Fatty Acid Composition and Some Physicochemical Properties of Oils from Allanblackia gabonensis and A. stanerana Kernels

The physicochemical properties and chemical composition of oils extracted from two varieties of mature seeds of Allanblackia gabonensis and A. stanerana were assessed. The physicochemical properties of oils from Allanblackia gabonensis and A. stanerana were respectively 5.35 and 22.023 % for the water content; 68.15 and 69.87 % for the extraction yield on a dry basis; 0.35 and 0.30 mg KOH/g oil for the acid index; 35.57 and 29.75 g of I₂/100 g oil for the iodine index; 1.3740 and 1.4150 for the refractive index. The fatty acid profile of those oils showed respectively four saturated fatty acids 60.61 and 70.94 %, two monounsaturated fatty acids 37.46 and 28.22 %, two polyunsaturated fatty acids 0.82 and 0.81 % for Allanblackia gabonensis and A. stanerana oils respectively. In both cases, fatty acids C18:0 and C18:1 were dominant. Most of the physicochemical properties showed significant variation (P < 0.05) from one oil to other, the difference being insignificant (P > 0.05) between the two chemical compositions. The analysis of these characteristics showed interesting application features for these oils.     

Impacts of Refining and Antioxidants on the Physico-Chemical Characteristics and Oxidative Stability of Watermelon Seed Oil

Compositional analyses of seeds from two cultivars (Mateera and Sugar baby) was performed to evaluate their suitability as oilseeds. Watermelon seeds and kernels contained 21.9–25.5 % and 38.9–46.9 % oil of exceptionally high quality. The crude oil was expelled with a screw press and then refined to obtain a odor free and colorless oil. The moisture content, unsaponifiable matter content, refractive index, and specific gravity were within the narrow ranges. Refining influenced the color, acid value, saponification value, peroxide value, and free fatty acid contents. Linoleic acid (C18:2) was the principal fatty acid constituting 64.5–67.2 % of the total fatty acids. Oxidative stability increased with the addition of tocopherols, butylated hydroxyl anisole (BHA), and tert-butyl hydroxyl quinine (TBHQ). The high amount of polyunsaturated fatty acids (PUFA) along with physicochemical properties were similar to soybeans, sunflower and other common vegetable oils, suggesting the suitabilty of watermelon seed oil for industrial production.     

Dragon Fruit (Hylocereus spp.) Seed Oils: Their Characterization and Stability Under Storage Conditions

Oil was extracted from the seeds of white-flesh and red-flesh dragon fruits (Hylocereus spp.) using a cold extraction process with petroleum ether. The seeds contained significant amounts of oil (32–34 %). The main fatty acids were linoleic acid (C18:2, 45–55 %), oleic acid (C18:1, 19–24 %), palmitic acid (C16:0, 15–18 %) and stearic acid (C18:0, 7–8 %). The seed oils are interesting from a nutritional point of view as they contain a large amount of essential fatty acids, amounting to up to 56 %. In both dragon fruit seed oils, tri-unsaturated triacylglycerol (TAG) was mainly found while their TAG composition and relative percentage however varied considerably. Therefore, they showed a different melting profile. A significant amount of total tocopherols was observed (407–657 mg/kg) in which the α-tocopherol was the most abundant (~72 % of total tocopherol content). The impact of storage conditions, cold and room temperatures, on the oxidative stability and behavior of tocopherols was monitored over a 3-month storage period. During storage, the oxidative profile changed with a favorably low oxidation rate (~1 mequiv O₂/week) whilst tocopherols decreased the most at room temperature. After 12 weeks, the total tocopherol content, however, still remained high (65–84 % compared to the initial oils). Hereto, the dragon fruit seed oils can be considered as a potential source of essential fatty acids and tocopherols, with a good oxidative resistance.     

