Results from portable and of low cost equipment developed for detection of milk adulterations

Abstract This work presents the results of a device, MilkTech, developed to detect milk tampering, based on electrical measurements. The device indicates possible frauds by water, sodium chloride, caustic soda, ethyl alcohol and sodium bicarbonate. The advantages in relation to traditional methods are portability, low cost and detection of mixed frauds. The experiments were conducted in dairy plants at Governador Valadares, in Brazil. The results were compared with cryoscopy and chloride tests. It is demonstrated there is high correlation between MilkTech and Cryoscopy. For instance, the detection limit of the equipment for water addition with the set of analyzed data was 0.78% with precision of 1.1%. Adulterations with sodium chloride, caustic soda, ethyl alcohol and sodium bicarbonate are detected qualitatively, even when added with water, and MilkTech indicates "SUSPECT" milk.

Quantification of whey in fluid milk using confocal Raman microscopy and artificial neural network.

In this work, we assessed the use of confocal Raman microscopy and artificial neural network as a practical method to assess and quantify adulteration of fluid milk by addition of whey. Milk samples with added whey (from 0 to 100%) were prepared, simulating different levels of fraudulent adulteration. All analyses were carried out by direct inspection at the light microscope after depositing drops from each sample on a microscope slide and drying them at room temperature. No pre- or posttreatment (e.g., sample preparation or spectral correction) was required in the analyses. Quantitative determination of adulteration was performed through a feed-forward artificial neural network (ANN). Different ANN configurations were evaluated based on their coefficient of determination (R2) and root mean square error values, which were criteria for selecting the best predictor model. In the selected model, we observed that data from both training and validation subsets presented R2>99.99%, indicating that the combination of confocal Raman microscopy and ANN is a rapid, simple, and efficient method to quantify milk adulteration by whey. Because sample preparation and postprocessing of spectra were not required, the method has potential applications in health surveillance and food quality monitoring.

Caracterização de leite em pó, soro de leite em pó e suas misturas por eletroforese em gel de poliacrilamida / Characterization of milk powder, whey powder and its blends by polyacrylamide gel electrophoresis

Pela legislação brasileira o leite em pó não pode conter sólidos de soro de leite. As autoridades competentes enfrentam dificuldades no controle desse tipo de fraude, apesar de diversos métodos terem sido estudados e propostos para detectar a adulteração. Neste estudo foi realizada a caracterização do leite em pó, utilizando-se a técnica de eletroforese adaptada, para determinar adulteração em amostras de leite em pó contendo diferentes concentrações de soro (2 por cento, 4 por cento, 6 por cento, 8 por cento e 10 por cento) e pelos perfis protéicos. Foi empregada a técnica de SDS-PAGE com modificações nos procedimentos de conservação dos géis após preparo, tempo entre preparo e aplicação, voltagem e corrente na fonte eletroforética, tempos de revelação e secagem, obtendo-se géis com resultados satisfatórios quando analisados por meio de software Image Quant TL. A técnica de SDS-PAGE adaptada foi eficiente para avaliar as características das amostras de leite em pó e de soro em pó separadamente. Houve possibilidade de identificar a adição de soro de leite, porém sem discernimento da correlação entre o nível de adição e a quantidade de soro adicionada. ASDS-PAGE modificada mostrou bom desempenho na caracterização de proteínas de leite em pó, de soro de leite em pó e de suas misturas.

Determination of soy proteins in calabresa sausage by densitometry on gel electrophoresis

Soy proteins are widely employed in meat products. However addition of non-meat proteins in calabresa sausages is not allowed according to the Brazilian legislation and in case of the non-declared addition of this foreign protein in consumed food, it may trigger allergic reactions in some consumers. Polyacrylamide gel electrophoresis (SDS-PAGE) was used for determining soy proteins in calabresa sausages. Fraud simulations were performed adding different concentrations (0%; 0.5%; 1%; 2%; 5%;10%; 20% and 100%) of soy proteins in sausages. The qualitative analysis was not sensitive to detect thelo west concentrations of soy proteins. On the other hand, by using semi-quantitative analysis by means of densitometry of selected protein fractions from soy and porcine meat, the presence of soy proteins could be determined in the all of analyzed concentrations. This methodology could be implemented, without large investments, for conducting quality control of sausages.