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

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 degrees 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 microg catechin equivalent/g), while crude oil, degummed oil, and gum contained 7.1, 6.1, and 6.0 microg 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 mug/g), whereas the lowest level (215 microg/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.

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

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 degrees C for 30 min or incubating at 60 degrees C for 5 d. After heating at 150 degrees 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 degrees 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 degrees 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.

Purification and characterization of arylsulfatase from Sphingomonas sp. AS6330.

Arylsulfatase was purified from Sphingomonas sp. AS6330 through ionic exchange, hydrophobic- and gel-chromatographies. The purity increased 12,800-fold with approximately 19.1% yield against cell homogenate. The enzyme was a monomeric protein with apparent molecular weight of 62 kDa as determined by sodium dodecylsulfate-polyacrylamide gel electrophoresis, and 41 kDa as determined by gel filtration. The enzyme had optimum reaction conditions for hydrolysis of sulfate ester bonds in agar and p-nitrophenyl sulfate (NPS) at pH 7.0 and 45 degrees C, with a specific activity of 3.93 and 97.2 U, respectively. The enzyme showed higher activity towards agar than other sulfated marine polysaccharides such as porphyran, fucoidan and carrageenan. The K(m) and V(max) of the enzyme for hydrolysis of NPS were 54.9 microM and 113 mM/min, respectively. With reaction of 200 g agar with 100 U arylsulfatase for 8 h at 45 degrees C, gel strength increased 2.44-fold, and 97.7% of the sulfate in the agar was hydrolyzed.

Antioxidant activity of tocopherols, tocotrienols, and gamma-oryzanol components from rice bran against cholesterol oxidation accelerated by 2,2'-azobis(2-methylpropionamidine) dihydrochloride.

The antioxidant activities of vitamin E (alpha-tocopherol, alpha-tocotrienol, gamma-tocopherol, and gamma-tocotrienol) and gamma-oryzanol components (cycloartenyl ferulate, 24-methylenecycloartanyl ferulate, and campesteryl ferulate) purified from rice bran were investigated in a cholesterol oxidation system accelerated by 2,2'-azobis(2-methylpropionamidine) dihydrochloride. All components exhibited significant antioxidant activity in the inhibition of cholesterol oxidation. The highest antioxidant activity was found for 24-methylenecycloartanyl ferulate, and all three gamma-oryzanol components had activities higher than that of any of the four vitamin E components. Because the quantity of gamma-oryzanol is up to 10 times higher than that of vitamin E in rice bran, gamma-oryzanol may be a more important antioxidant of rice bran in the reduction of cholesterol oxidation than vitamin E, which has been considered to be the major antioxidant in rice bran. The antioxidant function of these components against cholesterol oxidation may contribute to the potential hypocholesterolemic property of rice bran.

Influence of high-oryzanol rice bran oil on the oxidative stability of whole milk powder.

The effect of high oryzanol rice bran oil (RBO) on the oxidative stability of low-heat and high-heat whole milk powder (WMP) was investigated. Milk (3.6% fat) was fortified with RBO at 0.1 and 0.2% (wt/wt) and was concentrated and dried. Control WMP was made without RBO addition. Thiobarbituric acid reactive substances (TBARS) were used to monitor oxidation during storage at 45 degrees C for 40 d. The oxidation of low-heat WMP was significantly reduced by addition of 0.1% RBO, but there was no significant effect on the oxidation of high-heat WMP. An increase of RBO to 0.2% did not significantly improve the oxidative stability when compared with 0.1% RBO. The TBARS in RBO-fortified, low-heat WMP increased with storage time up to 30 d but decreased with further storage to 40 d. The TBARS in all high-heat WMP and low-heat control WMP increased up to 20 d storage and then decreased with further storage. The most likely reason for this increase was due to the reaction of TBARS with milk proteins. Addition of RBO reduced the L (lightness) value and increased the b (yellowness) value but had no effect on the a (redness) value. When compared with the control milk powder, consumers could not detect any effect on the flavor of the reconstituted 0.1% RBO WMP but could detect a flavor difference in the 0.2% RBO WMP.

Purification and identification of components of gamma-oryzanol in rice bran Oil.

High-purity gamma-oryzanol was obtained from crude rice bran oil using a normal-phase preparative scale HPLC. A reverse-phase HPLC method was used for separating the individual components of gamma-oryzanol present in rice bran oil. Ten fractions were isolated and collected using the reverse-phase HPLC method, and their structures were identified. Identification was accomplished using GC/MS with an electron impact mass spectrum after components were transformed into trimethylsilyl ether derivatives. The 10 components of gamma-oryzanol were identified as Delta(7)-stigmastenyl ferulate, stigmasteryl ferulate, cycloartenyl ferulate, 24-methylenecycloartanyl ferulate, Delta(7)-campestenyl ferulate, campesteryl ferulate, Delta(7)-sitostenyl ferulate, sitosteryl ferulate, compestanyl ferulate, and sitostanyl ferulate. Three of these, cycloartenyl ferulate, 24-methylenecycloartanyl ferulate, and campesteryl ferulate, were major components of gamma-oryzanol.

Purification and characterization of cathepsin L-like enzyme from the muscle of anchovy, Engraulis japonica.

Results relative to inhibitory effects and substrate specificity indicated that a protease from the muscle of anchovy, Engraulis japonica, was a cathepsin L-like enzyme. The enzyme was activated by thiol reagents and inhibited by thiol-blocking reagents. The molecular weight was estimated to be 25.8 kDa by SDS-PAGE. The enzyme exhibited its maximal activity at pH 6.0 and 50 degrees C for casein and N-benzoyl-D, L-arginine-beta-naphthylamide. The enzyme hydrolyzed at the position of Phe1, Asn3, Val13, Glu14, Val19 and Gly24 of the insulin beta-chain. The K'm and kcat of the enzyme were 73.4 microM and 0.5 microM/min, respectively, toward Z-Phe-Arg-MNap.

The enhancement of nonheme iron bioavailability by beef protein in the rat.

Beef protein was found to enhance the bioavailability of nonheme iron in the rat. Anemic rats were fed diets containing soy protein concentrate or rice bran as the source of nonheme iron with either lactalbumin or distilled water-washed beef, which was heme free. The criteria used to determine the relative biological value (RBV) of iron was the difference between the products of final hemoglobin x final weight and initial hemoglobin x initial weight during the repletion period. Animals fed diets with only lactalbumin as a source of dietary protein and graded levels of FeSO4 (RBV of FeSO4 = 100%) served as controls. The RBV of the endogenous iron in soy protein and rice bran was found to be 91 and 46%, respectively. Substituting washed beef for lactalbumin increased the RBV of soy protein iron to 96% (results not statistically significant) and of rice bran iron to 75% (results significant, P less than or equal to 0.05). These findings demonstrate the "meat factor" effect in the rat for the first time. Two days after completion of the 11-d hemoglobin regeneration period, the apparent absorption of iron was measured during a 60-h balance period. The apparent absorption of iron by rats fed diets containing beef tended to be higher, compared to animals fed diets containing lactalbumin.