Effect of plant extracts on the oxidative stability of sunflower oil and emulsion

The antioxidative activities of six plant extracts (catnip, hyssop, lemon balm, oregano, sage and thyme) were evaluated in sunflower oil and its 20% oil-in-water emulsion in the dark at 60°C. The oxidation process was followed by measuring the formation of primary (conjugated diene hydroperoxides) and secondary (volatile compounds) oxidation products. Sage extracts (600 and 1200 ppm) effectively inhibited the formation of conjugated dienes and volatile compounds (hexanal and pentanal) in oil and emulsion and showed the highest antioxidative activity compared with 300 ppm BHT. Thyme and lemon balm extracts inhibited hexanal generation more than formation of conjugated dienes in both oil and emulsion. Oregano extract was more active in oil than in emulsion. Catnip and hyssop extracts (600 ppm) showed prooxidative action to sunflower oil at 60°C. These two extracts increased the formation of conjugated dienes compared with the control oil. In emulsions, catnip extract (600 ppm) was active and significantly inhibited the formation of conjugated dienes more than BHT (300 ppm) during additional incubation.     

Effect of oregano and rosemary essential oils on lipid oxidation of stored frozen minced gilthead sea bream muscle

The study aimed to determine the effect of oregano and rosemary essential oils addition to minced gilthead sea bream muscle on lipid oxidation during frozen storage. Each essential oil was added to minced fish muscle at 500 mg/kg concentration which then was stored at ?22 °C for 12 months. Oregano essential oils inhibited the formation of conjugated diene and triene hydroperoxides and thiobarbituric reactive substances when compared with untreated samples after the first month and rosemary essential oils after the first and third month of frozen storage. Oregano and rosemary essential oils could be used as ingredients to prevent oxidation in stored frozen minced gilthead sea bream muscle, when long term preservation is not needed. The rate of lipid oxidation depends on antioxidant source. The rosemary essential oil proved to be more efficient in preventing lipid oxidation of minced gilthead sea bream muscle than oregano essential oil.     

Antioxidant efficacy of extracts produced from pickled and dried mustard in rapeseed and peanut oils

Antioxidant efficacy of 70% ethanol extract (EE), 70% methanol extract (ME), and water extract (WE) produced from pickled and dried mustard (Brassica juncea Coss. var. foliosa Bailey) was evaluated in rapeseed and peanut oils by using the Schaal oven method. The protective effects of aforesaid 3 extracts in stabilizing vegetable oils were tested by measuring their peroxide values, conjugated diene values, and p-anisidine values during storage of 15 d at 60 °C. Results showed that the different solvent extracts produced from pickled and dried mustard, at concentrations of 0.5% and 1.0% (w/w) in vegetable oils, could significantly (P < 0.05) lower the peroxide value, conjugated diene value, and p-anisidine value of oils during storage at 60 °C. However, the extracts at various concentrations showed a less antioxidant effect than butylated hydroxytoluene (BHT) at 200 ppm. The ultraviolet spectra of different extracts exhibited a single maximum absorbance at 268 nm. The qualitative analysis of antioxidants present in the extracts was carried out by reverse phase high performance liquid chromatography (HPLC) using a C18 column. Two phenolic compounds, gallic and protocatechuric acids, were identified. The antioxidant activity of the extracts might be attributed to the presence of these phenolics. These results indicated that the pickled and dried mustard could be used as a potential source of natural antioxidants. PRACTICAL APPLICATION: The antioxidant activity of extracts produced from pickled and dried mustard toward rapeseed and peanut oils oxidation and the characterization of active phenolic compounds may be useful in developing natural antioxidants for vegetable oils. Moreover, the extracts could safely be used as potential antioxidant to suppress lipid oxidation in lipid-containing food products.     

Effect of blackberry and raspberry juice on whey protein emulsion stability

The effect of raspberry and blackberry juice on oil-in-water (o/w) emulsion oxidative stability was investigated with different concentrations of whey proteins and rapeseed oil. The extent of lipid oxidation was measured by determining conjugated diene hydroperoxides and thiobarbituric acid reactive substances and that of protein oxidation by loss of natural tryptophan fluorescence and formation of protein carbonyl compounds. In addition, the anthocyanin colour stability and emulsion turbidity were measured. The increasing concentration of whey proteins and berry juices led to enhanced stabilization of the interface formed during emulsification. The anthocyanin concentration and colour decreased during oxidation leading to whiter emulsions. Raspberry juice provided a better overall antioxidant protection towards lipid and protein oxidation compared to blackberry juice. The antioxidant activity of berry juices towards lipid oxidation varied with concentration. The antioxidant activity increased with increasing concentration of berry juices. In conclusion, red berry juice anthocyanins, as well as other phenolic compounds, act as antioxidants improving the oxidative stability of whey protein emulsions. However, the antioxidant protection is different towards protein and lipid oxidation, and is also affected by other components present.     