Lipid composition and oxidative stability of oils in hazelnuts (Corylus avellana L.) grown in New Zealand

Hazelnut (Corylus avellana L.) samples were collected from six different cultivars of trees grown in an experimental orchard at Lincoln University. Three U.S. commercial cultivars (Butler, Ennis, and Barcelona), two European commerical cultivars (Tonda di Giffoni and Campanica), and one New Zealand selection (Whiteheart) were evaluated. The total oil, stability to oxidation of the oil, and fatty acid, tocopherol, and sterol composition were determined on samples of freshly extracted hazelnut oil. The total oil content of the seeds ranged from 54.6 to 63.2% while the stability of the oil, as measured by the Rancimat test ranged from 15.6 to 25.3 h. The content of the monounsaturated oleic acid in the oils ranged from 73.8 to 80.1% of the total fatty acids, while the tocopherol content ranged from 225.8 to 552.0 mg/g freshly extracted oil. The major desmethylsterols were sitosterol, ranging from 1416 to 1693 μg/g, campesterol, ranging from 78 to 114 μg/g, and Δ5-avenasterol, ranging from 110 to 170 μg/g. The oil extracted from the cultivar Whiteheart was more stable (measured by Rancimat) than the oil from all other cultivars grown at the same location and under the same conditions. Whiteheart contained higher levels of total and γ-tocopherol when compared to the other cultivars. The higher levels of tocopherol in Whiteheart help to explain the greater stability of the oil during the oxidative stress test. These results suggest that nuts from the cultivar Whiteheart could be stored longer than the other nuts tested. Presented as a poster at the 87th AOCS Annual Meeting, Indianapolis, Indiana, April 28–May 1, 1996.     

Contents of Fatty Acids, Selected Lipids and Physicochemical Properties of Western Australian Sandalwood Seed Oil

The study was designed to characterise two extracts of Western Australian sandalwood (Santalum spicatum) seed oils for their physicochemical and lipid characteristics. Sandalwood plantation’s surplus seeds could be used for their oil content, to improve the commercial viability of this industry. The seed oils were obtained by solvent extraction and supercritical carbon dioxide extraction respectively. Important physicochemical parameters were compared with other oils commonly used in pharmaceutical and cosmetic products. Acid values were found to be higher (6.0–7.5 mg KOH/1 g oil) while peroxide values (6.7–9.0 mequiv/Kg) were lower than reported for other oils. Tocopherols were found to be lower than those usually reported for nut oils (α-tocopherol 1–3 mg/100 g; δ-tocopherol 2.2–5.7 mg/100 g), squalenes and phytosterols were found in considerable quantities. The fatty acid content consisted largely of ximenynic acid (35 %) and oleic acid (52 %). No oxidative derivatives of fatty acids were observed. Although there were statistically significant differences in some properties, the magnitude of these were insufficient to conclude there were any notable differences in the two oil extracts.     

Composition and physicochemical properties of Combretum collinum,Combretum micranthum,Combretum nigricans,and Combretum niorense seeds and seed oils from Burkina Faso

Combretum collinum, Combretum micranthum, Combretum nigricans, and Combretum niorense are abundant unconventional seed oils of the African savannah. In this study, the proximate, mineral, amino acid, fatty acid, and triacylglycerol compositions of the four seed oils were quantified, and the oxidative and physicochemical properties were investigated. The amino acid, fatty acid, and triacylglycerol compositions were determined by using high performance liquid chromatography (HPLC) and gas chromatography respectively. Carbohydrates (57.35%–64.20%) followed by crude oils (20.07%–22.60%), proteins (11.95%–15.86%), and ashes (3.78%–6.19%) were the main constituents of the four seed species. The highest ash, crude fat, and protein contents were found in C. collinum, C. nigricans, and C. niorense, respectively. All four seed species were rich in Ca, K and Mg, and poor in methionine, cysteine, and lysine. The four seed oils had high saponification values (198.46–202.71 mgKOH/g), low acidity (1.12–2.26 mg of KOH/g of oil), and peroxide values (1.19–1.98 mEqO₂/kg of oil). The seed oils of C. micranthum and C. collinum exhibited the highest thermal oxidative stability (8.10 and 9.79 h at 160°C). Oleic (40.49%–56.69%), palmitic (15.17%–24.27%) and linoleic (9.49%–14.50%) acids were the predominant fatty acids of the four seed oils. The results showed that the four seed species and seed oils had good chemical composition and physicochemical properties making them suitable for food and non-food application.     

