Antioxidant activity of phenolic compounds in sunflower oil‐in‐water emulsions containing sodium caseinate and lactose

The aim of this work was to study the evolution of oxidation and the efficiency of phenolic antioxidants in sunflower oil‐in‐water emulsions containing sodium caseinate and lactose (Cas‐Lac) or stabilized by Tween‐20 (T‐20). Two groups of phenolic antioxidants which are structurally similar were tested, i.e. (1) α‐tocopherol and its water‐soluble analogue, Trolox; and (2) gallic acid and its ester derivatives propyl gallate and dodecyl gallate. Emulsion samples were oxidized at 40 °C and the progress of oxidation was followed through quantitation of oxidized triacylglycerol monomers, dimers and oligomers. Results showed that Cas‐Lac emulsions were more stable to oxidation than T‐20 emulsions. In both types of emulsions, the most protective antioxidants were the compounds of lower polarity, namely, α‐tocopherol and dodecyl gallate. It was also found that substantial amounts of α‐tocopherol coexisted with significant polymerization, which was indicative of the heterogeneity of oxidation, i.e. differences of oxidation rate in oil droplets.     

Antioxidant and prooxidant effects of α‐tocopherol in a linoleic acid‐copper(II)‐ascorbate system

The peroxidation of linoleic acid (LA) in the absence and presence of either Cu(II) ions alone or Cu(II)‐ascorbate combination was investigated in aerated and incubated emulsions at 37°C and pH 7. LA peroxidation induced by either copper(II) or copper(II)‐ascorbic acid system followed pseudo‐first order kinetics with respect to primary (hydroperoxides) and secondary (aldehydes‐ and ketones‐like) oxidation products, detected by ferric‐thiocyanate and TBARS tests, respectively. α‐Tocopherol showed both antioxidant and prooxidant effects depending on concentration and also on the simultaneous presence of Cu(II) and ascorbate. Copper(II)‐ascorbate combinations generally led to distinct antioxidant behavior at low concentrations of α‐tocopherol and slight prooxidant behavior at high concentrations of α‐tocopherol, probably associated with the recycling of tocopherol by ascorbate through reaction with tocopheroxyl radical, while the scavenging effect of α‐tocopherol on lipid peroxidation was maintained as long as ascorbate was present. On the other hand, in Cu(II) solutions without ascorbate, the antioxidant behavior of tocopherol required higher concentrations of this compound because there was no ascorbate to regenerate it. Practical applications: Linoleic acid (LA) peroxidation induced by either copper(II) or copper(II)‐ascorbic acid system followed pseudo‐first order kinetics with respect to primary (hydroperoxides) and secondary (e.g., aldehydes and ketones) oxidation products. α‐Tocopherol showed both antioxidant and prooxidant effects depending on concentration and also on the simultaneous presence of Cu(II) and ascorbate. The findings of this study are believed to be useful to better understand the actual role of α‐tocopherol in the preservation of heterogenous food samples such as lipid emulsions. Since α‐tocopherol (vitamin E) is considered to be physiologically the most important lipid‐soluble chain‐breaking antioxidant of human cell membranes, the results can be extended to in vivo protection of lipid oxidation.     

Kinetics of antioxidant action of α‐ and γ‐toco‐pherols in sunflower and soybean triacylglycerols

A kinetic analysis was performed to evaluate the antioxidant behavior of α‐ and γ‐to‐copherols (5—2000 ppm) in purified triacylglycerols obtained from sunflower oil (TGSO) and soybean oil (TGSBO) at 100 °C. Different kinetic parameters were determined, viz. the stabilization factor as a measure of effectiveness, the oxidation rate ratio as a measure of strength, and the antioxidant activity which combines the other two parameters. In the low concentration range (up to 400 ppm in TGSBO and up to 700 ppm in TGSO) α‐tocopherol was a more active antioxidant than γ‐tocopherol whereas the latter was more active at higher concentrations. It has been found that the different activity of the tocopherols is not due to their participation in chain initiation reactions, but that the loss of antioxidant activity at high tocopherol concentrations is due to their consumption in side reactions. The rates of these reactions are higher in TGSBO than in TGSO. Both α‐tocopherol itself and its radicals participated more readily in side reactions than γ‐tocopherol and its radicals. Both α‐ and γ‐tocopherol reduce lipid hydroperoxides, thus generating alkoxyl radicals which are able to amplify the rate of lipid oxidation by participating in chain propagation reactions.     

