Avocado, sunflower and olive oils as replacers of pork back-fat in burger patties: effect on lipid composition, oxidative stability and quality traits

The present study investigates the effects of avocado, sunflower and olive oils used as back-fat replacers, on the fatty acid composition, oxidative stability, volatiles profile and color and texture properties of cooked pork patties. The vegetable oils modified the fatty acid profiles of the patties by lowering the percentages of SFA (from 36.96% to ~ 25.30%) and reducing the atherogenic index (from 0.41 to ~ 0.24). Vegetable oils had higher amounts of antioxidant compounds such as tocopherols (10.8-53.9 mg/100 g) than back-fat (5.9 mg/100 g). Consistently, patties manufactured with the oils had significantly lower amounts of lipid and protein oxidation products than control patties. Avocado oil contributed with specific aroma-active terpenes to patties and had a significant impact on particular color and texture parameters. The results from this study highlight the technological applications of the vegetable oils as food ingredients in the design of healthier meat commodities.     

Olive oil oxidation: Rejection points in terms of polar, conjugated diene, and carbonyl values

The changes in polar (POV), conjugated diene (CDV), and carbonyl (CV) values of a set of olive oil samples with a wide range of compositional parameters were monitored during 16 h heating at 180 °C. The POV, CDV, and CV linearly changed till the end of the heating process and increased on average from 6.8%, 7.0 mmol/l, and 11.7 μmol/g to 30.1%, 29.3 mmol/l, and 58.1 μmol/g, respectively. The CDV and CV of the olive oil samples were significantly correlated with the POV (R² > 0.98). The limits of 24% and 27% POV corresponded to 24.5 and 27.4 mmol/l CDV and 45.1 and 51.0 μmol/g CV, respectively.     

Gas chromatographic–mass spectrometric characterisation of triterpene alcohols and monomethylsterols in developing Olea europaea L. fruits

Five triterpene alcohols and four 4-monomethylsterols were identified by GC–MS during the ripening of Picholine olive. The quantitative characterisation of these compounds was performed using GC–FID. The results showed that the maximum level of total triterpene alcohols (263.68 mg/100 g oil) was reached at 26th week after the flowering date (WAF) of olive; whilst the highest level of total 4-monomethylsterols (234 mg/100 g oil) was attained at 24th WAF of fruit. The percentage of these two classes represented 20–33% of total phytosterols during olive maturity. 24-Methylene cycloartenol (12–207 mg/100 g oil) and cycloartenol (27–198 mg/100 g oil) were the predominant triterpene alcohols during the ripening of Picholine olive; whereas citrostadienol (30–161 mg/100 g oil) and cycloeucalenol (11–74 mg/100 g oil) were the main 4-monomethylsterol compounds followed by obtusifoliol and gramisterol. β-Amyrin, δ-amyrin and traroxerol were less present in Picholine olive and they accounted for 14% of total triterpene alcohols at complete maturity of fruit. The level of these methylsterols was overwhelmed by the amount of 4-desmethylsterols at each stage of Picholine olive maturity.     

Hydroxytyrosyl acetate contributes to the protective effects against oxidative stress of virgin olive oil

The effects of virgin olive oil phenols, hydroxytyrosyl acetate (HTy-Ac) and hydroxytyrosol (HTy), on cell integrity and steady-state values of cellular redox status were assessed in HepG2 cells, as well as their potential protective effects against oxidative stress induced by tert-butyl hydroperoxide (t-BOOH). Direct treatment for 20 h with 0.5-10 μM HTy or HTy-Ac reduced ROS generation and increased glutathione peroxidase activity at the higher concentrations. Furthermore, after t-BOOH exposure, pretreatment with HTy-Ac and HTy for 2 or 20 h counteracted cell viability damage from 1 μM, counterbalanced reduced glutathione levels from 0.5 μM, protected against lipid peroxidation from 0.5 μM, decreased ROS generation from 1 μM as well as antioxidant enzyme activities from 1 μM. All these changes were statistically significant.HTy-Ac presents antioxidative stress protective effects at physiological concentrations similar to or even slightly higher than that of HTy, thus contributing to the protective role of virgin olive oil.     

