Roberto Gonçalves Junqueira

Flour mixture of rice flour, corn and cassava starch in the production of gluten-free white bread

The use of rice flour corn and cassava starch was evaluated in several formulations aiming to find a flour mixture to replace wheat flour in the production of free-gluten white bread. Production parameters were evaluated through sensory analysis. The resulting breads were evaluated taking into account physical parameters (crumb appearance, specific volume and moisture) and sensorial parameters (flavor, appearance, crumb texture, crust color and satisfaction). Regarding flavor and moisture, breads prepared with the three different ingredients were not statistically different at 5% probability by the Tuckey test. However, they differed significantly regarding the specific volume, crumb texture, crust color, degree of satisfaction and external appearance. Rice flour bread presented the best parameters, being preferred by the sensory evaluation panel, followed by corn starch bread and cassava starch bread. Breads prepared with rice flour resulted in a softer product, presenting a better consistency with small alveoli homogeneously distributed. As far as crumb texture was concerned, corn starch bread presented larger alveoli, while cassava starch resulted in bread with expandable and gummy crumb, with granulation without alveoli, and undesirable sensorial characteristics. Production parameters were established based on these results and a mixture of flours, composed by 45% rice flour, 35% corn starch and 20% cassava starch presented good results originating bread with crumb formed by uniform and well distributed cells, and pleasant flavor and appearance.

Influence of post harvest processing conditions on yield and quality of ground turmeric (Curcuma longa L.)

Studies were carried out to evaluate the influence of post harvest processing conditions on yield and quality of ground turmeric. Rhizomes were peeled, cooked (autoclave or immersion) in water or alkaline media, sliced, dehydrated, ground, sieved, packaged in polyethylene bags and stored for 60 days at room temperature. Yields ranged from 9.84 to 14.51 g of powder/100 g of rhizome with moisture varying from 8.84 to 9.86 g/100 g. Peel removal caused 30% mass loss but the powder obtained had higher intensity of yellow and red. Cooking caused a reduction in dehydration time and provided a powder with lower moisture content, higher levels of curcuminoid pigments and higher Hunter CIE L*, a* and b* values. Cooking by immersion provided higher quality powder compared to autoclave. Use of alkaline media resulted in a product with lower curcuminoid content, and higher intensity of yellow. There was no change in pigment and colour characteristics during storage.

Metodologia para avaliação das boas práticas de fabricação em indústrias de pão de queijo

Este trabalho objetivou adaptar uma metodologia para a avaliacao da aplicacao das Boas Praticas de Fabricacao (BPF) em industrias de massas congeladas de paes de queijo. Foram utilizados nove questionarios englobando perguntas pertinentes a avaliacao das condicoes de infra-estrutura, higienizacao e processamento adotados nessas industrias. Para a avaliacao quantitativa dos dados, cada item dos questionarios foi classificado como recomendavel, necessario ou imprescindivel e pontuado (1, 2 e 4 pontos, respectivamente). Os questionarios foram aplicados a uma industria de pao de queijo localizada em Belo Horizonte, Minas Gerais. A pontuacao ponderada do estabelecimento (PPE) foi calculada atribuindo-se pesos calculados em funcao da frequencia relativa dos itens imprescindiveis de cada bloco. A PPE foi utilizada para a classificacao da industria como excelente, muito boa, boa, regular ou ruim. Para certificar a eficiencia da metodologia, a mesma industria foi avaliada por analises microbiologicas das materias-primas, das massas congeladas de pao de queijo, do ar ambiente, das maos dos manipuladores de alimentos e dos equipamentos e utensilios. A metodologia empregada foi eficiente para avaliar a aplicacao das BPF e que a ponderacao dos blocos permitiu uma boa avaliacao do estabelecimento, dando-se maior importância (peso maior) aos blocos relacionados diretamente com a qualidade e seguranca do produto.

Detection of several common adulterants in raw milk by MID-infrared spectroscopy and one-class and multi-class multivariate strategies

A sequential strategy was proposed to detect adulterants in milk using a mid-infrared spectroscopy and soft independent modelling of class analogy technique. Models were set with low target levels of adulterations including formaldehyde (0.074g.L-1), hydrogen peroxide (21.0g.L-1), bicarbonate (4.0g.L-1), carbonate (4.0g.L-1), chloride (5.0g.L-1), citrate (6.5g.L-1), hydroxide (4.0g.L-1), hypochlorite (0.2g.L-1), starch (5.0g.L-1), sucrose (5.4g.L-1) and water (150g.L-1). In the first step, a one-class model was developed with unadulterated samples, providing 93.1% sensitivity. Four poorly assigned adulterants were discarded for the following step (multi-class modelling). Then, in the second step, a multi-class model, which considered unadulterated and formaldehyde-, hydrogen peroxide-, citrate-, hydroxide- and starch-adulterated samples was implemented, providing 82% correct classifications, 17% inconclusive classifications and 1% misclassifications. The proposed strategy was considered efficient as a screening approach since it would reduce the number of samples subjected to confirmatory analysis, time, costs and errors.