Aroma profiles of vegetable oils varying in fatty acid composition vs. concentrations of primary and secondary lipid oxidation products

The aroma compositions of oxidised sunflower oil, linseed oil and a blend thereof (85/15) were compared with frequently used indicators for primary and secondary lipid oxidation. Primary lipid oxidation was followed by the formation of conjugated dienes, secondary lipid oxidation by proponal and hexanal formation. Highest concentrations of conjugated dienes and propanal were measured in the linseed oil, followed by the blend and sunflower oil, respectively. Highest concentrations of hexanal were determined in the blend. At similar primary oxidation levels, volatile compounds of the oils were isolated in a model mouth system and subsequently analysed by gas chromatography/sniffing port analysis. Propanal, pentanal, 1-penten-3-one, hexanal, 1-pentanol, octanal, 1-octen-3-one, 1-octen-3-ol and (E,Z)-2,4-heptadienal possessed detectable odours. Comparing the three oils, most aroma compounds and greatest intensities were determined in the blend. Conjugated diene concentrations did not predict the formation of aroma compounds adequately. Although propanal and hexanal concentrations were reasonable indicators for aroma development in linseed and sunflower oil, respectively, neither of the indicators predicted aroma development in all three oils sufficiently.     

Activity of plant extracts for preserving functional food containing<Emphasis Type="Italic"> n</Emphasis>-3-PUFA

The ability of antioxidants obtained from natural sources to stabilise foodstuffs containing long n-3 fatty acids of marine origin has been determined. Food systems enriched in polyunsaturated fatty acids (PUFA) were: emulsified horse mackerel (Trauchurus trauchurus) muscle, fish oil-in-water emulsions (4% of n-3 PUFA) and fish oils (40% of n-3 PUFA). Rosemary leaves and extra virgin olive oil (EVO) were employed as sources of natural phenolic antioxidants. Both vegetable extracts were able to retard lipid oxidation in the different lipid systems. Rosemary extracts with a high content of carnosoic acid showed a significant synergism with fish proteins, by reinforcing their antioxidative effectiveness. Fish proteins and EVO-phenolics showed minor cooperative effects for inhibiting oxidation. The antioxidative partition into the different phases in the emulsified systems showed minor amounts of phenolics in the aqueous phases, except hydroxytyrosol and tyrosol, and a high adsorption on fish muscle.An erratum to this article can be found at     

Natural antioxidants from herbs and spices improve the oxidative stability and frying performance of vegetable oils

Lipid oxidation has been identified as the major deterioration process of vegetable oils. Undesirable effects are even more profound when food processing involves high temperatures in the presence of oxygen. Natural ground herbs (black pepper, ginger, turmeric, rosemary and oregano) were assessed for their antioxidant capacity, phenolic content and ability to improve the oxidative stability of vegetable oils. The most potent herb was incorporated in vegetable oils formulations which were subjected to consecutive frying cycles. The oxidative stability of the vegetable oils, the formation of conjugated dienes/trienes and the decimation of tocopherol levels after the frying process were assessed. Rosemary powder was the most effective antioxidant among the ones tested. The oxidative stability of tocopherol‐stripped corn oil with rosemary powder (1.53 ± 0.06 h) was significantly higher than the control (0.84 ± 0.02 h) and the oil with synthetic antioxidants (1.20 ± 0.03 h). Rosemary powder effectively improved the oxidative stability of sunflower (128.91%), olive (55.61%) and rapeseed (73.20%) oil during deep‐frying and prevented CD and CT formation in rapeseed oil.     