The effect of citric acid on the phenolic contents of olive oil

Response surface methodology was used to optimise the combined effects of malaxation time (t) and aqueous citric acid solution (C_A) added at the beginning of the malaxation step on total polyphenols (TP) and o-diphenols (OD) content and the antiradical power (ARP) of the olive oil extracted from the Italian olive fruits of Coratina cultivar. Different tests were performed according to a 3² full factorial design, varying t from 30 to 90 min and the C_A from 5 to 15 ml/kg_paste. Overall optimal conditions identified by a numerical optimisation for the three responses were found to be at t = 30 min and C_A = 13.79 ml/kg_paste under which the model predicted TP = 604.52 μgCAE/g_oil, OD = 80.44 μgCAE/g_oil and ARP = 28.73 μgDPPH/μlextract. There were also linear correlations between TP (R² = 0.8176) and OD (R² = 0.8633) values of olive oil and waste water. The results of this study demonstrate that considerably short malaxation time and relatively small amounts of citric acid were required to enhance the quality of olive oil. The outcome of our study will therefore be of great value for the commercial production of olive oil with high level of polyphenols and o-diphenols.     

Tocols in caneberry seed oils

The compositional analysis of tocols in oils extracted from Korean caneberry seeds was compared with commercial soybean, corn, olive, canola, perilla, and grape seed oils. The oils from caneberry seeds of six different species were extracted using either a chloroform–methanol–water system or hot hexane. Tocols from all of the oils were analysed using isocratic HPLC. The contents of total tocopherols in the caneberry seed oils were about 75–290 mg/100 g oil, whereas tocotrienols were not detected. γ-Tocopherol was the most abundant tocopherol (31.8–239 mg/100 g oil) in the caneberry seed oils, followed by α-tocopherol (7.6–58.2 mg/100 g oil). The contents of total tocols in soybean, corn, olive, canola, perilla, and grape seed oils were 99.9, 61.1, 28, 27, 45.4, and 52.2 mg/100 g oil, respectively. Total tocol content was higher in most of the caneberry seed oils including the refined ones than in the commercial vegetable oils.     

Differential scanning calorimeter application to the detectionof refined hazelnut oil in extra virgin olive oil

The potential application of differential scanning calorimetry (DSC) to verify adulteration of extra virgin olive oil with refined hazelnut oil was evaluated. Extra virgin olive oil and hazelnut oil were characterised by significantly different cooling and heating DSC thermal profiles. Addition of hazelnut oil significantly enhanced crystallisation enthalpy (at hazelnut oil ?20%) and shifted the transition towards lower temperatures (at hazelnut oil ?5%). Lineshape of heating thermograms of extra virgin olive oil was significantly altered by hazelnut oil addition: a characteristic exothermic event originated at −27 °C in extra virgin olive oil and progressively disappeared with increasing hazelnut oil content, while the major endothermic peak at −3.5 °C broadened (at hazelnut oil ?40%) and the minor endothermic peak at 8 °C shifted toward lower temperatures (at hazelnut oil ?5%). The preliminary results presented in this study suggest that DSC analysis may be a useful tool for detecting adulteration of extra virgin olive oil with refined hazelnut oil.     