Avaliação do ácido trans, trans-mucônico urinário como biomarcador de exposição ao benzeno

OBJECTIVE To assess the use of trans, trans-muconic acid as a biomarker of occupational exposure to benzene. METHODS Trans, trans-muconic acid in urine samples of exposed (exposed group, n=36) and non-exposed (non-exposed group, n=116) workers to benzene. Urinary levels of trans, trans-muconic acid were quantified by high-performance liquid chromatography. The study sample consisted of subjects exposed to benzene in an oil refinery in Belo Horizonte, Brazil. Non-parametric statistical analysis was carried out using Kruskall-Wallis test, Mann-Whitney test and Spearman correlation at p<0.05. RESULTS Workers were exposed on average to benzene levels of 0.15 +/- 0.05 mg/m3 (0.05 ppm) and they showed a urinary trans, trans-muconic acid mean value of 0.19 +/- 0.04 mg/g of creatinine. The reference value range of trans, trans-muconic acid in non-exposed subjects was 0.03 to 0.26 mg/g of creatinine (mean 0.10 +/- 0.08 mg/g of creatinine). There was seen a statistical difference between trans, trans-muconic acid levels in urine samples from exposed and non-exposed groups. There was no correlation between urinary trans, trans-muconic acid and air benzene levels. There was no correlation between urinary trans, trans-muconic acid levels in the exposed group and smoking. Alcohol consumption up to 48 hours before sampling procedure showed no effect on trans, trans-muconic acid levels in both exposed and non-exposed groups. There was however a correlation between age (range 18 to 25 years) and urinary metabolite levels in the latter group. CONCLUSIONS The results show that it is important to evaluate the effect of age and smoking habits on urinary trans, trans-muconic acid levels.OBJETIVO: Avaliar o uso do acido trans, trans-muconico urinario como biomarcador na monitorizacao da exposicao ocupacional ao benzeno. METODOS: Foi estudado o comportamento do acido trans, trans-muconico em amostras de urina de individuos expostos (N=36) e nao expostos (N=116) ocupacionalmente ao solvente. A concentracao urinaria do acido foi determinada por Cromatografia Liquida de Alta Eficiencia. A amostra foi constituida de individuos expostos ao benzeno em uma refinaria de petroleo localizada em Belo Horizonte, MG. Foram empregados os testes estatisticos nao-parametricos de Kruskall-Wallis, Mann Witney e de correlacao de Spearman, ao nivel de significância de 0,05%. RESULTADOS: A exposicao media ao benzeno dos trabalhadores selecionados foi de 0,15±0,05 mg/m³ (0,05 ppm) o que resultou em um valor medio do metabolito urinario de 0,19±0,04 mg/g de creatinina. A faixa de referencia do acido trans, trans-muconico no grupo nao exposto variou de 0,03 a 0,26 mg/g de creatinina (media de 0,10±0,08 mg/g de creatinina). Foi encontrada uma diferenca significativa entre os niveis de acido trans, trans-muconico do grupo exposto e nao exposto. Entretanto, nao houve correlacao entre os niveis do metabolito urinario e do benzeno no ar. Foi observada a correlacao entre acido trans, trans-muconico e habito de fumar no grupo de individuos expostos. A ingestao de alcool num periodo de ate 48 horas antes da coleta das amostras nao mostrou interferir nos niveis do metabolito nos dois grupos estudados. Foi observada a correlacao entre acido trans, trans-muconico e idade (faixa etaria de 18 a 25 anos) no grupo de nao expostos. CONCLUSOES: Os resultados obtidos evidenciaram a importância de ser mais bem avaliada a influencia do habito de fumar e da faixa etaria do trabalhador nos niveis urinarios do acido trans, trans-muconico.

TEORES DE HISTAMINA E QUALIDADE FÍSICO-QUÍMICA E SENSORIAL DE FILÉ DE PEIXE CONGELADO

The quality of 120 samples of different types of frozen fish fillet was evaluated with respect to sensory characteristics, pH, levels of total volatile basis, histamine and presence of sulfidric gas. The results from the sensory evaluation indicated good quality with scores of 5.52 (CV £ 13%) for both odor and general aspects. With respect to total volatile bases (TVB), mean levels of 62.71 mg N/100 g were found, with significantly higher values (> 80 mg N/100 g) for sandperch (Pseudopercis numida) and shark (families Carcharhinidae and Squalidae) and smaller than 68 mg N/100 g for the other types. Mean pH values varied from 6.11 in Brazilian codling (Urophycis brasiliensis) to 7.49 in Brazilian drum (Umbrina sp.). Based on these results, 79, 39 e 62% of the samples would not comply with the Brazilian legislation for TVB, pH and sulfidric gas, respectively. Histamine was found in 37% of the samples at levels ranging from 0.00 in flounder (Paralichthys sp. and Pleuronectes sp.) to 0.50 mg/100 g in sandperch. Histamine was not detected in Brazilian codling. There were significant differences among pH, TVB and histamine levels in samples from different families. In order to evaluate the potential use and critical limits of these parameters as an index of quality, samples should be monitored immediately after capture. The histamine concentrations found in these products, by itself, would not be sufficient to cause toxic effects.