Typoselectivity of Crude Geobacillus sp. T1 Lipase Fused with a Cellulose-Binding Domain and Its Use in the Synthesis of Structured Lipids

Typoselectivity of crude CBD-T1 lipase (Geobacillus sp. T1 lipase fused with a cellulose binding domain) was investigated. Multi-competitive reaction mixtures including a set of n-chain fatty acids (C8:0, C10:0, C12:0, C14:0, C18:1 n-9, C18:2 n-6 and C18:3 n-3) and tripalmitin-enriched triacylglycerols were studied in hexane. The crude CBD-T1 lipase discriminated strongly against C18:1 n-9 [competitive factor (α) = 0.23] and showed the highest preference for C8:0 (α = 1). Utilizing the catalytic properties of crude CBD-T1 lipase, acidolysis of soybean oil with C8:0 was selected as a model reaction to investigate the ability of the lipase to produce MLM-type (medium-long-medium) structured lipids. Several reaction parameters (added water amount, reaction temperature, substrate molar ratio and reaction time) examined for incorporating C8:0 into soybean oil, the optimum conditions were: 1:3 (soybean oil/C8:0) of molar ratio, 3 mL of hexane, 50 °C of temperature, 48 h of reaction time, 20 % of crude CBD-T1 lipase (w/w total substrates), and 7.5 % of water (w/w enzyme). Under these conditions, the incorporation of C8:0 was 29.6 mol%. The results suggest that crude CBD-T1 lipase, which showed different fatty acid specificity profiles, is a potential biocatalyst for the modification of fats and oils.     

<Emphasis Type="Italic">cis</Emphasis>-, <Emphasis Type="Italic">trans</Emphasis>- and Saturated Fatty Acids in Selected Hydrogenated and Refined Vegetable Oils in the Indian Market

The fatty acid composition of 27 samples of commercial hydrogenated vegetable oils and 23 samples of refined oils such as sunflower oil, rice bran oil, soybean oil and RBD palmolein marketed in India were analyzed. Total cis, trans unsaturated fatty acids (TFA) and saturated fatty acids (SFA) were determined. Out of the 27 hydrogenated fats, 11 % had TFA about 1 % where as 11 % had more than 5 % TFA with an average value of about 13.1 %. The 18:1 trans isomers, elaidic acid was the major trans contributor found to have an average value of about 10.8 % among the fats. The unsaturated fatty acids like cis-oleic acid, linoleic acid and α-linolenic acid were in the range of 21.8–40.2, 1.9–12.2, 0.0–0.7 % respectively. Out of the samples, eight fats had fatty acid profiles of low TFA (less than 10 %) and high polyunsaturated fatty acids (PUFA) such as linoleic and α-linolenic acid. They had a maximum TFA content of 7.3 % and PUFA of 11.7 %. Among the samples of refined oils, rice bran oil (5.8 %) and sunflower oil (4.4 %) had the maximum TFA content. RBD palmolein and rice bran oils had maximum saturated fatty acids content of 45.1 and 24.4 % respectively. RBD palmolein had a high monounsaturated fatty acids (MUFA) content of about 43.4 %, sunflower oil had a high linoleic acid content of about 56.1 % and soybean oil had a high α-linolenic acid content of about 5.3 %.     