Effect of different antioxidants on lycopene degradation in oil‐in‐water emulsions

There is interest in incorporating lycopene into foods because it is a natural pigment and can also play a role in preventing disease. Therefore, the effect of the addition of various antioxidants in lycopene containing oil‐in‐water emulsions stabilized with Tween 20 at acidic pH was studied in order to determine protection systems against lycopene oxidation. In this model, EDTA showed pro‐oxidant activity while other chelators like citric acid and tripolyphosphate showed no effect. The free radical scavengers, propyl gallate (PG), gallic acid (GA), and α‐tocopherol all had the ability to decrease lycopene oxidation with α‐tocopherol being the most effective. The combination of 1 µM α‐tocopherol and 10 µM GA was more effective than the individual antioxidants. Addition of ascorbic acid to the combination of α‐tocopherol and GA system accelerated lycopene loss. These results suggest that by the proper selection of free radical scavenging antioxidants, lycopene stability in oil‐in‐water emulsions could be significantly improved. Practical applications: Evidence that dietary lycopene decreases the risk for a number of health conditions has generated new opportunities for addition of lycopene to functional foods. A successful strategy to deliver lycopene into foods is by means of oil‐in‐water emulsions. However, lycopene may decompose thus causing nutritional loss and color fading. In order to prevent this, the effectiveness of various antioxidants and their combinations in Tween 20 stabilized oil‐in‐water emulsions was studied. Overall, lycopene oxidation in oil‐in‐water emulsions could be significantly reduced by the proper selection of free radical scavengers. This fact is of interest to food industry for increasing the shelf‐life of lycopene containing functional foods where the lycopene is dispersed in the food in the form of an oil‐in‐water emulsion.     

Emulsifier type,metal chelation and pH affect oxidative stability of n‐3‐enriched emulsions

Recent research has shown that the oxidative stability of oil‐in‐water emulsions is affected by the type of surfactant used as emulsifier. The aim of this study was to evaluate the effect of real food emulsifiers as well as metal chelation by EDTA and pH on the oxidative stability of a 10% n‐3‐enriched oil‐in‐water emulsion. The selected food emulsifiers were Tween 80, Citrem, sodium caseinate and lecithin. Lipid oxidation was evaluated by determination of peroxide values and secondary volatile oxidation products. Moreover, the zeta potential and the droplet sizes were determined. Tween resulted in the least oxidatively stable emulsions, followed by Citrem. When iron was present, caseinate‐stabilized emulsions oxidized slower than lecithin emulsions at pH 3, whereas the opposite was the case at pH 7. Oxidation generally progressed faster at pH 3 than at pH 7, irrespective of the addition of iron. EDTA generally reduced oxidation, as evaluated by volatiles formation in all emulsions, irrespective of pH and emulsifier type, except in the lecithin and caseinate emulsions where a pro‐oxidative effect was observed for some volatiles. The different effects of the emulsifier types could be related to their ability to chelate iron, scavenge free radicals, interfere with interactions between the lipid hydroperoxides and iron as well as to form a physical barrier around the oil droplets.     

