), the present findings indicated that a higher pectin yield is achievable with 0.5 mm as the optimal particle size of okra pod powder using phosphate buffer as extraction solvent.