Application of near-infrared spectroscopy for screening the potato flour content in Chinese steamed bread.

Near-infrared (NIR) spectroscopy combined with chemometrics was used as a technique to predict the potato flour content in Chinese steamed bread (CSB). The inner core of CSB was chosen as the measuring position for acquiring the NIR spectra. Spectra between 4000 and 10,000 cm-1 were analysed using a partial least-squares regression. The coefficient of determination (R CV 2) and the root mean square error of cross-validation in the calibration set were found to be 0.7940-0.8955 and 4.22-5.93, depending on the pre-treatment of the spectra. The external validation set gave an R2 and a ratio to performance deviation of 0.8865 and 3.07. Reasonable recovery (93.1-102.5%) and good intra-assay (3.3-8.3%) and inter-assay (7.6-17.2%) precision illustrated the feasibility of this method. The result of this study reveals that NIR spectroscopy could be used as rapid tool to determine the potato flour content in CSB (> 20%).

Chemical composition and antimicrobial activities of volatile oil extracted from Chrysanthemum morifolium Ramat.

Volatile oil in Chrysanthemum morifolium Ramat (C. morifolium) was extracted by the method of water vapor distillation and its chemical components was identified by gas-chromatography coupled with mass spectrometry (GC-MS). The volatile oil are evaluated for antibacterial activity against Escherichia coli, Staphylococcus aureus, Salmonella enteritids, Pseudomonas aeruginosa and Bacillus subtilis. Effects of surfactant, temperature, pH and ultraviolet light on antibacterial activity stability of volatile oil were analyzed too. Total 56 compounds were identified in C. morifolium volatile oil. The main constituents in C. morifolium volatile oil were monoterpenes and sesquiterpenes compounds, including hydrocarbons, esters, aldehydes, ketones, phenols and organic acids. α-curcumene was the most abundant volatile component (12.55%). The volatile oil showed promising antibacterial activity against 5 selected strains. The inhibitory effect on P. aeruginosa exhibited maximum inhibition zone diameter 20.43 mm, and E. coli showed 12.29 mm. The volatile oil treated with surfactant Tween 20 showed the strongest antibacterial activity, followed by Tween 80 and the SDS lowest, which showed the lowest. pH also had different effect on antibacterial activity stability of the C. morifolium volatile oil. No significant difference effect on antibacterial activity stability of volatile oil was observed with temperature and UV treatment.