Urea polyacrylamide gel electrophoresis combined with statistical methods was used to detect the addition of Ricotta to grated Parmigiano Reggiano cheese. The adulterated samples were prepared by adding grated Ricotta to grated Parmigiano Reggiano cheese in six different ratios. The logistic regression and rank correlation performed worse than the naïve Bayes classifier at identifying samples of grated Parmigiano Reggiano containing more than 20% Ricotta in terms of area under the receiver operating characteristic curve and classification accuracy. This work can be considered a pilot study to investigate the potential of machine-learning methods to predict the authenticity of Parmigiano Reggiano cheese.

O doce de leite é consumido em países do Mercosul e composto de água, proteínas, lipídeos, minerais e açúcar. A acidez titulável (AT) do leite, teor de lactose e de gordura alteram as características sensoriais e de coloração do produto. O objetivo foi evidenciar, em aula prática, a importância da qualidade da matéria-prima na elaboração do doce de leite. Os leites pasteurizados (integral, desnatado ou zero lactose) foram avaliados quanto a AT antes e após adição de ácido lático ou bicarbonato de sódio. Após, foi adicionado 20% de açúcar (seis formulações diferentes), seguido de aquecimento até o ponto final. Na avaliação dos produtos foi observada textura, coloração e grau de doçura (56 alunos). F1(controle) apresentou coloração caramelo média, textura lisa, sem grumos, e sabor doce característico. Em F2 havia um excesso de AT no leite, com doce de leite de uma tonalidade mais clara e granuloso. F3 foi elaborada com excesso de bicarbonato de sódio, produzindo um doce escuro, sem chegar ao ponto final, e sabor amargo. Em F4 foi utilizado creme de leite (17% de gordura), com cor caramelo médio, liso e menos doce. Na F5 foi utilizado leite desnatado, produzindo um doce de leite caramelo médio, liso e sabor doce um pouco mais acentuado. Já F6 utilizou leite zero lactose, produzindo um doce de leite marrom escuro, firme, com grumos e doçura marcante. Esta aula prática evidenciou a importância da qualidade da matéria-prima para o doce de leite e trouxe a realidade das Indústrias beneficiadoras, que a recebem com qualidade variada.   Palavras-chave: Pós-Graduação. Leite e Derivados. Acidez.   Abstract Dulce de leche is consumed in the Mercosul countries, and it is composed by water, proteins, lipids, minerals and sugar. Milk titratable acidity, lactose and fat contents change the product sensorial and color characteristic. The objective was to evidence, in a practical class, to Master level students, the importance of raw material in the dulce de leche manufacture. Pasteurized milk (whole, skimmed or lactose free) were evaluated for titratable acidity, before and after the lactic acid or sodium bicarbonate addition. Then, 20% of sugar was added to the milk (six different formulations), and it was heated until dulce de leche final point. In the products evaluation, texture, coloration and sweetness degree were evaluated by 56 students. F1 (control) presented medium caramel color, smooth texture, and characteristic sweet flavor. F2 presented an excess of titratable acidity, with lighter and grainy dulce de leche. F3 was elaborated with sodium bicarbonate excess, producing a dark dulce de leche, without reaching the final point, and bitter taste. F4 was produced with cream (17% fat), and presented a medium caramel color, smooth and less sweet. In F5 skimmed milk was used, resulting in a dulce de leche with medium caramel color, smooth and a slightly more pronounced sweet flavor. F6 was produced with lactose free milk, producing a dark brown dulce de leche, with lumps and marked sweetness. This practical class highlighted the importance of the raw material quality for dulce de leche production and brought the reality of the beneficiary industries, which receive raw materials of varying quality.   Keywords: Post Graduation. Milk and Derivatives. Titratable Acidity.

This research communication depicts the quality and authenticity of grated Parmesan cheese sold in Brazil, with novel emphasis on ripening time. The sampling included all brands manufactured and packed at Brazilian dairy plants under federal inspection and sold in Londrina between June and September 2017. A total of 24 samples were analyzed (3 batches of 8 brands) for microbiological and compositional characteristics, including urea-PAGE electrophoresis for the quantitative determination of the milk proteins. About 80% of the samples were insufficiently ripened and 32% with low-fat content. Faced with these economically motivated food frauds, the authenticity of grated Parmesan in Brazil may be under threat. It is high recommended that future surveys and regulatory agencies go further than microbiological assessment, including and emphasizing the ripening time as the main parameter of grated Parmesan cheese.

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