Natural antioxidants from herbs and spices

There is a growing interest in natural antioxidants found in plants because of the world‐wide trend toward the use of natural additives in food and cosmetics. Herbs and spices are one of the most important targets to search for natural antioxidants from the point of view of safety. This review presents the results on stabilization of lipids and lipid‐containing foods with different herbs and spices (ground materials or extracts) and reports the structure of the main antioxidatively acting compounds isolated from them. The review presents information about the antioxidative effects of rosemary, sage, oregano, thyme, ginger, summer savory, black pepper, red pepper, clove, marjoram, basil, peppermint, spearmint, common balm, fennel, parsley, cinnamon, cumin, nutmeg, garlic, coriander, etc. Among the herbs of the Labiatae family, rosemary has been more extensively studied and its extracts are the first marketed natural antioxidants. Sage and oregano, which belong to the same family, have gained the interest of many research groups as potential antioxidants.     

N,N’-双[3-(3’,5’-二叔丁基-4’-羟基苯基)丙酰]六甲撑二胺的合成

以 3 (3’ ,5’ 二叔丁基 4 羟基苯基 )丙酸甲酯 (简称 3,5 甲酯 )与己二胺为原料 ,有机锡为催化剂 ,二甲苯为溶剂合成了N ,N’ 双 [3 (3’ ,5’ 二叔丁基 4’ 羟基苯基 )丙酰 ]六甲撑二胺。通过实验考察了反应温度、催化剂及催化剂用量、反应时间及物料配比等因素对反应的影响。结果表明 ,最佳的反应条件是 :反应温度 135～ 14 5℃ ,催化剂为有机锡 ,催化剂用量0 6 0 g ,反应时间 3 5h ,3,5 甲酯与己二胺摩尔比 2 10∶1。在此条件下 ,收率在 97%以上 ,放大到 10 0 0ml,收率在 99%以上 ,产品熔点为 16 1～ 16 2℃ ,产品纯度较高 ,通过元素分析、红外光谱分析、核磁氢谱对产品进行了结构表征     

Abilities of some antioxidants to stabilize soybean oil in industrial use conditions

Antioxidants, chelators, and alcohols were screened at 0.01 and 1.28% by weight for their ability to delay viscosity increase in soybean oil in the presence of metallic colloidal copper and iron at 105°C with air flowing through the sample. Most substances did not significantly enhance the effect of the natural tocopherols in the soybean oil at 0.01%. A few substances were mildly prooxidant, and a few delayed the increase in viscosity significantly. TBHQ at 0.01% was the best antioxidant of those tested. At 1.28% ascorbyl palmitate, BHT, hydroquinone, and TBHQ increased the stability significantly. Again, TBHQ was the most effective. As measured by viscosity increase to 150 CP, TBHQ increased stability about five times over that of soybean oil controls.     

Oxidative stability of structured lipids produced from sunflower oil and caprylic acid

Traditional sunflower oil (SO), randomized lipid (RL) and specific structured lipid (SL), both produced from SO and tricaprylin/caprylic acid, respectively, were stored for up to 12 wk to compare their oxidative stabilities by chemical and sensory analyses. Furthermore, the effect of adding a commercial antioxidant blend Grindox 117 (propyl gallate/ citric acid/ascorbyl palmitate) or gallic acid to the SL was investigated. The lipid type affected the oxidative stability: SL was less stable than SO and RL. The reduced stability was most likely caused by both the structure of the lipid and differences in production/ purification, which caused lower tocopherol content and higher initial levels of primary and secondary oxidation products in SL compared with RL and SO. Grindox 117 and gallic acid did not exert a distinct antioxidative effect in the SL oil samples during storage.     

Flavonoids as stabilizers of fish oil: An alternative to synthetic antioxidants

The antioxidant activities against fish oil oxidation of six commercially available flavonoids and of five flavonoids purified from two Chilean native plants were compared to those ofdl-α-tocopherol and of two synthetic antioxidants, butylated hydroxytoluene and butylated hydroxyanisole. Among the commercial flavonoids, catechin, morin and quercetin showed a higher activity when fish oil oxidation (either spontaneous or Fe²⁺-induced) was assessed from the formation of peroxides or thiobarbituric acid-reactive substances. Among the native flavonoids, the 5,3′,4′-trihydroxy-7-methoxy flavanone (designated as Pt-2) showed the highest antioxidant activity. Mixtures of quercetin or of Pt-2 withdl-α-tocopherol produced better inhibitory effects when compared to that of each substance assayed by itself. Also, when Pt-2 and quercetin were assayed in combination (0.3 g/kg oil and 0.7 g/kg oil, respectively), a synergistic antioxidant effect was observed. Results indicate that several flavonoids could be used as natural antioxidants as a means to replace those synthetic antioxidants, the use of which has been questioned.     

