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Raman spectroscopy combined with chemometric methods was used to rapidly measure the content of fructose and glucose in honey. Seventy-five authentic honey samples from sixteen floral origins were obtained directly from bee-keepers in ten provinces of China from 2008 to 2010. The samples were stored at 6-8℃ in the laboratory before their analysis. Honey were liquefied in a water bath at 55℃ and manually stirred to ensure homogeneity before spectral measurements. Spectra of honey samples were recorded using an i-Raman spectrometer (BWS 415-785H, B&W TEK Inc., USA), which was equipped with a fiber-optic Raman probe, a thermoelectric cooled CCD detector with 2048 pixels and a 785 nm laser with a maximum output power of 495 mW in the signal range of 175-2 600 cm-1. The instrumental spectral resolution was 3 cm-1. Integration time was 15 s. Seventy-four samples were divided into 55 calibration sets and 19 validation sets by Kennard-Stone algorithm. AirPLS (adaptive iteratively reweighted penalized least squares) was used to correct the baseline of spectroscopy. CARS (competitive adaptive reweighted sampling) was used to screen variables. Thirty-one and forty-six variables were obtained from 1150 variables by CARS for glucose and fructose, respectively. Quantitative calibration models were developed with linear partial least squares (PLS) regression and non-linear support vector machine (SVM) regression, respectively. These models were used to predict the validation set samples. The prediction accuracies obtained from both glucose and fructose were satisfied by PLS model and SVM model. Correlation coefficient (R)of predicted values versus HPLC measured values and root mean square error of prediction (RMSEP) were 0.902 and 1.401 obtained from SVM model for fructose, respectively, which were higher than the values obtained by PLS model (R=0.892, RMSEP=1.604). PLS model's R and RMSEP were 0.968 and 0.669 for glucose, respectively, which were higher than SVM model's values (R=0.933, RMSEP= 1.410). Raman spectroscopy combined with chemometric methods is a rapid and non-destructive method, which can be applied to measure the content of fructose and glucose in honey. [ABSTRACT FROM AUTHOR]

Indocalamus leaves are the generic name of the leaves of Indocalamus (Graminales) plants. The essential oils in Indocalamus latifolius leaves and Indocalamus tessellatus leaves were extracted by steam distillation method. Ether was used as the solvent to extract volatile compounds many times. Both the volatile compounds in Indocalamus latifolius leaves and Indocalamus tessellatus leaves were analyzed by gas chromatography-mass spectrometry (GC-MS). The results showed that thirty-seven compounds were identified for the essential oils extracted from Indocalamus latifolius leaves, and its main components were found to be 3-hexen-1-ol, (Z)-; 1-hexanol; benzyl alcohol; hexanal; furan, 2-ethyl-; 3-buten-2-one, 4-(2,6, 6-trimethyl-1-cyclohexen-1-yl), (E)-; etc. Forty-nine components were identified for the essential oils extracted from Indocalamus tessellatus leaves, and its main components were found to be 3-hexen-1-ol, (Z)-; benzyl alcohol; 3-buten-2-one, 4-(2,6,6-trimethyl-1-cyclohexen-1-yl)-, (E)-; 2-hexenal; phenylethyl alcohol, 2-methoxy-4-vinylphenol; furan, 2-ethyl-; etc. 3-Hexen-1-ol, (Z)- was the most abundant compound in the essential oils from both Indocalamus leaves. There were ketone, aldehyde, alcohol, phenol and ester in them. The contents of ketones, aldehydes, and alcohols were found higher than those of other compounds in the two essential oils.