Process efficiency and long‐term performance of α‐tocopherol in film‐blown linear low‐density polyethylene

α‐Tocopherol was compared with a commercial phenolic antioxidant (Irganox 1076) as a long‐term and process antioxidant in film‐blown and compression‐molded linear low‐density polyethylene. The antioxidant function of α‐tocopherol was high in the film‐blown material, especially in the processing, according to oxygen induction time measurements with differential scanning calorimetry. The residual content of α‐tocopherol after processing, determined with chromatographic techniques, was less than that of the commercial phenolic antioxidant in both the film‐blown and compression‐molded materials. The process stabilizing efficiency was nevertheless higher for the material containing α‐tocopherol. During the long‐term stabilization, the efficiency of α‐tocopherol was less than that of the commercial phenolic stabilizer Irganox 1076 in the thin films, according to chemiluminescence and infrared measurements. The long‐term efficiency in the compression‐molded samples stabilized with α‐tocopherol or Irganox 1076 was equally good because of the low loss of both α‐tocopherol and Irganox 1076 from the thicker films. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2427–2439, 2005     

γ‐ and δ‐tocopherols are more effective than α‐tocopherol on the autoxidation of a 10% rapeseed oil triacylglycerol‐in‐water emulsion with and without a radical initiator

The antioxidative effects of γ‐ and mainly δ‐tocopherol in a multiphase system were hardly considered up to now. The aim of this study was i) to assess the effects and ii) to follow the degradation of α‐, γ‐ and δ‐tocopherol in concentrations of 0.01%, 0.05%, 0.1% and 0.25% during the oxidation of a 10% purified rapeseed oil triacylglycerol‐in‐water emulsion at 40 °C in the dark for 15 wk in a system containing a low oxygen concentration. Oxidation experiments were performed weekly by assessing the formation of hydroperoxides and hexanal, and the stability of the tocopherols was determined using high‐performance liquid chromatography. Storage tests were conducted with and without the addition of 0.01% α, α′‐azoisobutyronitrile (AIBN), which is a known radical initiator. α‐Tocopherol increased the formation of hydroperoxides in both tests as well as the generation of hexanal when the radical initiator was added; furthermore it was the least stable. γ‐Tocopherol delayed the formation of hexanal and prolonged the stability of the emulsion in a dose‐dependant manner. δ‐Tocopherol was the most stable and also the most effective in delaying lipid oxidation in the emulsions. Each concentration that was tested reduced the rate of hydroperoxide and especially hexanal formation. Hexanal was only formed to a slight extent after 15 wk of oxidation in the test with AIBN and the lowest dose of 0.01% δ‐tocopherol. For all tocopherols, strong correlations were found between tocopherol stability and the extent of oxidation. Results suggest that i) mainly δ‐tocopherol, but also γ‐tocopherol even less pronounced, are very good antioxidants in order to stabilize and prolong the shelf life of oil‐in‐water emulsions, ii) the antioxidative effects were intensified with increasing amounts.     

Solid Lipid Nanoparticles: Effect of Carrier Oil and Emulsifier Type on Phase Behavior and Physical Stability

The impact of surfactant type and carrier oil type on the phase behavior and physical stability of emulsified tripalmitin was investigated. Solid lipid nanoparticles (SLNs) were prepared by homogenizing lipid and aqueous phases at a temperature (≈80 °C) above the melting point of tripalmitin, and then cooling the resulting oil-in-water emulsion to induce lipid droplet crystallization. When stored at 37 °C, tripalmitin particles had good long-term stability (d < 150 nm) when coated with Tween 20, but were prone to aggregation and gelation when coated with modified starch (MS). Conversely, when stored at ≤20 °C tripalmitin particles coated by MS were more stable to aggregation/gelation than those coated by Tween 20. Blending tripalmitin with low melting point lipids (either medium chain triglycerides or orange oil) prior to homogenization led to a considerable alteration in the SLN phase behavior and stability. DSC measurements indicated that the presence of the carrier oils reduced the crystallization temperature, melting temperature, and melting enthalpy of tripalmitin. In addition, the carrier oils improved the stability of SLNs to particle aggregation and gelation, although some particle coalescence still occurred. These results have important implications for formulating colloidal delivery systems for utilization within the food and other industries.     

