Rodrigo Stephani

Spectroscopic and theoretical study of the "azo"-dye E124 in condensate phase: evidence of a dominant hydrazo form.

Spectroscopic techniques, including Raman, IR, UV/vis, and NMR were used to characterize the samples of the azo dye Ponceau 4R (also known as E124, New Coccine; Cochineal Red; C.I. no. 16255; Food Red No. 102), which is 1,3-naphthalenedisulfonic acid, 7-hydroxy-8-[(4-sulfo-1-naphthalenyl) azo] trisodium salt in aqueous solution and solid state. In addition, first principle calculations were carried out for the azo (OH) and hydrazo (NH) tautomers in order to assist in the assignment of the experimental data. The two intense bands observed in the UV/vis spectrum, centered at 332 and 507 nm, can be compared to the calculated values at 296 and 474 nm for azo and 315 and 500 nm for hydrazo isomer, with the latter in closer agreement to the experiment. The Raman spectrum is quite sensitive to tautomeric equilibrium; in solid state and aqueous solution, three bands were observed around 1574, 1515, and 1364 cm(-1), assigned to mixed modes including deltaNH + betaCH + nuCC, deltaNH + nuC horizontal lineO + nuC horizontal lineN + betaCH and nuCC vibrations, respectively. These assignments are predicted only for the NH species centered at 1606, 1554, and 1375 cm(-1). The calculated Raman spectrum for the azo (OH) tautomer showed two strong bands at 1468 (nuN = N + deltaOH) and 1324 cm(-1) (nuCC + nuC-N), which were not obtained experimentally. The (13)C NMR spectrum showed a very characteristic peak at 192 ppm assigned to the carbon bound to oxygen in the naphthol ring; the predicted values were 165 ppm for OH and 187 for NH isomer, supporting once again the predominance of NH species in solution. Therefore, all of the experimental and theoretical results strongly suggest the food dye Ponceau 4R or E124 has a major contribution of the hydrazo structure instead of the azo form as the most abundant in condensate phase.

FT-Raman and chemometric tools for rapid determination of quality parameters in milk powder: Classification of samples for the presence of lactose and fraud detection by addition of maltodextrin

FT-Raman spectroscopy has been explored as a quick screening method to evaluate the presence of lactose and identify milk powder samples adulterated with maltodextrin (2.5-50% w/w). Raman measurements can easily differentiate samples of milk powder, without the need for sample preparation, while traditional quality control methods, including high performance liquid chromatography, are cumbersome and slow. FT-Raman spectra were obtained from samples of whole lactose and low-lactose milk powder, both without and with addition of maltodextrin. Differences were observed between the spectra involved in identifying samples with low lactose content, as well as adulterated samples. Exploratory data analysis using Raman spectroscopy and multivariate analysis was also developed to classify samples with PCA and PLS-DA. The PLS-DA models obtained allowed to correctly classify all samples. These results demonstrate the utility of FT-Raman spectroscopy in combination with chemometrics to infer about the quality of milk powder.

Application of FT-Raman Spectroscopy and Chemometric Analysis for Determination of Adulteration in Milk Powder

In this work, FT-Raman spectroscopy is explored as a rapid technique for the assessment of the milk powder quality. Based on information provided by Raman spectra of samples adulterated with starch and whey, a quantitative method is developed to identify the fraud, using Partial Least Squares regression (PLS). In regression models using PLS the results are satisfactory, and such models can be used to identify and quantify samples presenting whey and starch in milk powder at concentrations of 2.32% and 1.64% (w/w), respectively. In the whey determination, the obtained values in the PLS model of the new samples are compared with those obtained by the spectrophotometric method of acid ninhydrin. This result shows that there is no significant difference with the 95% level of confidence between the values provided by the PLS regression method and the acid ninhydrin. The present work shows Raman spectroscopy as an analytical tool which can be used in quality control of milk powder, even in fraud processes, and the calculated figures of merit such as sensitivity, accuracy, limit of detection and limit of quantification clearly demonstrate this potential use. Although the multivariate models developed are not strictly quantitative, especially for low concentrations, they can be used as screening methods for routine analysis, as showed by this work.

Classification of frankfurters by FT-Raman spectroscopy and chemometric methods.

Frankfurters are widely consumed all over the world, and the production requires a wide range of meat and non-meat ingredients. Due to these characteristics, frankfurters are products that can be easily adulterated with lower value meats, and the presence of undeclared species. Adulterations are often still difficult to detect, due the fact that the adulterant components are usually very similar to the authentic product. In this work, FT-Raman spectroscopy was employed as a rapid technique for assessing the quality of frankfurters. Based on information provided by the Raman spectra, a multivariate classification model was developed to identify the frankfurter type. The aim was to study three types of frankfurters (chicken, turkey and mixed meat) according to their Raman spectra, based on the fatty vibrational bands. Classification model was built using partial least square discriminant analysis (PLS-DA) and the performance model was evaluated in terms of sensitivity, specificity, accuracy, efficiency and Matthews’s correlation coefficient. The PLS-DA models give sensitivity and specificity values on the test set in the ranges of 88%–100%, showing good performance of the classification models. The work shows the Raman spectroscopy with chemometric tools can be used as an analytical tool in quality control of frankfurters.

