Influence of sn‐1,3‐lipase‐catalysed interesterification on the oxidative stability of soybean oil‐based structured lipids

The oxidative stability of structured lipids (SLs) synthesised by specific sn‐1,3‐lipase catalysed interesterification of soybean oil (SBO) with caprylic acid (CA) in a stirred batch reactor was studied. SLs contained considerable amounts of tocopherol (TOH) isomers, although they lost almost 25% of endogenous TOHs during production. The effects of the addition of different TOH homologues (α, β, γ, δ), ascorbyl palmitate (AP, 200 ppm), lecithin (Le, 1000 ppm), butylated hydroxytoluene (BHT, 100 ppm) and butylated hydroxyanisole (BHA, 100 ppm) on the oxidative stability of SLs were investigated. Induction time (IT) of SBO, determined by the Rancimat method, decreased from 8.4 to 5.8 h at 110 °C after the modification. On the other hand, purified SLs and purified SBO had the same IT due to the tocopherol reduction during silica purification. No significant difference was observed between IT of SLs and SLs plus different α‐tocopherol concentrations (50, 100, 150, 200, 300, 500 and 1000 ppm) (P > 0.05). However, the addition of Le and/or AP significantly improved oxidative stability of purified SLs and SBO. The ternary blend containing δ‐TOH, AP and Le had higher IT than ternary blends of α‐TOH, β‐TOH or γ‐TOH. Furthermore, ternary blend containing BHA, AP and Le had higher IT than ternary blends of BHT, AP and Le. In addition, there was an increase in peroxide value (PV), conjugated diene (CD) content and p‐anisidine value (AV) during oxidation of oils at 60 °C. Antioxidant mixtures of α‐TOH (50 ppm) and δ‐TOH (500 ppm) with AP and Le decreased PV, CD and AV effectively. Copyright © 2006 Society of Chemical Industry     

Conversion of Isoflavone Glycosides to Aglycones in SoyLife and Soymeal Using β-glycosidase

ABSTRACT: Conversion of isoflavones from glycosides to aglycones in SoyLife and soymeal using varying concentrations of β-glycosidase, and different pH conditions and temperatures was investigated. The best conditions for the conversion of glycosides to aglycones were pH 5.0, 50 °C, and 5 h incubation with 5 units β-glycosidase/g Soy Life and 1.5 units/g soymeal. Under these conditions, the amount of genistein, daidzein, and glycitein in Soy Life treated with β-glycosidase were 4.22, 11.52, and 11.85 μmol/g compared to untreated controls of 0.26, 0.97, and 4.43 μmol/g, respectively. In soymeal, the amounts were 3.21, 2.02, and 2.12 μmol/g compared to untreated controls of 1.23, 1.25, and 1.51 μmol/g, respectively. Mole percent recovery of genistein was 87% in Soy Life and 80% in soymeal, respectively.     

Linseed oil stabilisation with pure natural phenolic compounds

Linseed has been used for a very long time in human and animal nutrition. Currently, there is an increasing interest in linseed oil because of its particularly high content in α-linolenic acid (ALA), an omega-3 fatty acid (FA). Unfortunately, ALA turns also the oil extremely sensitive to oxidation. This study aimed at assessing four pure representative phenolic compounds, myricetin (flavonol), (+)-catechin (flavanol), genistein (isoflavone), and caffeic acid (hydroxycinnamic acid) at a concentration of 555 μmol/kg as antioxidants in refined linseed oil (RLO). Their protective effect was assessed by monitoring the hydroperoxide formation, the FA profile and the residual antioxidant concentration in RLO, along its storage at 60 °C according to the Schaal oven test procedure. Caffeic acid, (+)-catechin and myricetin were found to be more efficient than butylated hydroxyanisole (BHA), a synthetic antioxidant. Interestingly, myricetin strongly reduced ALA oxidation. These results confirm that the chemical structure of the phenolic compounds plays a major role in their antioxidant properties.     

