Search

Analytical methods based on digital images coupled to chemometric tools are promising alternatives for developing analytical methodologies in determining quality parameters in foods. The total phenolics, monomeric anthocyanins, and tannin content were quantified based on digital images and pseudo-univariate calibration performed from Independent Components Analysis (ICA). Differences between ICA, Principal Component Analysis (PCA), and Multivariate Curve Resolution with Alternating Least Squares (MCR-ALS), highlighting the chosen ICA for this proposal, were explained. In all pseudo-univariate calibration curves, correlation coefficients higher than 0.9 were achieved. The results suggest that digital images coupled with ICA can give applicable pseudo-univariate calibration models to determine bioactive compounds. Even more, the device to obtain an image is cheaper than most analytical instruments. Digital images may have a promising future in developing analytical methodologies for complex samples such as foods from a pseudo-univariate calibration perspective (where a small data set is needed in the calibration step).

This work shows an alternative methodology based on a portable near-infrared (NIR) spectroscopy coupled to independent components analysis (ICA) in a pseudo-univariate calibration way to determine total anthocyanins (TA) concentration and antioxidant activity (AA) in whole grape juice. To this, the scores proportions more related to TA and AA were plotted against TA and AA obtained by its respective references methodology to build pseudo-univariate calibration models with correlation coefficients of 0.9699 and 0.9814, respectively. From the results, it is possible the suggestion that NIR spectra coupled to ICA enable to overcome interferences using first-order data and work properly when there is enough selectivity for the analyte profile in the sample data.

Meliponine is a honey with particular characteristics; it has a high percentage of humidity, which can favor the development of microorganisms, thereby causing changes in the quality of the product. The objective of this study was to evaluate the microbiological characteristics of meliponine honey produced by different species and marketed in the State of Paraná-Brazil. The sample unit was composed of honey of Tetragonisca angustula (n = 15), Scaptotrigona bipunctata (n = 05), Melipona quadrifasciata quadrifasciata (n = 05) and Melipona bicolor schencki (n = 01). The following microbiological parameters were evaluated: counts of total and thermotolerant coliforms, fungi count and detection of Salmonella spp. Principal component analysis (PCA) was used to evaluate the possible relationships among species, locality and type of microorganism. For microorganisms of the total coliform group, 15.38% of the analyzed samples had values >3 MPN/g. The presence of thermotolerant coliforms was observed in 7.69% of the samples, all of which were T. angustula samples. For fungi counts, 100.00% of the analyzed samples had values within the established range created by the Agricultural Defense Agency of Paraná. The presence of Salmonella spp. was not observed in any of the samples evaluated. The amount of water in the honey is related to the location of the apiary and edaphoclimatic factors. Adoption of good handling practices by beekeepers is indispensable for the safety of the final product. La meliponíne produce una miel diferenciada con características particulares, presenta un alto porcentaje de humedad, lo que puede favorecer el desarrollo de microorganismos provocando cambios en la calidad del producto. El objetivo de este estudio fue evaluar las características microbiológicas de la miel de meliponíne producida por diferentes especies y comercializada en el Estado de Paraná-Brazil. La unidad de muestra estuvo compuesta por miel de Tetragonisca angustula (n = 15), Scaptotrigona bipunctata (n = 05), Melipona quadrifasciata quadrifasciata (n = 05) y Melipona bicolor schencki (n = 01). Se evaluaron parámetros microbiológicos: recuento de coliformes totales y termotolerantes, recuento de hongos y detección de Salmonella spp. Análisis de componentes principales: se utilizó ACP para evaluar las posibles relaciones entre especies, localidad y tipo de microorganismo. Para los microorganismos del grupo de coliformes totales, el 15,38% de las muestras analizadas presentaron valores >3 NMP/g. En el 7.69% de las muestras se observó la presencia de coliformes termotolerantes, siendo todas muestras de T. angustula. Para contar hongos, el 100,00% de las muestras analizadas presentaron valores dentro de lo establecido por la Agencia de Defensa Agropecuaria de Paraná. No se observó presencia de Salmonella spp en ninguna de las muestras evaluadas. Algunas muestras fueron similares según la especie productora y la cantidad de agua en la miel está relacionada con la ubicación del meliponario, debido a factores edafoclimáticos. La adopción de buenas prácticas de manipulación por parte de los productores de miel es fundamental para garantizar la seguridad alimentaria del producto final. Os meliponíneos elaboram um mel diferenciado com características particulares, apresenta elevado percentual de umidade o que pode favorecer o desenvolvimento de microrganismo ocasionando alterações na qualidade do produto. O objetivo deste estudo foi avaliar as características microbiológicas do mel de meliponíneos produzido por diferentes espécies e comercializado no Estado do Paraná-Brasil. A unidade amostral foi composta de mel de Tetragonisca angustula (n=15), Scaptotrigona bipunctata (n=05), Melipona quadrifasciata quadrifasciata (n=05) e Melipona bicolor schencki (n=01). Parâmetros microbiológicos foram avaliados: contagem de coliformes totais e termotolerantes, contagem de fungos e detecção de Salmonella spp. A análise de componentes principais - ACP foi utilizada para avaliar as possíveis relações entre espécie, localidade e tipo de microrganismo. Para microrganismos do grupo coliformes totais, 15,38% das amostras analisadas apresentaram valores >3 NMP/g. Em 7,69% das amostras foi observado a presença de coliformes termotolerantes, sendo todas amostras de T. angustula. Para contagem de fungos, 100,00% das amostras analisadas apresentaram valores dentro do estabelecido pela Agência de Defesa Agropecuária do Paraná. Não foi observado a presença de Salmonella spp em nenhuma das amostras avaliadas. Algumas amostras se assemelharam segundo a espécie produtora e a quantidade de água no mel é relacionada com a localização do meliponário, devido a fatores edafoclimáticos. Adoção de boas práticas de manipulação pelos meliponicultores se tornam indispensáveis para conferir segurança alimentar ao produto final.

