The aim of the study was to examine and compare oxidative stability of refined (peanut, corn, rice bran, grapeseed, and rapeseed) oils. The oils were subject a Schaal Oven Test (temperature 63 ± 1 ...°C) and a Rancimat test (temperature 120 °C) and their stability was compared at the 1st and 12th month of storage. Changes in the peroxide (PV) and anisidine (AnV) values in the thermostat test were the fastest in rapeseed oil and grapeseed oil. The best quality was preserved by peanut and corn oils both in the first and the twelfth month of storage. The induction times for the rice bran, corn, peanut, and rapeseed oils were similar from 4.77 h to 5.02 h in the first month and from 3.22 h to 3.77 h in the twelfth month. The shortest induction times were determined for grapeseed oil: 2.4 h and 1.6 h, respectively. A decrease of oxidative stability of about 30% was found in all the oils after 12 months of storage. The PV of 10, determined in the thermostat and Rancimat tests, were achieved at the latest in corn oil and the fastest in rice bran oil.
Health benefits associated to ω-3 fatty acids consumption together with the high susceptibility to oxidation of ω-3 containing oils have led to the development of microencapsulated oils for ...nutraceutical and food enrichment applications. The aim of this work is to obtain different formulations for linseed oil microencapsulation by spray-drying with high encapsulation efficiency and evaluate their resistance to oxidation through the accelerated Rancimat test. Four formulations were tested; using different combinations of gum arabic (GA), maltodextrin (MD), methyl cellulose (MC) and whey protein isolate (WPI). Microcapsules made of 100% GA and ternary mixtures of GA, MD and WPI presented the highest protection from oxidation and microencapsulation efficiencies higher than 90%. They also presented spherical structures with smooth surfaces which kept unaltered after 10-month storage. GA containing formulation was included in bread manufacturing. Fortified bread resulted similar in appearance to control bread without microcapsules, but α-linolenic acid content was reduced significantly after preparation.
► Linseed oil was encapsulated with gum arabic, maltodextrin and whey protein isolate. ► Microencapsulation efficiency was around 90% for all samples. ► The ternary mixture was the most stable to peroxidation as determined by Rancimat. ► Gum Arabic microcapsules containing linseed oil were tested for bread fortification. ► α-linolenic acid content was reduced significantly after bread manufacturing.
The oxidative stability of microalgae oil (MO) and its enzymatic glycerolysis product (GP) have been determined by using the accelerated oxidation methods differential scanning calorimetry (DSC) and ...Rancimat at temperatures in the range 50–90 °C. Kinetic analyses of MO and GP provide Arrhenius activation energy and activation enthalpy and entropy, temperature coefficients, Q10 and oxidative stability index at 20 °C (OSI20), based on secondary and tertiary oxidation products. Susceptibility of microalgae oil to oxidation has been compared to that of fish and vegetable oils, with OSI20 values of 647 h for MO and 381 h for GP. The tcoeff and Q10 values are very similar to those observed for fish and vegetable oils. Protective effect from oxidation of a supercritical rosemary extract (RE) for both MO and GP have been evaluated. In the presence of this antioxidant, up to twofold increase of OSI20 has been obtained for MO. Lower protection for GP was observed. Activity antioxidant Index (AAI), related to the mechanism of action of the antioxidant, should be carefully examined for a reliable determination of OSI20 values.
•Oxidative stability of microalgae oil and its acylglycerol mixture has been studied.•Two accelerate oxidation techniques (Rancimat and DSC) were employed.•Self-life of microalgae oil is higher than that of the acylglycerol mixture.•Supercritical rosemary extract shows a good protective effect for both products.
Display omitted
•Phenolic acid derivatives (canolol and guaiacol) stabilized linoleic acid-rich oils.•Additive type was more important for oil oxidative stability than its concentration.•Canolol was ...4–18 times more effective antioxidant in tested oils than guaiacol.•The lower the initial oil quality, the weaker the protective effect of canolol.•At 100 ppm canolol proved the most efficient, particularly in hemp and poppy oils.
Oils high in linoleic acid are the main sources of polyunsaturated fatty acids in the human diet. The study attempted to increase the oxidative stability of 11 cold-pressed oils with various linoleic acid percentages by adding phenolic acid derivatives (canolol, guaiacol) at concentrations of 20–100 ppm. The oils were characterized by acid, peroxide and anisidine values, diene, triene, and water contents, fatty acid composition, and bioactive compounds. Their oxidative stability was evaluated before and after the addition of phenolic acid derivatives in the Rancimat test. The results indicate that both additives can be deployed as antioxidants in linoleic acid-rich oils, but canolol elicits a stronger protective effect (over fourfold). 100 ppm of canolol caused a significant increase in the oxidative stability of most oils (31–79%). The guaiacol effectiveness was greater (13–19% increase) at higher concentrations in hemp and poppy oils, but its lower amounts were more relevant for other oils.
Display omitted
•Butylated hydroxytyrosol (HT) derivatives are excellent lipophilic antioxidants.•HT derivatives are better antioxidants than HT and TBHQ at high temperatures.•Bulky alkyl group was ...added to the ortho-diphenolic structure of HT.•DPPH scavenging activity decreased in the presence of bulky alkyl moiety.•Arrhenius kinetic parameters were evaluated.