Trout‐Skin Gelatin‐Based Edible Films Containing Phenolic Antioxidants: Effect on Physical Properties and Oxidative Stability of Cod‐Liver Oil Model Food

Abstract: Trout‐skin (Oncorhynchus mykiss) gelatin‐based films containing antioxidants (epigallocatechin gallate (EGCG), 50 and 250 ppm w/w) and green tea powder (1% and 20% w/w of gelatin) were tested for tensile strength, elastic modulus, and elongation, and oxygen and water vapor transmission rates, in vitro antioxidant activity using the DPPH (2,2‐diphenyl‐1‐picrylhydrazyl) assay and effect on stabilizing cod‐liver oil held under mild thermal abuse conditions. Cod‐liver oil overlaid with films was stored at 40 °C for 20 d and analyzed for peroxide value (PV) and thiobarbituric acid reactive substances (TBARS). Antioxidant activity was retained in films containing green tea powder, but was reduced (P < 0.05) in EGCG films (20 d, 23 °C). Water vapor transmission rate of the films incorporated with antioxidants did not change significantly (P > 0.05), but the oxygen transmission rate for films with 50 ppm EGCG and 20% green tea powder was significant (P < 0.05). Other physical properties varied with antioxidant incorporation. The TBARS and PV of control oil increased from 0.05 ± 0.01 to 4.71 ± 0.30 g MDA/kg oil and from 3.6 ± 0.2 to 178.3 ± 24.5 millieq peroxides/kg oil, respectively, after 20 d. For cod‐liver oil covered with control or antioxidant‐containing films, TBARS remained below 0.37 g MDA/kg oil and PV below 7 millieq peroxides/kg oil. Incorporation of antioxidants to the films did not reduce oil oxidation (P > 0.05) at the levels tested and this was confirmed by activation energy calculations. The rate of oil oxidation was more dependent upon the inherent oxygen barrier property of the films than the presence of antioxidants. Practical Application: This research has the potential to enhance the utilization of fish skins, a valuable food processing by‐product, as edible films with natural antioxidants to extend the shelf life of foods. The film physical properties and barrier to oxygen and water are investigated.     

SYNERGISTIC ACTIVITY OF CAPELIN PROTEIN HYDROLYSATES WITH SYNTHETIC ANTIOXIDANTS IN A MODEL SYSTEM

Capelin protein hydrolysates (CPHs) were examined in a β-carotene-linoleate model system together with synthetic antioxidants, namely butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and tert-butyl hydroquinone (TBHQ). Addition of CPHs was at 0.25 and 1 mg per 5 mL in the above emulsion. BHA and BHT were added at levels of 2.5 and 5 μg and TBHQ at 5 and 10 μg. Absorbance of model emulsion system at 470 nm was recorded every 30 min for 2 h. CHPs and synthetic antioxidants inhibited oxidation of linoleic acid effectively. In the experiment with BHA, the influence of CPHs was significant (p<0.01) for the samples incubated for 60, 90, and 120 min; and in experiments with BHT and TBHQ during the entire incubation period. The influence of added BHA and BHT on inhibition of bleaching of β-carotene in the emulsion system was significant (p <0.01) during the incubation period and after 60, 90 and 120 min when TBHQ was used. A synergistic effect was observed only for CPHs and TBHQ when incubation time was 60, 90, and 120 min.     

STABILIZATION OF MARINE OILS WITH FLAVONOIDS

Antioxidant activity of a number of flavonoids in refined-bleached and deodorized (RBD) seal blubber oil (SBO) and menhaden oil (MHO) was compared with that of commercially used antioxidants, namely butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tert-butylhydroquinone (TBHQ) as well as α-tocopherol. The study was carried under Schaal oven conditions at 65C and progression of oxidation was followed by monitoring weight gain, peroxide value (PV) and 2-thiobarbituric acid reactive substances (TBARS) value. Among the flavonoids tested in this study, the flavonols, namely myricetin, quercetin and morin exhibited a stronger antioxidant activity than BHA and BHT and effectively stabilized both SBO and MHO. Myricetin was the most effective flavonoid tested in this study and its effect in reducing lipid oxidation was similar to that of TBHQ.     