Effects of pan-frying in margarine and olive oil on the fatty acid composition of cod and salmon

Effects on the fatty acid composition of cod (Gadus morhua) and salmon fillets (Salmo salar) after pan-frying in margarine and olive oil were determined. The fatty acids of the margarine used were 55.5% saturated (SFA), 33.0% mono-unsaturated (MUFA) and 11.5% polyunsaturated (PUFA). The olive oil used contained 15.4% SFA, 76.1% MUFA and 8.5% PUFA. Using margarine or olive oil increased the SFA and MUFA percentages, respectively, in both species. For cod fillets (lean), pan-frying increased the fat content (0.55–4.15 g/100 g and 0.55–2.30 g/100 g before and after pan-frying, with margarine and olive oil, respectively), whereas, for salmon fillets (fat), it decreased (13.91 to 10.57 g/100 g and 15.35 to 12.95 g/100 g before and after pan-frying with margarine and olive oil, respectively). In conclusion, the culinary fat selection affects the total fatty acid content and composition of the prepared fish fillet.     

High performance size-exclusion chromatography analysis of polar compounds applied to refined, mild deodorized, extra virgin olive oils and their blends: An approach to their differentiation

An investigation was carried out to evaluate the use of High Performance Size-Exclusion Chromatography (HPSEC) of polar compounds of refined, mild deodorized, extra virgin olive oils as well as of their blends, in attempting to reveal significant differences in the amounts of the substance classes constituting polar compounds among these oils. Two sets of blends were prepared by mixing an extra virgin olive oil with both refined and mild deodorized olive oils in increasing amounts. The obtained data highlighted that the triacylglycerol oligopolymers were absent or present in traces in the extra virgin olive oil, while their mean amount was equal to 0.04 g/100 g and 0.72 g/100 g in mild deodorized and refined olive oils, respectively. Oxidized triacylglycerols and diacylglycerols were more abundant in mild deodorized oil and refined oil than in extra virgin olive oil. The Factorial Discriminant Analysis of the data showed that the HPSEC analysis could reveal the presence of refined/mild deodorized oils in extra virgin olive oils. In particular, the classification functions obtained allowed designation of mixtures containing at least 30 g/100 g of mild deodorized oil and all those containing refined olive oil as deodorized oil, therefore as oils subjected to at least a mild refining treatment.     

Scaled-up production of zero-trans margarine fat using pine nut oil and palm stearin

An interesterified structured lipid was produced with a lipid mixture (600 g) of pine nut oil (PN) and palm stearin (PS) at two weight ratios (PN:PS 40:60 and 30:70) using lipase (Lipozyme TL IM, 30 wt.%) as a catalyst at 65 ^°C for 24 h. Major fatty acids in the interesterified products were palmitic (35.1–40.4%), oleic (29.5%), and pinolenic acid (cis-5, cis-9, cis-12 18:3; 4.2–5.9%). α-Tocopherol (1.1–1.3 mg/100 g) and γ-tocopherol (0.3–0.4 mg/100 g) were detected in the interesterified products. Total phytosterols (campesterol, stigmasterol, and β-sitosterol) in the interesterified products (PN:PS 40:60 and 30:70) were 63.2 and 49.6 mg/100 g, respectively. Solid fat contents at 25 ^°C were 23.6% (PN:PS 40:60) and 36.2% (PN:PS 30:70). Mostly β′ crystal form was found in the interesterified products. Zero-trans margarine fat stock with desirable properties could be successfully produced from pine nut oil and palm stearin.     

Rheological behaviour of emulsions of avocado and watermelon oils during storage

Rheological properties of emulsions made out of avocado pulp and watermelon seed oils with whey protein concentrate were determined during different storage periods. The oils, as well as the emulsions behaved like non-Newtonian liquids, having shear-thinning characteristics. Both oils showed moderate shear-thinning characteristics as the flow behaviour indices were between 0.86 and 0.88. The shear-rate/shear-stress data could be adequately fitted (r = 0.997–0.999) to a common rheological equation, e.g. the power-law model. Avocado pulp oil was markedly more viscous than was watermelon seed oil which was also evident from the higher apparent viscosity and consistency index values.     

