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A lexicon for flavor descriptive
Article in Journal of Sensory Studies · June 2007
Pusan National University
24 PUBLICATIONS 159
Delores Chambers Kansas State University 59 PUBLICATIONS 643 CITATIONS SEE PROFILE Available from: Jeehyun Lee Retrieved on: 17 October 2016
A LEXICON FOR FLAVOR DESCRIPTIVE ANALYSISOF GREEN TEA JEEHYUN LEE and DELORES H. CHAMBERS1 The Sensory Analysis Center Kansas State University Dept. HN, Justin Hall Manhattan, KS 66506 Accepted for Publication August 4, 2006 ABSTRACT A lexicon for describing green tea was developed using descriptive analysis methods. A highly trained, descriptive sensory panel identiﬁed, deﬁned and referenced 31 ﬂavor attributes for green tea. One-hundred and thirty-eight green tea samples from nine countries – China, India, Japan, Kenya, Korea, Sri Lanka, Taiwan, Tanzania and Vietnam – were selected to represent a wide range of green teas. Attributes could be categorized as “Green” (asparagus, beany, Brussels sprout, celery, parsley, spinach, green beans, green herb-like);
“Brown” (ashy/sooty, brown spice, burnt/scorched, nutty, tobacco); “Fruity/ Floral” (fruity, ﬂoral/perfumy, citrus, fermented); “Mouthfeel” (astringent, tooth-etching); “Basic Tastes” (overall sweet, bitter); and other attributes (almond, animalic, grain, musty/new leather, mint, seaweed, straw-like). Some attributes, such as green, brown, bitter, astringent and tooth-etching, were found in most samples, but many attributes were found in only a few samples.
Green tea processors, food industry, researchers and consumers will beneﬁt from this lexicon with precise deﬁnitions and references that reliably differentiate and characterize the sensory attributes of green teas.
PRACTICAL APPLICATIONSGreen tea (and white tea) processors, food industrialists, researchers and consumers will beneﬁt from this lexicon with precise deﬁnitions and references that reliably differentiate and characterize the sensory attributes of green tea.
Corresponding author. TEL: 785-532-0162; FAX: 785-532-0162; EMAIL: firstname.lastname@example.org
The fastest growing beverage category in the U.S.A. in the next few years is expected to be that of wellness or “functional” beverages to meet consumer demands for drinkable nutrition and health beneﬁts (Miller 2005). Mintel (2004) expects that functional-beverage sales will grow from $10 billion in 2004 to $12.8 billion in 2009, and Sloan (2005) reports that premium and exotic teas are expected to grow from $6.8 billion to $10 billion by 2010. Teas are popular around the world with claimed beneﬁts such as slimming, beauty and antistress. Speciﬁc health claims in various countries include promoting respiratory health, reducing cholesterol and balancing blood pressure (Mintel 2005a). Many people drink tea for the place it holds in their culture, while others drink it for its desirable sensory properties or its probable health beneﬁts.
Green tea is one of the three major types of tea (green, black and oolong).
For green tea, leaves are processed and dried immediately after harvesting, so that no fermentation occurs and the tea leaf often remains reasonably green (Taylor and McDowell 1993; Rinzler 2001). Different green teas exist because of different processing methods, harvest times of tea leaves, tea tree species (Camellia sinensis var. sinensis or var. assamica) and region (Jung 2004).
U.S. tea sales in retail volume approached 34,000 t in 2004 (Euromonitor 2005), although most of that tea was the black or fermented type. Many stores now carry green tea products; green tea is available for purchase online; and a number of different books have been published related to green tea, all of which may reﬂect increased consumption or demand for green tea in the U.S.
market as well as other Western countries. In addition, a large number of ready-to-drink iced teas have been formulated using green tea as a base (Mintel 2005b). In recent years, the number of green tea products or green tea-containing products in retail food stores has increased tremendously in many parts of the world. However, while there have been increasing sales volume of green tea, the U.S. palate, in particular, appears quite variable in its response to the ﬂavor and acceptance of green tea.