二氢杨梅素对4种植物油脂抗氧化作用研究

研究二氢杨梅素(DMY)对植物油脂抗氧化作用。采用紫外可见分光光度计和烘箱强化贮藏法,考察DMY对DPPH自由基清除能力和对山茶油、亚麻籽油、紫苏籽油和油酸的抗氧化作用。结果表明:DMY对DPPH自由基清除能力明显高于TBHQ、BHT、BHA和TP;当抗氧化剂添加量为0.05%时,不同抗氧化剂在山茶油和油酸中抗氧化作用强弱顺序为TBHQDMYBHABHTTP;不同抗氧化剂在紫苏籽油和亚麻籽油中抗氧化作用强弱顺序为TBHQBHABHTDMYTP;DMY还能协助增强其他抗氧化剂的作用;DMY对4种植物油脂抗氧化效果强弱顺序为山茶油油酸亚麻籽油紫苏籽油。     

The use of polyphenolic extract,purified hydroxytyrosol and 3,4-dihydroxyphenyl acetic acid from olive mill wastewater for the stabilization of refined oils: a potential alternative to synthetic antioxidants

Ethyl acetate extracts of olive mill waste water (OMWW) were prepared, under in optimal conditions, using a continuous counter-current extraction unit. The antiradical and antioxidant activities of the OMWW extract as well as pure phenolic compounds identified in this extract were evaluated. Results showed that pure hydroxytyrosol and 3,4-dihydroxyphenyl acetic acid had the highest radical-scavenging effects on 1,1-diphenyl-2-picrylhydrazyl radical and the highest antioxidant activities using the β-carotene linoleate model system.The effect of addition of individual phenolic compounds and OMWW extract to refined olive and husk oils was compared with that of control, BHA and BHT at 50 °C. Unexpectedly, 3,4-dihydroxyphenyl acetic acid had the highest protective effect against oil oxidation. Oils with added 3,4-dihydroxyphenyl acetic acid had lower PV than oils with added hydroxytyrosol, the most studied powerful antioxidant. Moreover, the addition of OMWW extract, at 500 ppm, resulted in lower PV values than BHA, p-hydroxyphenylacetic acid, tyrosol on the control.The results suggested that 3,4-dihydroxyphenyl acetic acid, hydroxytyrosol and OMWW extract possess useful antioxidant properties and may be used as alternatives in the search for natural replacement of synthetic antioxidant food additives.     

Antioxidant activity of ginger extract in sunflower oil

The antioxidant activity of dichloromethane extract from ginger was evaluated during 6 months of storage of refined sunflower oil at 25 and 45 °C. Free fatty acid (FFA) content, peroxide value (POV) and iodine value (IV) were used as criteria to assess ginger extract as an antioxidant. After 6 months of storage at 45 °C, sunflower oil containing 1600 and 2400 ppm ginger extract showed lower FFA contents (0.083 and 0.080%) and POVs (24.5 and 24.0 meq kg^?1) than the control sample (FFA contents 0.380%, POV 198.0 meq kg^?1). Sunflower oil containing 200 ppm butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) showed FFA contents of 0.089 and 0.072% and POVs of 26.5 and 24.7 meq kg^?1 respectively after 6 months of storage at 45 °C. Similarly, after 6 months of storage at 45 °C, IVs of sunflower oil containing 1600 and 2400 ppm ginger extract were 80 and 92 respectively, higher than that of the control sample (53). However, IVs of sunflower oil treated with 200 ppm BHA and BHT were 94 and 96 respectively after 6 months of storage at 45 °C. These results illustrate that ginger extract at various concentrations exhibited very strong antioxidant activity, almost equal to that of synthetic antioxidants (BHA and BHT). Ginger extract also showed good thermal stability and exhibited 85.2% inhibition of peroxidation of linoleic acid when heated at 185 °C for 120 min. Therefore the use of ginger extract in foods is recommended as a natural antioxidant to suppress lipid oxidation. © 2003 Society of Chemical Industry     