迷迭香脂溶性提取物在花生油中抗氧化性能研究

本文将化学抗氧化剂BHA+BHT和迷迭香脂溶性提取物鼠尾草酸及熊果酸+齐墩果酸添加至花生油中,经过20天高温加速氧化实验,测定花生油过氧化值、共轭二烯和酮类物质生成量、DPPH自由基清除率、ABTS自由基清除率、脂肪酸组成及非皂化物组成变化等指标,考察抗氧化剂对花生油抗氧化性的影响。结果显示：油样过氧化值和共轭二烯值的增长幅度大小顺序：无添加﹥熊果酸+齐墩果酸﹥BHA+BHT﹥鼠尾草酸,鼠尾草酸抑制花生油中过氧化物和共轭二烯类物质生成的效果最显著;不饱和脂肪酸含量下降幅度大小排序：无添加﹥熊果酸+齐墩果酸﹥BHA+BHT﹥鼠尾草酸,鼠尾草酸抑制不饱和脂肪酸的氧化作用最明显;花生油中8种非皂化物成分呈先上升后下降的趋势,在20天高温贮藏阶段并没有明显被消耗;油样DPPH自由基清除率下降幅度大小顺序：无添加﹥熊果酸+齐墩果酸﹥BHA+BHT﹥鼠尾草酸,鼠尾草酸减缓DPPH自由基清除率的下降速率最显著;油样ABTS自由基清除率下降幅度大小顺序：熊果酸+齐墩果酸﹥无添加﹥BHA+BHT﹥鼠尾草酸,鼠尾草酸减缓ABTS自由基清除率下降的速率最有效。综上可知迷迭香提取物鼠尾草酸对保持花生油抗氧化性的能力显著优于化学合成抗氧化剂BHA+BHT,而迷迭香提取物熊果酸+齐墩果酸抗氧化效果略逊于化学合成抗氧化剂。该研究可为迷迭香抗氧化剂在花生油及其它油脂产品生产中的推广运用奠定基础,为企业研究植物油新型抗氧化剂、实现迷迭香资源的综合利用提供参考。     

Antioxidative effect of cactus pear fruit (<Emphasis Type="Italic">Opuntia ficus-indica</Emphasis>) extract on lipid peroxidation inhibition in oils and emulsion model systems

The lipid peroxidation inhibitory effects of cactus pear fruit (Opuntia ficus-indica) extracts (CPFE) on fish oil, fish oil-in-water emulsion and linoleic acid were studied using conjugated diene hydroperoxides (CDH), weight gaining, peroxide value (PV), and thiobabituric acid reactive substances (TBARS) assays. A modified DPPH assay was used in the characterization of CPFE antioxidants for their thermal stability. CPFE successfully controlled lipid peroxidation at different stages of the pathway in a dose-dependent manner. Inhibition of the lipid peroxidation in oils and emulsion was successfully improved by increasing the level of CPFE from 0.01 to 0.1%. CPFE controlled conjugated diene formation from lipid radicals, demonstrating lower conjugated diene hydroperoxide values than its control counterpart. Moreover, it controlled the addition of oxygen to conjugated dienes to form lipid peroxyl radicals, resulting in lower weight gain. It also recorded a lower PV than its control counterpart, indicating its inhibitory effect on peroxyl radical formation. Such multiple and integrated effects controlled the overall lipid peroxidation, resulting in lower TBARS values than the control. Characterization of the CPFE antioxidants proved that those antioxidants are heat-resistant, although the color of the CPFE pigments disappeared rapidly.     

Effects of different polarity of onion skin extracts on antioxidative properties and non-volatile profiles

Onion skins are agricultural by-products that contain high levels of antioxidants, including quercetin and protocatechuic acid. The solubility of extracts can affect their antioxidant capacity in food oil matrices. The antioxidative properties of onion skin extracts with different polarity were compared and the chemical profiles of the extracts were identified by GC-MS. Highly lipophilic, moderately hydrophilic and highly hydrophilic onion skin extracts (HLE, MHE and HHE, respectively) were prepared and their antioxidant properties were tested using in vitro assays and bulk oil or oil-in-water (O/W) emulsions. The most abundant phenolic compounds in the onion skin extracts were quercetin and protocatechuic acid. The lipophilicity levels of HLE, MHE and HHE were 0.674, 0.394 and −1.225, respectively. HLE showed higher antioxidant capacity in bulk oil and O/W emulsion matrices compared to MHE and HHE. The antioxidant capacity of HLE was higher in the O/W emulsion than in the bulk oil system. Therefore, highly lipophilic onion skin extracts can be used as effective natural antioxidants in oil matrices, especially O/W emulsions.     

