جستجوی مقالات مرتبط با کلیدواژه « چای » در نشریات گروه « صنایع غذایی »

In recent years, the use of plant sources with bioactive compounds such as pigments and antioxidants in food has greatly expanded. Research has shown that these resources play an important role in improving quality properties and increasing the shelf life of food products such as cereals and dairy products. According to these points, in the present study, single levels of green tea extract (0, 1 , 2%), white tea (0, 1 , 2%) and ginger (0, 0/75 , % 1) were used in the sponge cake formulation and chemical and physicochemical experiments was performed on different treatments. To optimize the results, the Response Surface Methodology (RSM) was used. By increasing levels of green tea, white tea and ginger extracts, the fat, protein and total phenol content and pH value in the treatments increased. In contrast, moisture content, acidity and peroxide value decreased. All three extracts of green tea, white tea and ginger had significant effects on the quality characteristics of sponge cake samples. The results of the RSM showed that the low levels of the evaluated extracts in the studied parameters, except the peroxide value, gave better results.

Due to the rapid spoilage of fish, it is necessary to use new methods of packaging such as coating with natural antioxidants. Chitosan has been well received as a natural preservative due to its renewable properties and similar structure to cellulose. Also, phenolic compounds in tea and cinnamon and its antimicrobial and antioxidant properties have been considered in the packaging of protein substances that are prone to high corruption. In this study extracts of 0.05% tea, 0.5% cinnamon tea, and solution of 2% chitosan-cinnamon tea were prepared. Characteristics of oxidation, chemical changes, microbial analysis and FTIR spectroscopy were examined on trout fillets covered with extracts on 0, 5, 15, 20 days during storage in the refrigerator (4 ). The results showed that coatings containing extracts and chitosan had significant effects at the level of 5% in reduction of microbial load, volatile nitrogen bases and thiobarbiotic acid. Based on FTIR findings, the control sample showed the highest oxidation rate and the sample treated with chitosan extract, tea and cinnamon tea showed the lowest oxidation rate. Covering trout fillets with cinnamon tea and tea extract increased antimicrobial properties, but combining it with a powerful antioxidant such as chitosan has higher effectiveness. Chitosan-cinnamon tea cover can be used to improve the quality of fish fillets and increase its shelf life.

Tea has a variety of fermented, non-fermentable and white tea.Tea contains compounds such as polyphenols, proteins, amino acids and organic acids.In this study, differences in the composition of black, green and white tea were investigated.Total phenols, flavonoid, flavonol, tannin, catechin, epigallocatechin gallate, caffeine, theaflavin, thearubigin, theaborunin, vitamin C, vitamin E contents, free radical scavenging and IC50 levels were measured.White and green tea had higher total phenols and tannin than black tea.The amount of flavonoid and flavonol (38.4 and 29.35 mg/g DW), catechin and epigallocatechin (96.81 and 65.41 mg/g) in white tea were higher than the other two types of tea.Black tea had higher caffeine content (5.25mg/g) than the other two types of tea.Theaflavin, thearubigine and theaborunin were found only in black tea. This showed that the phenolic compounds of black tea change as a result of fermentation.Green tea had the highest (13.39 µg/g) vitamin C and (33.18 µg/g) vitamin E.White and green tea were able to free radical scavenging at 36.89% and 56.87%, respectively. The amount of bioactive compounds present in the three types of tea is different and is related to its processing steps. However, all three forms of tea have compounds that have high antioxidant properties.

Gilan’s black tea is obtained via the fermentation of the fresh leaves of Camelia sinensis var. assamica. In this study, the effect of tea production process and brewing methods, microwave and conventional methods were studied on their phenolic and flavonoid content and antioxidant activity (DPPH radical scavenging assay, iron atom reducing power). The results showed that due to the fermentation process, the antioxidant properties and phenolic content of tea were changed and also the tea brewing method was effective on these properties and the highest phenolic and flavonoid contents and antioxidant activity were determined in the rolling step on the microwave brewing method. While the lowest phenolic and flavonoid contents were observed in the withering step on microwave brewing method and the lowest antioxidant activity was related to the tea treatment under conventional brewing. Therefore, the microwave method with high extraction capability and reduced the processing time can be an alternative to the conventional methods in the food industry.

Iranian tea industry problems caused to related section damage. Low quality of Iranian black tea and change in sense of consumers taste is one of the reasons. It is produced various teas to attract of consumer opinion. Permissible additives using is not usual in Iranian tea industry (before packaging). One of the natural additives of black tea (i. e. Qare-Qat) evaluated in this experiment. The experiment carried out by using a Split-Plot with two factors in three replications. Storage period was distributed in four levels (0، 2، 4 and 6 months) in main plots and added Qare-Qat fruit amount in subplots in four levels (0، 5%، 10% and 15%). Qualitative traits of tea including organoleptical tests (as made tea apparent، color، perfume، and flavor of tea beverage) and chemical tests (as measuring of theaflavin (TF)، thearubigin (TR)، total color (TC) and brightness (B) of tea) studied. Chemical tests results showed that «Tea + 5 and 10 percent Qare-Qat fruits» treatment has more TF، B and TF/TR ratio than control (pure tea) and this difference was significance in 1% level. However، taste tests did not revealed significance difference between control and tea + Qare-Qat blends.