Bioactive Attributes and Analysis of Electronic Nose Feature Signals of Colombian Stingless Bees Propolis.

The volatile and non-volatile chemical composition and bioactivity of propolis from the species Apis mellifera has been widely studied, but there is very little knowledge regarding propolis of other bee species, which ultimately hinders their differentiation and potential use. In this work, 53 propolis samples of A. mellifera and four stingless bee species (Frieseomielitta sp., Melipona eburnea, Melipona sp., and Trigona sp.) were collected in Colombia. An electronic nose with 10 metal oxide semiconductor sensors (MOS) was used to generate a pattern of the representative volatile compounds of the samples. Ethanolic extracts were obtained to assess their antioxidant activity towards DPPH radical and ABTS radical cation, total phenolics, and color (CIELAB space). The results showed an overall similarity of the aromatic profiles between species. The antioxidant activity of Frieseomielitta sp. propolis was higher than that of A. mellifera and the other species, in correspondence with a higher phenolic content. CIELAB color parameter b* was the most differentiating variable among samples, indicating a variation of propolis colors between red and yellow. By combining the data from physico-chemical analysis and aromatic profile, it was possible to differentiate the propolis from each bee species, with the exception of those from Melipona sp. and Trigona sp., indicating their similarity. These results have practical significance since they are a starting point to recognizing and valuing native stingless bee propolis and their bioactive potential, which, in addition to geographical differentiation and further quality parameters evaluation, will enhance their commercial exploitation.

Effects of Solar Drying on the Structural and Thermodynamic Characteristics of Bee Pollen / Efectos del secado solar sobre las características estructurales y termodinámicas del polen apícola

Background: Bee pollen is a natural product collected and transformed by bees, intended for human consumption, given its nutritional and bioactive richness. The fundamental operation of adequacy is drying, which allows its preservation, avoiding chemical or microbiological degradation, typically using tray dryers with hot air that use electricity or fuel for heat generation. Solar drying is an alternative that uses radiation as an energy source. However, it should be ensured that this type of process guarantees the quality of the product while not degrading its properties and, therefore, maintaining its morphological integrity. Objective: to establish the effect of solar drying on bee pollen structure compared to the conventional cabin dehydration process. Methods: Bee pollen was dehydrated using two types of dryers: a solar dryer and a forced convection oven. The solar dryer operating conditions were an average temperature of 19-35 °C with a maximum of 38 °C and average relative humidity (RH) of 55 %. Cabin dryer operating conditions were a set point temperature of 55 ± 2 °C and 10 % RH average humidity. The morphologic and thermodynamic properties of dried bee pollen, such as phase transition enthalpy through Differential Scanning Calorimetry (DSC), porosity and surface area through surface area analysis, and microscopic surface appearance by Scanning Electron Microscopy (SEM), were measured. Results: The results showed dry bee pollen, both in the cabin dryer and solar dryer, did not suffer morphological changes seen through SEM compared to fresh bee pollen. Moreover, surface area analysis indicated the absence of porosity in the microscopic or macroscopic structure, demonstrating that solar or cabin drying processes did not affect the specific surface area concerning fresh bee pollen. Additionally, Differential Scanning Calorimetry (DSC) and Thermo Gravimetric Analysis (TGA) showed that endothermic phase transitions for dried bee pollen by cabin or solar dryer were at 145 °C and 160 °C, respectively. This can be mostly associated with free water loss due to the morphological structure preservation of the material compared to fresh bee pollen. Conclusion: These results demonstrate that solar drying is a reliable alternative to bee pollen dehydration as there were no effects that compromised its structural integrity

