Kinetic study and modeling of biosurfactant production using Bacillus sp

Background: Surfactants are one of the most important raw materials used in various industrial fields as emulsifiers, corrosion inhibitors, foaming agents, detergent products, and so on. However, commercial surfactant production is costly, and its demand is steadily increasing. This study aimed to evaluate the performance of typical strains of Bacillus sp. to produce biosurfactants through fermentation. It also included the investigation of the effect of initial glucose concentration and the carbon to nitrogen ratio. Results: The biosurfactant yield was in the range of 1­2.46 g/L at initial glucose concentrations of 10­70 g/L. The optimum fermentation condition was achieved at a carbon to nitrogen ratio of 12.4, with a decrease in surface tension of up to 27 mN/m. Conclusions: For further development and industrial applications, the modified Gompertz equation is proposed to predict the cell mass and biosurfactant production as a goodness of fit was obtained with this model. The modified Gompertz equation was also extended to enable the excellent prediction of the surface tension.

Emulsificantes: atuação como modificadores do processo de cristalização de gorduras / Emulsifiers: acting as modifiers of the crystallization behaviour of fats

Os emulsificantes são aditivos empregados com diversas finalidades na produção dos alimentos industrializados, dentre elas para melhorar a textura, o volume, a aeração e a homogeneidade dos produtos. Estudos indicam mais uma função para estes compostos que atuam usualmente estabilizando emulsões, como modificadores do processo de cristalização de óleos e gorduras. Produtos como chocolates, margarinas e sorvetes são elaborados com base nos compostos gordurosos que, ao atingirem a condição de super-resfriamento ou supersaturação, formam cristais e, posteriormente, uma rede cristalina tridimensional, responsável pelos atributos sensoriais dos produtos. Os emulsificantes podem interferir no tempo de indução, na velocidade de formação dos cristais de gordura, além de modificar a morfologia e o hábito cristalino desses cristais, retardando as transições polimórficas indesejáveis e afetando diretamente a qualidade dos produtos. Esta revisão abordou os diferentes efeitos de emulsificantes utilizados em alimentos na cristalização de matérias-primas gordurosas.

The emulsifiers are additives used for many purposes in the production of foods, among them to improve texture, volume, aeration and homogeneity of the products. Most studies indicate a new role for this compound that acts usually stabilizing emulsions, as modifier of the crystallization of oils and fats. Products such as chocolate, margarine and ice cream which are made of fats, upon reaching the condition of supercooling or supersaturation, form crystals and then a three-dimensional crystal lattice responsible for sensory attributes of products. The emulsifiers can alter induction time, the rate of formation of fat crystals and modify the morphology and crystal habit of these crystals, retarding undesired polymorphic transitions and affecting quality of products. This review evaluated the effects of different food emulsifiers on the crystallization of fats.