Rosemary Antioxidants Research Articles

Separation of rosemary antioxidant compounds by supercritical fluid chromatography on coated packed capillary columns

Antioxidant compounds in rosemary extracts obtained by supercritical fluid extraction (SFE) were separated by supercritical fluid chromatography (SFC) on packed capillary columns. The columns contained silica particles coated with SE-54 (5% phenyl, 95% methyl silicone) and Carbowax 20 M [poly(ethylene glycol)]. The use of coated packed capillary columns allowed the separation of polar compounds by SFC with neat CO 2. The SFC conditions were selected on the basis of previous work. High pressures (up to 370 atm; 1 atm = 10,325 Pa) and moderate temperatures (up to 100 °C) were used to separate the compounds responsible for the antioxidant activity such as carnosic acid and carnosol while lower pressures were sufficient to separate the compounds of the essential oil.

Commercial antioxidants control lipid oxidation in mechanically deboned turkey meat

Effects of commercial rosemary antioxidants on oxidative stability of mechanically deboned turkey meat (MDTM) compared with Trolox C (vitamin E), ascorbic acid (vitamin C) and control without antioxidant were investigated. Antioxidants were added to meat at three levels. Thiobarbituric acid (TBA) assay and dynamic headspace gas chromatography were used to assess the effects of commercial antioxidants on lipid stability of MDTM during 7 months of frozen storage. Increased levels of TBA-reactive substances (TBARS) and volatile carbonyl compounds were noticed in all meat samples during storage, however most distinctly in meat without antioxidants. Retarding effect of antioxidants on the development of oxidation depended on the level and type antioxidants. Trolox C—a water soluble, synthetic derivative of vitamin E possessed the greatest antioxidative activity reflected by the lowest values of TBARS and volatile compounds. Ascorbic acid was less efficient than Trolox C and Biolox HT-W (rosemary), but more potent than most rosemary extracts in suppressing lipid oxidation especially in the long term frozen storage MDTM. The DPPH method confirmed that antioxidant activity depends on the concentration of active compounds present in the samples available to scavenge the free radicals formed during the storage period. Supplementation of MDTM with antioxidants could be an alternative method to prevent oxidative degradation of the meat during frozen storage when vacuum packaging is not practical.

Subcritical water extraction of antioxidant compounds from rosemary plants.

Subcritical water extraction at several temperatures ranging from 25 to 200 degrees C has been studied to selectively extract antioxidant compounds from rosemary leaves. An exhaustive characterization of the fractions obtained using subcritical water at different temperatures has been carried out by LC-MS, and the antioxidant activities of the extracts have been measured by a free radical method (DPPH). Results indicate high selectivity of the subcritical water toward the most active compounds of rosemary such as carnosol, rosmanol, carnosic acid, methyl carnosate, and some flavonoids such as cirsimaritin and genkwanin. The antioxidant activity of the fractions obtained by extraction at different water temperatures was very high, with values around 11.3 microg/mL, comparable to those achieved by SFE of rosemary leaves. A study of the effect of the temperature on the extraction efficiency of the most typical rosemary antioxidant compounds has been performed.

Recovery mechanism of the antioxidant activity from carnosic acid quinone, an oxidized sage and rosemary antioxidant.

A solution of carnosic acid quinone, which is a radical chain-termination product having no antioxidant activity in the antioxidant reaction of carnosic acid, recovers potent antioxidant activity upon standing. The HPLC analysis of an aged solution of carnosic acid quinone revealed that several antioxidants are produced in the solution. From the time-course and quantitative analyses of the formation of the products and their structural analysis, an antioxidant mechanism from carnosic acid quinone is proposed that includes a redox reaction of carnosic acid quinone in addition to the isomerization to lactone derivatives. In the first stage of antioxidation, carnosic acid, the reduction product from carnosic acid quinone, contributes to the potent antioxidant activity of the solution. This proposed mechanism can explain one of the reasons for the strong antioxidant activity of the extract of the popular herbs sage and rosemary.

Evaluation of Antioxidant Activity of Rosemary Extracts, Carnosol and Carnosic Acid in Bulk Vegetable Oils and Fish Oil and Their Emulsions

The antioxidant effectiveness of two rosemary extracts, carnosol and carnosic acid, was significantly influenced by the type of system tested (bulk oils vs oil-in-water emulsions), by the oil substrates, the methods used to follow oxi-dation, and the concentrations of test compounds. The rosemary extracts and compounds effectively inhibited conjugated diene hydroperoxide formation in corn oil, soya bean oil, peanut oil and fish oil, when tested in bulk. Test compounds also inhibited hexanal formation in bulk vegetable oils, and propanal and pentenal formation in bulk fish oils. In contrast, these test compounds were either inactive or promoted oxidation in the corresponding vegetable oil-in-water emulsions. In fish oil emulsions, however, the rosemary compounds inhibited the formation of conjugated diene and pentenal but not that of propanal. Interfacial phenomena may explain why the hydrophilic rosemary antioxidants afford more protection in the bulk oil systems by being oriented in the air–oil interface, and less protection in the oil-in-water emulsion systems by partitioning into the water phase.