α‐, γ‐ and δ‐ Tocopherols as inhibitors of isomerization and decomposition of cis,trans methyl linoleate hydroperoxides

The effects of α‐, γ‐ and δ‐tocopherols on the stability and decomposition reactions of lipid hydroperoxides were studied. Isomerization and decomposition of cis,trans methyl linoleate hydroperoxides (cis,trans ML‐OOH) in hexadecane at 40 °C were followed by high‐performance liquid chromatography. Due to its higher hydrogen donating ability, α‐tocopherol was more efficient than γ‐ and δ‐tocopherols in inhibiting the isomerization of cis,trans ML‐OOH to trans,trans ML‐OOH. α‐Tocopherol stabilized hydroperoxides into the cis,trans configuration, whereas γ‐ and δ‐tocopherols allowed hydroperoxides to convert into trans,trans isomers. Thus, the biological importance of α‐tocopherol as compared to other tocopherols may be partly due to its better efficacy in protecting the cis,trans configuration of hydroperoxides formed, for example, in the enzymatic oxidation of polyunsaturated fatty acids. The isomeric configuration of hydroperoxides has an impact on biological activities of further oxidation products of polyunsaturated fatty acids. Paradoxically, the order of activity of tocopherols with regard to hydroperoxide decomposition was different from that obtained for hydroperoxide isomerization. γ‐ and δ‐tocopherols were more efficient inhibitors of ML‐OOH decomposition when compared to α‐tocopherol. A loss of antioxidant efficiency, observed as the tocopherol concentration increased from 2 to 20 mM, was highest for α‐tocopherol but was also evident for γ‐ and δ‐tocopherols. Thus, the differences in the relative effects of tocopherols at differing concentrations seem to result from a compromise between their radical scavenging efficiency and participation in side reactions of peroxidizing nature.     

Preparation,characterization, and oxygen scavenging capacity of biodegradable α‐tocopherol/PLA microparticles for active food packaging applications

In this work, a biodegradable oxygen scavenger system, which consists of α‐tocopherol‐loaded poly(lactic)acid microparticles containing 40 wt% of the natural antioxidant agent, was prepared by an oil in water (O/W) emulsion‐solvent evaporation method. The preparation procedure assured high encapsulation efficiency and production yield and gives no noticeable alteration of the molecular structure of the microencapsulated active α‐tocopherol, as demonstrated by Fourier‐transform infrared and thermogravimetric analyses measurements. The produced active microparticles are semicrystalline and are characterized by suitable morphology (size and shape) to have satisfactory flowability to be used as active powder additive in conventional polymer extrusion technologies. Both the scavenging capacity and rate are in line with the values required for an effective oxygen scavenger system. POLYM. COMPOS., 38:981–986, 2017. © 2015 Society of Plastics Engineers     

Dolichol: A Component of the Cellular Antioxidant Machinery

Dolichol, an end product of the mevalonate pathway, has been proposed as a biomarker of aging, but its biological role, not to mention its catabolism, has not been fully understood. UV‐B radiation was used to induce oxidative stress in isolated rat hepatocytes by the collagenase method. Effects on dolichol, phospholipid‐bound polyunsaturated fatty acids (PL‐PUFA) and known lipid soluble antioxidants [coenzyme Q (CoQ) and α‐tocopherol] were studied. The increase in oxidative stress was detected by a probe sensitive to reactive oxygen species (ROS). Peroxidation of lipids was assessed by measuring the release of thiobarbituric acid reactive substances (TBARS). Dolichol, CoQ, and α‐tocopherol were assessed by high‐pressure liquid chromatography (HPLC), PL‐PUFA by gas–liquid chromatography (GC). UV‐B radiation caused an immediate increase in ROS as well as lipid peroxidation and a simultaneous decrease in the levels of dolichol and lipid soluble antioxidants. Decrease in dolichol paralleled changes in CoQ levels and was smaller to that in α‐tocopherol. The addition of mevinolin, a competitive inhibitor of the enzyme 3‐hydroxy‐3‐methylglutaryl CoA reductase (HMG‐CoAR), magnified the loss of dolichol and was associated with an increase in TBARS production. Changes in PL‐PUFA were minor. These findings highlight that oxidative stress has very early and similar effects on dolichol and lipid soluble antioxidants. Lower levels of dolichol are associated with enhanced peroxidation of lipids, which suggest that dolichol may have a protective role in the antioxidant machinery of cell membranes and perhaps be a key to understanding some adverse effects of statin therapy.     