A follow-up oxidation study in dried microencapsulated oils under the accelerated conditions of the Rancimat test

The aim of this research was to study lipid oxidation in dried microencapsulated oils (DMOs) under Rancimat test conditions (100 °C, 20 L air/h). Samples were prepared by freeze-drying of sunflower-oil-in-water emulsions containing sodium caseinate and lactose. Lipid oxidation was evaluated in the free and encapsulated oil fractions of DMOs by quantitation of total non-volatile lipid oxidation products and their distribution in oxidized triacylglycerol monomers, dimers and oligomers. Peroxide value (PV), polymers and tocopherol levels, when indicated, were also determined. Results showed that oxidation in the free oil fraction of DMOs was responsible for the Rancimat response. Oxidation of the free oil fractions exhibited well-defined induction periods (IPs) as detected by either PV determination, direct analysis of polymers or analysis of total non-volatile oxidation products. During the IP, oxidized triacylglycerol monomers were the only oxidation products formed in the free oil fractions, and the end of the IP was marked by the start of significant polymerization. Contrasting results were obtained in the encapsulated oil fractions, wherein oxidation increased gradually from the start of the test but no IP was detected.     

Influence of Dietary Supplementation with α-Tocopheryl Acetate and Canthaxanthin on Cholesterol Oxidation in ω3 and ω6 Fatty Acid-enriched Spray-dried Eggs

ABSTRACT: The effect of feeding laying hens linseed oil or sunflower oil, with and without α-tocopheryl acetate and/or canthaxanthin, was evaluated on cholesterol oxidation in spray-dried whole egg at various storage periods. Storage of spray-dried eggs at room temperature in the dark resulted in an increase in cholesterol oxidation products from 18.1 μg/g, after spray drying, to 39.3 μg/g, at 12 mo of storage. No differences were found with either dietary oil or canthaxanthin supplementation. However, α-tocopheryl acetate supplementation resulted in a lower formation of cholesterol oxidation products during storage. No synergistic effect between α-tocopherol and canthaxanthin was detected.     

LIPID OXIDATION OF FISH LIVER OIL AS AFFECTED BY LIGHT, ANTIOXIDANTS AND TEMPERATURE

Crude and refined Mackerel liver oil with or without antioxidants were stored in artificial light or in darkness to assess the effects of photo-oxidative stress on the stability of oils and the antioxidant activity of butylated hydroxy-anisole (BHA) and tert-butylhydroquinone (TBHQ) on those oils. Changes in peroxide value (PV) and thiobarbituric acid value (TBA) were monitored over 18 days at 5C and 40C. The results showed that visible light exposure played the most critical role in the acceleration of fish liver oil oxidation. The addition of antioxidants showed a significant effect in retarding oxidation with TBHQ more effective than BHA. The oxidation rate of the oils decreased in the following order: control with light > control + BHA with light > control without light > control + TBHQ with light > control + BHA without light > control + TBHQ without light. Higher PV and TBA values were observed in refined oils versus crude oils. Increasing storage temperature accelerated the oxidation of only refined oils in light.     

Antioxidant activities of different colored sweet bell peppers (Capsicum annuum L.)

