Effect of Boiling and Fermentation on Physicochemical Properties, Fatty Acid and Micronutrients Composition of Hibiscus sabdariffa (Roselle) Seeds

Aim: To ascertain the effects of boiling and fermentation on the physicochemical properties, fatty acid, mineral and vitamin composition of Hibiscus sabdariffa (HS) seeds.

Study Design: Completely randomized design

Place and Duration of Study: Rivers and Anambra states, Nigeria, between February and September, 2018.

Methodology: Two portions of 200 grams of HS seeds each were subjected to boiling and fermentation. The three samples were designated HSR, HSB and HSF for raw, boiled and fermented HS seeds respectively. Standard methods were used in determining the physicochemical properties and micronutrient composition, while fatty acid constituents were identified using a gas chromatography.

Results: The acid, free fatty acid, peroxidase values and specific gravity were significantly increased (p<0.05), while iodine value was significantly reduced (p<0.05) after boiling and fermentation. Saponification value showed a mixed trend, while refractive index was not significantly (p>0.05) altered. Lauric (5.51–33.79%), palmitic (27.23–30.87%) and myristic (12.69–35.00%) acids were the predominant saturated fatty acids in HSR, HSB and HSF samples respectively. Oleic, linoleic, alpha-linolenic and arachidonic acids were the unsaturated fatty acids present in the samples. Boiling increased oleic acid level, while fermentation caused a drastic reduction (>90%) in its amount. Linoleic acid level improved up to 43% after fermentation. Magnesium, iron and sodium amounts significantly (p<0.05) reduced after boiling and fermentation, while zinc, calcium and molybdenum levels were significantly (p<0.05) improved after boiling. Na/K ratios for all the samples were greater than 0.60, while Ca/Mg values ranged between 0.82 and 3.46, below the recommended value (1.0). Vitamins B1, B3, B12 and D were significantly reduced (p<0.05) after boiling and fermentation, while fermentation significantly increased (p<0.05) vitamins B2, A, E and K levels.

Conclusion: HS seeds were shown to possess good physicochemical properties that can enhance its utility in the industry. Boiling and fermentation maximized the usefulness of HS seeds as quality nutritional plant.