Influence of Polymorphic Transformations on Gelation of Tripalmitin Solid Lipid Nanoparticle Suspensions

Solid lipid nanoparticle (SLN) suspensions, which consist of submicron-sized crystalline lipid particles dispersed within an aqueous medium, can be used to encapsulate, protect and deliver lipophilic functional components. Nevertheless, SLN suspensions are susceptible to particle aggregation and gelation during their preparation and storage, which potentially limits their industrial utilization. In this study, we examined the aggregation and gelation behavior of SLN suspensions composed of 10 wt% tripalmitin particles (r < 150 nm) stabilized by 1.5% Tween 20. The tripalmitin and aqueous surfactant solution were homogenized above the lipid melting temperature and cooled under controlled conditions to initiate SLN formation. The aggregation and gelation of SLN suspensions during storage was then examined by shear rheometry, differential scanning calorimetry (DSC), light scattering and microscopy. Rheology measurements indicated that gelation times decreased with increasing storage temperature, e.g., samples formed weak gels after 62, 23, and 10 min at 1, 5, and 10 °C, respectively. DSC revealed increasingly rapid α- to β-polymorphic transformations in SLN dispersions stored at 1, 5, and 10 °C, respectively. We propose that the observed aggregation and gelation of SLN suspensions are associated with a change in the shape of the nanoparticles from spherical (α-form) to non-spherical (β-form) when they undergo the polymorphic transition. When they change shape there is no longer sufficient surfactant present to completely cover the lipid phase, which promotes particle aggregation through hydrophobic attraction. Our results have important implications for the design and fabrication of stable SLN suspensions.     

Vitamin E – essential knowledge for supplementation

Misinterpretation of scientific data led vitamin E research in a wrong direction. Scientists focused on α‐tocopherol, ignoring other forms of vitamin E. However, natural α‐tocopherol supplementation significantly increased all‐cause mortality. This paradoxical observation demonstrates flaws in current understanding on vitamin E. Updated knowledge on vitamin E supplementation provides explanation of this paradoxical observation. The less well‐known tocotrienols, but not α‐tocopherol, fulfil the fundamentals for disease prevention which differ from antioxidant activity.     

Role of Emulsifiers in Emulsion Technology and Emulsion Crystallization

High‐pressure homogenization as an emulsification technique and the production of solid lipid nanoparticles are strongly interlinked. The impact of an emulsifier as an important influencing parameter for both processes is described exemplarily for Polysorbate 20 and sodium caseinate. Regarding the emulsification process, Polysorbate 20 led to a higher improvement of the droplet breakup than the protein sodium caseinate. These results were compared with different published investigations on the crystallization behavior of fats with the same emulsifiers. Considering the crystallization behavior of the lipid phase, sodium caseinate was more advantageous in stabilization of the crystallized particles. The most important factors which have to be taken into account were determined and analyzed.     

Effect of classic sterilization on lipid oxidation in model liquid milk‐based infant and follow‐on formulas

