• The Korean Journal of Food And Nutrition
• /
• v.26 no.2
• /
• pp.295-300
• /
• 2013

The objective of this study is to propose the motivation of the analysis on consumer's purchase behavior and willingness-to-pay for flower tea. Therefore, we survey the purchase behaviors on flower teas as compared with leaf teas such as green teas. We also analyze the willingness to purchase and pay for such teas. The reasons for consuming flower teas are 'flavor', 'beauty/diet', 'health', consecutively. Consumers prioritize 'safety', 'quality', 'price', and 'design' when purchasing flower teas. Nevertheless, it is also essential to consider 'flavor' as a quality factor. It is necessary to differentiate the process and marketing strategies for the development of flower teas.

• Korean journal of food and cookery science
• /
• v.15 no.2
• /
• pp.95-101
• /
• 1999

This study was carried out to prepare green teas by traditional roasting manufacturing process, Ku Geung Ku Po and to determine the quality charateristics of the green teas by examining the change of their main components induced during this roasting process. The content of total sugars in unroasted tea leaves was 7.82%. Its content of roasted teas was decreased by increasing the number of roasting and there was significantly differences between samples. The content of total sugars in 9th roasted green tea was 3.98%. The total nitrogen contents of green teas produced by this process were 4.96∼6.38%. The more the number of roasting and the less content of tannin in green teas. And the ratio of total nitrogen and tannin in tea leaves 21.97 but its ratio in 9th roasted tea was increased to 45.54. The ascorbic acid in tea leaves consisted in 1,820.3 mg/100g but its content was decreased by increasing the number of roasting process. Whereas the content of caffeine in green teas was not reduced significantly by this traditional method. Of all amino acids, green tea produced by Ku Jeung Ku Po was rich glutamic acid, lysine and aspartic acid. And especially, phenylalanine, which was rarely found in other green teas, was abundant in these green teas. The compositions of glutamic acid and methionine were increased as increasing the number of roasting process but those of aspartic acid and arginine decreased by these processing. The main fatty acids of Ku Jeung Ku Po green tea were linolenic acid, linoleic acid and palmitic acid and the contents of unsaturated fatty acid in green teas were composed over 70% of total fatty acid. And the fatty acid contents in green teas were not affected during Ku Jeung Ku Po's process. The contents of minerals in these teas was rich in the oder of potassuim. magnessuim and calciumim, and these contents were not observed the prominant change during the process.

• Preventive Nutrition and Food Science
• /
• v.9 no.3
• /
• pp.222-226
• /
• 2004

Hydrocarbons induced by gamma-irradiation of green, black, and oolong teas were analyzed to determine whether the hydrocarbons can be used as markers for detecting post-irradiation of these teas. The samples were irradiated at 0, 2.5, 5, 7.5, and 10 kGy. Detection was attempted by extracting fat from the teas, separation of hydrocarbons with florisil column chromatography, and identification of hydrocarbons by gas chromatography-mass spectroscopy (GC-MS). Concentration of hydrocarbons increased with the irradiation dose. The major hydrocarbons in irradiated green, black, and oolong teas were 1-tetradecence (14:1), pentadecane (15:0), 1,7-hexadecadiene (16:2), 1-hexadecene (16:1), 8-heptadecene (17:1), and heptadecane (17:0). Radiation-induced hydrocarbons in teas were 1,7-hexadecadiene and 8-heptadecene. These compounds were not detected in non-irradiated samples, so the hydrocarbons (16:2, 17:1) can be used as markers for detecting post-irradiation of the teas. Furthermore, detection of hydrocarbons after 12 months storage at room temperature remains a suitable method for identifying irradiated teas.

• Journal of the East Asian Society of Dietary Life
• /
• v.14 no.2
• /
• pp.156-160
• /
• 2004

This study was carried out to examine the changes of chlorophyll a and b contents by the extraction temperatures and the number of soaking using five kinds of Korean green teas(3 kinds of green tea and 2 kinds of tea bag) which were obtained from a local market in Daegu city, Korea. The chlorophylls were extracted with 80% acetone, and determined by a visible spectrophotometer. The concentration of chlorophyll in Sulrok(tea bag) were the highest among all kinds of teas when they were extracted at 60, and decreased with the number of soaking increased. On the other hand, the chlorophyll content of green teas was the highest at 80, and decreased with the increase of the number of soaking as the tea bag did. It was found that the Korean tea bag contained more chlorophyll than green teas did, and green teas contained significantly more chlorophyll b than chlorophyll a.

• Korean Journal of Food Science and Technology
• /
• v.54 no.2
• /
• pp.228-234
• /
• 2022

Various types of tea have been cultivated to obtain different flavors and enhance their functional properties. The objective of this study was to investigate the physicochemical properties of γ-aminobutyric acid (GABA) teas produced from commercial Korean green, white, and black teas. The concentration of total minerals was reduced in GABA green tea and GABA white tea but was improved in GABA black tea. The essential, non-essential, and total free amino acid contents were remarkably increased in the GABA teas. The amino acid GABA content was increased by 561.00 and 294.20 times in GABA white tea and GABA black tea, respectively. The antioxidant potential was not reduced, although the total polyphenol and total flavonoid contents decreased in GABA green tea and GABA black tea. The results indicated that the overall nutritional value of commercial green, white, and black teas could be improved by processing them into GABA teas.

