Starch enzymatic hydrolysis,structural, thermal and rheological properties of pigeon pea (Cajanus cajan) and dolichos bean (Dolichos lab-lab) legume starches

Cajanus Cajans and Dolichos lab-lab legume starches from Argentine cultivars were investigated under a technological and nutritional point of view. Their physico-chemical, structural, thermal and the rheological properties of their gels were evaluated. Rice (RS) and potato (PS) starches were included as references. In vitro digestibility from Englyst method was also evaluated. Legume starches had the highest amylose content and the most stable chemical structure. Their rapidly digestible starch and starch digestibility rate index were very low, similar to PS, and fivefold lower than RS. They had a much higher slowly digestible starch content than PS. Legume starches showed the highest gel stability versus heating and stirring and an intermedium pasting temperature between RS and PS. They formed viscoelastic gels at 6% concentration with stronger elastic-like behaviour and higher yield stress than references. Our results indicate these legumes represent an efficient starch source to provide tailor-made properties to food/industrial applications.     

Microwave diagnostics of shock-wave and detonation processes

A method for measuring the parameters of shock-wave and detonation processes using a microwave interferometer is proposed. The experimental technique used in the study and the employed method of processing experimental data are described. Examples of experimental studies carried out using a radio interferometer of the three-millimeter range are considered.     

Synthesis of Open Zeolite Structures from Mixtures of Tetramethylammonium and Benzylmethylalkylammonium Cations: A Step Towards Driving Aluminium Location in the Framework

Three bulky organic cations, benzylmethylpyrrolidinium (BMP), (S,S)-2-hydroxymethyl-1-benzyl-1-methylpyrrolidinium (BML) and benzylmethylhexamethyleniminium (BMH), were used in combination with the small cation tetramethylammonium (TMA) in the synthesis of zeolite materials. Two of them are distinguished by the number of carbon atoms forming the cyclic amine, which varies from 4 in BMP to 6 in BMH. In addition, a –CH₂–OH group has been introduced in the carbon atom belonging to the amine ring next to the nitrogen atom, to originate a chiral molecule, BML, the third SDA used in this work. It has been found that the combination of the small TMA with those three bulkier SDAs, promotes the crystallization of zeolite structures that contain cages and channels. BMP leads to the crystallization of the 10-ring zeolite ferrierite, where TMA is located inside the ferrierite cage. If the size of the N-cyclic amine moiety increases, the resulting cation cannot be accommodated in the relatively narrow 10-ring channels of ferrierite, and in these cases the zeolite MCM-22 crystallizes. This zeolite contains large cages whose cross section is delimited by a 12-ring, where both BMH and BML can be easily accommodated. In this system, cage-like, chlatrasil type structures often co-crystallize with the open structures, evidencing that an appropriate balance between TMA and the bulky SDA is required to achieve the crystallization of open-frameworks. When BMP is used, mixtures of structurally related ferrierite and cage-like RUB-10 are obtained if an excess of TMA is present in the synthesis gel, while MCM-22 crystallizes together with the structurally related cage-like MTN phase.     

Method for the characterization of hologram processing

Abstract

A novel method for the characterization of the processing of both absorption and phase holograms is proposed. Differently from the previous models, the square root of the diffraction efficiency of the processed hologram was directly related to the amplitude of the optical density modulation obtained at the developed step. This characteristic is a good indicator of the degree of nonlinearity of the hologram processing. While the Lin functions of phase holograms are similar to those of absorption holograms, the shape of the proposed function is completely different. The optical density and diffraction efficiency of holograms recorded using Agfa–Geveart 8E75HD plates and processed with AAC developer and a solvent bleach without a fixation step were measured and used to demonstrate the method.     