Two novel lipophilic derivatives of the natural olive oil phenol, hydroxytyrosol (HT), were synthesized using 3,4-dihydroxyphenylacetic acid as starting material. Their antioxidant activities and kinetics compared to HT and TBHQ were assessed by Rancimat, Schaal Oven, 2,2-diphenyl-1-picrylhydrazyl (DPPH) and deep-frying methods. All experiments, including kinetic data analysis based on the Arrhenius equation, utilized in assessing antioxidant activity except the DPPH assay revealed that the new lipophilic HT derivatives exhibited much stronger antioxidant activity than hydroxytyrosol. Tert-butylhydroquinone exhibited stronger antioxidant activity in bulk oil at 65 °C than the new HT derivatives, but showed much lower activity at higher temperatures (>110 °C). This demonstrates that the introduction of bulky alkyl moiety to the ortho-diphenolic structure of HT increased its antioxidant activity. It can be concluded that the new lipophilic HT derivatives satisfy industrial demands for bioactive compounds with strong antioxidant potential at high temperatures.
The present study investigates recovery of polyphenolic compounds from ripe mango (Mangifera indica L.) peel using deep eutectic solvents based on microwave-assisted extraction method. Lactic ...acid/sodium acetate/water (3:1:4) screened out from eight different types of deep eutectic solvent systems was used as extractant. A Box–Behnken design along with response surface methodology was applied to optimize the effect of microwave power (W), time (min), and liquid-to-solid ratio (mL g−1) on polyphenol extraction. The optimized conditions determined were power of 436.45 W, time of 19.66 min, and liquid-to-solid ratio of 59.82 mL g−1. Under the optimal conditions, the recovery of total phenolic content, ferric reducing antioxidant power, and 2,2-diphenyl-1-picrylhydrazyl scavenging activity was 56.17 mg gallic acid equivalent g−1 dw, 683.27 µmol ascorbic acid equivalent g−1 dw, and 82.64 DPPHsc%, respectively. High Performance Liquid Chromatography (HPLC) analysis revealed mangiferin as the prominent phenolic compound in the mango peel extracts. Microwave-assisted deep eutectic solvent extraction showed remarkable effects on the extraction efficiency of phenolic compounds as revealed from scanning electron microscopy analysis. Rancimat test results revealed that the oxidative stability almost doubled upon addition of purified mango peel extracts to the sunflower oil and thus paving way for the use of mango peel waste as a potential source of antioxidants.
Physicochemical parameters, total phenols contents (TPC), and oxidative stabilities at 120–160 °C were evaluated for two monovarietal (Arbequina and Cobrançosa cultivars, cvs.) and one blend ...extra‐virgin olive oil, confirming the label quality grade and allowing grouping them according to the different TPC (TPC = 88 ± 7, 112 ± 6 and 144 ± 4 mg CAE/kg, for cv. Arbequina, blend and cv. Cobrançosa oils, respectively). The lipid oxidation rate increased with the decrease of the TPC, being Cobrançosa oils (higher TPC) more thermally stable. Kinetic‐thermodynamic parameters were determined using the activated complex/transition‐state theory and the values did not significantly differ for Cobrançosa and blend oils, which had the highest TPC, suggesting a hypothetically threshold saturation of the beneficial effect. Cobrançosa oils had a significant more negative temperature coefficient, higher temperature acceleration factor, greater activation energy and frequency factor, higher positive enthalpy of activation, lower negative entropy of activation, and greater positive Gibbs free energy of activation, probably due to the higher TPC. The results confirmed that lipid oxidation was a nonspontaneous, endothermic, and endergonic process with activated formed complexes structurally more ordered than the reactants. A negative deviation from the Arrhenius behavior was observed for all oils being the super‐Arrhenius behavior more marked for Arbequina oils that had the lowest TPC. Finally, the kinetic‐thermodynamic parameters allowed classifying oils according to the binomial olive cultivar/total phenols level, being the temperature acceleration factor and the Gibbs free energy of activation at 160 °C the most powerful discriminating parameters.
: Large amounts of floral bio‐residues (92.6 g per 100 g of flowers) are generated and wasted in the production of saffron (Crocus sativus) spice. Progress in mechanization of saffron crop offer the ...opportunity to expand the uses of C. sativus flowers, beyond the spice (dried stigmas). The antioxidant potential of flowers of saffron, their separate parts (tepals, stamens, styles, and stigmas) and floral bio‐residues were evaluated by 4 in vitro assays: lipid peroxidation, deoxyribose assay, Rancimat test, and Trolox equivalent antioxidant capacity. Phenolic content and crocetin ester composition were also determined. All the samples studied showed to be potential antioxidants. The highest phenolic, flavonoid, and anthocyanin contents were observed in tepals. Stamens showed lower phenolic, flavonoid, and anthocyanin contents than those of whole flowers, tepals, and floral bio‐residues. Crocetin esters were not found in tepals or stamens. Stamens exhibited the most potent LOO• and OH• radicals scavenging activity, being higher than those of food antioxidant propyl gallate. Flowers of saffron, tepals, stamens, styles, and floral bio‐residues showed LOO•, OH•, and ABTS•− radicals scavenging activity, while stigmas showed LOO• and ABTS•− radicals scavenging activity. All samples studied improved the oxidative stability of sunflower oil in Rancimat test. These antioxidant properties could suggest the application of this floral material as functional ingredients with the subsequent added value.
Practical Application: Saffron spice, the most valuable spice worldwide, is the dried stigma that only represents 7.4% of Crocus sativus flowers. Other parts of the flowers different to stigmas are discarded. Flower harvest and all the postharvest steps to produce saffron spice are performed manually. Mechanization of flower collection, stigma separation, and dehydration process is a revolution in saffron spice production, which increases the productive capacity making it possible to extend the uses of C. sativus flowers, beyond the production of saffron spice. Flowers possessed high‐phenolic content and excellent antioxidant properties that could contribute to their application as functional ingredients.
PDF
