Fig seeds: Combined approach of lipochemical assessment using gas chromatography and FTIR-ATR spectroscopy using chemometrics

Abstract

Fig (Ficus carica L.) seeds are the less studied part of the species so far. They are usually discarded after their processing and scarcely studied for nutraceutical purposes. For this reason, the present work reports the lipochemical properties of fig seeds extracted from four fig cultivars conducted in an ex-situ collection. Oil was chemically extracted and screened using gas chromatography and FTIR-ATR coupled with chemometrics. Results, showed an important oil yield reaching up to 30 %, with a high UV absorbency values at 232 and 270 nm, suggesting the occurrence of hydrolytic reactions during the oil extraction. Iodine and saponification values were also high and displayed narrow ranges of variations (76.43 ± 0.067 g/100 g of oil and 201.6 ± 0.012, respectively). Chromatographic profile showed a high unsaturation rate up to 88 %, with a predominance of linolenic fatty acid, which ranged between 38.43 and 43.57 %. In order to avoid pollination effect, desaturation pathway ratios were calculated along with the balance between omega-6 and omega-3. These ratios showed statistically significant differences among samples and were in the range recommended for healthier diet. FTIR-ATR fingerprinting showed several spectral bands assigned to functional groups present in fig seed oil. Among them, two major peaks were identified around the fingerprint regions of 1650–1474 cm−1 and 3010–2924 cm−1 assigned to aliphatic groups and carbonyl groups belonging to the triacylglycerols, respectively. Data of both chromatographic profile and FTIR-ATR spectroscopy were involved in principal component analysis models, that showed high throughput resolution of discrimination and classification of samples studied. The findings herein reported, suggest the potential of fig seeds oil application in food and nutraceuticals. Besides, the use FTIR-ATR spectroscopy in fruit seeds screening and discrimination could be a better alternative to traditional analysis techniques.