The ultrasound-assisted extraction (UAE) is an alternative approach for the total lipid content determination in food samples. The high extraction efficiency, being less time-consuming and with the possibility of using less toxic solvents are the main advantages of UAE. It is, thus, an excellent alternative to be applied as a laboratory experiment for undergraduate students. The UAE procedure was optimized and the extraction parameters, such as extractor solvent, time and frequency of the ultrasound, were evaluated. The accuracy of the UAE procedure was evaluated by comparing the obtained results with those found by the traditional lipids extraction approach. The results showed that the lipids content found in the analyzed samples by using UAE were in agreement with the results obtained by the traditional lipids extraction. Therefore, the optimized UAE procedure was proposed as a laboratory experiment to 15 groups of undergraduate students to introduce the subjects of an alternative approach for total lipids determination in food samples. The results obtained showed that 80% of the student groups found results for total lipid contents in agreement with those found by traditional lipids extraction method. The proposed UAE procedure as a laboratory experiment proved to be simple and easy to be applied to undergraduate students.

Resumo O objetivo do trabalho foi determinar os teores de sódio (Na) e potássio (K) em refeições servidas em um restaurante universitário da região sul do Brasil, utilizando espectrometria de emissão atômica como método analítico. Foram coletadas 30 amostras de refeições do almoço e do jantar de um restaurante universitário, referentes a 131 diferentes cardápios no período de um semestre (4 meses), levando-se em conta o consumo de todos os alimentos oferecidos no cardápio, inclusive o suco e a salada temperada. Os resultados indicaram que o teor médio de Na em uma refeição ultrapassou o limite diário recomendado pela Organização Mundial da Saúde (OMS) em 25 das 30 amostras analisadas. Observaram-se teores maiores em refeições compostas por algum tipo de alimento industrializado, como linguiças e batata palha, ou com pratos tradicionalmente temperados, como barreado. Os menores teores de Na estavam presentes em cardápios nos quais havia batata frita ou ovo. Os teores de K encontrados em 19 refeições poderiam ser considerados satisfatórios segundo a recomendação da OMS, no entanto, levando-se em conta que o consumo de K deve ser 1,75 vezes maior que o de Na em uma mesma refeição, a oferta de K foi baixa em todas as amostras analisadas.

Abstract The objective of this study was to determine the levels of sodium (Na) and potassium (K) in meals served in a university restaurant in the southern region of Brazil, using atomic emission spectrometry as the analytical method. Thirty samples of lunch and dinner meals were collected from a university restaurant, referring to 131 different menus in a single semester (four months), taking into account the consumption of all food offered on the menu, including the juice and seasoned salad. The results showed that the average Na content in a meal exceeded the daily limit recommended by the Word Health Organization (WHO) in 25 of the 30 samples analysed. Higher levels were observed in meals including some kind of processed food, such as sausages and potato sticks, or traditionally spiced dishes such as one known as ‘barreado’. The lowest Na levels were found in menus including fried potato or egg. The K levels found in 19 meals could be considered satisfactory according to the WHO recommendations, but taking into account that the consumption of K should be 1.75 times greater than that of Na in the same meal, the supply of potassium was low in all the samples analysed.

A composição química do extrato aquoso de soja e de seu subproduto okara foi determinada. Em base seca, para o okara, o teor dos componentes encontrados foi de 2,8% de cinzas, 37% de proteínas, 13% de lipídios, 42,5% de fibras alimentares e 4,7% de carboidratos solúveis. Para o extrato aquoso esses valores foram de 2,4% de cinzas, 33% de proteínas, 17,7% de lipídios, 41,4% de carboidratos solúveis e traços de fibras alimentares. Pães do tipo francês foram adicionados de 0, 5, 10 e 15% de okara seco. Foi realizada a análise sensorial por meio do teste de preferência que demonstrou que os pães contendo 5% e 10% de okara tiveram níveis de aceitação iguais e superiores àqueles contendo 15%. Assim, os pães contendo 10% de okara foram submetidos ao teste sensorial de intenção de compra, revelando média 4,2 numa escala de 1 a 5, ou seja, uma avaliação favorável do ponto de vista comercial. Pães adicionados de 5% e 10% de okara podem ser denominados produtos "fonte" e "ricos" em fibras, respectivamente.

The chemical composition of soymilk and its byproduct okara were determined. In dry matter, for okara the concentration of nutrients was: 2.8% of ash, 37% of proteins, 13% of lipids, 42.5% of dietary fiber and 4.7% of soluble carbohydrates. For soymilk these values were: 2.4% of ash, 33% of proteins, 17.7% of lipids, 41.4% of soluble carbohydrates and traces of fibers. Dried okara was added to French type bread at 0, 5, 10 and 15%. A sensorial analysis was developed using a preference test which showed that bread containing 5 and 10% of okara had levels of acceptance that were equal and higher than bread containing 15%. Bread produced with 10% okara was tested in a purchase intent test. The result was on average 4.2 in the range of 1 to 5, which shows a positive evaluation of this product. Bread containing 5 and 10% of added okara can be labeled as "source" and "rich" in fiber, respectively.