Lycopene isomers in fresh and processed tomato products: Correlations with instrumental color measurements by digital image analysis and spectroradiometry

Tomatoes (Solanum lycopersicum L.) are food staples that contain high levels of lycopene (LYC), a red carotenoid thought to provide health benefits. Previous studies indicate that instrumental color measurements can be harnessed to estimate carotenoid levels in a rapid and non-destructive fashion, which offers important analytical advantages. In this investigation we have assessed the different LYC isomer contents by HPLC and the color of diverse tomato genotypes and tomato derived-products by SPR and DIA with four main purposes: 1) to compare the levels of LYC isomers in processed vs fresh tomato products, 2) to evaluate the validity of DIA and SPR to ascertain the color of these products, 3) to compare the ability of both instrumental methodologies to discriminate between the two different groups of samples, and 4) to compare the utility of both methodologies for estimating LYC levels. The results indicated that the parameters obtained by SPR and DIA were significantly correlated (p < 0.05) and that the higher regression coefficients were obtained for L*, C*ab and a*. This observation indicates that the DIA is appropriate to evaluate the color of tomato. It was also noticed that, overall, SPR led to better discriminations between samples considering the PCA data (97%).     

Holographic Noise Gratings for Analysing and Optimizing Photochemical Processings in Bleached Silver Halide Emulsions

Abstract

Recording noise gratings with single-beam exposures in bleached silver halide emulsions is used as a holographic spectroscopy technique in order to analyse and optimize photochemical processing. In particular, rehalogenating type bleachings are analysed by measuring the transmittance through the recorded and processed holographic plate as a function of the reconstruction angle, the exposure and the concentration of the rehalogenating agent in the bleach bath. The experimental results obtained show us that the analysis of these spurious gratings provides information about the bleaching action during the processing and allows us to identify the optimal concentration of the bleach bath.     

High-efficiency volume holograms recording on acrylamide and N,N′methylene-bis-acrylamide photopolymer with pulsed laser

In order to achieve a better understanding of the mechanisms of hologram formation and higher diffraction efficiencies in volume gratings stored in acrylamide based photopolymers, a crosslinker (N,N′methylene-bis-acrylamide) has been incorporated in the photopolymer to record holograms by pulsed laser exposure. The presence of this component increases the polymerization rate and refractive index modulation. The recording was performed using a holographic copying process. The original was a grating of 1000?lines/mm processed using silver halide sensitized gelatin. First, the effect of the pulse fluence was investigated. When the pulse fluence was optimized, the results obtained using the new composition of material were compared with those using the composition without a crosslinker. Using a pulsed laser at 532?nm the photopolymer without crosslinker presented diffraction efficiencies slightly less than 60%. On the other hand, when the crosslinker was introduced in the photopolymer composition, the diffraction efficiencies achieved were higher than 85%. The non-linearity of the material's response was also studied comparing the energetic sensitivity, diffraction efficiencies and index modulation of gratings recorded with pulsed and continuous laser exposure. This study was performed fitting the angular scan of each grating using Kogelnik's theory.     

Effect of kaolin nanofiller and processing conditions on the structure,morphology, and biofilm development of polylactic acid

The effect of high energy ball milling, HEBM, and the presence of kaolin on the structure, morphology, and biofilm development of polylactic acid, PLA, were studied. Biofilm development was evaluated in terms of structural and/or morphological variations so as the sole presence of kaolin. Composites based on PLA filled with kaolin were prepared by HEBM followed by hot pressing to obtain films. Structure was studied by X‐ray diffraction and Fourier transformed infrared spectroscopy whereas morphology was inspected by scanning electron microscopy and atomic force microscopy. To study biofilm development on the surface of these materials, Pseudomonas fluorescens B52 were used. The shear forces from the milling process favor kaolin dispersion within the PLA. Longer milling times and cryogenic conditions improve clay dispersion. Subsequent hot pressing process enhances the most ordered structure of PLA (α‐phase) which is also favored with previous milling at longer times and under cryogenic conditions. Changes in P. fluorescens biofilm development are mainly due to modifications of surface properties induced by structural variations, being the most ordered structures those which better support bacterial adhesion and proliferation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42676.