Study of the Physical, Chemical, and Structural Properties of Low- and High-Methoxyl Pectin-Based Film Matrices Including Sunflower Waxes.

The development of bio-based materials remains one of the most important alternatives to plastic materials. Although research in this field is growing, reporting various materials and methodologies, it is still necessary to increase exploration. The aim of this work was to expand and complement previous research on the preparation and characterization of high- and low-methoxyl pectin films obtained by casting, with the addition of commercial and recovered sunflower waxes. The results showed that the addition of sunflower waxes to the pectin matrix generated some discontinuity in the aggregate, increasing the thickness and roughness of the film. However, due to their hydrophobic nature, the waxes contributed to lower vapor transmission rate values of the films. On the other hand, the low-methoxyl pectin films had a more crystalline structure, which could help to diminish water vapor permeability values, mechanical resistance and rigidity, and improve their elongation. Regarding chemical characteristics, most of the raw materials' chemical groups were found in the resulting films, and the presence of C-H bending due to pectin gelation was observed. Finally, the compatibility and contribution of pectin and sunflower waxes to the production of the films were demonstrated, as well as the possibility of using materials from industrial waste in food packaging applications.

Pectin Films with Recovered Sunflower Waxes Produced by Electrospraying.

Valorization of by-products obtained from food processing has achieved an important environmental impact. In this research, sunflower wax recovered from oil refining process was incorporated to low and high-methoxyl pectin films produced by electrospraying. Film-forming solutions and wax-added electrosprayed films were physical and structurally evaluated. The addition of sunflower wax to the film-forming solutions reduces conductivity while raising surface tension and density, whereas the type of pectin had a larger impact on viscosity, with the low-methoxyl solution having the highest value. These changes in physical solution properties influenced the film characteristics, observing thicker films with lower water vapor transmission rate (WVTR) when adding wax. Micrographs obtained by scanning electron microscopy (SEM) revealed the presence of wax particles as small spherical shapes, having a good distribution through the sectional area of films. According to X-ray diffraction (XRD), atomic force microscopy (AFM) and mechanical properties analyses, the presence of wax had an impact on the degree of crystallinity, producing a more amorphous and rougher film's structure, without affecting the elongation percentage and the tensile stress (p>0.05). These results showed that wax addition improves the physical properties of films, while the suitability of using both pectins and the electrospraying technique was demonstrated.

Scavenging peptides, antioxidant activity, and hypoglycemic activity of a germinated amaranth (Amaranthus hypochondriacus L.) beverage fermented by Lactiplantibacillus plantarum.

Amaranthus hypochondriacus L. is a pseudocereal with nutritional properties. Some bioactive peptides have been identified from amaranth protein isolates. The metabolic reactions developed during seed germination have produced different functional foods. The present research aimed to develop a non-dairy germinated amaranth-based functional beverage fermented by Lactiplantibacillus plantarum (LP) strain using Lacticaseibacillus casei Shirota (LCS) as control. The content of betalains (BT), total phenolic compounds (TFC), antioxidant capacity (DPPH, ABTS, FRAP), color changes, and scavenging bioactive peptides were determined. BT in the original base was significantly increased after fermentation by LP and LCS (from 1.276 ± 0.030 to 2.732 ± 0.196 and 1.904 ± 0.760 mg/100 ml, respectively). TFC increased after fermentation; however, no significant differences were found between the two strains (p > .05). The fermentation did not decrease the antioxidant content of the germinated amaranth base. However, a slight increase in the antioxidant capacity was found by DPPH, ABTS, and FRAP in the beverage fermented by LP compared with the LCS one. Moreover, the peptidomic approach suggested 18 peptides with scavenging activity. Thus, a bioactive food product with antioxidant properties was obtained by germination of A. hypochondriacus and its subsequent fermentation by LP. PRACTICAL APPLICATIONS: Non-dairy fermented beverages are novel carriers for probiotics and beneficial metabolites. This research evaluated the antioxidant and hypoglycemic activity of a fermented drink made with amaranth (Amaranthus hypochondriacus) and a potential probiotic strain (Lactiplantibacillus plantarum). The results led to conclude that it is possible to develop functional drinks with potential antioxidant and hypoglycemic activities and provide the biochemical basis for further research and development.

A water adsorption study on wheat pericarp macrofibrils using atomic force microscopy.

Wheat pericarp, which is the most external layer of the wheat kernel, is composed of a polysaccharide matrix, where cellulose macrofibrils, hemicellulose, and lignin are their main components. These polysaccharides modified their structure due to the hydric condition to which they are subjected. This effect is considered as an advantage in the wheat milling process. However, no information about micro and nanostructural changes on wheat pericarp macrofibrils due to their hydric condition, studied by the AFM technique and image analysis, has been reported. On the other hand, cellulose macrofibrils have been extensively studied by AFM but performing the study at constant relative humidity (RH) level. Hence, this study aimed to investigate the water adsorption process on wheat pericarp macrofibrils using AFM and control the RH to which samples were subjected during examinations with a lab equipment specially developed for the AFM experiment. The RH was modified from 10 to 90 %, and peak force error images were acquired, from which macrofibrils' diameter, swelling behavior, and water adsorption isotherms were calculated, using image analysis tools. Also, as an application from the water adsorption isotherms, the specific surface area and the hygroscopic swelling coefficients were determined. Results showed that wheat pericarp macrofibrils presented an unusual swelling behavior, with the most notorious changes after reaching a moisture content in equilibrium to 40 % of RH. The average diameter of the macro-fibrils varied from 45 to 48 nm. The water vapor adsorption isotherm obtained from AFM micrographs image analysis did not resemble the sigmoidal IUPAC Type II, generally obtained by applying gravimetric methods. Results suggest that the macrofibrils swelling controls water accessibility to the internal macrofibrils structures. It was proved with this study the feasibility of using AFM and image analysis to build water vapor isotherms and other mass transport parameters based on the macrofibrils swelling.

Chitosan as a Coating for Biocontrol in Postharvest Products: A Bibliometric Review.

The aim of this work was to carry out a systematic literature review focused on the scientific production, trends, and characteristics of a knowledge domain of high worldwide importance, namely, the use of chitosan as a coating for postharvest disease biocontrol in fruits and vegetables, which are generated mainly by fungi and bacteria such as Aspergillus niger, Rhizopus stolonifera, and Botrytis cinerea. For this, the analysis of 875 published documents in the Scopus database was performed for the years 2011 to 2021. The information of the keywords' co-occurrence was visualized and studied using the free access VOSviewer software to show the trend of the topic in general. The study showed a research increase of the chitosan and nanoparticle chitosan coating applications to diminish the postharvest damage by microorganisms (fungi and bacteria), as well as the improvement of the shelf life and quality of the products.