The use of composite edible films made from biopolymers has attracted interest as a way to reduce pollution and recycling problems; however, the relation between barrier, mechanical and structural ...properties of the films have been scarcely studied. The aim of this work was to evaluate composite zein–chitosan edible films by applying common nanotechnology tools and to relate the results to zein concentration and film structural changes. Rougher, more elastic, and less hard film structures with better water vapour barrier properties were obtained using larger zein concentrations. Raman spectroscopy exhibited unexpected interactions, as indicated by the disappearance of the thiol groups of cysteine in the zein films and the appearance of OSO and COS groups in the blended materials in conjunction with the disappearance of zein ɛ-amino and NH2 functional groups in the zein film samples, thereby confirming changes in the blended film structure. Zein concentration presented linear correlations with water vapour permeability (R=−0.978) and film roughness (R=0.929). The composite films presented better barrier and mechanical properties than single ingredient films. This information shows the benefit of using protein–polysaccharide blends to prepare edible films.
The bakery market is developing new technologies based on dough partial baking and the study of the changes that dough undergoes through the whole baking process could help in the selection of baking ...times. The aim of this work was to study the changes of dough structure and their relationship with dough temperature, mass loss and loaf height during baking by applying image analysis techniques. Results showed that during baking, bubble coalescence was presented, observing a maximum at the first stages of baking (<250
s). This phenomenon was associated with an increment in dough height without a significant change in dough centre temperature. Fractal dimension of texture of crumb, fractal dimension of contour of cells and crumb grain features were useful indicators of coalescence as well as to distinguish the baking time needed for crumb features remain invariable.
The synthesis of carbon quantum dots (CQDs) from biomass could be the best application for biopolymeric materials with no further use in industry and that can have environmental effects when disposed ...of, such as pelagic Sargassum. This research compared the structural and luminescent properties of CQDs synthetized by two different methods (microwave and conventional hydrothermal synthesis) using pelagic Sargassum extract as a carbon source. The microwave method resulted in a better mass yield, while hydrothermal synthesis generated the best quantum yield (QY). Under optimized synthesis conditions, no statistical differences were observed in CQDs size or surface functional groups, as detected by TEM and FTIR analyses respectively. However, crystalline structure and light absorption varied between samples, explaining the higher values of QY observed in the conventional hydrothermal method. This study thus assists in furthering the understanding of the synthesis process, as well as providing supporting evidence for which synthesis methods are better for CDQ synthesis depending on the future uses of these nanoparticles.
•Luminescent CQDs using pelagic Sargassum are successfully synthesized.•Hydrothermal and microwave methods generate CQDs of similar size and structure.•The more CQDs crystalline structure, better fluorescent properties.•Conventional hydrothermal method produces CQDs with a higher quantum yield.•Microwaved synthesis method produces CQDs with a higher mass yield.
•Agave leaves were fractionated by the Acetosolv method.•Microstructural changes during Acetosolv delignification were monitored by microscopy.•Cellulose crystallinity increased with the severity of ...the treatment operating conditions.•Phenomena occurring in the delignification of agave fibers are described.•Paper with a whiteness similar to commercial Bond paper was obtained.
The Acetosolv process is an organosolv treatment that has been used to separate cellulose, hemicellulose and lignin from lignocellulosic material by taking advantage of the higher affinity for the lignin oligomers to dissolve in organic solvents. However, the process conditions depend on the material used, thus the influence of process variables (time process, acetic acid concentration and hydrochloric acid concentration) on the Acetosolv delignification of agave leaves to obtain cellulose was evaluated. Using a face-centered factorial design, it was possible to obtain high quality pulp by the Acetosolv pulping process with the following results: pulp yield 24.5%; 8.2kappa number and a pulp viscosity of 571mL/g. The low kappa number values obtained indicate a high degree of whiteness and a low content of lignin cellulose; this has been confirmed by confocal and scanning electron microscopy while Raman spectroscopy and X-ray diffraction analyses indicate that the type of cellulose remaining in pulp is cellulose I. Paper with a similar or higher quality than commercial Bond paper in terms of whiteness could was obtained from Acetosolv pulp. A comprehensive and quantitative view of the phenomena occurring in the delignification of agave fibers using different characterization techniques is demonstrated.