Evaluation of Antioxidant Activity of Rosemary Extracts, Carnosol and Carnosic Acid in Bulk Vegetable Oils and Fish Oil and Their Emulsions

The antioxidant effectiveness of two rosemary extracts, carnosol and carnosic acid, was significantly influenced by the type of system tested (bulk oils vs oil-in-water emulsions), by the oil substrates, the methods used to follow oxi-dation, and the concentrations of test compounds. The rosemary extracts and compounds effectively inhibited conjugated diene hydroperoxide formation in corn oil, soya bean oil, peanut oil and fish oil, when tested in bulk. Test compounds also inhibited hexanal formation in bulk vegetable oils, and propanal and pentenal formation in bulk fish oils. In contrast, these test compounds were either inactive or promoted oxidation in the corresponding vegetable oil-in-water emulsions. In fish oil emulsions, however, the rosemary compounds inhibited the formation of conjugated diene and pentenal but not that of propanal. Interfacial phenomena may explain why the hydrophilic rosemary antioxidants afford more protection in the bulk oil systems by being oriented in the air–oil interface, and less protection in the oil-in-water emulsion systems by partitioning into the water phase.

Antioxidant Activity of a Rosemary Extract and Its Constituents, Carnosic Acid, Carnosol, and Rosmarinic Acid, in Bulk Oil and Oil-in-Water Emulsion

This study was aimed at evaluating the antioxidant activity of a commercial rosemary extract and the active constituents carnosol, carnosic acid, and rosmarinic acid, in inhibiting the formation and decomposition of hydroperoxides in tocopherol-stripped corn oil and in the corresponding corn oil-in-water emulsions. In bulk corn oil, the rosemary extract, carnosic acid, rosmarinic acid, and α-tocopherol were significantly more active than carnosol. In contrast, in corn oil-in-water emulsion, the rosemary compounds were less active than in bulk oil, and the rosemary extract, carnosic acid, carnosol, and α-tocopherol were more active than rosmarinic acid. Similar results were obtained in corn oil-in-water phosphate buffer emulsion at pH 5, but α-tocopherol was less active. Carnosol and carnosic acid were much more active antioxidants in corn oil-in-water emulsions buffered at pH 4 and 5 than at pH 7. The decreased antioxidant activity of the polar hydrophilic rosemary compounds in the emulsion system may be explained by their interfacial partitioning into the water, thus becoming less protective than in the bulk oil system. The effect of pH may be related to the stability of the rosemary antioxidants. Keywords: Antioxidants; rosemary extracts; corn oil; hydroperoxides; hexanal; bulk oil; emulsion

The use of rosemary extracts to improve the flavor of precooked low fat ground beef patties

Reduced fat meat products are readily available in the marketplace. Precooked beef patties are used by foodservice establishments for their convenience but the quality of these products may be lower due to warmed-over flavor. The objective of this study was to determine if the fat content of precooked ground beef patties has an effect on the development of warmed-over flavor (WOF) and to determine if WOF could be reduced by using rosemary antioxidants. Ground beef patties (70, 80 and 90% lean) were formed into 100g patties, grilled to an internal temperature of 72°C and stored for 9 days at 4°C. Herbalock type D-20 (Kalsec, Inc.) was added at 0.45 percent (w/w). The thiobarbituric acid test (TBA) and gas chromatographic headspace analysis were performed to determine the extent of lipid oxidation. All patties with rosemary antioxidants had lower TBARS (thiobarbituric acid reactive substances) than those patties without rosemary. After 9 days of refrigerated storage TBARS for the patties with no antioxidant averaged 7.7 ± 1.6 mg/kg while the patties containing rosemary averaged 3.6 ± 1.1 mg/kg. Headspace analysis of volatile development supported this data with lower total area of volatiles for the patties with the rosemary antioxidant. No difference was found among the patties with the three levels of fat when no antioxidant was present. However, when rosemary was added, the lowest TBARS and total volatiles were found with the 90% lean patties. Fat content does affect the development of warmed-over flavor with the lower fat content patties developing less warmed-over flavor but only when a rosemary extract was used.

Scavenging effect of extracts of green tea and natural antioxidants on active oxygen radicals

With the use of the spin trapping methods, the scavenging effects of the extracts of green tea and other natural foods are studied. In stimulated polymorphonuclear leukocytes (PMN) system, water extract fraction 6 (F6) from green tea and green tea polyphenols (GTP) have the strongest scavenging effect on the active oxygen radicals, much stronger than vitamin C (Vc) and vitamin E (VE). Rosemary antioxidants (RA) and Curcumin (Cur) have weaker scavenging effects than Vc, but stronger than VE. In Fenton Reaction, Cur has the strongest scavenging effect (69%) on hydroxyl radicals. In irradiation, riboflavin system F6(74%) and GTP(72%) have very strong scavenging effects that are weaker than Vc, but much stronger than VE (23%). With the use of spin probe oxymetry, the oxygen consumption in respiratory burst of stimulated PMN were measured when the antioxidants existed in these systems. The results demonstrated that these antioxidants did not affect the respiratory burst of human polymorphonuclear leukocytes stimulated with PMA.