ABSTRACT:  Antioxidant compounds and their antioxidant activity in 4 different colored (green, yellow, orange, and red) sweet bell peppers ( Capsicum annuum L.) were investigated. The total phenolics content of green, yellow, orange, and red peppers determined by the Folin-Ciocalteau method were 2.4, 3.3, 3.4, and 4.2 μmol catechin equivalent/g fresh weight, respectively. The red pepper had significantly higher total phenolics content than the green pepper. Among the 4 different colored peppers, red pepper contained a higher level of β-carotene (5.4 μg/g), capsanthin (8.0 μg/g), quercetin (34.0 μg/g), and luteolin (11.0 μg/g). The yellow pepper had the lowest β-carotene content (0.2 μg/g), while the green one had undetectable capsanthin and the lowest content of luteolin (2.0 μg/g). The free radical scavenging abilities of peppers determined by the 2,2'-diphenyl-1-picrylhydrazyl (DPPH) method were lowest for the green pepper (2.1 μmol Trolox equivalent/g) but not significantly different from the other 3 peppers. All 4 colored peppers exhibited significant abilities in preventing the oxidation of cholesterol or docosahexaenoic acid (DHA) (C22:6) during heating. However, these 4 peppers did not show significant differences in their abilities in preventing cholesterol oxidation. The green pepper showed slightly higher capability in preventing the oxidation of DHA compared to the other 3 peppers.     

Effect of Extrusion on Lipid Oxidation

To examine extrusion temperature effects on oil stability, corn meal/ starch with soybean oil was extruded, frozen immediately in liquid nitrogen, freeze-dried and ground. The conjugable oxidation products (COP), oxodiene values (OV), peroxide values (PV) and conjugated dienes were determined during storage. There was an increase in COP, OV, PV, and conjugated dienes with an increase in extrusion temperature. An increase in transition metal content, particularly iron, occurred with an increase in extrusion temperature. Starch and soybean oil were extruded with 50 ppm ferrous acetate (dry weight) and 50 ppm butylated hydroxyanisole (BHA) (oil weight). Ferrous acetate reduced the oxidation relative to the control, which contained neither antioxidant nor iron, and relative to the sample containing BHA.     

Effects of monoacylglycerols on the oil oxidation of acidic water/perilla oil emulsion under light in the presence of chlorophyll

Monoacylglycerol (MAG) effects on the oil photooxidation of an emulsion containing chlorophyll were studied. The emulsion consisted of equal weights of hexaneextracted perilla oil and 0.5% acetic acid, and 4 ppm chlorophyll b and MAG at 0, 1, or 1.5% were added. The oxidation was performed under 1,700 lx light at 25°C for 48 h. Singlet oxygen was involved in the oil oxidation of the emulsion containing chlorophyll under light. MAG protected chlorophyll and polyphenol compounds from degradation during the oxidation of the emulsion under light. MAG significantly decreased and decelerated headspace oxygen consumption and hydroperoxide production in the emulsion, and thus acted as antioxidant in photooxidation of the acidic water/perilla oil emulsion containing chlorophyll. Antioxidant activity of MAG in the photooxidation of the emulsion could be due to combined results of increased retention of polyphenols and decreased oxygen diffusion by forming a physical barrier.     

Comparison of chemical and sensory methods of evaluating thermally oxidised groundnut oil

Seven chemical methods, namely peroxide value (PV), totox value (TV), anisidine value (AV), conjugable oxidation products (COP), oxodiene value (OV), induction period (IP), iodine value (IV) and a sensory analytical procedure (flavour score, FS) have been used in evaluating the oxidation state of groundnut oil heated at 100°C for varying lengths of time up to 20 h. As oxidation progressed, PV, TV, AV, COP and OV increased. IP and IV decreased with oxidation while FS showed a progressive deterioration on a seven-point scale from bland to very rancid. On the basis of sensitivity to oxidative changes, five of the methods (PV, TV, IP, IV and FS) were found to be satisfactory. However, the best correlation with flavour scores were obtained in the case of IP, IV and OV while AV and COP correlated poorly with FS. Three methods (PV, IP and IV) best satisfied the combined criteria of sensitivity to oxidative changes and correlation with flavour.     

