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Gelatin/chitosan/poly(vinyl alcohol) (PVA) hydrogels were fabricated with different polymer ratio using the freeze-drying process. The thermal stability, water state, rheological, and cytotoxic properties of the hydrogels were evaluated. Thermogravimetric/differential scanning calorimetry analyses showed a decomposition onset temperature below 242.7 AE 2.7 C. The samples did not show statistical differences (p < 0.05) on the onset temperature values. Nonfreezing water reached a constant value around of 1 g water/g polymer. Freezing water increased linearly with the increase of the water content independently of the polymer ratio. The hydrogels showed an equilibrium water content from 9 to 13 times their mass. The hydrogels exhibited a solid-viscoelastic behavior. The elastic modulus was higher with the increase of chitosan concentration (G 0 = 22 170 AE 85 Pa) independently of the temperature (5-55 C). In vitro assay showed that hydrogels are nontoxic in the HT29-MTX-E12 cell line. These results indicate that the gelatin/chitosan/PVA hydrogels could be considered for biomedical applications.

Physicochemical properties of eight samples of Mexican honeys from the West region were measured over 23 parameters, including moisture, water activity, soluble solids, hydroxymethylfurfural (HMF), ash, electrical conductivity, acidity (free, lactonic, and total), sugar content (fructose and glucose), color (L*, a*, b*), and mineral content. In addition, honey samples were classified according to the pollen quantitative analysis. According to the physicochemical parameters studied, the samples showed the values typical of honey. All honey samples were classified as dark according to the values of the L* color parameter. Only two honey samples were classified as monofloral and six as multifloral type. In general, the honey samples presented a good level of quality because they meet the physicochemical specifications of international regulation.

BACKGROUND: Hydrogels are materials with great potential in agricultural applications. Biodegradable hydrogels are used as preparations, for example to increase the substratum water capacity, and improve soil structure or agrochemical-controlled release. This work aimed to develop biodegradable hydrogels based on chitosan, gelatin and polyvinyl alcohol (PVA) for releasing inulin isolated from Dahlia tubers to induce protection in chili plants against Phytophthora capsici. The hydrogels were characterized by water absorption capacity, Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and stereomicroscopy microscopy, and degradation capacity using the soil burial test with sterile and inoculated soil. RESULTS: This work demonstrated the ability of a fabrication process in the preparation of gelatin-chitosan-PVA hydrogelsfor potential agricultural applications. The hydrogels showed a dense, tridimensional, interconnected and reticulated structure that was more evident in the hydrogel loaded with inulin. The hydrogels showed a water absorption capacity of ≤12 times its mass. FTIR and light microscopy demonstrated that the hydrogels were biodegradable. The percentage of degradation of hydrogels in inoculated soil was higher than in sterile soil using the soil burial test. Hydrogel loaded with inulin was found to be capable of inducing resistance in chili plants against Phytophthora capsici. CONCLUSION:The hydrogels prepared for the described methodology have great potential for use in the agricultural sector as a reservoir for agrochemicals and inductors in plant resistance treatments. Furthermore, the hydrogels were proven to be biodegradable, offering a promising tool in crop protection. Surface morphology of hydrogelsThe hydrogels have a polyhedral irregular shape. Figure 5(a) shows that the surface morphologies of the hydrogels revealed the formation of a reticulate heterogeneous network. When the hydrogel was loaded with inulin and freeze-dried again, inulin aggregates between the macro channels of the structure [Fig. 5(b)]. Biodegradation test of the hydrogelThe degradation of the hydrogels (H and HI), that were buried in the sterile and inoculated soil were monitored after 7, 14, J Chem Technol Biotechnol 2019; 94: 3495-3504

Gelatin/chitosan/polyvinyl alcohol hydrogels were fabricated at different polymer ratios using the freeze-drying and sterilized by steam sterilization. The thermal stability, chemical structure, morphology, surface area, mechanical properties, and biocompatibility of hydrogels were evaluated by simultaneous thermal analysis, Fourier transform infrared spectroscopy, X-ray diffraction, confocal microscopy, adsorption/desorption of nitrogen, rheometry, and 3-4,[5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide cell viability assay (MTT assay), respectively. The samples showed a decomposition onset temperature below 253.3 ± 4.8 C, a semicrystalline nature, and a highly porous structure. Hydrogels reached the maximum water uptake in phosphate-buffered saline after 80 min, showing values from nine to twelve times their dry mass. Also, hydrogels exhibiting a solid-like behavior ranging from 2,567 ± 467 to 48,705 ± 2,453 Pa at 0.1 rad/s (low frequency). The sterilized hydrogels showed low cytotoxicity (cell viability > 70%) to the HT29-MTX-E12 cell line. Sterilized hydrogels by steam sterilization can be good candidates as scaffolds for tissue engineering applications. K E Y W O R D Schitosan, hydrogels, porosity, swelling behavior, viscoelastic properties

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