effect of pH on flavor formation and antioxidant activity of amino acid and sugars interaction products

Flavor is the crucial part of eating quality. In the preparation of natural identical flavor in different model systems like cysteine- ribose [cys-rib], cysteine-glucose [cys- glu] and cysteine-beef fat [cys-BF] affected at different pH [4.5, 7 and 10] a wide range of flavors was obtained. The proteins as glutamine, glutamic acid and the sugars as D- ribose and D-glucose,l,l-diphenyl-2-picrylhydrazyl [DPPH] and beta-Carotene and all the lab grade chemical as Linoleic acid, Polyoxyethylene sorbitan monopalmitate [Tween-80], Chloroform [99%], Anhydrous sodium sulfate, Dichloromethane [99.8%], 0.1 N HC1 and 0.1N NaOH, Gallic acid, Sodium carbonate, Folin-Ciocalteu reagent were used to conduct research. In sugar and amino acid model system, roasted and burnt meat flavor was obvious while in beef fat model system boiled meat flavor was dominated which was strongly supported by sensory evaluation. In rib-cys and glu-cys model systems total phenolic contents [TPC] were highest at pH 7 and pH 4.5, respectively along with browning, leading to strong antioxidant activity. In beef fat-cys model system it was found that as pH increases TPC, browning increases and antioxidant activity becomes maximum at basic pH. All the results indicated that, there is a positive relationship between the TPC, browning and antioxidant activity of all model systems

Effect of Egyptian sage extract on antioxidant activity, hypercholesterolemia and bone calcification in the tibia of rats

Osteoporosis [major public health problem in the aging society] has been linked with arteriosclerotic vascular diseases characterized by hypercholesterolemia. Nutrition may appear as an alternative strategy for optimizing health skeleton instead of traditional therapies by hormone replacement treatment which increases the risk of heart disease and cancers. Phytochemicals with antioxidative properties that may act against hypercholesterolemia and positive in the prevention of osteoporosis. The present study was designed to investigate the effects of sage leaves aqueous extract on hypercholesterolemia and bone calcification in rats. Sage leaves aqueous extract was prepared by infusion of leaves in hot water, separation of its volatiles and identification using GC/MS and evaluation the radical scavenging activity of sage aqueous extract by ESR. Three groups of rats were used, group 1 to serve as control, group 2 was fed on diet rich with cholesterol and the third group was fed on diet rich in cholesterol and treated with sage leaves aqueous extract. The experiment continued for 6 weeks. The plasma total cholesterol [TC], triglycerides [TG], HDL-C, LDL-C, urea, creatinine, blood hemoglobin, and enzymes activities of transaminases [ALT and AST] were determined. Different minerals [calcium, magnesium, zinc, phosphorus and Ca/P] were assayed spectrophotometrically using atomic absorption. The GC/MS analysis showed that 1,8-cineol [eucalyptol] [22.34%], thujone [16.31%], camphor [16.9%], humulene [7.53%], alpha pinene [5.77%], borneol [4.59%], p-menthol [4.8%], camphene [4.31%] and bornyl acetate [3.16%] were the main volatile compounds of the sage leaves aqueous extract. Sage volatile extract showed significant antioxidant activity in vitro using ESR assay. Daily administration of sage leaves aqueous extract for 6 weeks to Swiss albino rats as drinking water, caused significant declines in the blood levels of triglycerides [TG] [30%], total cholesterol [TC] [10.3%], LDL-C [45%] and increase of HDL-C [81%] and tibial calcium [20%]. This study demonstrates one possible mechanism by which sage leaves aqueous extract which rich in phenolic substances can improve the bone calcification, and acting as hypocholesterolemic agent

Investigation of the chemical composition, antioxidant activity and hypoglycemic effect of the Egyptian guava leaves volatiles

Diabetes mellitus is a chronic metabolic disorder with many complications which has associated with oxidative stress. The present work aimed to study the protective effect of the Egyptian guava [Psidium guajava L.] leaves aqueous extract on streptozotocin [STZ]-induced diabetic rats and its complementary effects. The volatile compounds of guava leaves aqueous extract were isolated and analyzed by using GC and GC/MS. The total phenolic content and in vitro antioxidant activity were done by Folin-Ciocalteu reaction and thiobarbituric acid [TBA] assay, respectively. Four groups of rats [six rats each] used in this study [control, guava extract supplemented, STZ-diabetic, and protected groups]. Serum glucose level was determine as well as liver function, kidney function, lipid profile, activities of some antioxidant enzymes, blood hemoglobin, and histopathological changes in the liver, kidney and pancreas were investigated. Fifty six components were identified using GC and GC/MS. The main chemical compounds in guava leaves volatile oils were; alpha-pinene [11.77%], epi-alpha-bisabolol [10.85%], 1, 8-cineol [9.22%], 1-epi cubenol [8.56%], globulol [5.88%], thujone [5.35%], hexenal [5.03%] and terpipineol [4.35%]. The Egyptian guava volatile extract exhibited a high antioxidant activity in vitro. Also, the results revealed that administration of aqueous guava extract [1gm/dl] to streptozotocin [STZ] induced diabetic rats for 4 weeks as their only source of fluid, enhanced most of the endogenous antioxidant enzymes activity as glutathione reductase [GR], superoxide dismutase [SOD] and total antioxidant capacity [TAC] and produced a pronounced hypoglycemic effect as well as the amelioration of most of the studied biochemical parameters in STZ-induced diabetic rats, which confirmed by histo-pathological examination of different body organs, The potential antioxidant and hypoglycemic activities of guava leaves extract, respectively, are attributed to the presence of relatively high percentage of phenolic compounds [456 +/- 10.4 mg gallic acid equivalent/L] and other active volatile compounds with high antioxidant activity. Egyptian guava aqueous extract is effective in controlling hyperglycemia, reducing diabetic complications arising due to oxidative stress in diabetic rats, improve lipid metabolism as well as amelioration of the associated biochemical parameters

Chemical compositions and antioxidant and antimicrobial activities of various samples prepared from Schinus terebinthifolius leaves cultivated in Egypt

This study was designed to examine the chemical compositions and antioxidant and antimicrobial activities ofessential oil, dichloromethane extract, and ethanol extract were prepared from fresh Schinus terebinthifolius leaves cultivated in Egypt. The essential oil was analyzed by gas chromatography and gas chromatography/mass spectrometry. The essential oil comprised 4.97% monoterpenes, 56.96% sesquiterpenes, 34.37% oxygenated monoterpenes, and 3.32% oxygenated sesquiterpenes. The major compounds in the essential oil were cis-beta-terpineol [GC peak area%, 17.87%], [E]-caryophyllene [17.56%], beta-cedrene [9.76%], and citronellal [7.03%]. The major phenolic compounds identified in the ethanol extract were caffeic acid [5.07 mg/100 mg extract], coumaric acid [1.64 mg], and syringic acid [1.59 mg]. The antioxidant activity of ethanol extract, which was comparable with that of butylhydroquinone, was superior to essential oil and dichloromethane extract in 2,2-diphenylpicrylhydrazyl and beta-carotene/bleaching assays. The dichloromethane extract exhibited the greatest antimicrobial activity against 6 strains, followed by the ethanol extract and the essential oil