Exploring the potentials of local triglyceride oil plants as source materials for biodiesel production

Among the shrubs, three plants namely 'tangan-tangan' (Ricinus communis L.) known for the commercial castor oil, 'tuba-tuba', and 'malunggay' were more or less already established oil sources. However, except for 'Kamoteng Kahoy' (Manihot esculenta), the other shrubs, 'balatong aso' (Cassia occidentalis L.), 'caballero' (Caesalpinia pulcherrima), 'kulot-kulotan' (Triumfetta bartramia L.), 'phyllan' (Phyllanthus acidus), 'tungaw' (Tabermaemontara pamdacaqui) and 'tubang-morado' (Jatropha gossipifolia) were not that popular and were even considered undersirable plants in the field. Majority of the shrubs except for balatong aso (C. occidentalis L.) and caballero (C. pulcherrima) had oil contents ranging from 25% to 50%, which was lower compared to that of coconut (64%). On the other hand, all oils had average molecular weights close to 1,000 compared to coconut oil's triglyceride molecules, which had an average of only about 668. In terms of color, the oils exhibited a range of color from yellow to red and brown. Usually, darker colors were associated with higher degree of unsaturation. As for the trees, half of them had relatively low seed oil content of about 15% or less while the other half were quite promising with approximately 30-70% oil content. The trees 'bitaog' (Calophyllum inophyllum), Manila elemi/'Piling-liitan' (Canarium luzonicum) and mahogany (Swietenia mahogany L.) had almost the same oil richness as that of coconut. On the average, the oils from these trees had molecular sizes that were bigger but closer to that of coconut oil. On the other hand, the colors of the oil were comparable with those of the shrub oils but mahogany, bitaog, 'talisay' (Terminalia catappa), and 'bangulo' (Litsea garciae Vidal) had lighter colors. The fruit trees/vines had low oil content with the highest at only about 55% for pomelo (Citrus maxima). This was followed by guyabano (Annona muricata L.), and papaya (Carica papaya) with about 35% and 30%, respectively then passion fruit (Passiflora edulis), rambutan (Nephelium lappaceum L.), and 'atis' (Annona squamosa) with close to 25%. The rest 'abokado' (Persea gratissima), 'tisa' (Pouteria campechiana), Granada (Punica granatum), and 'santol' (Sandoricum Koetjape Merr.) had oil content of less than 10%. The oils from the fruit tree and fruit vine seeds had high molecular weights and their overall molecular was even higher compared to the shrubs. The color of the oils ranged from yellow to brown except for rambutan, which had a light, yellowish color. Only one of the three palms had oil content very much similar to that of coconut. The unidentified palm's oil had an average molecular weight that was the closest to coconut among all the oils described in this study. Unlike the oils from the other plant groups, the oils in this group were light-colored. In particular, the unidentified high-yielding palm extract was colorless, much like the coconut oil.