The colorant properties of pigments from Opuntia stricta, Opuntia undulata, and Opuntia ficus-indicafruits were studied. The pigments were extracted with different solvents and identified by high-performance liquid chromatography. On the basis of their visible light spectra, the pigments were identified as betalains. In O. undulata and O. ficus-indica fruits, both betacyanins and betaxantins were identified, while in O. stricta fruits only betacyanins (betanin and isobetanin) were detected. O. stricta fruits showed the highest betacyanin content (80 mg/100 g fresh fruit). The thermal stability of the pigment extracts was dependent on the pH, with the maximum stability being at pH 5, as expected for betacyanins. At this value and a storage temperature of 4 degrees C, a deactivation half-life time of more than 1 year, with no added stabilizers, was determined. According to these studies, cactus pears from O. stricta may well be considered as a potential source of natural red colorants.

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The prebiotic fibres, resistant dextrin and fructooligosaccharides (FOS), were studied for use as drying-aid agents for the spray-drying of concentrated pomegranate juice, a low-caloric juice containing interesting health-related compounds. Resistant dextrin was the best drying-aid agent as only 0.5 g g CPJ À1 of resistant dextrin was needed to avoid powder stickiness, compared with 1 g g CPJ À1 of maltodextrins and 1.5 g g CPJ À1 of fructooligosaccharides. The best conditions for spray-drying a concentrated pomegranate juice (62.6% dry matter) using the resistant dextrin (NUTRIOSE) were 1.25 g NUTRIOSE g CPJ À1 and 0.10 g CPJ g solution À1, a liquid feed rate of 1.08 L h À1 and an air temperature of 160°C. Powders were easily solubilised in water, while storage at 25°C maintained the pomegranate bioactive components, and there were no stickiness problems for at least 2 months. Resistant dextrin could be used with all kind of fruit juices in substitution of maltodextrins, and the resulting prebiotic powders could be employed for formulating novel functional foods.

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Generalized internal vibrational coordinates are optimized and used to describe highly excited vibrational motions in the N2O molecule. These coordinates are defined as the magnitudes of two vectors, which are expressed as linear combinations of the internal displacement vectors and the angle formed between them. They depend on two parameters and contain, as particular cases, valence and orthogonal (Jacobi, Radau, etc.) coordinate systems. The coordinates are optimized by minimizing unconverged variationally computed vibrational energies with respect to the external parameters. A comparison of the optimal internal coordinates derived for N2O with valence and hyperspherical normal coordinates is made. The optimal internal coordinates are also used to determine a new potential energy function for N2O from the observed vibrational frequencies up to 15 000 cm−1 using fully variational calculations. The quality of the adjusted potential energy function is checked by computing vibrational-rotation energy levels and rotational constants for Σ, Π, Δ, Φ, and Γ states and comparing them with the observed values.

Fermentation of juice and homogenized fruits of Opuntia stricta fruits has been developed and optimized. The aim was to obtain the red food colorant betanin from prickly pear, at high concentration and low viscosity. Among three strains assayed, Saccharomyces cerevisiae var. bayanus AWRI 796 has been the optimum for this process. The optimum temperature value was found to be 35 degrees C for both sugar consumption and pigment preservation. After fermentation, biomass and residual vegetal tissue were discarded by centrifugation. Supernatant was concentrated under vacuum. Therefore, liquid concentrated betanin was obtained, with low viscosity and being sugar free. Besides, bioethanol was obtained as byproduct. Characteristics of the final product obtained were pH 3.41, 5.2 degrees Brix, 9.65 g/L betanin, color strength of 10.8, and viscosity of 52.5 cP. These values are better than obtained by other procedures.

We present exact quantum calculations of the photodissociation of ozone in the Hartley band. These calculations rely on an hyperspherical description of the system, including rotation. A pseudospectral approach has been used for an efficient implementation of this scheme. The autocorrelation function has been directly computed by means of a Lanczos scheme, augmented by a complex absorbing potential. Using a single excited potential energy surface (D 1B2), calculations up to J=17 are reported. It is shown that in these conditions rotation has only marginal effects over the first 500 fs. The origin of the observed experimental temperature dependence is discussed in this context.