Antecedentes: El polen apícola es un producto natural recolectado y transformado por las abejas. La operación fundamental de adecuación del polen es el secado, lo que permite su conservación, evitando su degradación química o microbiológica, típicamente se utilizan secadores de bandejas con aire caliente que emplean electricidad o combustibles para la generación de calor. El secado solar es una alternativa que utiliza la radiación solar como fuente de energía. Sin embargo, se debe garantizar que este tipo de proceso asegure la calidad del producto a la vez que no degrade sus propiedades, manteniendo su integridad morfológica. Objetivo: Establecer el efecto del secado solar sobre la estructura del polen apícola en comparación al proceso convencional de deshidratación en cabina. Métodos: El polen de abeja se deshidrató utilizando dos tipos de secadores: secador solar y horno de convención forzada. Las condiciones de operación del secador solar fueron una temperatura promedio de 19-45 °C con un máximo de 38 °C y una humedad relativa (HR) promedio de 55 %. Las condiciones de operación del secador de cabina fueron una temperatura de referencia de 55 ± 2 °C y una humedad promedio de 10 % HR. Se midieron las propiedades morfológicas y termodinámicas del polen de abeja desecado, como la entalpía de transición de fase mediante calorimetría diferencial de barrido (DSC), la porosidad y el área superficial mediante análisis de área superficial y el aspecto microscópico de la superficie mediante microscopía electrónica de barrido (SEM). Resultados: Los resultados mostraron que el polen seco tanto en el secador de cabina como en el secador solar muestra que no sufrió cambios morfológicos vistos a través de Microscopía Electrónica de Barrido y en comparación con el polen fresco de abeja, además un análisis de sortometría indicó la ausencia de porosidad en la estructura microscópica y macroscópica, lo que indica que los procesos de secado solar o en cabina no tuvieron efectos sobre el área superficial específica con respecto al polen fresco de las abejas. En adición, los resultados de calorimetría diferencial de barrido (DSC) y análisis termogravimétrico (TGA) muestran que las transiciones de fase endotérmicas para el polen seco tanto en secado de cabina como solar fueron a 145 °C y 160 °C, que puede asociarse mayormente a la pérdida de agua libre, debido a la conservación de la estructura morfológica del material y en comparación al polen fresco. Conclusión: Estos resultados demuestran que el secado solar es una alternativa viable para la deshidratación del polen al no existir efectos que comprometan su integridad estructural

Nonconventional Hydrocolloids' Technological and Functional Potential for Food Applications.

This review aims to study the alternatives to conventional industrial starches, describing uncommon sources along with their technological characteristics, processing, and performance on food products. Minor components remaining after extraction play an important role in starch performance despite their low percentage, as happens with tuber starches, where minerals may affect gelatinization. This feature can be leveraged in favor of the different needs of the food industry, with diversified applications in the market being considered in the manufacture of both plant and animal-based products with different sensory attributes. Hydrocolloids, different from starch, may also modify the technological outcome of the amylaceous fraction; therefore, combinations should be considered, as advantages and disadvantages linked to biological origin, consumer perception, or technological performance may arise. Among water-based system modifiers, starches and nonstarch hydrocolloids are particularly interesting, as their use reaches millions of sales in a multiplicity of specialties, including nonfood businesses, and could promote a diversified scheme that may address current monocrop production drawbacks for the future sustainability of the food system.

Pullulan nanofibers containing the antimicrobial palindromic peptide LfcinB (21-25)Pal obtained via electrospinning.

Electrospinning technology is useful for making ultrafine drug-eluting fibers for the clinical treatment of wounds. We show the incorporation of an antimicrobial LfcinB-derived peptide into Pullulan nanofibers. The palindromic peptide LfcinB (21-25)Pal: RWQWRWQWR was synthesized, purified, and characterized by means of the RP-HPLC and MALDI-TOF MS methods. The peptide's antibacterial activity against the E. coli ATCC 25922 strain was evaluated, and the peptide LfcinB (20-25)Pal exhibited significant antibacterial activity. Nanofibers were obtained by electrospinning a Pullulan or Pullulan-LfcinB (21-25)Pal solution. The obtained nanofibers were characterized via microscopy (AFM and SEM) and RP-HPLC chromatography. The peptide incorporation efficiency was 31%. The Pullulan-LfcinB (21-25)Pal nanofibers were soluble in water, and the peptide was liberated immediately. The Pullulan-LfcinB (21-25)Pal nanofibers exhibited the same antibacterial activity against E. coli strain as the free peptide LfcinB (21-25)Pal. The results suggest that Pullulan-LfcinB (21-25)Pal nanofibers could be considered for designing and developing antibacterial wound dressings.