Hop aroma components, which mainly comprise terpenoids, contribute to the character of beers. However, pretreatments are necessary before analyzing these components because of their trace levels and complicated matrixes. Here, the stir bar-sorptive extraction (SBSE) method was used to detect and quantify many terpenoids simultaneously from small samples. This simple technique showed low coefficients of variation, high accuracy, and low detection limits. An investigation of the behavior of terpenoids identified two distinct patterns of decreasing concentration during wort boiling. The first, which was seen in myrcene and linalool, involved a rapid decrease that was best fitted by a quadratic curve. The second, which was observed in beta-eudesmol, humulene, humulene epoxide I, beta-farnesene, caryophyllene, and geraniol, involved a gentle linear decrease. Conversely, the concentration of beta-damascenone increased after boiling. As the aroma composition depended on the hop variety, we also examined the relationship between terpenoid content and sensory analysis in beer.

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The microbiologic method described here is rapid and sensitive, and this method has potential for the screening of PCs contaminated with bacterial cells. Furthermore, this method could contribute to further evaluation of inactivation techniques.

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Staphylococcus epidermidis (S. epidermidis) often cause sepsis and related diseases by transfusion of contaminated platelet concentrates (PCs). The proliferation process of this bacterium in PCs has been unclear, thus, bio-imaging system was applied for analyzing the dynamics of S. epidermidis in PCs. S. epidermidis were spiked into PCs or Luria Bertani (LB) broth. These samples were collected at each sampling time during incubation (up to 7 days), and colony-forming-units were counted. Bacterial number and their size distribution in each sample were also determined with a new bio-imaging system. The morphological characters of S. epidermidis growing in the samples were observed precisely by scanning electron microscopy (SEM). The numbers of S. epidermidis were stable for 48 hr after the spiking as lag-phase, while the bio-imaging analysis also showed that aggregates proliferated during "lag-phase." The aggregates were also observed in LB media, however, their sizes were much smaller than those in PCs. SEM suggested that the aggregates were micro-colonies (MCs) of staphylococcal cells and cores of the MCs are composed with platelets (PLTs). Out results suggested that S. epidermidis formed floating MCs in PCs during "lag-phase." Therefore, the term of lag phase of S. epidermidis in PCs should be called as "pseudo-lag phase." The initial processes of forming MCs in PCs are thought to be an interaction between bacterial cells and PLTs. Floating MCs would be the source of biofilms on the inside of PC storage bags. New information obtained in this study would be useful for understanding the dynamics of growing bacteria in PCs.