Sedigheh Yazdanpanah; Sara Mohammadi; Amir Hossein Elhami Rad
Abstract
Introduction: White tea is a new ingredient in a wide range of phenolic, antioxidant and antimicrobial compounds. The most important catechins in white tea are epicatechin, epigallocatechin, epicatechin- 3- galate, and epigallocatechin- 3- galate, which are flavonol gallates. The concentration of these ...
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Introduction: White tea is a new ingredient in a wide range of phenolic, antioxidant and antimicrobial compounds. The most important catechins in white tea are epicatechin, epigallocatechin, epicatechin- 3- galate, and epigallocatechin- 3- galate, which are flavonol gallates. The concentration of these phenolic compounds in white tea is higher than green tea. Sesame seed oil, which is produced by cold pressing method, has a great ability to preserve antioxidant compounds. Significant oxidative stability of sesame oil is due to the presence of lignan non-soapy substances. Strong antioxidant compounds in sesame seed oil include sesamol, sesamulin (antioxidant precursor), sesaminol and its isomers. The aim of this study was to investigate the effect of natural antioxidants of sesame oil and white tea on inhibiting the effect of metals on oxidation of sesame oil. Materials and Methods: In this study, aqueous extract of white tea was extracted and sesame oil was produced using cold press. In the next step, six samples including control sample (sesame oil), sesame oil containing white tea extract, sesame oil containing white tea extract and 0.1 ppm iron, Sesame oil containing white tea extract and 0.1 ppm copper, sesame oil with tea and 0.1 ppm zinc extract and sesame oil containing 100 ppm BHT were prepared. In all samples, aqueous extract of white tea in the amount of 6 mg/ 10 g was added to sesame oil. Total phenol, antioxidant capacity, power reducing on white tea extract and antioxidant power, peroxide number, oxidation stability and fatty acids profile were measured. All experiments were performed in a completely randomized design with three replications and the means were compared with Duncan’s test at the level of (P<0.05). SAS V 9.1 software was used for statistical analysis of quantitative data. Results and Discussion: The results showed that the aqueous extract of white tea contained 4.06 (mg gallic acid per gram of sample) total phenol, 6.00 (μg/ ml) antioxidant capacity 0.020 (mg/ g). Ml) is a reducing power. The reducing power of BHT antioxidant was 40 times and the antioxidant power of BHT was 14.85 times more than the aqueous extract of white tea. In the inhibition of free radicals in sesame oil, the aqueous extract of white tea had a significantly greater effect than the control sample. The iron- containing sample had more oxidation than other samples. In the inhibition of free radicals in sesame oil, the aqueous extract of white tea had a significantly greater effect than the control sample. The iron- containing sample had more oxidation than other samples. Rancimat value for samples of control sesame oil, sesame oil with tea and iron extract, sesame oil with tea and copper extract, sesame oil with tea and zinc extract, sesame oil with tea extract and sesame oil with synthetic antuioxidant BHT respectively 8.79 4.80, 9.08, 9.35, 9.42 and 9.61 hours were measured. The highest stability was related to the sample of sesame oil and synthetic antioxidant BHT and the Results and Discussion: The results showed that the aqueous extract of white tea contained 4.06 (mg gallic acid per gram of sample) total phenol, 6.00 (μg/ ml) antioxidant capacity 0.020 (mg/ g). Ml) is a reducing power. The reducing power of BHT antioxidant was 40 times and the antioxidant power of BHT was 14.85 times more than the aqueous extract of white tea. In the inhibition of free radicals in sesame oil, the aqueous extract of white tea had a significantly greater effect than the control sample. The iron- containing sample had more oxidation than other samples. In the inhibition of free radicals in sesame oil, the aqueous extract of white tea had a significantly greater effect than the control sample. The iron- containing sample had more oxidation than other samples. Rancimat value for samples of control sesame oil, sesame oil with tea and iron extract, sesame oil with tea and copper extract, sesame oil with tea and zinc extract, sesame oil with tea extract and sesame oil with synthetic antuioxidant BHT respectively 8.79 4.80, 9.08, 9.35, 9.42 and 9.61 hours were measured. The highest stability was related to the sample of sesame oil and synthetic antioxidant BHT and the lowest stability was related to the sample of sesame oil with tea and iron extracts. In comparison with the effect of metals on the oxidation of sesame oil, the addition of iron to sesame oil has increased the oxidation rate compared to the two other examined metals (copper and zinc). Rare metals increase the oxidation rate of edible oils by increasing the production of free radicals from fatty acids or hydroperoxides. The composition of of fatty acids profile showed that palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid were the predominant fatty acids in sesame oil. In the iron- containing sample, with increasing oxidation rate, the amount of linolenic acid decreased compared to other samples. The results of the Se index were confirmatory on the results of oxidative stability index. White tea extract and sesame oil due to their antioxidant and phenolic compounds have been able to inhibit free radicals and metal peroxidants, especially copper and zinc. Sesame oil extracted by cold pressing is not suitable for frying due to its low heat resistance, but it can be used in the formulation of salad dressings.