Selection for Some Olive Oil Quality Components Through the Analysis of Fruit Flesh

Selection for oil quality is commonly conducted at the latest stages of olive breeding programs, as oil quality traits are measured in extracted oils. At the initial stages of breeding, the number of genotypes is high and fruit production is low, which makes it difficult to conduct oil extraction. The objective of this research was to evaluate the feasibility of conducting selection for some important oil quality traits in olive by analyzing fruit flesh instead of extracted oils. Fatty acids, tocopherols, phytosterols, and squalene were measured in fruit flesh and extracted oils from 22 individual olive trees showing variability for oil quality traits. Correlation coefficients between analyses conducted on fruit flesh and extracted oils were r = 0.98 for the main fatty acids palmitic, oleic, and linoleic acid, r = 0.96 for tocopherol content, r = 0.89 for phytosterol content, r = 0.97 for squalene content, and r = 0.91 and 0.94 for the concentrations of the two main sterols β-sitosterol and Δ⁵-avenasterol, respectively. The results revealed that selection for the mentioned oil quality traits can be efficiently conducted through the analysis of fruit flesh instead of extracted oil, which facilitates selection on larger numbers of genotypes at the initial stages of olive breeding programs.     

Physicochemical and Antioxidant Characteristics of Kapok (Ceiba pentandra Gaertn.) Seed Oil

In view of the growing demand for vegetable oils and fats, currently exploration of some under-utilized and non-conventional oil seed crops is of great concern. This work presents data on the detailed physicochemical and antioxidant attributes of kapok (Ceiba pentandra Gaertn.) seed oil. The kapok seeds contained an appreciable amount of oil (27.5 %), protein (35.0 %) and fiber (19.0 %). The extracted kapok seed oil (KSO) had an iodine value of 101.8 g of I₂/100 g of oil, a saponification value of 187 mg of KOH/g of oil), and unsaponifiable matter 0.83 %. KSO also showed a good oxidation state as indicated by the measurements of the peroxide value, conjugated dienes, conjugated trienes, para-anisidine and the induction period (Rancimat method). The tested oil showed a considerable amount of total phenolics (2.50 mg/100 g) and an appreciable free radical scavenging capacity. Gas liquid chromatographic analysis of fatty acids (FA) reveals that KSO mainly has linoleic acid (33.6 %) followed by oleic acid (23.4 %) and palmitic acid (22.4 %). Besides, a notable amount of cyclopropenoid fatty acids such as malvalic acid (9.1 %) and sterculic acid (2.8 %) was also detected. The FA composition of the tested oil was further verified by recording FTIR and NMR spectra. Among the oil phytosterols, analyzed by GC/GC–MS, β-sitosterol was found to be the principal component whereas RP-HPLC analysis showed the occurrence of γ-tocopherol (550 mg/kg) as the major tocopherol along with considerable amount of α-tocopherol (91 mg/kg) and δ-tocopherol (5.52 mg/kg). It can be concluded from the results of this comprehensive study that under-utilized kapok seeds are a potential feed stock for the production of a useful oil for edible and/or oleochemical applications.     

Using a Strong Anion-Exchange Resin to Deacidify Red Palm Oil

This work aims to evaluate the use of an alternative process to deacidify palm oil using a strong anion-exchange resin (Amberlyst A26 OH). The effects of the feed flow rate and the free fatty acids content in the feed stream were investigated by measuring breakthrough curves for bleached palm oil dissolved in n-propanol. The resin had sufficient capacity and affinity to remove palmitic and oleic acids (98–99 %). The bed utilization efficiency can be optimized by choosing lower flow rates for oils with low levels of acidity, while higher flow rates can be used for oils with higher free fatty acids content. The ion-exchange process can be used to obtain deacidified red palm oil, while preserving carotenoid and tocopherol/tocotrienol content. This alternative process has the advantage of occurring under mild conditions (44.0 ± 0.8 °C and atmospheric pressure) when compared with the conditions used in molecular distillation (150.0–170.0 °C and 2.7–3.3 Pa).     