The use of chemometric tools is progressing to scientific areas where analytical chemistry is present, such as food science. In analytical food evaluation, oils represent an important field, allowing the exploration of the antioxidant effects of herbs and seeds. However, traditional methodologies have some drawbacks which must be overcome, such as being time-consuming, requiring sample preparation, the use of solvents/reagents, and the generation of toxic waste. The objective of this study is to evaluate the protective effect provided by plant-based substances (directly, or as extracts), including pumpkin seeds, poppy seeds, dehydrated goji berry, and Proven&ccedil, al herbs, against the oxidation of antioxidant-free soybean oil. Synthetic antioxidants tert-butylhydroquinone and butylated hydroxytoluene were also considered. The evaluation was made through thermal degradation of soybean oil at different temperatures, and near-infrared spectroscopy was employed in an n-way mode, coupled with Parallel Factor Analysis (PARAFAC) to extract nontrivial information. The results for PARAFAC indicated that factor 1 shows oxidation product information, while factor 2 presents results regarding the antioxidant effect. The plant-based extract was more effective in improving the frying stability of soybean oil. It was also possible to observe that while the oxidation product concentration increased, the antioxidant concentration decreased as the temperature increased. The proposed method is shown to be a simple and fast way to obtain information on the protective effects of antioxidant additives in edible oils, and has an encouraging potential for use in other applications.

Digital images associated with chemometric tools, in a non-destructive approach, have been applied for the evaluation of the Brazilian monovarietal extra virgin olive oil. Independent component analysis (ICA) was employed in the image data evaluation of olive oils produced from distinctive olive varieties, and it was successful in highlighting the natural grouping among the samples based on the color histograms (red, green and blue (RGB) channels). The study’s proposal indicates the ability of accurate separation of the twenty-four samples considering their color. To conclude and support the hypothesis, principal component analysis (PCA) was applied in the visible spectra of the Brazilian monovarietal extra virgin olive oil, to observe the similarities between the samples, and the results are in agreement with those obtained by image analysis coupled with ICA. This method demonstrates the possibility for the characterization of olive oils respecting the principles of Green Chemistry.