An appropriate and systematized procedure for validating qualitative methods: its application in the detection of sulfonamide residues in raw milk.

The lack of well-established references for the validation of qualitative analyses and the increasing demand for reliable binary responses were the main motivating factors for this study. A detailed procedure for single-laboratory validation of qualitative methods is proposed. The experimental design and the tools for data analysis were based on the theoretical background, as well as the aspects of efficiency, convenience and simplicity. Four experimental steps were defined, as follows: (i) preliminary tests for the determination of the concentration range, (ii) a study of the rates, unreliability region, detection limit, and the accordance and concordance values, (iii) a study of the selectivity in the presence of known interferences, and (iv) a study of robustness. The applicability of the procedure was demonstrated by the validation of a qualitative commercial kit for detecting sulfonamide residues in raw milk using both the visual and instrumental reading techniques. Reliability rates of 100% were obtained for the blank samples. For the samples spiked with sulfamethazine at 10.8 and 108 μg L(-1) and with sulfadimethoxine or sulfathiazole at 10 and 100 μg L(-1), the reliability rates ranged from 93.3 to 100%. Selectivity was demonstrated using trimethoprim as a potential interferent. The method was considered robust for the factors of the temperature (54 and 58°C) and time (6 and 10 min) for incubating the test strips. The estimated detection limits and unreliability regions confirmed the suitability of the kit for this purpose, based on the legislated residue limits.

Atividade antimicrobiana in vitro do rizoma em pó, dos pigmentos curcuminóides e dos óleos e dos essenciais da Curcuma longa L.

Este trabalho teve como objetivo avaliar a atividade antimicrobiana da curcuma em po, da curcumina disponivel no comercio, dos pigmentos curcuminoides purificados e dos oleos essenciais da curcuma. As amostras foram analisadas quanto aos teores de pigmentos curcuminoides por cromatografia liquida de alta eficiencia. O oleo essencial foi tambem analisado quanto a densidade, indice de refracao e perfil das substâncias volateis por cromatografia gasosa e detector de ionizacao de chamas. A atividade antimicrobiana in vitro foi determinada pelo metodo de difusao em agar com discos de papel estereis, impregnados com os extratos, sendo os diâmetros dos halos de inibicao medidos com paquimetro. Os extratos etanolicos da curcuma, da curcumina comercial, e dos pigmentos curcumina e desmetoxicurcumina nao inibiram o crescimento de Staphylococcus aureus, Bacillus subtilis, Salmonella choleraesuis, Escherichia coli, Aspergillus niger, Saccharomyces cerevisiae, e Candida albicans. Apenas o extrato etanolico da bisdesmetoxicurcumina apresentou atividade antimicrobiana em relacao ao B. subtilis. O oleo essencial da curcuma apresentou atividade antimicrobiana para o B. subtilis, S. choleraesuis, E. coli, A. niger e S. cerevisiae, sendo que essa atividade aumentou em funcao do aumento da concentracao. Os halos de inibicao, obtidos com o oleo essencial, foram significativos, quando comparados aos respectivos antibioticos tradicionais, cloranfenicol e anfotericina, indicando ser o oleo essencial da curcuma um agente antimicrobiano em potencial.

Eficiência de um kit de ELISA na detecção e quantificação de aflatoxina M1 em leite e investigação da ocorrência no estado de Minas Gerais

Procedures for intralaboratory validation of an ELISA kit were adopted to verify its efficiency in aflatoxin M1 detection and quantification in milk. Assays were accomplished with standard solutions provided with the kit, spiked samples and naturally contaminated samples. The mean recovery values obtained for the kit standard solutions were between 85.6 and 114.8%, with coefficient of variation ranging from 11.6 to 23.1%. Working with spiked samples, a concentration range for quantitative analysis (0.019 to 0.090µg/L) was defined. The occurrence of aflatoxin M1 in 110 milk samples from the State of Minas Gerais was investigated. Five of the 27 positive samples in the screening for ELISA were confirmed by thin layer chromatography.

PROPRIEDADES EMULSIONANTES E SOLUBILIDADE DA CASEÍNA BOVINA: 2. EFEITO DA ADIÇÃO DE NaCl

The effect of the NaCl addition on the emulsifying properties of casein and tryptic casein hydrolysates was studied in two pH values (4,0 e 5,0). A 0.02 M concentration of salt was added to the buffer solutions used for preparing the samples. The protein solubility, the emulsifying capacity (EC), the emulsifying activity index (EAI) and the emulsion stability (ES) were determined. The mean radius (R) of fat droplets was also calculated. The results showed that the addition of NaCl increased the solubility and the EC of casein and casein hydrolysates, in both pH values. However, this salt addition reduced the EAI of casein and increased that of the hydrolysates.The opposite was observed relating to the R of fat droplets. Regarding the ES, that of casein presented little increase in pH 5.0, and the same result was obtained for only some hydrolysates in pH 5.0 or 4.0.