جستجوی مقالات مرتبط با کلیدواژه « gallic acid » در نشریات گروه « کشاورزی »

 Thermal process is the most prominent option for treating foods. During the heat treatment, food nutrients response simultaneously but adversely under pH, temperature, moisture, and other provided conditions. It might result in an irreversible transformation of composition and structure that influences oxidative stability and sensory properties. The use of antioxidants is one of the most common methods to prevent edible oils oxidation. Safety concerns of synthetic antioxidants including tert-butylhydroquinone (TBHQ) as food additives have led to increasing demands for natural ones. Phenolic compounds such as Gallic Acid (GA) and Methyl Gallate (MG) represent to possess markedly high activity to scavenge free radicals which are among the most powerful natural sources of oxidative inhibitors in foods. Apart from their antioxidant activity, GA and MG also exhibit multiple biological characteristics such as anti-atherogenic, anti-spasmodic, and anti-microbial activities. This study aimed to investigate the oxidative stability of the in-use sunflower (S) and palm (P) oils as affected by the GA, MG, (GA+MG), and TBHQ to clarify their antioxidant behavior.

Antioxidants Gallic acid, Methyl gallate and TBHQ (Purity>98%) were purchased from Sigma Aldrich, USA. All solvents and chemicals were provided from Merck, Germany and Sigma Aldrich, USA with analytical grade. Antioxidant-free sunflower and palm oil were prepared from Three Goals factory, Neyshabur, and potatoes (Agria variety) from Fariman region, Khorasan Razavi.

Chemical changes, oxidative stability and quality indices of the in-use sunflower oil (S) and palm (P) (65:35 w.t. %) were evaluated during 8-hour heat treatment at 180 °C through GA, MG, GA/MG (25:75, 50:50 and 25:75) and TBHQ. All experiments were carried out in quadruplicate, and data were subjected to analysis of variance (One-way-ANOVA). Mean data were compared based on Duncan's multiple range test at 5% level (p<0.05). Observations of the chemical properties showed that sample S mainly contained Linoleic fatty acid (61.53%) and Oleic acid (25.50%) and for sample P, Oleic acid (41.90%) and the saturated long-chain fatty acid of Palmitic acid (38.9%). Also, the total phenolic content (TPC) and tocopherol (TTC) of sample P were 53.12 and 185)µg.g-1(, respectively, and sample S were 36.01 and 490 )µg.g-1(. The results of oxidation stability test were analyzed based on Carbonyl value (CV), Conjugated diene value (CDV) and acidity (FFA) parameters. According to our findings, all parameters increased significantly at different speeds during the heat treatment (p<0.05). Moreover, the oxidative stability of the in-use oil was significantly promoted by the antioxidants added, meaning that the control treatment and the treatment containing synthetic antioxidant TBHQ had the highest and lowest FFA%, respectively. The CDV of the antioxidant-free treatment was reduced by 68.6% in the presence of GA75+MG25.In addition, the CV change rate of the antioxidant-free sample in the presence of TBHQ was reduced by 70.2%. It was concluded that the natural antioxidants were capable of being competed with TBHQ antioxidants.

The results of this study showed that the heat treatment affected the nutritional value, quality indexes and chemical structure of the treatments, decreasing the quality and stability of the oil. As observed, all FFA, CDV and CV parameters increased significantly at different speeds during 8-hour frying process. The analysis also indicated that the oxidative stability of the treatments increased at the presence of antioxidants during the heat treatment at 180 °C. Thus, the control treatment and the treatment containing synthetic antioxidant TBHQ had the highest and lowest acidity, respectively. Also, the CDV of the antioxidant-free treatment decreased by 68.6% in the presence of GA75+ MG25. In addition, the rate of CV changes was declined by 70.2% through the TBHQ. The results indicated the key role of this synthetic antioxidant in preventing the formation of secondary compounds in the advanced stages of oxidation.It is evident that most synthetic antioxidants are volatile and heat sensitive. Furthermore, there are some limitations in applying TBHQ to promote oxidative stability of food products due to its toxic potential. Evidences have also been reported on the mutation caused by  the synthetic antioxidant TBHQ in the living organism's body. Compared to synthetic antioxidants, natural polyphenolic antioxidants such as MG and GA which widely distribute in plants mainly have antioxidative properties. Compared to GA and MG, GA+MG antioxidants have a longer induction period and higher oxidative stability. Promoting oxidative stability with such an arrangement of antioxidants is a good option in taking advantage of this class of natural antioxidants. According to the results of this study, it can be inferred that with a slight increase in natural antioxidants levels, we might be able to obtain the oxidative stability level comparable to the behavior of synthetic antioxidant TBHQ. Of course, it is worth noting that the addition of natural antioxidants to food such as edible oils should also be done according to national and international standards.