Food Chemistry
Sedigheh Yazdanpanah; Shadi Jokar; Tahereh Zandilak; Maryam Haghighi
Abstract
Introduction: Coffee is the second most profitable commercial products in the world and in addition to beverage consumption, it is widely used in food industry. Among natural sources, coffee has the highest amount of caffeine. The amount of caffeine in coffee varies depending on the variety of coffee ...
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Introduction: Coffee is the second most profitable commercial products in the world and in addition to beverage consumption, it is widely used in food industry. Among natural sources, coffee has the highest amount of caffeine. The amount of caffeine in coffee varies depending on the variety of coffee and how it is brewed. Coffee beans contain other compounds such as phenol, magnesium, potassium and fiber. Plants are the most important route for the transfer of heavy metals to the human food chain and the natural cycle. Heavy metals in the body can cause everything from biochemical changes in low levels of contamination to effects on the nervous system and even death in high concentrations. They slow down the reaction with enzymes and even stop the body's essential physiological reactions and have the ability to be stored in the bones, which enter the bloodstream after being saturated in the bone. Heavy metals are important because they are non-degradable in the human body. Contamination with mycotoxins in coffee beans such as ochratoxin produced by Aspergillus and Penicillium occurs under the influence of environmental conditions such as temperature, humidity, water activity, transport conditions, storage until consumption. Therefore, the aim of this study was to investigate and compare the physicochemical properties, fungal contamination and metal elements in 4 samples of instant coffee powder Eagle Lux, Good Day, Nestle and Torabika. Materials and Methods: In 4 samples of instant coffee powder fat, moisture, ash, pH, total sugar, caffeine (using HPLC), ochratoxin A contamination (using HPLC) and lead and arsenic metallic elements (using hydride atomic absorption spectroscopy) were determined. The results were reviewed and compared with national and international standards. All experiments were performed in a completely randomized design. Data analysis was performed using SPSS software. The means were compared using Duncan's test at 5% probability level. Results and Discussion: Comparing the results obtained with the permissible limits of national and international WHO standards, all results are within the permitted standard range (pH 5 to 7, maximum moisture 4%, total sugar maximum 72%, ash 4%, fat in cappuccino powder maximum 30%, Caffeine was based on dry matter up to 2.8%, lead 0.5 mg/ kg, arsenic 1 mg/ kg, ochratoxin 10 ppb). The highest pH value (6.83± 0.05) was determined in Good Day sample. The low pH in the Nestle sample may be due to acid rain and low soil pH in the exporting countries. Minimum amount of ash (2.38± 0.05%), moisture (1.41± 0.05%), lead (0.026± 0.000 mg / kg) and arsenic (0.013± 0.000) mg / kg) was observed in Torabika sample. Lead level was similar in Good Day and Torabika samples. The highest amount of caffeine (0.23 ±0.05 wt %) was obtained in Good day sample. Ochratoxin A was not detected in all samples. The lowest amount of total sugar (42.75± 0.05 g /100 g) was observed in Nestle sample. Therefore, it is the most suitable sample for diabetic patients. Torabika sample is recommended as the best sample due to the low amount of lead, arsenic, ash and fat, as well as low moisture content. With increasing moisture and sugar, the possibility of liquid steps forming between particles increases and this causes the degree of cohesion and agglomeration of the powder and the marketability of the powder disappears. Increased mineral consumption causes disease due to inhibition of the mechanism of control of absorption in the small intestine and accumulation in the body. Therefore, as the amount of total ash in coffee increases, its adverse effects on the body intensify. Torabika is the most suitable sample for people with cardiovascular disease due to the lower fat content.