The ﬂavor of green tea has been studied using both chemical and sensory methods. Volatile fractions of various green teas showed more than 50 aroma active compounds, including ones that could yield nutty, popcorn-like, metallic, ﬂoral, meaty, fruity, potato, green, cucumber-like and hay-like characteristics (Kumazawa and Masuda 2002). Wang et al. (2000) found that epigallocatechin gallate and epigallocatechin appeared to play the key role in the changes of sensory qualities of a processed green tea beverage. Age and processing had clear effects on volatile ﬂavor compounds, with those teas containing the youngest leaves and certain processing parameters generally having the highest amounts of catechins and amino acids, which could result 258 J. LEE and D.H. CHAMBERS in off-ﬂavors (Kinugasa et al. 1997). In Vietnamese green tea, linalool; cis and trans linalool oxides; 3,7-dimethyl-1,5,7-octatriene-3-ol; 2,5 (or 2,6)dimethylpyrazine; and 1-ethyl-2-formylpyrrole were the predominant components, but anethole and dimethoxybenzene, which can give a licorice-like ﬂavor, were also found (Nguyen and Yamanishi 1975).
A number of sensory terms have been used for tea. Ellis (2002) used a variety of terms to describe green tea ﬂavor in her book intended for the public.
The terms included: sweet, fragrant, malty, strong, full-bodied, spicy, fragrantly fruity, fresh, herbaceous, smoothly fragrant, deep, astringent, grassytasting, smoky, savory strength, bitter and refreshing. No precise deﬁnitions or references were provided. Other publications, intended for a scientiﬁc audience (Yamanishi 1977; Park et al. 1996, 1998, 1999), have also provided some sensory terminologies. Those authors included terms related to appearance (e.g., color of dried green tea leaves, shape of tea leaves and color of infused green tea); ﬂavor (fresh ﬂoral, sweet ﬂoral, citrus, sweet fruity, fresh green, sweet, resinous, roasted, dimethyl sulﬁde-like, green, burned, acidic, fermented, oily, earthy, moldy, seaweed, dried leaf, nutty, juice of motherwort, acrid); fundamental tastes (bitter, sweet, aftertaste, umami); and mouthfeel properties (astringent, biting/pungent). Togari et al. (1995) used the 16 sensory terms developed by Yamanishi (1977) to evaluate and differentiate among green, oolong and black tea, but did not provide references to help with understanding of the attributes. Cho et al. (2005) used descriptive analysis to compare 10 canned tea products using 17 different attributes, including ﬂoral, lemon, roasted tea, roasted rice tea (artiﬁcial), sweet odor, green tea, oolong tea, black tea, boiled milk, arrowroot/rooty, sour taste, sweet taste, chestnut shell, oily, burnt leaf, bitter taste and astringency. Perhaps because the products tested were processed canned products, the list included somewhat generic names of tea such as green tea, oolong tea and black tea to describe tea products. Character references were used, but intensities of the references were not given. All of the studies found were conducted on a limited number of samples that may not represent a broad range of green teas.
A sensory lexicon for the category of green tea (1) can help in identifying the characteristics common to major varieties of green tea; (2) can provide more useful sensory data to track experimental modiﬁcations; (3) can be better compared to instrumental measures of sensory properties such as ﬂavor compounds; and (4) may help identify ﬂavor characteristics that appeal to particular subsets of the global marketplace, for example, U.S. versus Asian consumers. At present, no such lexicon appears to exist. A lexicon needs to cover the wide range of green tea available in the category, provide terms that are appropriately deﬁned, have references to assist in describing the ﬂavor notes and anchor attribute intensities consistently, and demonstrate their reliability in distinguishing the ﬂavor properties across the category of samples.
FLAVOR DESCRIPTIVE ANALYSIS OF GREEN TEA 259Precisely deﬁned and referenced lexicon can be reproduced at different places or at different times (Drake and Civille 2003). A number of such lexicons have been developed: e.g., Johnson et al. (1987), Prell and Sawyer (1988) and Chambers and Robel (1993) for ﬁsh; Johnson and Civille (1986) for warmed-over ﬂavor in meat; Lyon (1987) for chicken ﬂavor; Heisserer and Chambers (1993), Drake et al. (2001) and Retiveau et al. (2005) for natural cheeses; Smith et al. (1994) for off-odors in raw grains; Lotong et al. (2000) for wheat sourdough bread; Day N’Kouka et al. (2004) and Chambers et al.
