Headspace GC/MS and fast GC e-nose combined with chemometric analysis to identify the varieties and geographical origins of ginger (Zingiber officinale Roscoe)

Food authenticity regarding different varieties and geographical origins is increasingly becoming a concern for consumers. In this study, headspace gas chromatography-mass spectrometry (HS-GC-MS) and fast gas chromatography electronic nose (fast GC e-nose) were used to successfully distinguish the varieties and geographical origins of dried gingers from seven major production areas in China. By chemometric analysis, a distinct separation between the two varieties of ginger was achieved based on HS-GC-MS. Furthermore, flavor information extracted by fast GC e-nose realized the discrimination of geographical origins, and some potential flavor components were selected as important factors for origin certification. Moreover, several pattern recognition algorithms were compared in varietal and regional identification, and random forest (RF) led to the highest accuracies for discrimination. Overall, a rapid and precise method combining multivariate chemometrics and algorithms was developed to determine varieties and geographical origins of ginger, and it could also be applied to other agricultural products.

A non-destructive sampling method for food authentication using gas chromatography coupled to mass spectrometry or ion mobility spectrometry

The study of volatile compounds obtained by gas chromatography (GC) coupled to mass spectrometry (MS) or ion mobility spectrometry (IMS) may be very useful to protect food quality, especially when using a non-destructive sampling method. In this work, the authentication of the highly appreciated dry-cured Iberian ham by those techniques was studied and compared. The results obtained show the suitability of a non-destructive sampling method coupled to headspace sampling (HS)-GC-IMS or HS-GC-MS to determine volatile markers in the feeding Iberian pig regime. Although both methods were suitable to differentiate the ham categories, HS-GC-IMS was more sensitive detecting a higher number of compounds than HS-GC-MS, which provided accurate qualitative results. The results of principal component analysis showed that ethanol, 2-propanol and 3-methylbutanol, identified by HS-GC-IMS, and 3-methylbutanal and heptane, identified by HS-GC-MS, could be considered potential markers to identify ham from different feeding regimes.

Staphylococcus pasteuri (BCVME2) Resident in Buffalo Cervical Vaginal Mucus: A Potential Source of Estrus-Specific Sex Pheromone(s)

Mammals have microbes resident in their reproductive tract, some of which can be pathogenic while others may play a role in protecting the tract from infection. Volatile compounds play a role as sex pheromones that attract males for coitus during female estrus or heat. It is likely that these compounds themselves are secondary metabolites of bacterial flora resident in the vagina. In order to substantiate this hypothesis, bacteria were isolated from cervico-vaginal mucus (CVM) of buffalo during various phases of the estrous cycle and identified, using morphological, biochemical and molecular characteristics, as Bacillus during preestrus and diestrus, and as Staphylococcus during all three phases of the estrous cycle. Populations of Staphylococcus differed between different phases of the estrous cycle, the predominant forms being S. warneri (BCVMPE1_1) during preestrus, S. pastueri (BCVME2) during estrus and S. epidermis (BCVMDE3) during diestrus. Mice were used as chemosensors to differentiate the estrus-specific S. pasteuri (BCVME2) from the others. Chemical analysis showed that S. pasteuri (BCVME2) produced acetic, propanoic, isobutyric, butyric, isovaleric and valeric acids. In addition, it was shown that S. pasteuri (BCVME2) volatiles influenced the sexual behaviors, flehmen and mounting, of the bull. Thus, S. pasteuri (BCVME2) is a potential source of vaginal pheromone(s) during estrus in buffalo.