Tilapia (Oreochromis niloticus) is the most cultivated fish species in Brazil. Studies have shown that fish consumption is related to the prevention of cardiovascular diseases due to its high contents of polyunsaturated fatty acids, as omega-3 (n-3) and omega-6 (n-6). In this sense, a new method to determine omega-3 and omega-6 by near-infrared (NIR) spectroscopy and multivariate calibration based on partial least squares (PLS) was proposed. Spectra of fillets of Nile tilapias packed under vacuum were obtained and compared to the reference method (gas chromatography) used for quantification of fatty acids. The outliers were evaluated in the models that were validated by calculation of the parameters for model performance estimation, showing promising results. The appropriate values achieved for accuracy, limits of detection and quantification, indicate that the NIR/PLS models can be an alternative to chromatography in the determination of omega-3 and omega-6 in fillets of Nile tilapia. Furthermore, the spectra acquisition on the vacuum-packed fillet contributes to the NIR/PLS method in terms of cost and quickness.

This article contains data related to the research article entitled “Quantitative assessment of specific defects in roasted ground coffee via infrared-photoacoustic spectroscopy” (Dias et al., 2018) [1] . A method potentially able for assessing the quality of roasted ground coffees is described in the origin paper. Infrared spectroscopy and photoacoustic detection (FTIR-PAS) associated with multivariate calibration were used. The samples were obtained blending whole and healthy coffee beans (C. arabica and C. canephora) with specific blends of defects, named selections, which contain broken, sour, and black beans, skin, woods and healthy beans still not collected. In addition to a reduction in commercial value, the presence of defects compromises the sensory attributes of coffee. On the other hand, selections are commonly found in coffee crops and can be added intentionally to the product. Twenty-five selections were used to obtain a panel of 154 blends. The FTIR-PAS spectra of each sample generated the prediction model of Partial Least Squares Regression parameters, which are also presented here.

This chapter presents the correlation between coffee compounds identified by 1H Nuclear Magnetic Resonance (1H NMR) spectroscopy with psychological attention tests in order to verify which compounds are related to the focus and/or diffuse attention. Psychometric tests applied by a clinical psychologist, before and after coffee intake, were the focus attention AC-vector and the diffuse attention TADIM, and the focus attention TACOM-B and the diffuse attention TEDIF, respectively. Different tests to measure the attention before and after coffee intake were used to avoid learning effects. After AC-vector and TADIM tests, each volunteer consumed a total of 40 mL of coffee with different cup qualities (four different coffee blends – 10 mL per beverage) and indicated the order of preference in relation to the smell. This approach was used to create a greater metabolic variation between the samples tested, allowing to build a robust chemometric model. For each preferred coffee, a 1H NMR spectrum was obtained and a chemometric data treatment based on Partial Least Squares (PLS) regression and Variable Importance in Projection scores (VIP scores) was used to correlate the spectra with the psychological test results and to verify which metabolites of the coffee beverage could be related to the focus or diffuse attention. In general, our results showed that coffee intake attenuated diffuse attention and improved focus attention in most volunteers. The major metabolites that contributed to both diffuse and focus attention were caffeine, trigonelline, chlorogenic acids, acetate, lipids, lactate, γ-quinide, and polysaccharides. Among metabolites exclusively important to focus attention, formate, choline, myo-inositol, citrate, and malate were the most important. Therefore, the 1H NMR profile, in combination with chemometric tools, is interesting to assess the correlation between coffee compounds and human attention.

The ComDim chemometrics method for multi-block analysis was employed to evaluate thirty-two vegetable oil samples analyzed by near infrared (NIR) and ultraviolet-visible (UV-Vis) spectroscopy, and by Gas Chromatography with flame ionization detection (GC-FID) for their fatty acids composition. This unsupervised pattern recognition method was able to extract information from the tables of results that could be presented in informative graphs showing the relationship between the samples through the scores, the predominance of information in particular tables through the saliences and the contribution of the variables in each table which were responsible for the similarities observed in the samples, through the loadings plots. It was possible to infer similarities and differences among the samples studied according to the specific absorption in the UV-Vis and NIR region, as well as their fatty acids composition. The proposed methodology demonstrates the applicability of ComDim for the characterization of samples when different variables (different techniques) describe the same samples. In this particular study, the ComDim chemometrics method was able to discriminate samples by their characteristics and compositions.