Characterization of press and solvent extraction oils from new sunflower seeds with modified phytosterol compositions

Abstract

BACKGROUND Phytosterols are plant components with health benefits. Oleaginous seed hybridization can be relevant to increase phytosterols in diet through enriched oils. Sunflower oils obtained by press (PO) and subsequent solvent extraction (SO) from three types of phytosterol‐enriched seeds were characterized. One presented a phytosterol composition of common sunflower seeds, whereas the other two were rich in campesterol and Δ7‐stigmasterol, respectively. Seeds from two different harvests, 2015 and 2017, were studied. RESULTS The type of extraction did not have a significant influence on the fatty acid composition. However, considerable differences were found between harvests. The oleic‐to‐linoleic ratio decreased from 0.71 in 2015 to 0.47 in 2017. The phytosterol compositions of the PO were similar to their SO homologues and no substantial differences were found between harvests. However, the SO presented higher total contents of phytosterols (4849–9249 mg kg−1) than the PO (2839–5284 mg kg−1) and the oils of 2017 showed higher levels (4476–9249 mg kg−1) compared to 2015 (2839–5754 mg kg−1). Unlike phytosterols, no significant differences were found in the tocopherol contents between the PO and SO or between harvests. The PO met Codex specifications for edible oils, except for trace metals, with concentrations close or above the limits for Cu, Fe, Pb and As. CONCLUSIONS Differences in environmental and/or cultivation conditions between harvests may result in substantial differences in the fatty acid composition and phytosterol content in oils from the new sunflower seeds. Rigorous measures and controls to avoid trace metal contamination are required so that the PO can be considered as edible virgin oils. © 2020 Society of Chemical Industry

Attempts of Physical Refining of Sterol-Rich Sunflower Press Oil to Obtain Minimally Processed Edible Oil

“…Similar reductions have also been observed for iron [41][42][43]. In this respect, bleaching using combinations of earths and silica could be employed to remove the low levels of P found in POs from new PS-enriched sunflower seeds [23], as well as trace metals to meet the levels allowed in the regulation [24].…”

“…The crude oils were those characterized in a previous report [23]. They were obtained by press and subsequent solvent extraction, respectively, from PS-enriched sunflower seeds that were rich in campesterol (CAM) and ∆7-stigmastenol (STIG), respectively, and from seeds with conventional content and composition of PS, referred to as the control (CON) following the operation conditions described in a previous report [23]. The seeds were harvested in 2015 and 2017, respectively.…”

“…The POs obtained in harvests from 2015 and 2017 showed different responses to the bleaching conditions applied. The contents of P in the oils from 2015 (9.3-11.9 mg kg −1 ) [23] were reduced to optimal levels for PhR (<10 mg kg −1 oil) by applying a bleaching treatment with a blend of Trysil and Tonsil 278 FF (TR1) (Table 2). In contrast, the relatively higher contents in the POs from 2017 (15.4-36.4 mg kg −1 ) as compared to those from the 2015 harvest, did not allow for appropriate reductions of P when treated under the same conditions.…”

“…However, the composition of minor components differs between POs and SOs [20][21][22]. Specifically, total PS contents in oils from PS-enriched seeds have been reported to range from 2839 to 5284 mg kg −1 for POs and from 4849 to 9249 mg kg −1 for SOs [23]. Most importantly, it would be not possible to commercialize POs as unrefined or virgin oils due to their high content in phosphorus (P) and metals, beyond the levels allowed by regulations [24].…”

“…On the one hand, oils containing high PS contents naturally would be produced by mechanical means and, on the other hand, a minimal refining processing would be required as compared to classical ChR. The oils obtained from two different harvests, 2015 and 2017, which were characterized in a previous report [23], were studied. Different bleaching treatments in combination with amorphous silica were tested to reduce the phospholipid content to the levels required for PhR (P < 10 mg kg −1 of oil).…”