جستجوی مقالات مرتبط با کلیدواژه "gc" در نشریات گروه "صنایع غذایی"

The present study was conducted to investigate the chemical composition of the Caper flower and flower buds essential oil in two harvesting stages of before and after sunrise. Harvesting of perennial plants in July 2017 was carried out on wilding specimens at Imamzadeh Jafar Research Farm in Gachsaran City. Essence of the samples of the Clevenger apparatus were extracted and the essential oils were identified by GC / MS. In the study of the chemical composition of Capparis spinosa L. flower and flower buds essential oil in two harvesting periods, it was determined that generally, the essential oil of flowers after sunrise, flower buds before sunrise, flowers opened before sunrise, and flowers opened after sunrise contain 30, 20, 27 and 7 chemical compositions respectively.
Isobutyl isothiosyanate was found in all essential oil samples. There were 17 compositions in flower and flower buds samples after sunrise. The results showed that carvacrol in the harvested samples in flower and flower buds essential oil after sunrise was the dominant composition. In general, the isothiocyanate and terpene compositions are the dominant components in all specimens. The results showed that in samples after sunrise, the amount of essential oil composition is higher than that before sunrise, which is due to the presence of light and heat that causes changes in essential oil composition

The drying process plays an important role in the treatment of medicinal plants, in order to maintain the quantity and quality of the essential oil extracted from the plant. Because Medicinal herbs containing essential oils If they are not dried immediately or their essence is not extracted, they will lose their active ingredients and volatile compounds.The aim of this study is design a hybrid dryer to drying medicinal plants and comparison their results with traditional drying methods (sun and shade).The effects of different drying methods (hybrid dryer, oven and shade drying) on the essential oil content and chemical composition of thyme were studied. The essential oils from each organ type were extracted by hydrodistillation and the chemical components were analyzed by GC/MS systems. Mathematical modeling results showed that the Midilli model can fit the drying curves with high accuracy. The highest essential oils yield of 2.4 % (v/w) was obtained by a hybrid dryer. Results indicated that hybrid dryer could keep the 24 Kinds of volatile compounds of Thymus while these values were 10 and 6 for oven and shadow methods, respectively. The main components of the essential oils in different drying methods were including alpha and beta pinene, caryophyllene, caryophyllene oxide, carotol, thymol, thymol methyl ether, terpinene-4-ol, gama-terpinene, p-cymene.In general, hybrid drying method is recommended as the best method for post-harvest thyme processing.

The aim of the current study was to investigate the antioxidant activity of Hawthorn's woods ethanol and acetone extracts and the effect of their antimicrobial on Escherichia coli, Staphylococcous aureus and Bacillus cereus bacteria. Extraction was performed by maceration method with two acetone and ethanol (96 percent) solvents at a ratio of 1:20 of sample to solvent. Total phenol content was measured by Folin– Ciocalteu method, and also the antioxidant properties were measured. Antibacterial activity of the extracts was determined at 0.7, 0.8, 0.9 and 1 percent (v/v) concentrations by well diffusion and test broth macro dilution method, respectively. The results showed that TPC and the percentage of inhibition of DPPH and ABTS free radicals of acetone extract were higher than methanol extract, and the highest effect on the diameter of the non–growth zone was related to 1 percent (v/v) of both extracts. Also, the results of antibacterial tests showed that the minimum inhibitory bactericidal were obtained with 1 percent of the extracts against B. cereus. The results of GC/MS also showed several functional compounds in the acetone extract.

