Chemical composition of seeds from major passion fruit species: Passiflora edulis Sim,Passiflora eduli F flavicarpa and Passiflora maliformis grown in Uganda

Abstract

Passion fruit (Passiflora spp.) seeds are usually discarded after extraction of the juice. The seeds, however, represent an important source of edible oil with a high proportion of polyunsaturated fatty acids and other vital components required for good health. The study determined the proximate composition, mineral content and fatty acid profile of the seeds of major passion fruit species (Passiflora edulis Sims, Passiflora edulis F.jlavicarpa and Passiflora maliformis L) grown in Uganda. In addition, stability tests including total carotenoids of oil extracted from these seeds were determined. Passion fruit seeds presented substantial amounts of oil, crude fibre and carbohydrates in the respective ranges of24.70±0.29 to 37.24±0.09%, 31.56±0.43 to 36.28±0.50% and 16.19±1.71 to 22.53±0.03% with significant differences at p~0.05. Crude ash content ranged from 1.36±0.10 to 2.32±0.01% with significant difference at p~0.05. The seeds had substantial amounts of proteins which ranged between 10.68±0.96 and 11.72±0.06% with no significant difference at p~0.05. Mineral composition analysed included Potassium (K), Sodium (Na), Calcium (Ca), Zinc (Zn), Copper (Cu), Iron (Fe), Selenium (Se) and Manganese (Mn) using AAS. The dominant mineral element was Potassium, highest in Passiflora ma/iformis L at 9.52±0.00 mg/l OOg and lowest at 4. 77±0.00mg/1 OOg in Passiflora edulis Sims followed by Fe, Zn, Ca, Cu, Se, Mn, then Na in their respective ranges of 2.32±0.008 to 5.98±0.002 mg/lOOg, 1.19±0.007 to 6.71±0.008 mg/lOOg, 1.45±0.035 to 2.01±0.033 mg/ lOOg, 1.34±0.006 to 1.94±0.001 mg/lOOg, 0.20±0.011 to 2.09±0.013 mg/lOOg, 0.77±0.008 to 1.82±0.001 mg/lOOg and 0.15±0.00 to 0.19±0.00 mg/OOg with significant differences at p~0.05. Passion fruit seed oil contained 14 detectable and quantifiable fatty acids including 4 major essential ones (linoleic acid, oleic acid, palmitic acid and stearic acid). The amount of linoleic acid and oleic acid were in the ranges of 67.57±0.85 to 72.18±0.86% and 14.59±0.17 to 16.41±0.21% of fatty acids, respectively with significant differences at p~0.05. Palmitic acid ranged between 8.68±0.1 1 and1 1.18±0.14%. Levels of Stearic acid were the lowest in the oil in the range of 2. 78±0.03 and 3.16±0.04% with significant differences at p~0.05. The unsaturated fatty acid content in oil was found to be high ranging from 85.68±0.98 to 87.60±0.15% with significant differences at p~0.05. Iodine values ranged from 125.25±0.04 to 135.35±0.02 g/lOOg of oil while saponification values ranged from 174.98±1.45 to 191.74± 1.32 mgKOH/g of oil with significant differences at p~0.05. The peroxide value was 0.10±0.00 meqOilkg in all species with no significant difference at p~0.05 . These results were within the recommended ranges by WHO and Codex standards for edible oils. Total carotenoids expressed as mg P-carotenoid/1 OOg of oil were significantly higher (p<0.05) m Passiflora edulis F.jlavicarpa with value of21.41±0.4 mg P-carotenoid/lOOg. In general, passion fruit seed oil contains substantial amounts of unsaturated fatty acids and is stable to peroxidation and can therefore be utilized in the human diet for health benefits .