Biological, physicochemical, structural, and thermal properties of PVA-based electrospun wound dressings added with hydrolyzed collagen (HC) and different concentrations of Hypericum perforatum ...ethanolic extract (EEHP) were studied. Membrane characterization was carried out by X-ray diffraction, Fourier infrared spectroscopy, differential scanning calorimetry, barrier properties, scanning electron microscopy, image analysis (diameter and pore size), as well as antimicrobial and anti-inflammatory activities. Results showed that the PVA/HC/EEHP materials, fabricated under controlled conditions of temperature and humidity, generated fiber membranes with diameters between 140−390 nm, adequate porosity and pore size for cell growth (67−90% and 4−16 µm, respectively), and good barrier properties (0.005−0.032 g·m−2 s−1) to be used in the treatment of conditions on the skin, and was even better than some commercial products. Finally, they showed to have anti-inflammatory (>80%), and antimicrobial activity against S. aureus and S. epiderm. Furthermore, higher crystalline structure was observed according to the EEHP concentration. In addition, this is the first report in which PVA/HC/EEHP membranes are successfully fabricated and characterized.
The levels of different nutraceutical metabolites present in the jicama root were measured when subjecting the plant to induced biotic stress via infestation with Phyllophaga spp. (white grubs). The ...change in secondary metabolites on the stressed jicama roots (SJ), mostly antioxidants, was followed over 100, 140, and 180 days and compared against the non-infested control jicama (CJ). Our results show that infested (SJ) samples contained higher concentrations of tannins, flavonoids, and total phenols, measured using spectrophotometric methods, peaking at 140 days, and higher overall concentration of saponins. SJ samples showed higher DPPH inhibition, peaking at 100 days. Chlorogenic acid had the highest concentration among the phenolic compounds (7.47 mg g−1), followed by protocatechuic acid, both in SJ, which was possibly related to the lower observed concentrations of caffeic and ferulic acids. As for flavonoids, we observed a high concentration of rutin in CJ and a low concentration of pelargonidin and myricetin in SJ, possibly promoted via the dihydrokaempferol pathway. Taken together, these results show that Phyllophaga spp.-mediated biotic stress affects the concentrations of secondary metabolites in the different maturity stages in jicama, having an effect on its metabolic pathways, which presents an opportunity for the use of material such as agro-industrial waste.
The use of pectin from coffee mucilage (P
I
) is an alternative to reduce the environmental impact of the wet processing coffee industries by applying it in the generation of degradable films. Hence, ...the aim of this work was to valorize industrial coffee waste as a source of pectin to prepare biodegradable films by a novel methodology (electrospraying), perform chemical characterization of pectin, and compare the films with a control method (casting) and pectin (citric, P
C
). Coffee mucilage pectin composition (P
I
) was different, having smaller galacturonic acid content (52.2%) than P
C.
The presence of neutral sugars (ribose, xylose, glucose), the high degree of esterification (84.92 ± 1.70) and the diffractogram and Raman spectra results, gave the basis to consider P
I
as a high methoxyl pectin. P
I
films showed different physical properties and structure than Pc, depending on the composition and method of production. Regarding mechanical and barrier characteristics, films prepared with pectin from coffee mucilage presented a typical behavior of rigid polymers; they were also more permeable to water vapor (2.91 ± 0.02 × 10
−12
g/s m Pa) and were highly biodegradable and soluble in water. Due to these characteristics, the production of films from coffee mucilage pectin becomes a suitable alternative to give added value to this unexploited waste.
Graphic Abstract
•Chia seed mucilage can emerge as a potential industrial additive.•Chia mucilage release can be studied by applying drug release mathematical models.•Microscopy and Image analysis can be used to ...model chia mucilage release process.