Inhibition of oxidation of omega-3 polyunsaturated fatty acids and fish oil by quercetin glycosides

The antioxidant properties of naturally occurring flavonols, quercetin glycosides, were examined and compared with common food antioxidants butylated hydroxytoluene (BHT) and α-tocopherol. Antioxidants were incorporated into selected polyunsaturated fatty acids (PUFA) or fish oil in aqueous emulsions and bulk oil systems. The effectiveness of quercetin was similar to or greater than quercetin glycosides in inhibiting lipid oxidation in the oil-in-water emulsion systems when oxidation was induced by heat, light, peroxyl radical or ferrous ion. In bulk fish oil, C-3 glycosylation enhanced the antioxidant activity of quercetin. The effectiveness of quercetin and its glycosides was greater than that of α-tocopherol in the emulsions. Quercetin and quercetin-3-O-glucoside exhibited a better antioxidant activity than BHT in bulk fish oil; however, the reverse was observed in the emulsions of omega-3 PUFA and fish oil systems in agreement with the polar paradox theory. Quercetin and its glycosides were more effective than α-tocopherol in emulsion systems.     

基于GC-IMS分析三种植物油炒制海鲈鱼鱼松中挥发性风味物质的研究

本研究以海鲈鱼鱼松为研究对象,通过感官评分、色差和质构确定了植物油最佳添加量为3%。在此基础上,采用气相色谱-离子迁移谱（Gas Chromatography-Ion Mobility Spectroscopy,GC-IMS）技术深入分析了三种植物油（花生油、棕榈油和葵花籽油）炒制鱼松过程中挥发性风味物质的组成情况。结果表明,三种植物油炒制的鱼松中共鉴定出40种挥发性风味物质,包括醛类、醇类、酯类和酮类化合物等,其中,花生油、棕榈油和葵花籽油炒制鱼松中醛类的相对含量最高,分别为63.33%、57.58%和43.75%。不同植物油炒制鱼松中存在特征风味物质,其中,丙醛、苯甲醛分别只存在于花生油、棕榈油炒制鱼松中;3-甲基-1-丁醇和己醛同时存在于花生油和葵花籽油炒制鱼松中。本研究结果表明根据GC-IMS建立的三种植物油炒制鱼松指纹图谱相似度较低,能有效区分炒制鱼松的植物油来源,可作为植物油炒制鱼松的鉴定及掺伪鉴别的有效手段。     

Antioxidants in lipid foods and their impact on food quality

This paper reviews the antioxidant properties of tocopherols and ascorbic acid in edible oils, and the impact of interfacial phenomena on their activities in emulsions and the effects of edible oil processing. Tocopherols are the most important natural antioxidants found in vegetable oil-derived foods. These antioxidants can interrupt lipid autoxidation by interfering with either the chain propagation or the decomposition processes. α-Tocopherol at high concentrations inhibits hydroperoxide decomposition but promotes hydroperoxide formation. The effect of antioxidants in inhibiting hydroperoxide decomposition may thus be critical in preserving food quality by reducing rancidity due to aldehyde formation. Ascorbic acid can regenerate α-tocopherol, inactivate metal initiators and reduce hydroperoxides. The activity of natural antioxidants is greatly affected by complex interfacial phenomena in emulsions and multi-component foods. In an oil-in-water emulsion system, the lipophilic antioxidants α-tocopherol and ascorbyl palmitate are more effective than in bulk oil, while the opposite trend is found for the hydrophilic antioxidants Trolox and ascorbic acid. The methodology to evaluate natural antioxidants must be carefully interpreted depending on whether oxidation is carried out in bulk oils or in emulsions, and what method is used to measure lipid oxidation.     