Pressurized fluid extraction of pistachio oil using a modified supercritical fluid extractor and factorial design for optimization

A pressurized fluid extraction (PFE) method for the extraction of pistachio oil was developed mainly as an analytical tool to determine oil content and/or its quality. The supercritical fluid extractor was modified to be able to pump liquid solvent and CO₂ into the extraction vessel alternatively. The extraction yield was found independent of the pressure in the range 10-150 bar tested. The addition of crushed glass increased the extraction yield by more than 15 g/100 g, while the extraction reproducibility expressed by percentage RSD was improved from 4 to 1. Furthermore, the use of crushed glass reduced the solvent consumption from 35 to 20 mL. The effective variables of temperature (40-80 °C), solvent volume (5-25 mL), and crushed glass percentage (30-60 g/100 g) were optimized by a factorial design method. The model allows the prediction of the extraction yield at different conditions. The PFE yield (i.e. 52.6 g/100 g) and fatty acid composition of pistachio oil were found similar to Soxhlet extraction and their variations were within the experimental uncertainty verified by statistical t-test analysis. Two different solvents of n-hexane and ethanol were used for PFE of pistachio oil. The extraction yield was about one-third (i.e. 18 g/100 g) when ethanol was used as solvent.     

Physicochemical characterisation and oxidative stability of fish oil and fish oil–extra virgin olive oil microencapsulated by sugar beet pectin

Spray-dried microcapsules were prepared at 25% and 50% w/w oil load from sugar beet pectin-stabilised emulsions (pH 3) containing fish oil, and a blend of fish oil and with extra virgin olive oil (1:1 w/w). Microencapsulation efficiencies were high (≥90%). However, deterioration in microcapsule wall integrity and an increase in oil droplet size were observed during storage (25 °C, 0–3 months). Lipid oxidation increased with both increased oil load (P < 0.05) and storage duration (P < 0.05), but was independent of oil composition (P > 0.05). These results suggest that sugar beet pectin functions poorly as a wall material and its residual metal ions exacerbate omega-3 oxidation, despite the presence of endogenous antioxidants found in extra virgin olive oil. Interestingly, under accelerated storage conditions (OxiPres® at 80 °C, 0.5 bar oxygen pressure), microcapsules containing the oil blend showed the best oxidative stability (P < 0.05), irrespective of oil load. A possible explanation for the superior oxidative stability of the microencapsulated oil blend at high storage temperature is discussed.     

Direct determination of phenolic compounds and phospholipids in virgin olive oil by micellar liquid chromatography

A simple HPLC method is reported for fast separation and determination of phenolic compounds (tyrosol, caffeic acid, p-coumaric acid and oleuropeina) and phospholipids (phosphatidylethanolamine and phosphatidylcholine) in virgin olive oil samples. The samples were diluted with 2-propanol and injected into the column directly without previous extraction. Samples with an olive oil content of up to 65% were injected without any problems. The analytes were separated on a C-18 column by a micellar mobile phase containing 0.07 M SDS and 2.5% 2-propanol at pH 3, and were detected at 210 nm. Linear calibration curves [r² > 0.997] were obtained with detection limits ranging from 0.052 to 0.16 μg/g and 1 to 8.6% repeatability for the phenolic compounds. Several virgin olive oil samples were analysed and the recovery values were around 110%.     

Study on chemical composition and biological activities of essential oil and extract from Salvia pisidica

