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.
Analysis of chemical components in oolong tea in relation to perceived quality.
Summary 
Properties of leaf and infusion colours, chemical components and volatile flavour compounds of oolong teas and their correlation with perceived quality score given by tea-tasting panel were analysed. The scores for appearance and infused leaf correlated strongly with concentrations of chlorophyll a (chl a), chlorophyll (chl b) and chlorophyll (chl) (r = 0.355–0.433, P < 0.05) and the total quality score (TQS) positively correlated with concentrations of chl a, chl b and chl (r = 0.517–0.533, P < 0.01). The perceived taste score and TQS positively correlated with the concentration of total free amino acid (r = 0.514, 0.694, P < 0.01) and theanine (r = 0.500, 0.684, P < 0.01). The volatile composition and their quantities varied widely among oolong tea samples. Nerolidol, indole, benzeneacetaldehyde, linalool, linalool oxide I, hexanal, benzyl nitrile, geraniol and 1-penten-3-ol were prevailing volatile compounds detected in most of oolong tea samples. Principal component analysis screened ten principal components with the first three (glutamic acid, total catechins and benzeneacetaldehyde) explaining 27.86%, 20.00% and 14.46% of the total variance, respectively. Regression analysis upon the ten principal components formulated a prediction model on the total quality score with 78.5% probability. The result showed that oolong teas could be partially classified by cluster analysis based on principal components.
Gut immunity in Lepidopteran insects.
Lepidopteran insects constitute one of the largest fractions of animals on earth, but are considered pests in their relationship with man. Key to the success of this order of insects is its ability to digest food and absorb nutrition, which takes place in the midgut. Because environmental microorganisms can easily enter Lepidopteran guts during feeding, the innate immune response guards against pathogenic bacteria, virus and microsporidia that can be devoured with food. Gut immune responses are complicated by both resident gut microbiota and the surrounding peritrophic membrane and are distinct from immune responses in the body cavity, which depend on the function of the fat body and hemocytes. Due to their relevance to agricultural production, studies of Lepidopteran insect midgut and immunity are receiving more attention, and here we summarize gut structures and functions, and discuss how these confer immunity against different microorganisms. It is expected that increased knowledge of Lepidopteran gut immunity may be utilized for pest biological control in the future.