[Study on brand traceability of vinegar based on near infrared spectroscopy technology].

In the present paper, 152 vinegar samples with four different brands were chosen as research targets, and their near infrared spectra were collected by diffusion reflection mode and transmission mode, respectively. Furthermore, the brand traceability models for edible vinegar were constructed. The effects of the collection mode and pretreatment methods of spectrum on the precision of traceability models were investigated intensively. The models constructed by PLS1-DA modeling method using spectrum data of 114 training samples were applied to predict 38 test samples, and R2, RMSEC and RMSEP of the model based on transmission mode data were 0.92, 0.113 and 0.127, respectively, with recognition rate of 76.32%, and those based on diffusion reflection mode data were 0.97, 0.102 and 0.119, with recognition rate of 86.84%. The results demonstrated that the near infrared spectrum combined with PLS1-DA can be used to establish the brand traceability models for edible vinegar, and diffuse reflection mode is more beneficial for predictive ability of the model.

Classification of Sherry vinegars by combining multidimensional fluorescence, parafac and different classification approaches.

Sherry vinegar is a much appreciated product from Jerez-Xérès-Sherry, Manzanilla de Sanlúcar and Vinagre de Jerez Protected Designation in southwestern Spain. Its complexity and the extraordinary organoleptic properties are acquired thanks to the method of production followed, the so-called "criaderas y solera" ageing system. Three qualities for Sherry vinegar are considered according to ageing time in oak barrels: "Vinagre de Jerez" (minimum of 6 months), "Reserva" (at least 2 years) and "Gran Reserva" (at least 10 years). In the last few years, there has been an increasing need to develop rapid, inexpensive and effective analytical methods, as well as requiring low sample manipulation for the analysis and characterization of Sherry vinegar. Fluorescence spectroscopy is emerging as a competitive technique for this purpose, since provides in a few seconds an excitation-emission landscape that may be used as a fingerprint of the vinegar. Multi-way analysis, specifically Parallel Factor Analysis (PARAFAC), is a powerful tool for simultaneous determination of fluorescent components, because they extract the most relevant information from the data and allow building robust models. Moreover, the information obtained by PARAFAC can be used to build robust and reliable classification and discrimination models (e.g. by using Support Vector Machines and Partial Least Squares-Discriminant Analysis models). In this context, the aim of this work was to study the possibilities of multi-way fluorescence linked to PARAFAC and to classify the different Sherry vinegars accordingly to their ageing. The results demonstrated that the use of the proposed analytical and chemometric tools are a perfect combination to extract relevant chemical information about the vinegars as well as to classify and discriminate them considering the different ageing.

A new FT-IR method combined with multivariate analysis for the classification of vinegars from different raw materials and production processes.

BACKGROUND: Due to the diversity of vinegars on the market and the increase in demand, it is considered necessary to investigate and establish criteria for classifying them in order to obtain more information concerning their real origin. New spectroscopic techniques such us mid-infrared spectroscopy with Fourier transform (FT-IR) are capable of providing information in relation to these aspects. FT-IR combined with multivariate analysis has been used to classify vinegars according to the raw materials and production processes (with or without ageing in wood). Principal component analysis (PCA), partial least-squares discriminant analysis regression (PLS-DA) and stepwise linear discriminant analysis (SLDA) were used. RESULTS: The results obtained have been compared to those achieved using different analytical parameters (polyphenolic content, organic acids and volatile compounds). SLDA and PLS-DA results show the ability of mid-FT-IR spectra to discriminate among vinegars from different raw materials and with or without ageing in wood, with correct classification percentages similar to those obtained using different analytical parameters. CONCLUSION: The discriminative ability combined with other advantages (e.g. rapid and non-destructive analysis, low cost) makes this new FT-IR method a promising tool for the classification and/or differentiation of vinegars.

Technological and microbiological aspects of traditional balsamic vinegar and their influence on quality and sensorial properties.

The term "balsamic" is widespread and popular all over the world of vinegar and fancy foods; it is used generally to refer to vinegars and sauces with a sweet and sour taste. However, the original is the European Protected Denomination, registered as "Aceto Balsamico Tradizionale of Modena, or of Reggio Emilia" that should not be confused with the "Aceto Balsamico di Modena" very similar in the name, but completely different for technology, raw material, quality, and sensorial properties. Traditional balsamic vinegar is made by a peculiar procedure, that starts with a thermal concentration of freshly squeezed grape juice, followed by alcoholic and acetic fermentations and, finally, long aging in a wooden barrel set, by a procedure which requires a partial transfer of vinegar from cask to cask with the consequential blending of vinegars of different ages. In addition, water transfer occurs across the wood of the barrels, the result being an increase of solute concentration of the vinegar. The chemical and physical transformations of the vinegar are mainly directed by the low water activity of the vinegar. High-molecular polymeric compounds are the main and characteristic constituents of original and old traditional balsamic vinegar, and the major cause of its rheological and sensorial properties.

Relaxometric studies for food characterization: the case of balsamic and traditional balsamic vinegars.