Metabolomic fingerprinting of volatile organic compounds for the geographical discrimination of rice samples from China, Vietnam and India

Rice is one of the most important cereals for human nutrition and is a basic staple food for half of the global population. The assessment of rice geographical origins in terms of its authenticity is of great interest to protect consumers from misleading information and fraud. In the present study, a head space gas chromatography mass spectrometry (HS-GC-MS) strategy for characterising volatile organic compounds (VOCs) profiles to distinguish rice samples from China, India and Vietnam is described. Partial Least Square Discriminant Analysis (PLS-DA) model exhibited a good discrimination (R² = 0.98182, Q² = 0.9722, and Accuracy = 1.0) for rice samples from China, India and Vietnam. Moreover, Data-Driven Soft Independent Modelling of Class Analogy (DD-SIMCA) and K-nearest neighbors shown good specificity 100% and accuracy 100% in identifying the origin of samples. The present study established VOC fingerprinting as a highly efficient approach to identify the geographical origin of rice.

Characterization of the incense ingredients of cultivated grafting Kynam by TG-FTIR and HS-GC-MS

Agarwood is a resinous wood of Aquilaria species and has been used for various applications. Burning agarwood incense is a common practice in temples and homes in Asia. Kynam is widely regarded as high-quality agarwood in the market. Recently, cultivated grafting Kynam (CGK) has emerged as a new agarwood product in the market, which greatly affects the price of high grading Kynam agarwood. In this study, the morphology, ethanol extract content, and incense chemical profile of CGK was investigated and compared with those of wild Kynam (WK) and cultivated common agarwood (CCA). The incense smoke of CGK was analyzed by thermogravimetric Fourier transform infrared spectroscopy (TG-FTIR) and headspace gas chromatography-mass spectrometry (HS-GC-MS). The results showed that the heating of most incenses occurred below 200 °C, and the mass-loss rate value of CGK was between those of WK and CCA. The HS-GC-MS analysis showed the chemical compounds of incense smoke of CGK at 40, 100, and 180 °C, corresponding to the head, middle, and tail of the heating process, respectively. The results suggested that the sesquiterpenes compounds were the major contributors to the mysterious and elegant odoriferous character of agarwood incense. However, a peak area percentage analysis revealed a significant difference in the predominant compounds between CGK and WK, especially at lower temperatures. Therefore, it is not straightforward to substitute WK with CGK. The results are helpful for the study and usage of the new cultivated grafting Kynam agarwood and the development of the agarwood incense industry.

Espresso coffee design based on non-monotonic granulometric distribution of aromatic profile

Coffee beverages may be obtained using several extraction methods, among which espresso coffee (EC) represents now a worldwide adopted system. Recent advances in coffee grinding equipment allow today to achieve a detailed control of granulometric distribution, and the grinding process is an essential step of coffee production cycle both for the aromatic profile composition and for the chemical properties of the beverage (Severini, 2015). The comminution process consists of the breaking down particles into smaller fragments; as well-known, its main objective is to increase the overall particle surface area exposed to water leading to a more efficient extraction of soluble substances (Illy, 2005a). Basically, the coffee brewing process includes two steps: a washing phase concerning the snapshot dissolution of free solubles at the particle surface followed by diffusion phase of solubles within the porous particles (Spiro 1992, Baggenstoss 2008). The variability in particle size distribution on the quality of EC has been studied by various authors. Severini et al. has tackled the influence of the grinding level on the aromatic profiles and chemical attributes (percolation time, caffeine content, pH and titratable acidity) as a consequence of changes in the microstructural properties of the coffee cake. Generally speaking such results would imply that the final effect in terms of aromatic compounds extraction follows a monotonic law respect to granulometric size. This result is true in an average sense but it cannot be given for granted for any aromatic compounds if we refine the resolution of granulometric class. The reasons for which some aromatic compounds do not follow the supposed trend (the lower the grain size, the higher the aromatic compound content) can be most probably related to the internal distribution of precursors and to the different non-isotropic roasting grade of the bean, where the external part undergoes to an increased thermal load. This will change at the same time the kinetics and formation of aromatic compounds, and the mechanical properties as well, strictly correlated to the way the bean is crashed during the grinding phase and consequently to the granulometric distribution of different parts of the coffee bean. Results presented in this work allow to correlate choices in terms of granulometric distribution to characteristics aromatic compounds, in order to enhance specific flavors in espresso coffee.