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.

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Treatment by field‐scale bioscrubber of exhaust air, including ammonia (NH3) and the greenhouse gases methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2), from 13 intensive pig production houses located in northern Germany were investigated in 2013 and 2015. NH3 removal efficiencies varied between 35 and 100% with an overall average value of 79% under the NH3 inlet fluctuations from 34 to 755 g d−1 m−3 in both 2013 and 2015. Results of the electron microscopic analyses demonstrated that the bacteria Nitrosomonas sp. and methanotrophs type I were the dominant NH3 and CH4 oxidizers, respectively. However, overall average removal efficiencies of CH4 was approximately zero, which means CH4 is hard to remove in bioscrubbers under normal operation. The pH of recirculation water in the bioscrubber varied from 6.1 to 8.1, and the bioscrubbers with low pH values (<7.0) had high NH3 removal efficiencies (>79%). Electrical conductivity was commonly used to diagnose the bioscrubbers’ performance; in the present study, electrical conductivity presented a significant linear relationship with dissolved inorganic nitrogen, which indicates the performance stability of the 13 selected bioscrubbers.