The aim of this study was to extract and identify the volatile constituents of the essential oils of two species of citrus named Clementine and Mandarin and to investigate their antioxidant and antimicrobial potential. The compounds of the essential oils prepared by steam distillation were identified by gas chromatography-mass spectrometry (GC/MS). The antioxidant abilities of the essential oils were evaluated by ABTS and DPPH assays. The antimicrobial activities of the essential oils were investigated using the disc diffusion method against three Gram-positive (Staphylococcus aureus, Bacillus ceruse, and Bacillus subtilis) and two Gram-negative (Escherichia coli and Salmonella typhi) bacteria, a yeast (Candida albicans) and a fungus (Aspergillus niger) in comparison with the synthetic antibiotics.The GC/MS results revealed that both essential oils were rich in hydrogenated monoterpens and limonene was the main compound in both essential oils. The highest percentage of DPPH and ABTS free radical scavenging was shown about 34.38% and 48.44%, respectively for Clementine essential oil and for Mandarin essential oil was 67.53% and 96.44%, respectively, at 900 ppm. The results showed that both essential oils inhibited the growth of the studied microorganisms and increasing the essential oil concentration, increased the zone of inhibition. The highest diameter of inhibition zone was observed in Candida albicans in both essential oils. The lowest inhibition zone for Clementine and Mandarin essential oils was also observed in Escherichia coli and Aspergillus niger, respectively. In general, the antifungal effect of both essential oils was more than their antibacterial effect. In conclusion, citrus peel essential oil could be suggested as a natural antioxidant and antimicrobial substance for use in food products.

Oils are one the main means for consumed by human and their quality is largely dependent on the amount and type of fatty acids content. Due to high oil absorption by eggplant When blush, find a way to absorb less oil when frying is the most important. in this study, olive oil was used to deep fry and surface fry eggplant (with three pre- treatments: dry salt, brine and control) and frying was done in two steps. The fatty acid profile was determined by GC. The profile reviled that after two steps of frying, a decrease in amount of unsaturated fatty acids was seen in all samples and this decrease in the sample with surface frying was more significant. Also result indicated that oil uptake (absorption) in fryer was higher than pan and brine pretreatment increased oil uptake (absorption), it might be due to water uptake as the eggplant immersed in brine. When di en conjugate number was compared, the highest number was related to the samples deep fried with brine pre-treatment and the lowest number related to surface frying the control samples.