Proximate Analysis of <Emphasis Type="Italic">Adenanthera pavonina</Emphasis> L. Seed Oil,a Source of Lignoceric Acid Grown in Pakistan

Adenanthera pavonina L. is indigenous to Pakistan a proximate analysis of the seeds was carried out and a physicochemical characterization of the seed oil and also a quality evaluation of the oil was made. The hexane-extracted oil content of the seed was 13.32 ± 0.55 %. Analysis showed the seed of A. pavonina contained appreciable amounts of protein (22.14 ± 0.78 %). Fiber and ash contents were 3.13 ± 0.64 and 4.53 ± 0.47 %, respectively. Triacylglycerol (97.51 ± 1.12 %) was predominantly present in the seed oil. Unsaponifiable matter (0.95 ± 0.10 %), peroxide value (11.43 ± 0.51 mequiv./kg) and saponification value (196.3 ± 0.87 mg of KOH/g of oil), iodine value (83.73 ± 1.18 g I/100 g oil) are in close agreement with the edible seed oils. α-Tocopherol was the predominant tocopherol 152.33 ± 13.19 mg/kg of oil while sterols are present at a significant level. Linoleic acid (42.97 ± 0.91 %) and oleic acid (17.89 ± 0.54 %) were found predominantly in unsaturated fatty acids while lignoceric acid (20.24 ± 1.12 %) was the predominant one among the saturated fatty acids. Lignoceric acid is rarely found in seed which is an essential nutrient for growth, development and maintenance of the brain. It is concluded that A. pavonina seeds appear to be a potential source of lignoceric acid and linoleic acid. This oil can be utilized in the manufacture of cosmetics, paints, varnishes, soaps, pharmaceutical products, biodiesel and blended formulations. The high protein content revealed that the seeds could be a good source of energy.     

Fatty Acid Profile of Kenaf Seed Oil

The fatty acid profile of kenaf (Hibiscus cannabinus L.) seed oil has been the subject of several previous reports in the literature. These reports vary considerably regarding the presence and amounts of specific fatty acids, notably (12,13-epoxy-9(Z)-octadecenoic (epoxyoleic) acid, but also cyclic (cyclopropene and cyclopropane) fatty acids. To clarify this matter, two kenaf seed oils (from the Cubano and Dowling varieties of kenaf) were investigated regarding their fatty acid profiles. Both contain epoxyoleic acid, the Cubano sample around 2 % and the Dowling sample 5-6 % depending on processing. The cyclic fatty acids malvalic and dihydrosterculic were identified in amounts around 1 %. Trace amounts of sterculic acid were observed as were minor amounts of C17:1 fatty acids. The results are discussed in the context of the fatty acid profiles of other hibiscus seed oils.     

Minor Constituents in Canola Oil Processed by Traditional and Minimal Refining Methods

The minimal refining method described in the present study made it possible to neutralize crude canola oil with Ca(OH)₂, MgO, and Na₂SiO₃ as alternatives to NaOH. After citric acid degumming, about 98 % of the phosphorous content was removed from crude oil. The free fatty acid content after minimal neutralization with Ca(OH)₂ decreased from 0.50 to 0.03 %. Other quality parameters, such as peroxide value, anisidine value, and chlorophyll content, after traditional and minimal neutralization were within industrial acceptable levels. The use of Trisyl silica and Magnesol R60 made it feasible to remove the hot-water washing step and decreased the amount of residual soap to <10 mg/kg oil. There were no significant changes in chemical characteristics of canola oil after using wet and dry bleaching methods. During traditional neutralization, the total tocopherol loss was 19.6 %, while minimal refining with Ca(OH)₂, MgO, and Na₂SiO₃ resulted in 7.0, 2.6, and 0.9 % reductions in total tocopherols. Traditional refining removed 23.6 % of total free sterols, while after minimal refining free sterols content did not change. Both traditional and minimal refining resulted in almost complete removal of polyphenols from canola oil. Total phytosterols and tocopherols in two cold-pressed canola oils were 774 and 836 mg/100 g, and 366 and 354 mg/kg, respectively. The minimal refining method described in the present study was a new practical approach to remove undesirable components from crude canola oil meeting commercial refining standards while preserving more healthy minor components.     