In this study, total contents of phenolic, flavanol and flavonol, antioxidant activities and antimicrobial activities of the Turkish endemic Salvia pisidica Boiss. & Heldr. ex Bentham (Lamiaceae) extract and essential oil were assessed in vitro. Total phenolic, flavanol and flavonol contents in the extract were 54.57 mg gallic acid equivalents (GAE)/g, 16.70 mg catechine equivalents (CE)/g and 18.19 mg rutin equivalents (RE)/g, respectively. Antioxidant activities (IC₅₀ value) of the extract and essential oil were determined as 4.88 and 6.41 mg/mL by DPPH assay, respectively. 31 compounds were determined in the essential oil using GC-MS and the major compounds (%) were camphor (23.76), sabinol (19.2), α-thujone (14.2) and eucalyptol (1.8-cineole) (5.8).The antimicrobial activity of the methanolic extract and the essential oil against 13 bacterial and two yeast strains was determined. The extract (concentration 5 g/100 ml or 10 g/100 ml) was effective against most of the strains tested, yet not against Bacillus cereus, Staphylococcus aureus, Aeromonas hydrophila and the two yeast strains tested. The essential oil (2 g/100 ml) showed an antimicrobial effect against all the gram (+) bacteria tested, against Saccharomyces cerevisiae, but was not effective against all gram (−) bacteria and Candida albicans. These results show that S.piscidica essential oil and extract could be considered as a natural alternative to traditional food preservatives and be used to enhance food safety and shelf life.     

Determination of vitamin K1 content in olive oil,chard and human plasma by RP-HPLC method with UV–Vis detection

The contents of phylloquinone (Vitamin K₁) were investigated in olive oil, chard and human plasma based on a reversed phase high performance liquid chromatographic method with acetonitrile/dichloromethane/methanol (60:20:20, v/v/v) as eluent in a C₁₈ μ-Bondapak column (10 μm, 300 × 3.9 mm) at 20 °C. Detection was by UV–Vis detector at 248 nm. In olive oil, the mean content of phylloquinone ranged from 12.7 to 18.9 μg/100 g, in chard ranged from 65.5 to 77.5 μg/100 g. In human plasma, phylloquinone content varied between 0.22 and 0.56 ng/ml.     

Fish oil encapsulation with chitosan using ultrasonic atomizer

An encapsulation technique was developed using an ultrasonic atomizer and three processing steps: emulsification, ultrasonic atomization, and freeze drying. Emulsion preparation variables such as concentration of wall materials [chitosan (CS), maltodextrin (MD) and whey protein isolate (WPI)] and tuna oil were optimized. The size and stability of the emulsion droplet and the properties of the encapsulated powders after freeze drying were characterized. At 20 g/100 g tuna oil, the optimum ratios of CS to MD and of CS to WPI were 1:10 and 1:1, respectively. There was a significant difference (P<0.05) in the emulsion particle sizes when the preparation conditions were varied. The combination of CS and MD giving the smallest particle size had the highest emulsion stability. The EPA and DHA content (240 mg/g) of the encapsulated powder were slightly higher than commercial specification (100 mg/g) and they had low moisture content and water activity, acceptable appearance and encapsulation efficiency. The ultrasonic technology used in this study could lead to application in the food industry improving the stability of tuna and other oils.     

Diet supplementation with fish oil and sunflower oil to increase conjugated linoleic acid levels in milk fat of partially grazing dairy cows

The objective of this study was to determine the long-term effect on milk conjugated linoleic acid (cis-9, trans-11 CLA) of adding fish oil (FO) and sunflower oil (SFO) to the diets of partially grazing dairy cows. Fourteen Holstein cows were divided into 2 groups (7 cows/treatment) and fed either a control or oil-supplemented diet for 8 wk while partially grazing pasture. Cows in group 1 were fed a grain mix diet (8.0 kg/d, DM basis) containing 400 g of saturated animal fat (control). Cows in the second group were fed the same grain mix diet except the saturated animal fat was replaced with 100 g of FO and 300 g of SFO. Cows were milked twice a day and milk samples were collected weekly throughout the trial. Both groups grazed together on alfalfa-based pasture ad libitum and were fed their treatment diets after the morning and afternoon milking. Milk production (30.0 and 31.2 kg/d), milk fat percentages (3.64 and 3.50), milk fat yield (1.08 and 1.09 kg/d), milk protein percentages (2.97 and 2.88), and milk protein yield (0.99 and 0.91 kg/d) for diets 1 and 2, respectively, were not affected by the treatment diets. The concentrations of cis-9, trans-11 CLA (1.64 vs. 0.84 g/100 g of fatty acids) and vaccenic acid (5.11 vs. 2.20 g/100 g of fatty acids) in milk fat were higher for cows fed the oil-supplemented diet over the 8 wk of oil supplementation. The concentration of cis-9, trans-11 CLA in milk fat reached a maximum (1.0 and 1.64 g/100 g of fatty acids for diets 1 and 2, respectively) in wk 1 for both diets and remained relatively constant thereafter. The concentration of vaccenic acid in milk fat followed the same temporal pattern as cis-9, trans-11 CLA. In conclusion, supplementing the diet of partially grazing cows with FO and SFO increased the milk cis-9, trans-11 CLA content, and that increase remained relatively constant after 1 wk of oil supplementation.     