Oxidative degradation of lipids is a major factor limiting the shelf life of foods. The free radical reaction of lipid peroxidation is generally responsible for the deterioration of fatty foods. In general, use of synthetic antioxidants during the manufacturing process are applied to prevent fat oxidative and rancidity while their carcinogenic effects have been approved. Since the use of synthetic preservatives in food have been declined, researches on alternative natural products such as aromatic plants extract and essential oil have been extended.Aromatic plants are used traditionally in various regions of Iran for their preservation and medicinal properties, in addition to enhancing the aroma and flavor of foods. Aromatic plants components that have antiradical activities were used as natural antioxidant in food and biological products. The aim of this research was extraction and identification of the chemical compounds of Ferula gummosa Bioss essential oil and investigation of its antioxidant capacity in frying oil.
Aerial parts of F. gummosa were collected during fall 2013 from Khouzestan province of Iran. The collected aerial parts were then dried in the shade. The essential oil of aerial parts was extracted by hydro-distillation technique using Clevenger apparatus. Analyses of isolation, identification, and quantification of the component of the essential oil of F. gummosawere performed with a GC coupled with a mass spectrometer detector GC/MS. Analyses were carried out using helium as the carrier gas on DB-5 column (30 m×0.25 mm i.d., 0.25 μmfilmthickness). Injector and detector were hold at 240 and 300°C, respectively, and 0.5 μL of the diluted essential oil was injected. Identification of most of the compounds was made according to GC-MS retention times (authentic chemicals), Kovats indices (KI) in reference to n-alkanes (C8–C24), and mass spectra (authentic chemicals and NIST05 spectral library collection). Identification was considered tentative when it was based on mass spectral data only. Volatile compounds were quantified using percentage peak area calculations by means of a GC-FID with the same column and nitrogen as the carrier gas. The total phenol content in the F. gummosaessential oil was determined by a spectrometric method, according to the Folin–Ciocalteu phenol method by mixing of 0.2 ml of the essential oil with Folin-Ciocalteau reagent diluted and Na2CO3. The absorbance was measured at 765 nm after incubation in the dark at ambient temperature. The results of the total phenolic contents were expressed as gallic acid equivalents.The DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS [(2,2´-azino-bis 3-ethylbenzthiazoline-6-sulphonic acid)]tests were used for estimating antioxidant effects because the DPPH and ABTS radicals are the two most widely used and stable chromogen compounds to measure the antioxidant activity of biological material. In addition, the model of the DPPH radical-scavenging and ABTS radical cationdecolorization assay can be used to evaluate the antioxidant activities in a relatively short time compared with other methods. For this purpose 0.05 ml of the essential oil at different concentrations (0.05, 0.1, 0.2, 0.5, 1, 2, 5, 10 mg/ml) were mixed with 5 ml of 0.2 mMmethanolic DPPH solution and kept in the dark for 30 min at room temperature, then absorption-decrease was measured at 517 nm. The radical scavenging activity assessed by the ABTS method was expressed as the TEAC (trolox equivalent antioxidant capacity) value based on absorbance at 734 nm. In this test, ascorbic acid was used as positive control. The antioxidant activity of essential oil was evaluated against Tertiary butylhydroquinone (TBHQ) as an synthetic antioxidant in frying oil by peroxide value and thiobarbituric acid (TBA) index under rush condition in 90° C during one week.
GC-MS analysis of the volatile constituents of the F. gummosa essential oil allowed the identification of twenty-nine compounds representing 96.80% of the total volatile oil. The main components were β- pinene (37.9%), α- pinene (9.05%), terpinene-4-ol (7.78%) and ρ- cymene (6.58%). The mean amount of total phenolic of obtained essential oil was 59.7 mg gallic acid/g dry plant material.In the present study, the essential oil showed good free radical scavenging capacity at all concentrations studied, however the scavenging activity increased with increasing concentration of the essential oil. Antioxidant activity of essential oil from F. gummosa at 1 mg/ml was similar to TBHQ at 0.1 mg/ml (P ≤ 0.05%). The scavenging capacity test showed that the EC50 value of the essential oil was found to be 0.094 mg/ml. ABTS test showed that the F. gummosaessential oil was able to reduce the stable radical and 1mg/ml of essential oil had the highest antiradical activity (0.113 mg/ml ascorbic acid equivalent). Oven test revealed that 500 and 1000 ppm of essential oil had the higher activity than TBHQ in 200 ppm in frying oil.
The results indicated that F. gummosa had high total phenolic content. Also, according to these results, there was a relationship between totalphenolic content and antioxidant activity.The findings of this study showed that F. Gummosa essential oil can exhibit strong antioxidant activity, probably due to its particular chemical composition, mainly the high amounts of monoterpenes. Therefore, this essential oil could be used for the preservation of edible oil against oxidation and for increasing its shelf life as a natural preservative ingredient.

Milk fat is frequently adulterated to meet the demand which exceeds the supply and to increase profit margins. Samples of butter adulterated with different levels (5, 10 and 15% w/w) of margarine were prepared and analysed using different methods including refractive index, iodine, reichert-meissl and polenske values. GC and HPLC were utilized to determine fatty acid and tocol profiles of samples, respectively. Results showed that margarine addition up to the level of 15%, had a significant (05/0P)

Regarding the increasing usage of pesticides to a broad variety of crops in Iran، and the importance of public concerns about possible health risks from pesticide residues، chlorinated pesticide residues in vegetables were determined in National Nutrition & Food Technology Research Institute in 2005. Thirty samples (melon، maskmelon، watermelon) were evaluated by an descriptive method. Sample extraction was carried out with ethyl acetate، and the extracts were cleaned up by high performance gel permeation chromatography. Pesticide residues were identified and quantified using gas chromatography ion trap mass spectrometry detector. Recoveries of chlorinated pesticides were within a range from 95-178%. Detection limit of pesticide residues were from 0. 01 to 0. 05 mgkg-1. The data demonstrated that the samples analysed did not contain residues of the monitored pesticides above the accepted maximum residue limit (MRL) as adapted by the FAO/WHO Codex Alimentarius Commission. This method proves to be successful in analyzing pesticides in vegetables and provides reliable and accurate results.