Daniel Granato

Chemical Composition, Sensory Properties, Provenance, and Bioactivity of Fruit Juices as Assessed by Chemometrics: A Critical Review and Guideline

The use of univariate, bivariate, and multivariate statistical techniques, such as analysis of variance, multiple comparisons of means, and linear correlations, has spread widely in the area of Food Science and Technology. However, the use of supervised and unsupervised statistical techniques (chemometrics) in order to analyze and model experimental data from physicochemical, sensory, metabolomics, quality control, nutritional, microbiological, and chemical assays in food research has gained more space. Therefore, we present here a manuscript with theoretical details, a critical analysis of published work, and a guideline for the reader to check and propose mathematical models of experimental results using the most promising supervised and unsupervised multivariate statistical techniques, namely: principal component analysis, hierarchical cluster analysis, linear discriminant analysis, partial least square regression, k-nearest neighbors, and soft independent modeling of class analogy. In addition, the overall features, advantages, and limitations of such statistical methods are presented and discussed. Published examples are focused on sensory, chemical, and antioxidant activity of a wide range of fruit juices consumed worldwide.

Analytical strategy coupled with response surface methodology to maximize the extraction of antioxidants from ternary mixtures of green, yellow, and red teas (Camellia sinensis var. sinensis).

This work aimed at using a simplex-centroid design to model the effects of green, yellow, and red tea mixtures (Camellia sinensis var. sinensis) on metal chelation activity, phenolic composition, antioxidant activity, and instrumental taste profile. The regression models that described the extraction of flavan-3-ols, o-diphenols, total phenolic compounds (TPC), free radical scavenging activity toward 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), cupric ion reducing antioxidant activity (CUPRAC), and ferric reducing antioxidant power (FRAP) were significant, and data were fit satisfactorily (R(2) > 80%). A mixture of green and red teas had a synergism in CUPRAC and TPC, whereas a mixture of yellow and red teas had a positive effect on CUPRAC and DPPH. An optimization was performed to maximize the antioxidant activity and flavan-3-ol content and to render a tea with mild bitterness, and results showed that a mixture of 14.81% green, 56.86% yellow, and 28.33% red teas would be the most suitable combination of factors.

Authentication of Geographical Origin and Crop System of Grape Juices by Phenolic Compounds and Antioxidant Activity Using Chemometrics

The main goal of this work was to propose an authentication model based on the phenolic composition and antioxidant and metal chelating capacities of purple grape juices produced in Brazil and Europe in order to assess their typicality. For this purpose, organic, conventional, and biodynamic grape juices produced in Brazil (n = 65) and in Europe (n = 31) were analyzed and different multivariate class-modeling and classification statistical techniques were employed to differentiate juices based on the geographical origin and crop system. Overall, Brazilian juices, regardless of the crop system adopted, presented higher contents of total phenolic compounds and flavonoids, total monomeric anthocyanins, proanthocyanidins, flavonols, flavanols, cyanidin-3-glucoside, delphinidin-3-glucoside, and malvidin-3,5-glucoside. No differences were observed for trans-resveratrol, malvidin-3-glucoside, and pelargonidin-3-glucoside between countries and among crop systems. A total of 91% of Brazilian and 97% of European juices were adroitly classified using partial least squares discriminant analysis when the producing region was considered (92% efficiency), in which the free-radical scavenging activity toward 2,2-diphenyl-1-picrylhydrazyl, content of total phenolic compounds, gallic acid, and malvidin-3-glucoside were the variables responsible for the classification. Intraregional models based on soft independent modeling of class analogy were able to differentiate organic from conventional Brazilian juices as well as conventional and organic/biodynamic European juices.

Nutritional aspects of second generation soy foods.

Samples of 15 second generation soy-based products (n = 3), commercially available, were analyzed for their protein and isoflavone contents and in vitro antioxidant activity, by means of the Folin-Ciocalteu reducing ability, DPPH radical scavenging capacity, and oxygen radical absorbance capacity. Isoflavone identification and quantification were performed by high-performance liquid chromatography. Products containing soy and/or soy-based ingredients represent important sources of protein in addition to the low fat amounts. However, a large variation in isoflavone content and in vitro antioxidant capacity was observed. The isoflavone content varied from 2.4 to 18.1 mg/100 g (FW), and soy kibe and soy sausage presented the highest amounts. Chocolate had the highest antioxidant capacity, but this fact was probably associated with the addition of cocoa liquor, a well-known source of polyphenolics. This study showed that the soy-based foods do not present a significant content of isoflavones when compared with the grain, and their in vitro antioxidant capacity is not related with these compounds but rather to the presence of other phenolics and synthetic antioxidants, such as sodium erythorbate. However, they may represent alternative sources and provide soy protein, isoflavones, and vegetable fat for those who are not ready to eat traditional soy foods.

Geographical provenancing of purple grape juices from different farming systems by proton transfer reaction mass spectrometry using supervised statistical techniques

BACKGROUND Organic, biodynamic and conventional purple grape juices (PGJ; n = 79) produced in Brazil and Europe were characterized by volatile organic compounds (m/z 20-160) measured by proton transfer reaction mass spectrometry (PTR-MS), and classification models were built using supervised statistical techniques. RESULTS k-Nearest neighbours and soft independent modelling of class analogy (SIMCA) models discriminated adequately the Brazilian from European PGJ (overall efficiency of 81% and 87%, respectively). Partial least squares discriminant analysis (PLSDA) classified 100% European and 96% Brazilian PGJ. Similarly, when samples were grouped as either conventional or organic/biodynamic, the PLSDA model classified 81% conventional and 83% organic/biodynamic juices. Intraregional PLSDA models (juices produced in the same region - either Europe or Brazil) were developed and were deemed accurate in discriminating Brazilian organic from conventional PGJ (81% efficiency), as well as European conventional from organic/biodynamic PGJ (94% efficiency). CONCLUSIONS PGJ from Brazil and Europe, as well as conventional and organic/biodynamic PGJ, were distinguished with high efficiency, but no statistical model was able to differentiate organic and biodynamic grape juices. These data support the hypothesis that no clear distinction between organic and biodynamic grape juices can be made with respect to volatile organic compounds.

