Physicochemical and microbiological characterization of linolenic acid-rich oils from seeds of two tropical plants: <i>Corchorus olitorius</i> L. and <i>Hibiscus sabdariffa</i> L.

Abstract

This work was carried out to determine the potential applications of Corchorus olitorius and Hibiscus sabdariffa oil seeds by investigating their physicochemical and microbiological characteristics. Physicochemical parameters of the extracted oils were respectively as follow: refractive index (1.46 and 1.45), acid value (3.74 ± 1.62 and 2.80 mg KOH/g), peroxide value (6.67 ± 0.58 and 5.33 ± 0.60 meq O₂/kg), iodine value (132.54 ± 1.22 and 118.57 ± 1.22 g I₂/100 g), saponification value (183.63 ± 3.24 and 189.23 ± 1.62 mg KOH/g), unsaponifiable matter (0.88 ± 0.04 and 0.85 ± 0.05 %), vitamin A (0,45 ± 0.01 and 0.60 ± 0.01 mg/g), cholesterol (0.00 mg/g) for C. olitorius and H. sabdariffa respectively . Absorbances of the two oils decreased abruptly in the range of UV-B and UV-A wavelengths. C. olitorius and H. sabdariffa seeds showed relatively high content of linolenic acid (about 29 and 37% of total fatty acids) with extremely low n-6/n-3 ratio (0.26 and 0.46). Microbiological analysis revealed that the crude extracted oilseeds were pathogenic bacteria free and the lipolytic bacteria counted belonged to Micrococcus genus. All these interesting characteristics should arouse attention for the usage of these oilseeds in food, pharmaceutical and cosmetic industries.

Key words: Corchorus olitorius, Hibiscus sabdariffa, seed oils characterization, linolenic acid, lipolytic bacteria.