Analysis of spreadable cheese by Raman spectroscopy and chemometric tools.

In this work, FT-Raman spectroscopy was explored to evaluate spreadable cheese samples. A partial least squares discriminant analysis was employed to identify the spreadable cheese samples containing starch. To build the models, two types of samples were used: commercial samples and samples manufactured in local industries. The method of supervised classification PLS-DA was employed to classify the samples as adulterated or without starch. Multivariate regression was performed using the partial least squares method to quantify the starch in the spreadable cheese. The limit of detection obtained for the model was 0.34% (w/w) and the limit of quantification was 1.14% (w/w). The reliability of the models was evaluated by determining the confidence interval, which was calculated using the bootstrap re-sampling technique. The results show that the classification models can be used to complement classical analysis and as screening methods.

EFEITO DA CONCENTRAÇÃO DE GORDURA NAS PROPRIEDADES FÍSICAS, QUÍMICAS E SENSORIAIS DO QUEIJO PETIT SUISSE ELABORADO COM RETENÇÃO DE SORO

Faced with the need to increase the yield of the petit suisse and the need to reduce the fat content of the product, the objective was to evaluate the effect of the concentration of fat in the physical, chemical and sensory characteristics in petit suisse strawberry-flavored cheese prepared with retention of whey. Five formulations were prepared petit suisse cheese with different concentrations of fat. The data analyzed were: composition, texture characteristics, viscosity, water activity and sensory attributes in relation to appearance, taste, texture and overall impression The fat concentration was directly related to the decrease of water activity and increased caloric value of elasticity, chewiness, gumminess, hardness and viscosity.. Evaluating the acceptance based on attributes of appearance, taste, texture and overall impression, the ideal fat content of Petit suisse cheese was 4.73%, at that percentage, the level of calories was 166 kcal/100g. Comparing with different brands is possible to reduce fat petit suisse cheese prepared with retention of whey (100% yield).

Study of Thermal Behaviour of Milk Protein Products Using a Chemometric Approach

This study deals with the evaluation of the behavior of viscosity evolution of the Milk Protein Products (MPPs) solutions in different concentrations used in different conditions of thermal processing by means of Rapid Visco Analyzer (RVA). Skimmed milk powder (SMP), whey protein Original Research Article Stephani et al.; BJAST, 7(1): 62-83, 2015; Article no.BJAST.2015.126 63 concentrate (WPC), milk protein concentrate (MPC), whey powder (WP) and demineralized whey powder (DWP) were analyzed; the evaluated solid-liquid ratio solutions were 0.1 g∙g -1 to 0.45 g∙g -1 of dry solids in water (DSW) for the MPC, 0.1 g∙g -1 to 0.4 g∙g -1 of DSW for the WPC and 0.5 g∙g -1 to 0.8 g∙g -1 of DSW for SMP, WP and DWP. Brazilian industrial heat treatment set ups were used, with temperatures ranging from 65°C to 95°C and retention time from 5 to 30 minutes. The results were interpreted according to the viscosities during heating and cooling, being possible to optimize the MPPs different parameters conditions with the interpretations of the viscographic profiles based on the thermal behavior of proteins, especially for the SMP, MPC and WPC. The data showed similarity in viscographic characteristics of the solutions when evaluated at 65°C for 30 minutes, at 85°C for 15 minutes and 95°C for 5 minutes, for the MPC and WPC at 95°C for 5 minutes, all of them for different concentrations of proteins in water.

Influência das condições de operação em spray dryer piloto sobre a umidade e a atividade de água do leite em pó integral

The aim of this study was to determinate the influence of pilot spray dryer settings on moisture and water activity of whole milk powder. In this experiment were applied six treatments and the variables were: the temperature of inlet air, the air flow and the flow rate of product. The treatment with the lowest temperature of the inlet air, air flow and outlet air temperature allowed water activity values higher than 0.200 (0.236) in the whole milk powder. It was not possible standardize the moisture and water activity of the whole milk powder controlling only one attribute of the spray dryer settings

ATRIBUTOS TECNOLÓGICOS DE CONTROLE PARA PRODUÇÃO DO DOCE DE LEITE

A few technological attributes should be controlled during the Doce de Leite production for different reasons: regulations, costs, operational security, food safety and standardization of the final product. This work shows the main technological attributes for the production of doce de leite.

Lactose-hydrolyzed milk powder: Physicochemical and technofunctional characterization

ABSTRACT The objective of this work is to demonstrate the effect of operational drying parameters on the physicochemical and techno-functional properties of lactose-hydrolyzed milk powder (LHMP). LHMP showed water content superior to the control regardless of drying conditions, which is a direct result of the difficulties encountered in drying the product. For a lab-scale spray dryer, the LHMP produced at θair,in = 145°C and mCM = 1.0 kg · h−1 was the only sample that met all stipulated quality parameters: water content <5% (w/w), aw < 0.20 and luminosity value >93, particle sizes similar to control, and complete rehydration.