Plasma Modified Membrane for Daily Recovery of Oil from Repeated Frying Operation with Frequent Oil Replenishment

Sunflower oil was used for deep frying of potatoes at 170 ± 5 °C and for 8 h per day for 5 days in a fryer with an automatic oil filtration system. Three different frying operations were performed: operation (OP)-1, OP-2 and OP-3; that correspond to the oil unfiltered at the end of each frying day, the oil filtered through the fryer's own filter (passive filtration) and the oil firstly subjected to passive filtration and then filtered through a polyethersulfone membrane modified with hexamethyldisiloxane via radio frequency plasma (75 W-5 min, discharge power–time), respectively. The performance of each operation was investigated in terms of free fatty acids (FFA), conjugated dienoic acids (CD), TOTOX value, total polar content (TPC), Hunter color, viscosity, fatty acid composition, and tocopherol content. The results showed that OP-3 could decrease FFA, CD, TOTOX, TPC, L*a*b* value, viscosity and linoleic acid (18:2)/palmitic acid (16:0) ratio in 29.6, 11.7, 25, 30.8, 6.1*11.3*20.8*, 7.8, 12.2 %, respectively, compared to the unfiltered oil (OP-1). Regenerated oil from OP-3 had a frying life approximately 17 h more than oils from both OP-1 and OP-2.     

Laboratory-Scale Optimization of Roasting Conditions Followed by Aqueous Extraction of Oil from Wild Almond

The effects of roasting and aqueous extraction conditions for oil recovery from wild almond were optimized using response surface methodology (RSM). Optimum conditions for oil extraction were obtained at 142 °C roasting temperature, 16.5 min roasting time, 5.67 extraction pH and 4.6 h extraction time. Under these conditions, the extraction yield of 34.5% (w/w, based on the original weight of the sample) was obtained, which is equivalent to 80.0% of the total oil in the kernel. This was lower than that obtained by hexane Soxhlet (HS) extraction (43.1%, w/w, considered as 100% of total oil) but higher than that of cold pressing (CP) (18.5%, w/w; i.e., 42.9% of total oil). The refractive indices and saponification values of the oils were not affected by the extraction method. However, fatty acid and tocopherol compositions and DPPH radical scavenging capacities as well as unsaponifiable matter, iodine, peroxide and acid values of the obtained oils were impacted by the extraction method. The results showed that the quality attributes (omega-6 fatty acid content, peroxide and acid values, total tocopherol contents and antioxidant activity) of the oil obtained by AEP were somewhat similar to those of the oil extracted by CP and much superior to those of the oil obtained by HS.     

Chemical and Physical Characterization of Donkey Abdominal Fat in Comparison with Cow, Pig and Sheep Fats

The objective of this research was to investigate the physicochemical properties of donkey fat. Results show that donkey fat contains 59.38 % unsaturated fatty acids, 38.37 % saturated fatty acids, and 0.21 % trans fatty acids. The sn-2 monoglyceride present in donkey fat contain 67.91 % unsaturated fatty acids and 30.97 % saturated fatty acids. Donkey fat is also characterized by a total tocopherol content of 8.59 mg/100 g fat (7.90 mg/100 g fat α-tocopherol, 0.51 mg/100 g fat β + γ-tocopherol, and 0.18 mg/100 g fat δ-tocopherol), 0.0032 mg/100 g fat cholesterol, an acid value of 0.091 KOH (mg/g), an iodine value of 76.47 g/100 g, a peroxide value of 0.68 mmol/kg, a saponification value of 193 mg/g, a refractive index of 1.4666, and a specific gravity of 0.9144. The complete melting temperature was 40 °C. The content of unsaturated fatty acids (total and sn-2) in donkey fat is higher than cow, pig and sheep, while the content of trans fatty acids is lower. The tocopherol content is also higher in donkey fat compared to cow, pig and sheep fat. Interestingly, the fat with such processing has nearly no cholesterol. Generally speaking, donkey fat could be a good animal fat for human consumption.     