Chia seed mucilage could be used as industrial additive due to its outstanding physical properties. However, not many reports about this gel have been published, maybe due to it remains tightly bounded to the coat seed during processing. The aim of this work was to characterise the chia seed structure and the mucilage release by microscopy, spectroscopy and image analysis techniques. Results showed that the mucilage is excreted from the polygonal cells of the epidermis coat, being composed mainly by carbohydrates fibres (18–45nm width). It was observed from the kinetic modelling that the mucilage release follows a non Fickian process (0.5<n<1.0), presenting the best fitting the Peppas and Sahlin equation (R2=0.9984 and EDM %=0.8). Chia mucilage could be used for the controlled release of drugs, or, as a result of the size of its fibres, for the production of nanocomposites.
Electrospraying is a technique now applied for the production of food nanoparticles, nanofibres and nanocapsules, which could constitute a good alternative for the development of films. The goal of ...this work was to determine the electrospraying operation conditions and the zein concentration that would allow a film to be produced and also to evaluate the structural characteristics and barrier and thermal properties of films developed at different thicknesses. Results showed that films can be obtained by electrospraying, resulting possible to produce homogeneous films, without electrical arc formation during processing when using a 11.4% zein solution, an electrical voltage of 7.8–8.7 kV and a distance of 1.5 ± 0.5 cm between the nozzle and the deposit plaque. Regarding the effect of the production methods (electrospraying and casting) and the film thickness on film appearance, both variables had significant effect on colour parameters, observing a more yellowish colour (b* = 72.3 ± 6.8) and lower transparency (%T = 90.6 ± 0.21) at larger thicknesses (100 μm), and a smoother and more homogeneous surface (ESEM) when films were obtained by electrospraying. Water vapour permeability was only influenced by film thickness (1.51 × 10−08 to 3.11 × 10−08 g/s-m-Pa) in both methodologies. The glass transition temperatures (Tg) for electrospraying and casting films were different (222 °C and 231 °C respectively) and higher than that of zein powder (165 °C), indicating a possible change in the film structure due to the process. Under the process conditions tested in this work, electrospraying can be considered as an alternative technique to produce films.
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•Electrospraying can be used to produce zein films.•Electrospraying generates similar films to those produce by casting.•Electrosprayied zein generates different products as varying process conditions.
Many approaches to evaluate bread crumb features by applying free or at least not too expensive image analysis (IA) software have been published; however, the described procedures showed noticeable ...differences. The aim of this work was to compare different image scanning resolutions and thresholding techniques to quantify sweet bread crumb features (cell density, mean cell area, shape factor) and their relation with fractal dimension. Two sets of experiments were carried out, one to determine the effect of scanning resolution and thersholding method and the other to validate the previous results by evaluating breads with different crumb structures. Nine different scanning resolutions (75, 100, 150, 200, 300, 355, 435, 515, 555 dpi) and two segmentation procedures (Otsu and Manual) were tested. Three different types of commercial sweet breads and a yeasted sweet bread added with different concentrations (six, 12%) of Chia flour (
Salvia hispanica
) were evaluated. Results showed that the percentage of particles with areas between 0.1 and 4.0 mm
2
remained almost constant when using 350 dpi or larger resolution values, while the smallest particles (<0.1 mm
2
) increased their proportion up to 87% at the highest scanning resolution for both thresholding methods. IA was useful to detect crumb structure differences among commercial breads and breads added with Chia flour as obtained from cell density (154 ± 4.6–246 ± 2.5) and mean cell area (0.81 ± 0.02–0.7 ± 0.03) results. However, the number of selected objects to calculate these parameters produced different results. The addition of 6% of Chia flour did not affect the bread crumb features, while at the largest proportion more and smaller pores were obtained. Fractal texture was useful to evaluate bread crumb structure, as it not depends on the number of particles detected.
