β-D-Galactosidase from Kluyveromyces lactis was immobilized on glutaraldehyde-activated chitosan and used in a packed-bed reactor for the continuous hydrolysis of lactose and the synthesis of galactooligosaccharides (GOS). The biocatalyst was tested for its optima pH and temperature, thermal stability in the presence of substrate and products, and operational stability. Immobilization increased the range of operational pH and temperature, and the enzyme thermal stability was sharply increased in the presence of lactose. Almost complete lactose hydrolysis was achieved for both milk whey and lactose solution at 37 °C at flow rates up to 2.6 mL min(-1). Maximal GOS concentration of 26 g L(-1) was obtained at a flow rate of 3.1 mL min(-1), with a productivity of 186 g L(-1) h(-1). Steady-state operation for 15 days showed the reactor stability concerning lactose hydrolysis.

In this research, the effects of ultrasound stirring and the addition of molecular sieves on esterification reactions between butyric acid and several alcohols catalyzed by immobilized lipase from Rhizomucor miehei (Lipozyme RM-IM) were studied. Among the tested alcohols, 1-propanol and isobutanol allowed the highest activities, whereas Lipozyme RM-IM showed poor activities for esterification using secondary and tertiary alcohols. Different solvents were also tested and n-hexane was selected because of its reaction effects, besides being cheaper, available at low boiling point, and ease of recovery. Using the preselected alcohol and solvent, other reaction parameters (butyric acid concentration, temperature, substrate molar rate, and biocatalyst content) were studied to optimize the reaction conditions. Optimal conditions were acid concentration, 0.7 M; substrate molar ratio, 1 : 1 alcohol-acid; temperature 45 C; biocatalyst content, 14% (by substrate mass). Under these conditions, it was possible to obtain a yield of 86% of butyl butyrate in 2.5 h. When molecular sieves (90 mg mmol À1 butytic acid) were added to the reaction, the observed yield increased to 96%. The biocatalyst was used in 5 successive reaction cycles keeping 100% of its initial activity. The overall process productivity was improved 2-fold when compared to the traditional mechanical agitation, showing that ultrasound is a promising technology for application in biocatalysis.

No abstract

No abstract

No Rio Grande do Sul, destaca-se a relevância socioambiental de diferentes espécies de butiá (butiá yatai). Este trabalho teve como objetivo avaliar como o processo de despolpa de butiá interfere, ao longo de três meses de armazenamento, na composição do alimento, particularmente no valor calórico, no teor de fibras e na estabilidade do ácido ascórbico. Os frutos de butiá foram coletados e analisados entre os meses de março e junho de 2017, analisando-se parâmetros físico-químicos e centesimais da fruta e da polpa de butiá. Do ponto de vista físico-químico, a polpa, quando comparada à fruta, apresenta maior teor de umidade, de açúcares dissolvidos e teor de ácido cítrico. A polpa apresentou aumento de 24,5% na quantidade energética total, porém, quando se trata das fibras alimentares totais, houve redução de 47,9%. O teor de ácido ascórbico diminuiu 44,6% durante o período estudado. Tanto a fruta como a polpa apresentaram alto teor de fibras alimentares. Portanto, foi possível identificar que o processo de beneficiamento do butiá acarreta em mudanças nas características da fruta para a polpa, mas ambos os alimentos podem ser considerados nutritivos para compor a base da alimentação regional. Palavras-chave:Processamento. Fruta Nativa. Guia Alimentar. Nutritional evaluation of Butia (Butia yatai) processedIn the state of Rio Grande do Sul, Brazil, it is important to highlight the socioenvironmental relevance of different butia species. The objective of this work was to evaluate how butia (Butia yatai) pulping process interferes, within three months of storage, in the food composition -particularly caloric value, fiber content and the stability of ascorbic acid. Butia fruits were collected and analyzed between March and June 2017, analyzing physico-chemical properties and centesimal composition of butia fruit and pulp. Regarding the physico-chemical characteristics, the pulp, when compared to the fruit, presents a higher content of moisture, dissolved sugars and citric acid. Also, the pulp showed a 24.5 % increase in the total energy content. However, when it comes to the total dietary fiber, there was a 47.9 % reduction. The ascorbic acid content decreased 44.6 % during the studied period. Both fruit and pulp presented a high fiber content. Therefore, it was possible to identify that the fruit processing involves changes on the pulp characteristics, but both, the in nature fruit and processed, can be considered nutritious and of good assistance in the regional diet.