• Food Science and Biotechnology
• /
• v.14 no.1
• /
• pp.1-5
• /
• 2005

Photostimulated luminescence (PSL), thermoluminescence (TL), electron spin resonance (ESR), and direct epiflourescent filter technique/aerobic plate count (DEFT/APC) were applied to detect dried green, black, and oolong teas irradiated between 0-10 kGy. Teas irradiated at 2.5 kGy and higher showed over 5000 photon counts/60 sec, while non-irradiated teas yielded 650-1000 photon counts/60 sec. TL glow curves for minerals separated from teas were detected at about $300^{\circ}C$ with low intensity in non-irradiated samples, whereas around $150^{\circ}C$ with high intensity in all irradiated samples. Ratio of $TL_1/TL_2$ based on re-irradiation step, showing lower than 0.1 and higher than 1.44 for non-irradiated and irradiated samples, respectively, enhanced reliability of TL results. ESR measurements for irradiated teas showed signals specific to irradiation. Log DEFT/APC ratio increased with irradiation dose; this result could be applied to identify irradiated tea samples.

• Korean Journal of Medicinal Crop Science
• /
• v.19 no.4
• /
• pp.276-286
• /
• 2011

Morus alba (Mulberry) leaves were exposed to fermentation for varying amounts of time: no fermentation (0 min, MANF), medial fermentation (10 h, MAMF), and full fermentation (24 h, MAFF). The chemical compositions of the teas were determined and compared with those of commercial Camellia sinensis teas. The results showed that mulberry leaf teas contained significantly higher amounts of ash and fat than Camellia sinensis tea. Compared with Camellia sinensis teas, all mulberry leaf teas contained significantly more total free amino acids (24.26~54.25mg L-glutamic acid equivalent $g^{-1}$), but the concentration of caffeine was relatively low for mulberry leaf teas. High thiamine, riboflavin, and niacin contents were found in all mulberry leaf teas, but ascorbic acid and pyridoxine were found at higher levels in Camellia sinensis teas than in mulberry leaf teas. Color measurements demonstrated that mulberry leaf tea infusions generally had lower $a^*$ (greenness) and $b^*$ (yellowness) values than Camellia sinensis tea infusions. All infusions exhibited low turbidity levels (less than 10%). The contents of total phenols were measured as 71.8 and 74.9mg 100 $ml^{-1}$ infusion in MANF and MAFF, respectively, but the MAMF tea infusion showed significantly lower total phenols (64.6mg 100$ml^{-1}$ infusion). The total flavonoid contents of mulberry leaf tea infusions were lower (8.9~20.6mg 100 $ml^{-1}$ infusion) than those of Camellia sinensis teas and thus had lower antioxidant capacities (DPPH: 326.8~526.9 ${\mu}M$ trolox equivalent $g^{-1}$ and FRAP: 364.6~387.6 ${\mu}M$ trolox equivalent $g^{-1}$) than Camellia sinensis teas. The amounts of ${\gamma}$-aminobutyric acid (GABA) and rutin were higher in fermented mulberry leaf teas; the level of GABA increased with increasing fermentation time and the content was highest in MAFF, but rutin content was highest in MAMF.

• Journal of Wetlands Research
• /
• v.9 no.1
• /
• pp.91-98
• /
• 2007

Antifungal activity of compost teas was evaluated in vitro and in vivo experiments. In vitro test, fourteen compost teas were produced using five different composts and through six different methods for compost tea production. Eleven pathogenic fungi were used as indicators of antifungal activity of compost teas. In vivo test, one of the compost teas used in vitro test was sprayed to cucumber leaves which were infected with powdery mildew in order to evaluate antifungal activity of compost tea. From the results of the tests, it was found that all compost teas used this study showed antifungal activity and the proper application of compost teas against pathogenic fungi for obtaining optimal effects was important to know.

• Food Science and Biotechnology
• /
• v.17 no.2
• /
• pp.408-412
• /
• 2008

Determining the elution of water-soluble substances from herbal teas is an important factor in their efficient use in terms of taste, perfume, and content of health-related components. The antioxidant activity and content of catechins in commercial Chrysanthemum indicum (gamguk) teas were determined for optimum elution conditions. The water extract of gamguk teas did not differ significantly in yield compared to methanol extracts and showed stronger antioxidant activity. Catechin contents in gamguk teas were 8-18% of the extracts when individual peaks in high-performance liquid chromatography analysis were compared to standard catechin peaks. Gamguk teas exhibited faster release of antioxidants, and the antioxidant activity was positively correlated with the thermal treatments. Gukhwacha (GC) was the best tea for rapid release (30 sec) of antioxidants with the $50^{\circ}C$ treatment, whereas antioxidants in other teas were relatively slower released.

• Korean Journal of Food Science and Technology
• /
• v.38 no.1
• /
• pp.5-9
• /
• 2006

Method for separation and quantification of methylxanthins, catechins, and theaflavins in Korean commercial teas (green, oolong, and black teas) was developed using reversed phase high-performance liquid chromatography (HPLC). After extraction with hot water, tea compounds were separated on Inertsil ODS-3v $(5\;{\mu}m)$ column, eluted with gradient of 7% acetonitrile and 93% of 20 mM phosphate buffer mixture for 7 min. Column effluent was monitored at 270 nm. This technique was effective for analyses of m methylxanthins, catechins, and theaflavins in teas and biological samples. In green and oolong teas, two kinds of methylxanthins and 7 of catechins were identified, whereas 4 theaflavins were only identified in black tea. Among seven catechins in green and oolong teas, EGCG showed highest amount, whereas ECG was highest in black tea. (theaflavins were found only in black teas) In all teas, theobromine content was lower than that of caffeine.