Oregano and rosemary extracts inhibit oxidation of long-chain n-3 fatty acids in menhaden oil

ABSTRACT:  Capabilities of methanol extracts from oregano and rosemary in retarding oxidation of long-chain polyunsaturated fatty acids, docosahexaenoic acid C22:6 (DHA) and eicosapentaenoic acid C20:5 (EPA), in menhaden oil were investigated. The fish oils after mixing with the extracts at different concentrations were oxidized in an accelerated study by heating at 150 °C for 30 min or incubating at 60 °C for 5 d. After heating at 150 °C, only 15.9% of DHA and 18.5% of EPA remained in the fish oil without extract, while 38.8% to 65.9% of DHA and 44.7% to 69.0% of EPA were retained in the fish oil mixed with 1% to 5% of oregano extract. The highest retained DHA (56.9%) and EPA (58.0%) in the fish oils mixed with rosemary extract were observed at 2.5% addition. Increasing rosemary extract to 5% lowered its capability of inhibiting DHA and EPA oxidation. After incubation at 60 °C for 5 d, the highest inhibition capability was also found at 2.5% of added rosemary extract, and the oil retained 88.2% DHA and 88.3% EPA. However, only 18.8% DHA and 23.6% EPA were retained in the fish oil mixed with 5% of oregano extract and no DHA and EPA were detected in the fish oil without extract after 5-d incubation at 60 °C. Thus, antioxidant activity of the rosemary extract was greater than that of oregano extract, but was sensitive to heat. The rosemary extract also demonstrated higher DPPH (2,2'-diphenyl-1-picrylhydrazyl) free radical scavenging capability, which was approximately 3 times higher than oregano extract, although there was no significant difference in the total phenolic contents between both extracts.     

Influence of lipid type on gastrointestinal fate of oil-in-water emulsions: In vitro digestion study

The potential gastrointestinal fate of oil-in-water emulsions containing lipid phases from different sources was examined: vegetable oils (corn, olive, sunflower, and canola oil); marine oils (fish and krill oil); flavor oils (orange and lemon oil); and, medium chain triglycerides (MCT). The lowest rates and extents of lipid digestion were observed for emulsified flavor oil, followed by emulsified krill oil. There was no appreciable difference between the final amounts of free fatty acids released for emulsified digestible oils. Differences in the digestibility of emulsions prepared using different oils were attributed to differences in their compositions, e.g., fatty acid chain length and unsaturation. The particle size distribution, particle charge, microstructure, and macroscopic appearance of the emulsions during passage through the simulated GIT depended on oil type. The results of this study may facilitate the design of functional foods that control the digestion and absorption of triglycerides, as well as the bioaccessibility of hydrophobic bioactives.     

Green tea extract as food antioxidant. Synergism and antagonism with α-tocopherol in vegetable oils and their colloidal systems

The antioxidant effects of α-tocopherol (TOH) in combination with green tea extract (GTE), the green tea polyphenol (−)-epicatechin (EC) or the isomeric (+)-catechin (C), were investigated using different lipid systems based on high linoleic sunflower oil: bulk oil, o/w-emulsion and a phosphatidylcholine-based liposome system. Both polyphenols as well as TOH were efficient antioxidants in all systems when used alone, as detected by the formation of free radicals and conjugated dienes and by oxygen consumption. Strong synergistic effect was found for the combination of TOH and GTE in a methyl linoleate o/w-emulsion and in the pure bulk oil, while only an additive effect was observed in a liposome system. The synergism was already evident for the tendency for radical formation in the bulk oil as detected by electron spin resonance (ESR) spectroscopy. On the contrary, combinations of TOH with either EC or C showed clear synergistic effects in both heterogeneous systems, but antagonistic or additive effects in bulk oil. GTE may accordingly be used to protect both vegetable oils and their emulsions against oxidation through enhancement of the activity of their endogenous antioxidants, while GTE is less efficient in the protection of phospholipids as in liposomes.     

Inhibition of lipid oxidation by encapsulation of emulsion droplets within hydrogel microspheres

The purpose of this study was to assess whether the oxidation of polyunsaturated lipids could be inhibited by encapsulating them within protein-rich hydrogel microspheres (size range 1-100 μm). Filled hydrogel microspheres were fabricated as follows: (i) high methoxy pectin, sodium caseinate, and casein-coated lipid droplets were mixed at pH 7, (ii) the mixture was acidified (pH 5), (iii) casein was cross-linked using transglutaminase, (iv) the pH was adjusted to pH 7. Samples were stored in the dark at 55 °C and were monitored for lipid hydroperoxide formation and headspace propanal. Oxidation of fish oil (1% vol/vol) in the microspheres was compared with that in oil-in-water emulsions stabilised by either sodium caseinate or Tween 20. Emulsions stabilised by Tween 20 oxidised faster than either microspheres or emulsions stabilised by casein, while microspheres and the casein stabilised emulsion showed similar oxidation rates. Results highlight the natural antioxidant properties of food proteins.     