The objective of this study was to evaluate the effect of classic sterilization on lipid oxidation of liquid infant and follow‐on formulas by analyzing formation of oxidized and dimeric TAGs. Model systems containing similar components and proportions to those normally found in manufactured samples and a mixture of high‐oleic sunflower oil, rapeseed oil, and fish oil were used to obtain a fatty acid composition profile in accordance with the EU regulations. For comparative purposes, some samples were prepared with high‐oleic sunflower or fish oil and others without the protein components and added Tween‐20. Quantification of total oxidized TAGs provided complete information of the oxidation state and showed clear advantages versus the other methods used, i.e., loss of PUFA and peroxide value. The results showed that the heat treatment used for sterilization did not lead to significant lipid oxidation, but the tocopherol concentration decreased significantly. The marked tocoherol losses found in protein‐free formulas together with the significantly lower tocopherol concentrations in infant formulas (80% whey in protein fraction) compared to follow‐on formulas (80% caseinate in protein ratio) showed the protective effect of the protein fraction, specially sodium caseinate. Practical applications: This study provides useful information on the utility of different methods used to evaluate oxidation in infant and follow‐on formulas. Quantification of total oxidized TAGs standed out because it is a direct and sensitive method and provides complete information at any stage of the oxidative process. Also, this study shows that important decreases of tocopherols may occur during formula processing and special cautions should therefore be taken during storage and commercialization to avoid additional antioxidant losses.     

2,2′‐Bis(monoacylglycero) PO4 (BMP), but Not 3,1′‐BMP,Increases Membrane Curvature Stress to Enhance α‐Tocopherol Transfer Protein Binding to Membranes

Previous work revealed that α‐tocopherol transfer protein (α‐TTP) co‐localizes with bis(monoacylglycero)phosphate (BMP) in late endosomes. BMP is a lipid unique to late endosomes and is believed to induce membrane curvature and support the multivesicular nature of this organelle. We examined the effect of BMP on α‐TTP binding to membranes using dual polarization interferometry and vesicle‐binding assay. α‐TTP binding to membranes is increased by the curvature‐inducing lipid BMP. α‐TTP binds to membranes with greater affinity when they contain the 2,2′‐BMP versus 3,1′‐BMP isomers.     

Efficacy of myricetin as an antioxidant in methyl esters of soybean oil

The antioxidant activity of myricetin, a natural flavonol found in fruits and vegetables, was determined in soybean oil methyl esters (SME) and compared with α‐tocopherol and tert‐butylhydroquinone (TBHQ) over a 90‐day period employing EN 14112, acid value, and kinematic viscosity methods. Myricetin had greater antioxidant activity than α‐tocopherol, but was inferior to TBHQ. Synergism was observed between myricetin and TBHQ, but antagonism between α‐tocopherol and either myricetin or TBHQ was discovered. A binary mixture of myricetin and TBHQ at 1000 ppm (1:1) was the most effective treatment investigated at inhibiting oxidation of SME. Myricetin was not completely soluble in SME at 1000 ppm, suggesting that 500 ppm is a more appropriate treatment level. Pro‐oxidant activity of α‐tocopherol was observed when added to SME obtained from crude soybean oil, but antioxidant behavior was observed in distilled SME. Addition of α‐tocopherol to methyl esters initially free of antioxidants revealed that 600–700 ppm was the optimum concentration for antioxidant activity. Acid value and kinematic viscosity remained within prescribed specifications after 90 days, despite failure of a number of samples with regard to EN 14112, suggesting that these parameters are insufficient as sole indicators of oxidation stability.     

Influence of cholesterol on the kinetics of lipid autoxidation and on the antioxidative properties of α‐tocopherol and quercetin

The autoxidation kinetics of triacylglycerols of sunflower oil (TGSO) in the presence of 10% cholesterol (Chol) at 80, 90 and 100 °C has been studied. The process was followed by monitoring the peroxide value and the formation of conjugated dienes. Cholesterol has been found to exhibit a prooxidative effect. During the oxidation of the mixture (TGSO/Chol), cholesterol peroxides were not registered. It is supposed that the initial amount of cholesterol peroxides formed decomposes to free radicals and that these radicals accelerate TGSO oxidation. A kinetic analysis of the antioxidative behavior of α‐tocopherol and quercetin (2.9 x 10^?4‐17.8 × 10^?4 M) in both TGSO and TGSO/Chol at 100 °C was performed. It was found that the effectiveness, strength, and activity of α‐tocopherol are greater in TGSO/Chol than in TGSO, while these parameters for quercetin are practically the same in both lipid systems. The differences in the mechanism of action of α‐tocopherol and quercetin are discussed.     

