Estimation of tea quality by infusion colour difference analysis
The colour differences in terms of deltaL, deltaa, deltab and deltaE between distilled water and infusions of 29 green teas, 16 black teas and 13 oolong teas and their correlation with sensory quality attributes of tea were investigated. The results showed that the deltaL value decreased but the deltaa, deltab and deltaE increased with the degree of fermentation of the three kinds of tea. The deltaL was positively correlated to quality attributes of green tea and oolong tea but negatively correlated to those of black tea. The deltaa of tea infusions is a reliable descriptor to differentiate among green and black teas. The regression of total quality score of green tea (TQSg) upon the deltaa was TQSg = -2.26deltaa + 77.2 (R2 = 0.22, p < 0.01), that of total quality score of black tea (TQSb) upon deltab was TQSb = 0.70deltab + 44.6 (R2 = 0.31, p < 0.05) and that of total quality score of oolong tea (TQSo) upon deltaL was TQSo = 1.09deltaL + 94.5 (R2 = 0.75, p < 0.01). Because the infusion colour difference indicators of deltaa, deltab and deltaL can be done rapidly, it could be very useful for on-site or on-line quality monitoring during tea manufacture and storage.
Comparison of chemical compositions of Ilex latifolia Thumb and Camellia sinensis L.
Abstract Chemical composition of two beverage plant species, i.e. Ilex latifolia and Camellia sinensis were investigated. Fifteen and sixteen amino acids were detected in I. latifiolia and C. sinensis, respectively. Major amino acids were histidine, aspartic acid and glutamic acid in I. latifolia but theanine, glutamic acid and histidin in C. sinensis. Ascorbic acid and polyphenols in I. latifiolia were 0.46 mg g−1 and 90.1 mg g−1, less than one fourth and one half of those in C. sinensis, respectively. Eight catechin compounds were found in C. sinensis but only four in I. latifolia, i.e. l -catechin (C), l -epicatechin (EC), l -epicatechin gallate (ECG) and l -catechin gallate (CG). Three flavonoids, i.e. rutin, mericetin and quercetin were detected and their total contents in I. latifolia and C. sinensis were 4781 mg kg−1 and 580 mg kg−1, respectively. Caffeine was not detected in I. latifolia. The higher concentration of flavonoids in leaf of I. latifolia may be related to its value for a healthy beverage.
Inhibition of Root Growth and Polyamine Metabolism in Sunflower (Helianthus annuus) Seedlings Under Cadmium and Copper Stress
Although sunflower is usually regarded as a highly tolerant crop, impairment of root growth at initial stages of plant development may result in poor crop establishment and higher susceptibility to pathogen attack. In order to evaluate if Cd2+ and Cu2+ may impact on sunflower germination and initial root development, a pot experiment under controlled conditions was carried out. Possible involvement of polyamine metabolism in sunflower response to these stressors was also investigated. Although Cd2+ and Cu2+ treatments affect neither seed germination nor radicle emergence, sunflower seedlings grown in the presence of these heavy metals showed significant inhibition of root growth, being this inhibition greater for Cd2+. Both metals caused significant increases in proline contents at the highest concentrations tested (0.5 and 1 mM), and these increments were more pronounced for Cd2+ treatments, especially between days 3 and 10. Metals also increased putrescine (Put) contents at all concentrations assayed from the seventh day onward, causing no variations on this polyamine time-course pattern. Spermine and spermidine contents, however, were increased only by 1 mM Cd2+. Arginine decarboxylase seems to have been the enzyme responsible for Put increases under both metal treatments. This work demonstrates that initial root growth of sunflower seedlings may be significantly impaired in Cd2+ or Cu2+ contaminated soils. It also shows that polyamines are key biological compounds, which are probably involved in signaling pathways triggered under stress environmental conditions.