In the present study, oxidative stability of gallic acid, methyl gallate, and syringic acid at four concentration (200, 400, 800, and 1600 ppm) and three temprature (110, 120, and 130 °C) levels in soybean oil was studied using rancimat. The results showed that the fatty acid profile of this oil, mainly consist of linoleic acid (51.01 %), oleic acid (24.50 %), palmitic acid (12.20 %), and linolenic acid (7.10 %). Among various tempretures, the induction period of gallic acid, methyl gallate, and syringic acid (200-1600 ppm) was at the range of 2.90 to 17.49, 2.38 to 16.94, 1.27 to 5.41 h, respectively. With increasing the conceration of gallic acid, methyl gallate, and syringic acid or decreasing temperature, the oxidative stability was increased, thus oxidation rate was decreaed. Antioxidant activity of gallic acid and methyl gallate in soybean oil were not difference at different temperatures, but syringic acid showed lower power in oxidative stability of soybean oil, as compered with control sample. Generally, gallic acid and especially methyl gallate have high potential in increasing oxidative stability of edible oils, specially soybean oil.

The genus Laurencia(Rhodomelaceae), a complex group, has 285 species and infraspecific names. Identification and taxonomy of these taxa, mainly has been based on flexible morphological characters which have led to a complicated taxonomy in this group. Nowadays, taxonomical study of this group has changed a lot by using reproductive characters, anatomical differences and modern molecular studies. In this study, the samples have been collected from some areas of the Persian Gulf coasts and islands of Hormozgan province (southern Iran). Afterward, their anatomical, reproductive and chemical properties have been examined. The outcomes revealed that, the Folin-Ciocalteau method can be utilized as a taxonomical character in ultimate identification and the confirmation among species and varieties of this genus. It became clear that, there is a meaningful difference between two samples which were under study due to measuring the amount of polyphenols and finally, L. obtusa var. mollissima was separated from type variety of L. obtusa.

In order to study morphological characteristics, yield, elements and Gallic acid contents in Rhus coriaria L. fruits under the influence of manure and chemical fertilizers, a factorial experiment was conducted in a randomized complete block design with three replications at the Research Institute of Forests and Rangelands. Manure factor was included control, 20 and 40 tons per hectare and chemical fertilizers (Mixture of nitrogen, phosphorus and potassium) were N0P0K0 (control), N50P25K25 and N100P50K50 kg ha-1 from urea, triple superphosphate and potassium oxide sources. Results showed that the interaction of manure and chemical fertilizer on plant height and trunk diameter was significant at 1% probability level. Manure had a significant effect on leaf number and width, fresh and dry yield of cluster at a probability level of 5%, and on leaf length and leaf weight at 1% probability level. The effect of chemical fertilizer on leaf weight was significant at 1% probability level. The effect of manure fertilizer on nitrogen, phosphorus, potassium and iron was significant at 1% probability level. Mean comparisons of morphological traits showed that the highest number of leaves (683.44 number per plant), leaf length (24.06 cm), leaf weight (1754.9 g per plant), fresh cluster yield (301 g per plant) and dry cluster yield (281.2 g per plant) were achieved with using of 40 tons per hectare manure. The highest percent of nitrogen, phosphorus and potassium were obtained with mean of 1.9, 0.32 and 0.71%, respectively with consumption of 40 tons per hectare manure. The highest amount of Gallic acid was obtained from manure application of 40 tons per hectare with 0.44 mg/kg of fruit. Results showed that this plant has been affected by fertilizer and increased fruit and Gallic acid with the use of fertilizers.

The performance of antioxidants depends on different factors, including chemical structure, interaction with oxidative environment, hydrophobicity and thermal conditions of the oil, and due to behavioral complexities, their results are unpredictable in oil systems. Therefore, gallic acid and syringic acid antioxidant activity were evaluated by DPPH assay, its oxidative stability by Rancimat and fatty acids profile of sunflower oil using GC-MS. In oven test, sunflower oil without antioxidants was monitored in presence of four levels of syringic acid and gallic acid (200, 400, 800 and 1600 ppm) at 110 and 120 °C. Sampling was carried out at continuous time intervals and the induction period of hydroperoxides, conjugated dienes and trienes formation was determined. The results showed the fatty acid structure of sunflower oil consisted mainly of unsaturated fatty acids (especially linoleic acid, C18:2 ω3) and saturation ones (especially palmitic acid, C16:0), respectively. The results of oxidative parameters showed that both antioxidants increased the stability of sunflower oil compared to the control sample, and the antioxidant activity of gallic acid was significantly higher in both temperatures than syringic acid and synthetic antioxidant, BHT. Also, with increasing temperature, the stabilization factor (F) and antioxidant activity (A) of gallic acid in the most treatments had significantly lower reduction than that of syringic acid, which is due to the higher carry-through property of gallic acid. In general, gallic acid and syringic acid have high potential for enhancing the oxidative stability of edible oils and can be used as a substitute for synthetic antioxidants.