(2006) for soymilk; and Vara-ubol et al. (2004) and Bott and Chambers (2006) for beany chemicals.
The purpose of this study was to develop a lexicon for describing green tea, including a deﬁnition and reference for each attribute.
MATERIALS AND METHODS
Tea Samples One-hundred and thirty-eight green teas (leaf form) were used to represent a wide range of various tea species, countries of origin, manufacturing methods and prices. “White” tea, the very earliest and tiniest leaves of the larger green tea category, recently has been suggested by some people to be a separate tea category, but is included in the green tea category for this research.
This large number of teas was used to ensure the lexicon included the widest range of ﬂavor characteristics that may be present in the category of green teas, a tenet proposed by Drake and Civille (2003). Samples were purchased or donated by companies and were obtained either by mail or by personal delivery from China, India, Japan, Kenya, Korea, Sri Lanka, Taiwan, Tanzania and Vietnam. These countries, and regions within these countries, represent most of the major tea growing areas that produce green tea for commercial sale. The largest number of samples in this study came from China, Japan and Korea.
Samples included a range of leaf “age” from the ﬁrst picking of very young leaf buds (now sometimes called “white” tea) to older leaf teas picked at the end of the season (approximately 6–7 months older). Teas also represented different production methods, including steaming and roasting, hand processing and machine processing, and crushing, rolling or tying leaves together into bunches. Tea samples included “fresh” samples (brewed within several months of picking and processing) and older samples (aged up to 2 years after picking and processing). Speciﬁc age and processing details were not available for approximately half the samples tested, but general information was gathered from most manufacturers to ensure a range was present. Retail prices for the samples ranged from approximately $2 per 100 g (older leaves, machine 260 J. LEE and D.H. CHAMBERS processed, large growers/manufacturers) to more than $400 per 100 g (ﬁrst picking, organic, wild plants, hand processed, small high-mountain growers).
All tea leaf samples were stored at 4C for less than 2 months before evaluation.
Tea Preparation Green tea samples were removed from the refrigerator at least 1 h before brewing and allowed to reach room temperature. For each “pot” of tea, a 6-g portion of green tea leaves was measured and set aside for brewing. Brewing was carried out in a small white porcelain teapot, approximately 350 mL in volume, representative of those typically used for tea preparation in many Asian countries. Reverse osmosis, deionized, carbon ﬁltered water was heated to 70C; small amounts were poured into the teapot and each serving cup to warm the containers. After pouring out the “warming” water from the teapot, the 6 g of green tea was placed inside the pot, to which 300 mL of the 70C water was added. The green tea was brewed for 2 min and while it was brewed, the pot was swirled 10 times. The green tea was poured into a bowl through a porcelain strainer and approximately 45 mL of brewed tea was poured into each prewarmed white porcelain teacup. These processes are typical of green tea preparation in homes and restaurants in Asia, where the largest amount of green tea is consumed. The water temperature used in this study represents a common temperature recommended for brewing green tea. Boiling water, typically used for brewing black or oolongs teas, is not recommended and typically is not used for green teas.
Panelists A six-member highly trained panel from the Sensory Analysis Center at Kansas State University participated in this study. The panelists had completed 120 h of general training and had a minimum of 1,200 h of general sensory testing including beverages, vegetables and other food products with descriptors similar to those that might be found in tea.
Serving Procedure Samples were served coded with three-digit random codes in a random order, in part dictated by the availability of the samples. The order was controlled to ensure that panelists did not see all samples for a particular country, a speciﬁc age or other speciﬁc variables close to each other in the design. One sample was served at a time. The same sample was prepared again 10 min later to provide a second, warm sample for the panelists to examine.
Panelists generally tasted in 1.5-h sessions, although some were only 1 h in length. Development of the lexicon with references took a total of 60 h.