Physicochemical Properties and Minor Lipid Components of Soybean Germ

This study aimed to determine and to compare the main phytochemicals from soybean and soybean germ of different Chinese varieties. The results indicate that the soybean germ contains low protein (38.19 %), lipids (10.98 %), and crude fiber (7.47 %) compared with soybean. Specific gravity, refractive index, and saponification values of soybean germ oil were comparable to those of soybean oil. However, unsaponifiable matter of the germ oil was significantly higher (6.982 %) than soybean oil (1.072 %). The tocopherol contents in soybean germ oil ranged as follows: γ-tocopherol, 176.39 mg/100 g oil; δ-tocopherol, 57.29 mg/100 g oil; α-tocopherol, 50.67 mg/100 g oil; and β-tocopherol, 8.15 mg/100 g oil. The main sterols in soy germ oil were β-sitosterol (1,681.90 mg/100 g oil), crevesterol (358.02 mg/100 g oil), stigmasterol (189.62 mg/100 g oil), and brassicasterol (3.70 mg/100 g oil). Furthermore, soybean germ oil seemed to be an important source of triglyceride, fatty acids, and particularly the fatty acids in the sn-2 position of triacylglycerol. The important nutritional value of all these phytochemicals makes soybean germ and particularly germ oil sources of functional molecules and additives for the food industry.     

Quality of Rapeseed Oil Produced by Conditioning Seeds at Modest Temperatures

Conditioning rapeseed can significantly increase the amount of bioactive compounds in the crude oil, but if the conditioning temperatures are too high, they can cause unwanted side effects such as darker color and sensory defects. Modest conditioning temperatures may be more suitable, but little is known about the effects on the quality and bioactive composition of the resulting oil. Oil was recovered from five rapeseed cultivars by cold pressing (CP) or by pressing seeds conditioned at 80 °C for 30 min (HP). Conditioning rapeseed increased oil yield without changing fatty acid composition and increased the amount of total sterols by 16 %, total tocopherols by 20 %, and the levels of polyphenols. Levels of the polyphenol canolol were up to 55-fold higher in HP oil than in CP oil. These higher levels of bioactive compounds gave HP oil higher radical scavenging activity. Although HP oil also had higher free fatty acid contents, peroxide levels, and specific UV extinctions (K values). The quality parameters of HP and CP oils were within codex limits indicating high quality. Modest conditioning temperatures can be used to produce rapeseed oil with high quality and radical scavenging activity.     

Thermal Stability of Rapeseed Oil Fortified with Unsaturated Fatty Acid Sterol Esters

The thermal stability of rapeseed oil fortified with 3 % sterol linolenate, sterol linoleate, and sterol oleate was investigated using the Rancimat accelerated oxidation method. The results indicated that the sterol ester content in fortified oil displayed positive correlations (P < 0.05) with total phenols and tocopherols and significant negative correlations (P < 0.05) with acid value (AV), peroxide value (POV), conjugated diene value, \(\varDelta E\) value, viscosity, and polyphenols and γ-tocopherol levels. The sterol ester content in fortified oil was found to significantly decrease when the oil was heated at 110 °C. The rate of increase of the AV, POV, \(\varDelta E\) value, and viscosity, and the rate of decrease of polyunsaturated fatty acid, tocopherol, and polyphenol contents were accelerated with the increase of the degree of unsaturation of fatty acid sterol esters in rapeseed oil during heating. Therefore, the oxidative stability is further reduced by increasing the degree of unsaturation, as the instability of fortified oil is mainly due to the decomposition of unsaturated fatty acid sterol esters. The addition of lipid-soluble polyphenols is an effective method to improve the stability of rapeseed oil fortified with unsaturated fatty acid sterol esters.