Chemical composition of volatiles from male and female specimens of Baccharis trimera collected in two distant regions of southern brazil: a comparative study using chemometrics

GC/MS/FID analyses of volatile compounds from cladodes and inflorescences from male and female specimens of Baccharis trimera (Less.) DC. collected in the states of Parana and Santa Catarina, Brazil, showed that carquejyl acetate was the primary volatile component (38% to 73%), while carquejol and ledol were identified in lower concentrations. Data were subjected to hierarchical cluster analysis and principal component analysis, which confirmed that the chemical compositions of all samples were similar. The results presented here highlight the occurrence of the same chemotype of B. trimera in three southern states of Brazil.

Elevados teores de sódio em alimentos industrializados consumidos pela população brasileira

Sodium is an essential compound for regulating the intracellular and extracellular mineral fluids, and for maintaining the blood pressure. An inadequate diet with ingestion of large quantities of salt may cause the chronic non-communicable diseases (NCDs) such as hypertension, cardiovascular diseases, cerebrovascular accidents, among others; thus, decreasing the intake of this mineral can reduce the risk factors of such diseases. The present study aimed at determining the sodium contents in some processed foods consumed by the Brazilian population: corn-based snacks, biscuit, hamburger, sausage and noodles, by means of inductively coupled plasma atomic emission spectrometry technique (ICP OES). The high sodium contents detected in these products revealed the importance of implementation and maintenance of food monitoring programs in the country. These strategies will provide tools to assist the food producers for controlling the sodium addition in processed products. Also, these actions will yield data which will be useful for the competent authorities to establish a legal provision which limits the amount of sodium added into the processed food, to ensure the offering of healthy foods to the population, in order to promote satisfactory public health.

Estabilidade dos soros para o controle de qualidade interno de testes imunodiagnósticos de HIV/AIDS

Introduction: The use of reference materials in order to assure and perform the quality control of analytical measurements is a requirement in clinical laboratories. Objectives: Stability of serum samples, kept frozen at -20°C for long-term storage and at varied temperatures during short periods, was evaluated by investigating the persistency of anti-human immunodeficiency virus (HIV) antibodies reactivity on enzyme-linked immunosorbent assay/enzyme immunoassay (ELISA/EIA), Western blot and indirect immunofluorescence assays. Method: The analyzed sera were part of serum panels (comprised of anti-HIV positive and negative samples), produced at the Immunology Center of Instituto Adolfo Lutz, which have been the reference specimens for producing the internal quality assurance sera of HIV/acquired immunodeficiency syndrome (AIDS) immunodiagnostic assays. Sera stability was assessed in samples stored at -20°C for 56 weeks, and at various temperature conditions: from 2°C to 8°C (refrigerator), from 15°C to 25°C (room temperature), at 37°C (incubator) and at -80°C (freezer) for 24 and 48 hours. The statistical analyses on HIV-negative serum samples (long-term storage) were significant (p < 0.05), and neither adverse effects on these samples as the occurrence of false-positive results nor false-negative results in HIV antibody positive sera were found in both studies. Conclusion: It was possible to conclude that the reference material remained stable for 48 hours at different temperatures (short-term) and it remained stable at -20°C for 56 weeks (long-term).

Comparação de diferentes métodos estatísticos utilizados para avaliar o desempenho de participantes em um programa de ensaio de proficiência

Five statistical approaches were applied for assessing the performance of participants in 19 rounds (2007-2011) of the Proficiency Testing Program for lead in blood determination (PEP-Pbs), conducted by Instituto Adolfo Lutz. The performance evaluation was provided by using the z-score. The following statistical approaches were tested: 1 – mean and standard deviation, after rejecting outliers; 2 – median and normalized inter-quartile range; 3 – robust mean and robust standard deviation; 4 – robust mean and standard deviation for proficiency assessment of 3 μg/100 mL (for concentrations up to 40 μg/100 mL and a standard deviation for proficiency assessment of 7.5 % of the assigned value (for concentrations above 40 μg/100 mL); 5 – robust mean and standard deviation for proficiency assessment of 2 μg/100 mL (for concentration up to 40 μg/100 mL) or 5 % of the assigned value (for concentrations above 40 μg/100 mL). The approach 4 showed to be the most adequate statistical methodology to assess the performance of participating laboratories in the PEP-Pbs.Five statistical approaches were applied for assessing the performance of participants in 19 rounds (2007-2011) of the Proficiency Testing Program for lead in blood determination (PEP-Pbs), conducted by Instituto Adolfo Lutz. The performance evaluation was provided by using the z-score. The following statistical approaches were tested: 1 – mean and standard deviation, after rejecting outliers; 2 – median and normalized inter-quartile range; 3 – robust mean and robust standard deviation; 4 – robust mean and standard deviation for proficiency assessment of 3 μg/100 mL (for concentrations up to 40 μg/100 mL and a standard deviation for proficiency assessment of 7.5 % of the assigned value (for concentrations above 40 μg/100 mL); 5 – robust mean and standard deviation for proficiency assessment of 2 μg/100 mL (for concentration up to 40 μg/100 mL) or 5 % of the assigned value (for concentrations above 40 μg/100 mL). The approach 4 showed to be the most adequate statistical methodology to assess the performance of participating laboratories in the PEP-Pbs.