Characterization of the fruit proteolytic system of Bromelia serra Griseb. (Bromeliaceae) and its application in bioactive peptides release.

A crude extract with proteolytic activity was prepared from edible fruits of Bromelia serra, containing cysteine peptidases with molecular masses between 24.1 and 25.9 kDa.

Bromide counterion as a spectroscopic sensor at the interface of cetyltrimethylammonium micelles.

The strong UV absorption of the bromide in aqueous solution undergoes a remarkable red shift of more than 10 nm induced by the addition of the salts that constitute a saline buffer. The maximum absorption wavelength of the bromide is displaced from approximately 194 nm in ultrapure water to wavelengths above 200 nm, depending on the composition of the solution. The bromide spectrum as counterion of the cetyltrimethylammonium in the surfactant CTAB also shows sensitivity to the aggregation behavior of the tensioactive, being able to detect intermolecular interactions even at concentrations lower than the critical micelle concentration.

Host-guest molecular interactions in vanillin/amylose inclusion complexes.

The interaction of 4-hydroxy-3-methoxybenzaldehyde (vanillin) and Hylon VII due to the formation of an inclusion complex is studied using Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), and circular dichroism (CD). The results confirm the close interaction among the different functional groups of vanillin and its host. In addition, a second case study was carried out with an amylose from a different source (100% amylose [APT III]).

Customized design of electronic noses placed on top of air-lift bioreactors for in situ monitoring the off-gas patterns.

A specially designed electronic nose was coupled to an air-lift bioreactor in order to perform on-line monitoring of released vapors. The sensor array was placed at the top of the bioreactor sensing the headspace in equilibrium with the evolving liquor at any time without the need of aspiration and pumping of gases into a separated sensor chamber. The device was applied to follow the off-gas of a bioreactor with Acidithiobacillus thiooxidans grown on beds of elemental sulfur under aerobic conditions.

PDMS-based porous particles as support beds for cell immobilization: bacterial biofilm formation as a function of porosity and polymer composition.

The objective of this work is to test the performance of new synthetic polydimethylsiloxane (PDMS)-based bed particles acting as carriers for bacteria biofilms. The particles obtained have a highly interconnected porous structure which offers a large surface adsorption area to the bacteria. In addition, PDMS materials can be cross-linked by copolymerization with other polymers.