Influence of rosemary (Rosmarinus officinalis, L.) on plant sterol oxidation in extra virgin olive oil

The objective of this study was to investigate the potential role of rosemary compounds in inhibiting the plant sterol oxidation in extra virgin olive oil during heating. The stability of plant sterols was measured by quantification of plant sterol and sterol oxide formation upon 6 h of heating in both the extra virgin olive oil and its respective oil at 10% rosemary concentration (ROE). The total sterol and sitosterol oxide contents were determined by GC-flame ionization detection (GC-FID) and GC-MS techniques, respectively. Heating experiments were carried out at 180 degrees C for 0, 1, 3 and 6 h. The total sterol content in the extra virgin olive oil was 255 mg/100 g and that in the ROE 270 mg/100 g. Sitosterol was the most abundant sterol in both samples (50% of total sterol). The ROE showed a lower content of sitosterol oxides with respect to the extra virgin olive oil during heating: after 6 h of heating only 6.1% of sitosterol oxides were formed, while up to 11.5% of sitosterol oxidized in the extra virgin olive oil. Our findings suggested that rosemary compounds were able to counteract the oxidation of plant sterols in the extra virgin olive oil during heating, preventing formation of potentially harmful compounds to human health.     

Characteristics and composition of Washingtonia filifera (Linden ex André) H. Wendl. seed and seed oil

Characteristics of seeds and oil extracted from Washingtonia filifera seeds are evaluated. The percentage composition of the W. filifera seeds is: ash 1.37%, oil 16.30%, protein content 3.46%, total carbohydrate 77.19% and moisture 3.22%. The major nutrients (mg/100 g of seeds) found in the seeds are: potassium (67.33), magnesium (34.35), calcium (187.85) and phosphorus (23.26). Physicochemical properties of the oil include: iodine value 67.33 g/100 g of oil; saponification value, 191.63 mg KOH/g of oil; refractive index (25 °C), 1.469; unsaponifiable matter, 0.83%; acidity, 0.41%; p-anisidine value, 0.87; peroxide value, 7.60 mEq O₂/kg of oil; carotenoid content 14.8 mg/100 g and the chlorophyll content = 0.13 mg/100 g. W. filifera seed oil shows some absorbance in the UV-B and UV-C ranges with potential use as a broad spectrum UV protectant. The oil contains high levels of oleic acid (40.60%) followed by lauric acid (17.87%), linoleic acid (16.26%), myristic acid (11.43%) and palmitic acid (9.23%). The triacylglycerols (TAGs) with equivalent carbon number ECN 44 (20.47%) are dominant, followed by TAGs ECN 46 (16.71%), TAGs ECN 42 (15.43%) and TAGs ECN 48 (15.41%). The DSC melting curves reveal that: melting point = 2.25 °C and melting enthalpy = 82.34 J/g. γ-Tocotrienol is the major tocol (72%) with the rest being δ-tocotrienol and α-tocotrienol. The results of the present analytical study show that W. filifera seed oil could be used in cosmetic, pharmaceutical and food products.