NMR spectroscopy is a powerful technique for investigating the structure and composition, as well as the physicochemical properties, of foodstuff. NMR-field cycling modality reports about the relaxation times of solvent molecules as a function of the applied magnetic field strength. In the case of aqueous solutions, this methodology is particularly valuable in assessing the interactions of water molecules with paramagnetic and large-size macromolecular systems. (1)H NMR field cycling relaxometry has been used to characterize traditional balsamic vinegars and balsamic vinegars of Modena. It has been found that the longitudinal relaxation time (T(1)) of the water proton resonance is mainly determined by the water molar fraction and the occurrence of dissolved macromolecules and paramagnetic metal ions. Actually, the observed (1)H nuclear magnetic resonance dispersion (NMRD) profiles appear markedly affected by the formation of paramagnetic macromolecular adducts. It has been shown that counterfeit specimens can be identified on the basis of the comparison of their T(1) and T(2) (transverse relaxation time) values with respect to the corresponding values of genuine samples. For the latter ones, a relationship has been found that relates the observed T(1) to the age of the vinegar.

Defining the typical aroma of sherry vinegar: sensory and chemical approach.

The aroma of the three different classes of Sherry vinegar was evaluated by gas chromatography/mass spectrometry (GC-MS) and gas chromatography/olfactometry (GC-O). GC-O was employed to identify substances responsible for aromatic notes associated with the selected descriptors of the typical aroma of Sherry vinegar and odor activity values (OAV) calculated to measure the single impact effect of different compounds selected by GC-O. Diacetyl, isoamyl acetate, ethyl isobutyrate, isovaleric acid, sotolon, and ethyl acetate reached high OAVs, turning out to be characteristic odor active compounds in Sherry vinegars. A total of 58 compounds were quantified, among them, 7 had not been previously reported in Sherry wine vinegars: ethyl 2-methylbutyrate, ethyl heptanoate, ethyl furoate, and ethyl benzoate, acetophenone, nonanoic acid, and sotolon. Linear discriminant analysis (LDA) reveals that using aroma compounds as variables, we can classify Sherry vinegars with 100% correct scores as different from red wine vinegars.

Analytical method for authentication of Traditional Balsamic Vinegar of Modena.

(13)C NMR spectroscopy was employed for evaluating glucose and fructose isoforms content in Traditional Balsamic Vinegar of Modena. With the use of reference spectra recorded in water for samples obtained with respect to set rules, a shift determination method for fructose carbon isoforms was introduced to determine the frauds present in unknown Traditional Balsamic Vinegar of Modena samples. No sample preparation yields this approach highly reliable and time saving. Following this approach, for the first time, an objective analytical technique can be used alternatively to the actual procedures for Traditional Balsamic Vinegar certification.

Vinegar classification based on feature extraction and selection from headspace solid-phase microextraction/gas chromatography volatile analyses: a feasibility study.

Headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography (GC) and multivariate data analysis were applied to classify different vinegar types (white and red, balsamic, sherry and cider vinegars) on the basis of their volatile composition. The collected chromatographic signals were analysed using the stepwise linear discriminant analysis (SLDA) method, thus simultaneously performing feature selection and classification. Several options, more or less restrictive according to the final number of considered categories, were explored in order to identify the one that afforded highest discrimination ability. The simplicity and effectiveness of the classification methodology proposed in the present study (all the samples were correctly classified and predicted by cross-validation) are promising and encourage the feasibility of using a similar strategy to evaluate the quality and origin of vinegar samples in a reliable, fast, reproducible and cost-efficient way in routine applications. The high quality results obtained were even more remarkable considering the reduced number of discriminant variables finally selected by the stepwise procedure. The use of only 14 peaks enabled differentiation between cider, balsamic, sherry and wine vinegars, whereas only 3 variables were selected to discriminate between red (RW) and white wine (WW) vinegars. The subsequent identification by gas chromatography-mass spectrometry (GC-MS) of the volatile compounds associated with the discriminant peaks selected in the classification process served to interpret their chemical significance.

[Effects of different types and standard of processing vinegaron inherent constituents in rhizoma of Corydalis yanhusuo].

OBJECTIVE: To investigate the effects of processing adjuvants-different types of processing vinegar on effective constituents in rhizoma of Corydalis yanhusuo, and evaluate the quality of different types of vinegar in China. METHOD: The HPLC method was adopted to determine the extraction solubility of dl-tetrahydropalmation and total alkaloids in rhizoma of Corydalis yanhusuo processed by vinegar. The sample extracts were separated on kromasil ODS column with mobile phase of methanol-1% phosphoric acid solution(65:35) and detection wavelength was 280 nm. RESULT: There was a remarkable increase in extraction solubility of dl-tetrahydropalmation and total alkaloids in the rhizoma of Corydalis yanhusuo processed by the vinegar products with high content of total acids or with known trademarks. CONCLUSION: Some types of vinegar with known trademarks had been preliminarily selected for the process of Chinese traditional medicine and they also met the requitrement of processing adjuvants with medicine grade. The results will be benefited to the foundation of standardization of vinegar.

1H NMR studies on Italian balsamic and traditional balsamic vinegars.

In the present work Principal Component Analysis applied to (1)H NMR spectra of balsamic and traditional balsamic vinegars is used to establish a simple and rapid aging determination protocol. Chemical composition of vinegar is dominated by carbohydrates even though several small components can be clearly observed in the proton NMR spectrum. Quantitative determination of some selected metabolites such as ethanol, acetic acid, malic acid, glucose, and HMF, considered as potential aging indicators, has been performed. (1)H NMR spectroscopy provides noninvasive characterization of such compounds, and our data demonstrate the validity of this approach, giving very promising results for assessing the quality of the final product.