Antioxidative effect of extracts from red grape seed and peel on lipid oxidation in oils of sunflower

The antioxidative effect of red grape seed (RGS) and red grape peel (RGP) ethanolic extracts on primary and secondary lipid oxidation in sunflower and conjugated sunflower (SF/CSF) oils was evaluated. Lipid oxidation was analysed at 60 °C using three methods; conjugated diene (CD) measurements for primary oxidation product development, static headspace gas chromatography (SHGC), and proton transfer reaction-mass spectrometry (PTR-MS) to follow the formation of secondary lipid oxidation products (propanal, 1-penten-3-one, hexanal and octanal).The phenolic content (200 mg/kg) in extracts did not have any effect on the conjugated diene hydroperoxides. After 6 days, high antioxidative effect was found for the secondary oxidation products in CSF for peel extract followed by seed extract. The antioxidative activity for the peel extract was up to 41.2% for propanal measured by PTR as compared with 17.1% for seed extract. On the other hand, at 6 days the peel and seed extracts were shown to expect prooxidative effect on SF for the secondary oxidation products. It has been noticed that SF has high stability for lipid oxidation among all the mixtures tested using the three determination methods. Obviously, PTR-MS succeeded, as an accurate method, to measure the concentration as low as 10 μg/kg, and also to solve the solvent interference.     

Extraction of lipid-soluble antioxidants from rosemary leaves using vegetable oils

The objective of this research was to extract carnosic acid and carnosol, natural lipid-soluble antioxidants, from rosemary leaves without the use of chemical aid. Three different vegetable oils [high oleic soybean oil (HOSO), peanut oil (PO) and cottonseed oil (CO)] were used as the medium for extracting rosemary's lipid-soluble antioxidants. Dried rosemary leaves were ground into fine particles, added two of the selected vegetable oils, mixed and heated. The vegetable oil containing the extracted antioxidants was filtered from the rosemary particles and analysed using high-performance liquid chromatography (HPLC). As a control, a common extraction method using ethanol was performed to compare the oil extraction efficiency for carnosic acid and carnosol. HPLC analysis confirmed the presence of carnosic acid and carnosol in all three vegetable oil solutions. Compared to the ethanol extraction, a higher level of the carnosic acid was found in the vegetable oil solutions. Among the vegetable oils, high oleic soybean oil contained the most carnosic acid; however, there were similar amounts of carnosol in all three vegetable oil solutions. The extractions' efficacy was tested on soybean oil's (SO) oxidative stability by adding 2% (w/w) of the antioxidant–vegetable oil solution. The results obtained from peroxide value (PV) and p-anisidine value (AnV) analysis documented a significantly lower degree of oxidation in the soybean oil containing the extracted antioxidant solutions, compared to the pure soybean oil.     

Activity of caffeic acid in different fish lipid matrices: A review

Caffeic acid, a hydroxycinnamic acid common in different vegetable sources, has been employed as a natural antioxidant for inhibiting oxidation of fish lipids present in different food matrices. The aim of this review is to discuss the mechanisms involved in the antioxidative and prooxidative effects of caffeic acid found in different model systems containing fish lipids. These model systems include bulk fish oils, liposomes from cod roe phospholipids, fish oil emulsions, washed cod mince, regular horse mackerel mince and a fish oil fortified fitness bar. The data reported show that the antioxidant activity depends on the physical state of the lipids and the composition of the intrinsic matrix in which they are situated. Caffeic acid significantly prevented rancidity in both unwashed and washed fish mince, the latter which was fortified with haemoglobin. In the unwashed mince, the activity was however clearly dependent on the lipid to antioxidant ratio. In these systems, an important redox cycle between caffeic acid and the endogenous reducing agents ascorbic acid and tocopherol were further thought to play an important role for the protective effects. The effect of caffeic acid was also highly dependent on the storage temperature, showing higher effectiveness above than below 0 °C. Caffeic acid was not able to inhibit oxidation of bulk fish oils, fish oil in water emulsions and the fish-oil enriched fitness bar. In the liposome system, caffeic acid inhibited haemoglobin (Hb)-promoted oxidation but strongly mediated Fe²⁺ mediated oxidation. In conclusion, caffeic acid can significantly prevent Hb-mediated oxidation in fish muscle foods but its activity in food emulsions and liposomes is highly dependent on the pH, the emulsifier used and the prooxidants present.