Exploring the Potential of Wild Andean Blueberries for Powdered Juice Production through Spray Drying.

The Andean blueberry (Vaccinium meridionale Sw) is an underutilized wild fruit native to South America. It is known for its antioxidant properties and potential health benefits. In this study, Andean blueberry juice powders were produced via spray drying, using maltodextrin (MD), gum Arabic (GA) or a combination of both (MD:GA) as wall materials. The spray-dried juices were analyzed for the recovery percentage of total polyphenols and monomeric anthocyanins, as well as for their physicochemical and technological properties. Results showed that the type of carrier agent used caused statistically significant differences in the bioactive content and the antioxidant activity of the powders (p < 0.05). It was found that the MD samples has the highest monomeric anthocyanins content (0.88 ± 0.02 mg cyanidin 3-glucoside equivalents/g) and the highest anthocyanins recovery (96.3 ± 1.7%), while the MD:GA powders showed the highest values of total polyphenol content (5.70 ± 0.09 mg gallic acid equivalents/g), DPPH scavenging capacity (2.49 ± 0.02 mg gallic acid equivalents/g) and phenolics recovery (87.2 ± 1.1%). Furthermore, all the spray-dried powders exhibited low moisture content (<5.5%) and water activity (<0.40), as well as high solubility in water (>94%) and good flowability. Future prospects include evaluating the stability of the Andean blueberry juice powders during storage and exploring the formulation of new foods and beverages that incorporate these spray-dried powders.

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

Probiotics in anthocyanin-rich fruit beverages: research and development for novel synbiotic products.

Anthocyanin-rich fruit beverages are of special interest as functional products due to their antioxidant activity, antimicrobial properties against pathogens, and, more recently, evidence of prebiotic potential. The stability and bioactivity of anthocyanins, probiotics, prebiotics, and synbiotics have been extensively documented in beverage models and reviewed separately. This review summarizes the most recent works and methodologies used for the development of probiotic and synbiotic beverages based on anthocyanin-rich fruits with a synergistic perspective. Emphasis is made on key optimization factors and strategies that have allowed probiotic cultures to reach the minimum recommended doses to obtain health benefits at the end of the shelf life. The development of these beverages is limited by the high acidity and high content of phenolic compounds in anthocyanin-rich fruits. However, a proper selection of probiotic strains and strategies for their media adaptation may improve their viability in the beverages. Fermentation increases the viability of the probiotic cultures, improves the safety and stability of the product, and may increase its antioxidant capacity. Moreover, fermentation metabolites may synergistically enhance probiotic health benefits. On the other hand, the inoculation of probiotics without fermentation allows for synbiotic beverages with milder changes in terms of physicochemical and sensory attributes.

Debittering of Grape Juice by Electrospun Nylon Nanofibrous Membranes: Impact of Filtration on Physicochemical, Functional, and Sensory Properties.

The effect of electrospun nylon-6 nanofibrous membranes (NFMs) on the concentration of bitter compounds and antioxidants of grapefruit juices during dead-end filtration processes was studied. Filtration experiments with aqueous standard solutions of different molecules showed that NFMs retain low molecular weight antioxidants (i.e., ascorbic and caffeic acids) only at early filtration stages, whereas they remove bitter glycosylated phenolics (i.e., naringin and narirutin) at a more stable ratio, variable according to the membrane thickness. Experiments with fresh grapefruit juice of two varieties (pink and yellow) showed that NFM-filtration reduces (17 to 30%) flavanones associated with the immediate bitterness and allows for the complete removal (>99.9%) of limonin, responsible for the persistent bitterness of many citrus juices. In contrast, the same process causes a lower loss of ascorbic acid (5%) and does not affect acidity, nor sugar concentration. The results confirmed that NFMs feature permselectivity towards bitterness-related compounds. This work highlights the NFM potential as filter devices for the selective reduction of the bitter terpenoid (limonin) and glycosylated flavonoids (naringin and narirutin) from grape juice citrus juices in the production of industrially-relevant beverages.

New Freeze-Dried Andean Blueberry Juice Powders for Potential Application as Functional Food Ingredients: Effect of Maltodextrin on Bioactive and Morphological Features.

Andean blueberry (Vaccinium meridionale Swartz) fruits are an underutilized source of anthocyanins and other valuable bioactive phytochemicals. The purpose of this work was to obtain Andean blueberry juice powders via freeze-drying processing and evaluate the effect of maltodextrin as a drying aid on their physicochemical, technological, microstructural, and bioactive characteristics. Andean blueberry juices were mixed with variable proportions of maltodextrin (20-50%); freeze-dried; and characterized in terms of their tristimulus color, Fourier transform infrared spectra (FTIR), moisture content, water activity, morphology, water solubility, flow properties, total polyphenols and anthocyanins content, and DPPH•-scavenging capacity. The powders obtained presented suitable characteristics in terms of their water activity (<0.5), solubility (>90%), and bioactive compound recovery (>70% for total phenolics, and >60% for total monomeric anthocyanins), with antioxidant activities up to 4 mg equivalent of gallic acid/g of dry matter. Although an increased content of maltodextrin resulted in lower concentrations of phytochemicals, as expected, it also favored an increased % recovery (over 90% of total phenolics at the highest maltodextrin proportion) and improved their flow properties. Freeze-dried juice powders are a potential alternative for the stabilization and value addition of this fruit as a new source of functionality for processed foods.

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.

Encapsulation of volatiles in nanofibrous polysaccharide membranes for humidity-triggered release.

A single-step electrospinning process will be applied to a blend of edible carbohydrate polymers (pullulan and ß-cyclodextrin) to encapsulate bioactive aroma compounds and allow a humidity-triggered release. The encapsulation is rapid and efficient and the final product is an active nanofibrous membrane that can be directly used for food or active packaging applications. The membrane hosts small and homogeneously dispersed crystals of cyclodextrin-aroma complexes which are formed during the electrospinning. With this type of structure, the release of aroma compound is negligible at ambient conditions (23 °C and 55% UR) even at high temperature (up to 230 °C), and it occurs beyond a given relative humidity threshold (90%), useful for food packaging applications. The mass fraction of free aroma released is directly related to the water activity of the system, namely, φ=aW(n)/(aW(n)+Kapp) explaining the observed key role played by the relative humidity on the release of the aroma compounds.

Sugar determination via the homogeneous reduction of Au salts: a novel optical measurement.

A novel optical assay for sugar determination based on the catalytic and biocatalytic growth of gold nanoparticles (AuNPs) is presented. The reaction of carbohydrates with these Au salts in alkaline media generates AuNPs at room temperature (RT) without the need for Au seeds in the solution or fibrous mesh. The optical properties of the resulting AuNPs relates to the total reducing sugar content of the samples analyzed. The development of such inexpensive optical assay was evaluated qualitatively and quantitatively on food beverages and honey samples. Its application can be of help to control the glucose content of the diet or easily extended in a host of industrial, biomedical and clinical fields.