The effect of antioxidants on butter in relation to storage temperature and duration

The effects of antioxidants on the oxidative stability of butter, under different storage time and temperature conditions, were evaluated. Natural (α‐tocopherol) and synthetic (BHA and BHT) antioxidants were added to the butter samples at two concentrations (50 and 100 ppm) immediately after the butter samples were produced from the pasteurised sweet cream, after which they were kept in the dark at 4 and ?20 °C for 6 months. Peroxide value (PV) and thiobarbituric acid (TBA) number and the residual antioxidants of the samples were examined at 30‐day intervals, starting on the second day until the end of the storage period. The measurements obtained by assaying PV and TBA number in butter samples showed that both the synthetic and natural antioxidants used were capable of protecting the butter samples against oxidation during storage at both temperatures. The butter samples with 50 ppm antioxidant could be stored for more than 180 days at 4 °C without spoilage. At ?20 °C, the addition of BHA, BHT and α‐tocopherol caused a reduction in the TBA number from 0.31 (control) to 0.21, 0.23 and 0.27 mg malonaldehyde/kg butter, respectively, and the PV decreased from 0.75 (control) to 0.46, 0.56 and 0.54 meq O₂/kg butter, respectively, after 6 months of storage. The highest residue values were determined in both the 100 and 50 ppm α‐tocopherol‐containing samples. These results indicate that α‐tocopherol exhibited a very strong antioxidant activity, which was almost equal to that of the synthetic antioxidants. Therefore, the use of α‐tocopherol is recommended as a natural antioxidant to suppress the development of rancidity in butter.     

3, 4‐Dihydroxymandelic acid amides of alkylamines as antioxidants for lipids

The antioxidative and radical scavenging activity of the 3, 4‐dihydroxymandelic acid (DHMA) amides of hexylamine, 2‐ethylhexylamine, octylamine, and cyclohexylamine was determined by several physicochemical test systems. The amides were synthesized by protecting group‐free coupling of in situ prepared N‐hydroxysuccinimidylester of DHMA and the amines. The radical scavenging activity was determined using the DPPH (2, 2‐diphenyl‐1‐picrylhydrazyl) method and by quenching superoxide anions generated using a horse radish peroxidase/H₂O₂ system. In the DPPH assay, all amides show higher radical scavenging activity (EC₅₀ 0.09‐0.12 mol/mol_DPPH) compared to the standard antioxidants ascorbic acid (EC₅₀ 0.27 mol/mol_DPPH) and tocopherol (EC₅₀ 0.25 mol/mol_DPPH). The amides are also more potent superoxide radical scavengers (IC₅₀ < 600 nm) than standard ascorbic acid (IC₅₀ 700 nm). Activity against lipid peroxidation was determined by accelerated autoxidation of highly unsaturated oils and squalene using the Rancimat. Again, the antioxidative potentials of the DHMA amides against lipid oxidation as determined by the Rancimat, are at least equal or higher compared to the standard lipid antioxidants tocopherol, BHT, BHA, and ascorbylpalmitate (concentration in soybean oil 0.05%, all other oils 0.025%, squalene 0.005%). In squalene, an equi‐amount mixture of DHMA octylamide and α‐tocopherol shows a synergistic effect. Last but not least, the amides are able to protect an emulsion of linoleic acid/β‐carotene against oxidation initiated by N, N‐azodiisobutyramidine dihydrochloride (IC₅₀ 0.19‐0.77 mmol/l, ascorbic acid > 0.9, tocopherol 0.08). The DHMA octylamide in combination with ascorbic acid shows a synergistic antioxidative effect in the emulsion model. In conclusion, the new alkylamides of DHMA are easy to synthesize, potent radical scavengers and protect lipids, in particular the highly unsaturated, both in bulk and in emulsions against autoxidation.