Utilization of Lactoferrin as an Iron-Stabilizer for Soybean and Fish Oil

ABSTRACT: We investigated the oxidative stability of soybean oil and fish oil fortified with iron solubilized by lactoferrin (FeLF). Oxidative stability was evaluated by measuring the induction period of the Rancimat test. The induction time of soybean oil added FeCl₃ was decreased; however, that of added FeLF was not. This effect of lactoferrin was also observed in the iron-catalyzed oxidation offish oil at temperatures ranging from 50°C to 120°C, and at concentrations of iron ranging from 0 to 500 ppm. Thus, lactoferrin is considered useful as a natural iron stabilizer for food products containing polyunsaturated fatty acids.     

Potato Peel Waste: Stability and Antioxidant Activity of a Freeze-Dried Extract

Aqueous extracts of potato peel waste were freeze-dried. High performance liquid chromatography (HPLC) of the freeze-dried extracts revealed that chlorogenic (50.31%), gallic (41.67%), protocatechuic (7.81%), and caffeic (0.21%) acids were the major phenolics. During 15 days storage of the freeze-dried extract, no degradation of phenolics occurred. After 4 days storage at 63°C, 5.00g of sunflower oil containing either the freeze-dried extract (200 ppm) or butylated hydroxyanisole (BHA) (200 ppm) reached peroxide values (PV) of 37.38 and 37.47 meq kg^-1 respectively. L-ascorbic acid-6-palmitate was the best antioxidant (PV= 10.65 meq kg^-1) but the freeze-dried extract was as good as BHA.     

Oxidative Stability of ω3-rich Camelina Oil and Camelina Oil-based Spread Compared with Plant and Fish Oils and Sunflower Spread

ABSTRACT: The oxidative stability of ω3‐rich oil from Camelina sativa and the storage stability of a camelina oil‐based spread were evaluated. Camelina oil was more stable than fish oil and linseed oil, but less stable than sunflower, corn, sesame, and olive oils, indicated by measuring peroxide values (PV), ρ‐anisidine values (AV), total oxidation values (Totox), thiobarbituric acid reactive substances (TBARS), conjugated diene levels (CD), and conjugated triene levels (CT) during storage at 65 °C for 16 d. The camelina oil‐based spread had higher PV, AV, Totox, TBARS, CD, and CT than the sunflower spread but maintained adequate sensory quality for 16 wk of storage at 4 °C or 8 °C.     

Comparison of soybean oils, gum, and defatted soy flour extract in stabilizing menhaden oil during heating

ABSTRACT:  Capabilities of crude soy oil, degummed oil, gum, and defatted soy flour extract in preventing the oxidation of menhaden oil and its omega-3 fatty acids, DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid), during heating were evaluated. The menhaden oil mixed with defatted soy flour extract demonstrated the greatest stability by producing the lowest TBA reactive oxidation products and retaining the highest concentrations of DHA and EPA after heating at 150 °C for 30 min. A range of 62.8% to 71.5% of DHA and 67.7% to 75.9% of EPA remained in the fish oil with defatted soy flour extract, while only 29.9% of DHA and 37.2% of EPA were retained in the fish oil with no addition. Stabilizing capability from highest to lowest was defatted flour extract > gum > degummed oil = crude oil. The defatted flour extract had the highest level of total phenolic content (11.3 μg catechin equivalent/g), while crude oil, degummed oil, and gum contained 7.1, 6.1, and 6.0 μg catechin equivalent/g, respectively. The level of isoflavones in the defatted soy flour extract was 55 mg/g, which was over 100 times higher than in the crude oil or gum. Although isoflavones were not detected in the degummed oil, it contained the highest level of tocopherols (414 μg/g), whereas the lowest level (215 μg/g) was found in the defatted flour extract. The order of free radical scavenging capability measured from high to low was the defatted soy flour extract, crude oil, degummed oil, and gum.