Release of α-Tocopherol from Poly(lactic acid) films, and its effect on the oxidative stability of soybean oil

Poly(94% l-lactic acid) (PLA) films (PT0) and PLA films containing 2.58% wt. α-Tocopherol (PT2.5) were extruded in a pilot-plant size blown-extrusion machine. PT2.5 films were obtained with a slightly yellowish color and absorption of UV-visible light at 320-260 nm. The kinetics of release of α-Tocopherol from the PT2.5 films to ethanol and vegetable oil at temperatures between 13 and 43 °C was evaluated. Diffusion of the α-Tocopherol from the PT2.5 films to ethanol showed a Fick’s behavior with diffusion coefficients (D) at levels between 10⁻¹¹ and 10⁻¹⁰ cm²/s and with 26.9-99% of release. Diffusion of α-Tocopherol to oil was slower than to ethanol with 5.1-12.9% of release. However, it was enough to delay the induction of the oxidation of soybean oil stored in contact with the PT2.5 film at 20 and 30 °C, compared with that of oil in contact with the PT0 film. The processing conditions and the temperature of diffusion process had an effect on the reduction of the weight average molecular weight (M_W) of PLA. PLA packaging added with α-Tocopherol could be used for protection of oily foods stored at room temperature.     

Dehydration of Malay Apple (Syzygium malaccense L.) Using Ultrasound as Pre-treatment

This work examined the influence of the ultrasonic pre-treatment prior to air drying on dehydration of jambo (Syzygium malaccense L.) also known as Malay apple. This study allowed the estimation of water loss and sugar gain during the pre-treatment and the effective water diffusivity in the air-drying process for jambo subjected to ultrasonic pre-treatment. Results showed that during the ultrasonic treatment, in distilled water, the Malay apples lost sugar, so such a pre-treatment stage can be a practical process to produce dried fruits with lower sugar content. The water effective diffusivity increased by 28.1% (best result) after application of ultrasound, which caused a reduction of about 27.3% in the total drying time.     

Channel forms and vegetation adjustment to damming in a Mediterranean gravel‐bed river (Serpis River,Spain)

This paper focuses on the analysis of changes observed in channel morphology in the Serpis River (Alicante, Spain), a gravel‐bed river dammed since 1958. The paper analyses flow series and several aerial images, prior and subsequent to dam construction, to analyse changes in channel morphology and vegetation colonisation using Geographical Information Systems (GIS) techniques. Results show a concatenation of morphological changes throughout an adjustment sequence (60 years), which started with the transformation from wandering to single thread channel pattern, was followed by a slow vegetation encroachment, and culminated with the stabilization of channel migration. The role of vegetation (particularly Salicaceae species) has been critical in controlling floods' effectiveness, reducing river mobility and shifting, and consolidating a channel planform model adapted to the post‐dam flow conditions.     

Structural and antigenic preservation of plant samples by microwave-enhanced fixation, using dedicated hardware, minimizing heat-related effects

We explored the use of microwave technology in fixation with the objective of achieving quicker fixation regimes, lower concentrations of toxic and volatile reagents, and enhanced antigen detection. We used a modified domestic microwave oven (900 W) and a low-power (5 W) microwave bench. The work was done on plant materials. The oven was supplemented with a cooling device, a stirring system, and a record of the sample temperature and the time of effective irradiation. The sample, immersed in a fixative solution of 1% paraformaldehyde (PFA) in PBS, was irradiated for only 10 minutes. The sample temperature did not exceed 37 degrees C. In these mild conditions, the quality of the (ultra)structural preservation of the samples, morphometrically assessed, was at the same level as obtained with the same fixative, using conventional methods. On the contrary, samples fixed in the same conditions without irradiation showed a poor structural preservation. The antigenic preservation of the irradiated samples was excellent, since the labeling levels of two nucleolar proteins, detected by immunogold, were three times higher than in conventionally fixed samples. In the so-called microwave bench, the pathway of microwaves is guided, so that low-power microwaves directly hit the sample and there is no dispersion of energy. Temperature of fixative did not increase after microwave irradiation. Fixation in the bench with either 4% PFA, or 1% PFA, for 20 minutes resulted in structural preservation of samples similar in quality as obtained with conventional fixation and in a similar or better level of antigen preservation. Therefore, controlling temperature and effective irradiation is crucial in order to obtain optimal structural and antigen preservation with microwave-enhanced fixation. The dramatic differences observed between microwave-irradiated samples and samples fixed in the same conditions without irradiation, strongly support the existence of specific effects of microwaves on fixation, independent from the mere heating of the samples.     

Effect of Spray-Dried Flavonoid Microparticles on Oxidative Stability of Methyl Linoleate as Lipid Model System

Microencapsulated quercetin (Q) and epicatechin (E) were prepared by spray-drying using inulin (IN) as encapsulating agent (Q–IN and E–IN) as well as with Capsul (C) as channelizing agent (Q–IN–C and E–IN–C). Microparticles were added to methyl linoleate (ML) and results showed that Q microparticles markedly improved its oxidative stability by increasing the induction period values and delaying the formation of oxidation compounds, as determined by high-performance size-exclusion chromatography, with respect to E microparticles, thus suggesting the importance of flavonoid C-ring substitution. Remaining levels of Q in the lipid system throughout oxidation of ML added with Q microparticles seemed to show two releasing zones: the first one corresponds to the equilibrium zone, when Q released from microparticles replaces Q that is being degraded; the second zone corresponds to the degradation of Q, when the release rate of the encapsulated Q is slower than its degradation rate. In contrast, E microparticles showed only one zone corresponding to the release of surface E. The end of the induction period was in line with the exhaustion of Q and E and the initiation of formation of advanced oxidation products (polymers). In conclusion, Q microparticles have a potential application to extend the shelf-life of lipid matrixes.     

Ultrasound-Assisted Osmotic Dehydration of Strawberries: Effect of Pretreatment Time and Ultrasonic Frequency

Pretreatment of fruits prior to drying has shown success in reducing drying time and costs. In this work, ultrasound-assisted osmotic dehydration has been implemented as a method to increase water diffusivity and reduce drying time in strawberries. Strawberry halves were immersed in distilled water and in two different concentrations of sucrose solutions while pretreatment time and ultrasonic frequency levels were varied to determine their effect on drying time, water loss, and soluble solids gain. A microscopic analysis was carried out to evaluate the formation of microchannels and other changes to the fruit tissue structure. Greater sucrose concentration used in ultrasound-assisted osmotic dehydration resulted in greater water loss with greatest loss observed for the strawberry halves pretreated for 45 min in a 50% w/w sucrose solution. The pretreatment carried out for 30 min employing an osmotic solution of 50% w/w of sucrose resulted in the highest drying rate among the pretreatments. Osmotic dehydration used alone during pretreatment increased total processing time, whereas osmotic dehydration combined with ultrasonic energy during pretreatment reduced total processing time and increased effective water diffusivity. Cell distortion and breakdown were observed not only in pretreatments employing ultrasound-assisted osmotic dehydration but in conventional osmotic dehydration. Formation of microchannels through ultrasonic application and effects of osmotic pressure differential were considered to be largely responsible for reducing drying time for strawberry halves.