In this study chitosan and gallic acid nanogels is producted and three concentration 0 ¡100 ¡200ppm were added to sunflower oil mayonnaise The prepared samples stored for 60 days. particle size determined. Acidi number¡peroxide valu¡ oven shal ¡measuring carotenoid and Fourier transformation infrared (FTIR) spectrometry analysis was investigate . Acidi number and peroxide valu increased during storage time increase in control sample was more than other samples and in 200 ppm sample was lower than rest. In oven Shal test peroxide valu increase during storage time but the increase in the control sample was more than other . Amount of carotenoids in all samples decreased but in control sample carotenoids decrease was more than other samples. Among tree treatment, the sample containing 200 ppm nanogel and control sample had best and wrost results, respectively. The result showed that chitosan gallic acid nanogel could show good antioxidant properties.

Phenols are important secondary metabolites with important role in tolerance to the environmental stresses, and quince leaves and fruits are significant sources of phenolic compounds. The current research was conducted to study the contents and variations of total phenolic compounds in the leaves and fruits tissues of selected quince genotypes from Isfahan and investigate its eventual role in the fire blight resistance in this species.Twelve quinces genotypes, KVD4, SHA1, KVD3, PH2, ET1, NB3, KVD1, KM1, SVS1, SVS2, NB2 and cv. Isfahan as control were evaluated.The ethanol extracts of the leaves and fruits were prepared during spring and summer and total phenol contents were determined by the folin-ciocalteu method, based on equivalent gallic acid. The results showed differences in phenolic compounds in the leaves, of the genotypes, so that genotype KVD4 and cv. Isfahan, with 17.8 and 2.7 mg gallic acid/g fresh weight of the leaves, had the highest and lowest total phenols, respectively. Also a constant increase was observed in the phenol contents of the leaves up to end of the summer. On the other hand, no significant difference was found between the amounts of total phenols in fruits of genotypes. The evaluation of phenol content as major components of non-enzymatic anti-oxidative defense system, against fire blight invasion showed negative correlation of Isv, with phenolic contents of the quince leaves from early summer.

In this study, oxidation kinetic parameters of soybean oil affected by three different concentrations of gallic acid antioxidants (100, 200 and 300 ppm) in comparison with a blank sample were studied by rancimat in three different temperatures 383, 403 and 423 k. Factors calculated in this study were temperature coefficient (Tcoeff), special constant reaction (A), activation nergy (Ea), enthalpy (ΔH++) and entropy (ΔS++). They were estimated based on the Arrhenius, Vant Hoff and the Eyrings equations. Generally, reaction constant of oxidation increased with the rise of temperature, and there was a logarithmic relationship between them. Stability of the oil was also increased by the increase of the antioxidant concentration. The results indicated that there was a significant difference among the temperature coefficient, enthalpy, activation energy and special constant reaction values in the blank sample and samples with antioxidant. No difference was observed between samples with 200 and 300 ppm antioxidant. Concerning the entropy, there was a difference between the blank sample and samples with antioxidant, and a high correlation was observed among the regression relations (0.9479

Keywords: Oxidation kinetic, Soybean oil, Gallic acid, Rancimat}

Traditional butter ghee contains little α-tocopherol and some microbial, enzymatic and metallic contaminations and it is susceptible to decay during production. Hence, for increasing its shelf-life the combinatory antioxidants can be used. In this study, the 0.05%, 0.1% and 0.15% concentrations of Gallic Acid, Quercetin, Citric Acid and BHT antioxidants have been evaluated by Rancimat apparatus at 120 and 150 ˚C. As a result, the selected best antioxidant treatments were preserved at refrigerator (4±1 ˚ C) and ambient (24±1 ˚ C) temperatures for two months. During this period, Rancimat tests, acid value and peroxide number were measured once in two weeks. As a result, at 120 and 150˚ C the best antioxidant was proved to be Gallic Acid with a concentration of 0.15% and during the preservation period, 0.15% Gallic Acid at the ambient temperature was stronger than the other samples and 0.15% Quercetin placed second. The combinatory samples of 0.05% Gallic acid with all levels of Citric Acid showed a significant synergistic effect at 120˚ C.

In order to study the effect of elements in early splitting and the effect of phenolic compounds and Gallic acid in control of aflatoxin, an experiment was conducted in Rafsanjan pistachio research station. At harvest, from the trees of 3 pistachio’s varieties(Ahmadaghaii, Kalehghuchi, Ohadi) 15 clusters in each variety collected as randomized and phenolic compounds and Gallic acid in hulls were determined. From all varieties, many fruits of each type such as early split, cracked and true fruits collected and their hulls examined for macro and micro elements. These experiments were performed in 1385 according to complete randomized design and results analyzed in 3 replications by Duncan test with SAS and Sigma plot soft wares. Highest rate of Nitrogen (2.15%) in the intact fruit hulls and lowest rates was in early split and cracked fruit hulls (1.94 & 1.97%). Highest rate of Mg (0.13%) was in the intact fruit hulls and lowest rates were in early split pistachio hulls (10%). Maximum rates of phenolic compound determined in the fruit hulls of Ohadi variety (1398mg/100gr) and the minimum rates measured in the fruit hulls of Ahmadaghaii 1131 mg/100g. Results showed that increase rates of phenolic compound caused to reduction or prevention of aflatoxin in the pistachio’s fruits.