Silphium integrifolium Michx. (silflower), a perennial plant, is of great interest as a potential new oilseed crop due to its long, strong, deep, extensive root systems, which can prevent erosion, capture dissolved nitrogen, and out-compete weeds eliminating the need for frequent irrigation and herbicide uses. In this study, oil was extracted from unhulled silflower seeds, and its composition and oxidative stability were evaluated. The oil content in unhulled silflower seeds was 15.2 % (w/w), and its fatty acid composition was similar to that of sunflower oil. The level of total polar compounds (TPC) in the oil was 12.3 % (w/w), and the content of total phenolics was 1.12 mg gallic acid equivalent (GAE)/g oil. Noteworthily, 4.89 % squalene was isolated from silflower oil indicating its potential application as an alternative source of squalene. Silflower oil had lower oxidative stability as indicated by the oxidative stability index (OSI) at 110 °C and thermogravimetric analysis (TGA), presumably due to its high level of chlorophyll (1002.8 mg/Kg). Even after a typical refining process involving degumming, alkali refining, and bleaching with Fuller’s earth, silflower oil contained 725.5 mg/kg chlorophyll, and its oxidative stability was not improved. Further treatments with bleaching agents including bentonite, sepiolite, and Tonsil® lowered the chlorophyll level to 4.2, 474.5, and 38.5 mg/kg, respectively, and some aspects of oxidative stability were improved and better than those of refined sunflower oil. This study presents the potential of silflower oil as new edible oil and a great plant source of squalene.

Cold-pressed hempseed oil (HSO) is known to have many health benefits due to many phytochemicals and high polyunsaturated fatty acids content. In this study, HSO oleogels were prepared with 3, 5, and 7% natural waxes including sunflower wax (SW), rice bran wax (RBW), beeswax, and candelilla wax to evaluate their potential as solid fat replacements in margarines and spreads. Firmness, crystal structures, and melting properties of these oleogels were evaluated. In general, wax-based HSO oleogels except for RBW-HSO oleogels had lower firmness and weaker crystal network than the corresponding soybean oil (SBO) oleogels. In contrast, RBW-HSO oleogels had similar firmness, comparable or stronger crystal network, and higher melting and crystallization enthalpies compared to those of SBO oleogels. After removing polar compounds from HSO, waxes except for RBW provided oleogels with greater firmness, higher melting and crystallization enthalpies, and stronger crystal network. Therefore, it was concluded that polar compounds negatively affected the physical properties of wax-HSO oleogels but not those of RBW-HSO oleogels. Margarine samples were prepared with SW- and RBW-HSO oleogels, and their firmness and melting properties were examined. The firmness of these margarines indicated that wax-HSO oleogels may achieve the firmness of commercial spreads with less than 3% wax while the firmness of stick margarines cannot be achieved even with 7% wax. Although the properties of wax-HSO oleogels should be further improved, they showed potential as solid fat replacements in margarines and spreads.

Previous studies reported that several amino acids had strong antioxidant activity in vegetable oils under frying conditions. In this study, the carboxylic acid group of amino acids was converted to a carboxylate group (-COO-Na+ or -COO-K+), a heating study was conducted with amino acid salts in soybean oil at 180 ºC. Sodium salts of amino acids including alanine, phenylalanine, and proline and disodium glutamate had significantly stronger antioxidant activity than the corresponding amino acids, and potassium salts had stronger antioxidant activity than sodium salts. Potassium salts of alanine and phenylalanine more effectively retained tocopherols in soybean oil than the corresponding amino acids during heating. Phenylalanine potassium salt had stronger antioxidant activity than phenylalanine in other vegetable oils including olive, high oleic soybean, canola, avocado, and corn oils. Phenylalanine potassium salt at 5.5. mM more effectively prevented oil oxidation than tert-butyl hydroquinone (TBHQ), a synthetic antioxidant, at its legal concentration limit (0.02%) indicating its feasibility as a new antioxidant for frying.

The food industry is seeking natural antioxidants for edible oils that have comparable activity to synthetic counterparts. In this study, Osage orange extract (OOE) rich in osajin (42.9%) and pomiferin (30.0%) was obtained after hexane extraction of the fruit, and its antioxidant activity was examined in stripped soybean oil (SBO) and fish oil (FO), in which antioxidants and polar compounds were removed. The antioxidant activity of OOE was compared with commercial natural antioxidants (i.e., rosemary extract and mixed tocopherols) and a synthetic antioxidant, butylated hydroxytoluene (BHT), during storage at 25 and 40 ℃. The 0.1% OOE had stronger antioxidant activity than 0.1% rosemary extract and 0.1% mixed tocopherols in both oils at 25 and 40 ℃. Its activity was similar to 0.02% BHT in SBO and was similar or slightly stronger than 0.02% BHT in FO. When OOE was studied at 0.05, 0.1, and 0.2%, there was a weak dose-response in SBO but a stronger dose-response in FO. Headspace volatile analysis using solid phase micro-extraction (SPME) combined with GC-MS indicated that 0.1% OOE was very effective in preventing the formation of volatile oxidation products in both oils. Although it should be further tested for safety before the actual use, this study shows that OOE can be developed as an antioxidant for edible oils.