Evaluation of Antioxidant Activity of Green Tea Extract and Its Effect on the Biscuits Lipid Fraction Oxidative Stability

ABSTRACT:  This article investigates the effect of green tea extract (GTE) on biscuits lipid fraction oxidative stability. The antioxidant activity of GTE was compared with commonly used synthetic antioxidant butylated hydroxyanisole (BHA). Biscuits were prepared in 3 variations. Control samples were prepared without addition of antioxidants. The other variations were prepared by adding BHA (0.02%) and GTE at 3 different levels: 0.02%, 0.1%, and 1%. Biscuits were subjected to sensory studies and instrumental and chemical analysis. Phenolic compounds of GTE characterized powerful antioxidant activities evaluated using free radical, 2,2-diphenyl-1-picrylhydrazyl method, compared with gallic acid and significantly better than BHA. Antioxidants added to the samples clearly slowed down the process of oxidation of fatty acids, inhibiting the monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) decomposition. Addition of GTE at the level of 1% gave an excellent antioxidant effect on the biscuits lipid stability, inhibiting hydroperoxides formation by about 47% to 73% compared with BHA, which showed about 16% to 60% inhibition. However, GTE did not improve significantly lipid stability, measured by anisidine value ( p -AV), and inhibited formation of secondary oxidation products only by 3.5%. After accelerated storage time, insensitivity of oxidized-like flavor was about 2 times higher for control samples compared to samples with addition of antioxidants. Moreover, after storage biscuits treated with natural antioxidant received a higher panel score of overall acceptance compared to samples with BHA. Using volatile compound formation as a marker of lipid oxidation, both GTE and BHA were effective inhibitors of the decomposition of hydroperoxides.     

A chemiluminescence study of the oxidation of vegetable oils and model compounds and the effects of antioxidants

Chemiluminescence was used to study the course of oxidation of sunflower oil samples at a number of temperatures between 70 and 121°C. The induction time was determined for each sample and used to estimate the shelf life of the oils at 25°C. In addition, Chemiluminescence during oxidation in air on alumina at 80°C was used to study both sunflower oil and, as a model compound, methyl linoleate with and without added artificial antioxidants. By using the method of inhibitors, the reaction rate and level of hydroperoxide were determined. It was also possible to determine the level of naturally occurring antioxidant in the vegetable oil.     

Effect of the phenol antioxidant type on the kinetics and mechanism of inhibited lipid oxidation in the presence of fatty alcohols

A kinetic analysis of inhibited lipid autoxidation in the presence of a phenol antioxidant and a hydroxy compound is proposed. It is based on studies of the dependence of the W^ROH/W_inh ratio (between the inhibited oxidation rates in presence and absence of a hydroxy compound) on the hydroxy compound concentration. This analysis permits establishing the mechanism of action of the hydroxy compound in the presence of different types of phenol antioxidants during inhibited lipid oxidation. The kinetic analysis has been applied to the oxidation at 80°C of triacylglycerols of sunflower oil (TGSO) inhibited by 0.1 mM hydroquinone, butylated hydroxytoluene (BHT) or α-tocopherol in the presence of different concentrations of 1-tetradecanol (1-TD) and 1-octadecanol (1-OD). A linear character of this dependence is established during hydroquinone-inhibited oxidation of triacylglycerols of sunflower oil in presence of 1-TD. In the case of α-tocopherol this dependence is linear for both 1-TD and 1-OD. The equilibrium constant of interaction between the phenol antioxidant and the fatty alcohols is determined by the angle coefficient of the linear dependence. The hydroquinone-inhibited autoxidation of TGSO in the presence of 1-OD has shown a non-linear character of the dependence under consideration. A kinetic model describing simultaneous participation of 1-OD in reaction with both the phenol antioxidant and the lipid hydroperoxides is deduced. Studying the kinetics of BHT-inhibited autoxidation of TGSO in the presence of 1-OD, it has been shown that due to steric reasons there is no interaction between 1-OD and BHT, 1-OD participating in the process only by accelerating the decomposition of the lipid hydroperoxides.     

α-Tocopherol and Ascorbate Delay Oxymyoglobin and Phospholipid Oxidation In Vitro

An oxymyoglobin liposome model was used to study the effects of α-tocopherol and/or ascorbate upon oxymyoglobin and lipid oxidation. Both oxidations were delayed (P<0.05) by increased concentrations of α-tocopherol alone and α-tocopherol/ascorbate relative to controls. The 14 μ Mα-tocopherol/140 μM ascorbate treatment resulted in greatest delay in both oxymyoglobin and lipid oxidation. Ascorbate alone delayed oxymyoglobin oxidation; effectiveness diminished as ascorbate increased. Ascorbate showed a prooxidant effect toward lipid oxidation which was unchanged in the presence of EDTA. Results support the hypothesis that α-tocopherol retards lipid oxidation directly and OxyMb oxidation indirectly.