Abstract Stevia rebaudiana (Bert.) Bertoni contains steviol glycosides with emphasis to rebaudioside A, which presents a stronger sweet flavor, more stability, good solubility and lower bitter residual taste, which benefits its application in foods and drinks. The objective of this study was to determine the equivalent amount of rebaudioside A necessary to promote the same degree of sweetness of sucralose in the grape- and peach-flavored soy beverages and evaluate their physicochemical characteristics and consumer acceptance. At the Natural Products Center of the State University of Maringa, the rebaudioside A was purified from the M1 Alvarez variety of Stevia plants. Through sensory analysis established that the ideal quantity of rebaudioside A to substitute sucralose in foods with peach soy and grape soy would be 3 times the quantity of sucralose. The results revealed no signifcant differences for the physicochemical and sensorial characteristics (p < 0.05) between the two formulations. The results also indicate that the rebaudioside A with high purity rate (97%) obtained from selected stevia varieties can substitute sucralose in peach soy foods and grape soy foods.

Abstract The objective of this work was to perform the ethanolic pretreatment of stevia leaves from the plant Stevia UEM-13 line and to characterize its physical-chemical properties aiming its use as a sweetener in the development of a diet cereal bar. The same formulation of the cereal bar with stevia leaves without pretreatment was elaborated for comparative purposes. The following ingredients were used in the preparation of the produtc: fine oat flakes, no sugar granola, cranberry, dehydrated apricots, water, gum acacia and stevia leaf pretreated (F1) and without treatment (F2). According to the results, the diet cereal bars presented significant amounts of crude fiber, protein and antioxidant activity. The product was microbiologically safe for human consumption, reporting lower microbiological valuesthan those foreseen by official regulation. The overall sensory evaluation indicates that the two formulations did not present statistically significant differences regarding the analyzed attributes, being the averages between “liked very much” and “moderately liked”. However, considering the group of cereal bars consumers, the formulation sweetened with pretreated leafs (F1) was found more than twice the acceptance regarding to the formulation sweetened with the leaf in natura (F2). These results demonstrate a viable option of a diet food product naturally sweetened.

RESUMO Objetivo: Obtenção de um concentrado proteico do soro do leite por meio de processos de separação por membranas, adoçado com rebaudiosídeo A, análise sensorial em humanos e avaliação de propriedades funcionais em modelos de ratos induzidos por estreptozotocina. Métodos: Foram produzidos dois concentrados, mas apenas o segundo, que apresentou teor proteico de 74,3 e 17,3% de lactose, foi utilizado na suplementação de animais diabéticos. Esse concentrado foi obtido a partir da concentração em sistema de osmose reversa (180 Daltons), seguida de nanofiltração em membrana de 500 Daltons e secagem emspray dryer de uma solução a 5% do primeiro concentrado desenvolvido. O concentrado foi adoçado com rebaudiosídeo A (26 mg de rebaudiosídeo A/100 g de concentrado) obtido por meio da extração, separação e purificação das folhas de Stevia rebaudiana. Todos os processos foram realizados no Núcleo de Estudos em Produtos Naturais, da Universidade Estadual de Maringá. Foram estabelecidos três grupos experimentais (n=6): dois de animais diabéticos, um controle e outro suplementado; e um grupo de animais não diabéticos controle. O grupo suplementado recebeu o concentrado adoçado com rebaudiosídeo A na dose de 100 mg/kg peso corporal/dia, por sonda esofágica, por um período de 35 dias. Em todos os grupos, foram avaliadas semanalmente as glicemias de jejum e no estado alimentado, e o peso corporal. Ao final do período de suplementação, os parâmetros plasmáticos de glicose, colesterol total, triglicérides e da frutosamina; os valores séricos de aspartato aminotransferase e alanina aminotransferase e a ingestão hídrica e alimentar foram analisados. Órgãos e tecidos foram retirados e pesados a fim de se avaliarem alterações de massa e anatômicas. Resultados: O produto formulado apresentou 74% de proteínas e 17% de lactose e apresentou perfil sensorial satisfatório por meio da adição de 26 mg de rebaudiosídeo A/100 g de concentrado. A suplementação do produto reduziu a hiperglicemia, os níveis plasmáticos de frutosamina, triglicérides e colesterol total e ainda melhorou o ganho de peso corporal dos ratos diabéticos induzidos. Conclusão: Os processos de separação por membranas utilizados neste estudo proporcionaram a obtenção eficiente de um concentrado proteico do soro do leite, com teor proteico importante, superior a 70% e com baixo teor de lactose. A adição de rebaudiosídeo A ao produto na concentração de 26 mg/100 g de rebaudiosídeo A proporcionou dulçor equivalente ao da sucralose, com perfil sensorial satisfatório, o que indica que esse edulcorante natural não calórico tem potencialidade para substituir os artificiais. O produto obtido (concentrado proteico do soro do leite adoçado com rebaudiosídeo A) apresentou propriedades funcionais importantes, reduzindo alguns distúrbios metabólicos decorrentes dessa síndrome.

ABSTRACT Objective: To develop a natural dietary product with functional benefits for diabetic patients. Whey protein concentrate was obtained through the separation membrane processes and sweetened with rebaudioside A. This product was submitted to sensory testing in humans and used to evaluate possible functional properties in male Wistar rats models with diabetesMellitus induced by streptozotocin. Methods: Two concentrates were produced. Only the second showed protein content of 74.3 and 17.3% of lactose was used as supplementation in induced diabetic rats. This concentrate was obtained from the concentration by reverse osmosis system (180 k Daltons), followed by nanofiltration in a 500 k Daltons membrane and spray drying at 5.0% solution of the first concentrate developed. The concentrate was sweetened with rebaudioside A (rebaudioside A 26 mg/100 g concentrate). All procedures were performed at the Center for Studies in Natural Products, at the Universidade Estadual de Maringá. Three experimental groups were established (n=6): two groups of diabetic animals, one control group and one supplemented group; and a control group of normal mice (non-diabetic). The supplemented group received concentrates sweetened with rebaudioside A in a dose of 100 mg/kg bw/day by an esophageal tube for 35 days. Fasting, the fed state and body weight were assessed weekly for all groups. At the end of the supplementation period, the following were analyzed: plasma parameters of glucose, total cholesterol, triglycerides and fructosamine; the serum levels of aspartate aminotransferase and alanine aminotransferase, water and food intake. Organs and tissues were removed and weighed to assess mass and anatomical changes. Results: The product presented 74% of proteins and 17% of lactose and showed satisfactory sensory testing by the addition of 26 mg of rebaudioside A/100 g concentrate. Supplementation of the product reduced hyperglycemia, plasma fructosamine levels, triglycerides and total cholesterol, and improved body weight gain of streptozotocin-induced diabetic rats. Conclusion: Whey protein concentrate with substantial content of protein (above 70%) and low lactose was obtained through the membrane separation processes. The addition of rebaudioside A at the concentration of 26 mg/100 g rebaudioside A proved to be as sweet as sucralose with satisfactory sensory testing, which indicates that this is a non-caloric natural sweetener that can replace artificial sweeteners. The product (whey protein concentrate sweetened with rebaudioside A) presented important functional properties and reduced the metabolic disorders caused by the syndrome.