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.

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.

Ultrathin single and multiple layer electrospun fibrous membranes of polycaprolactone and polysaccharides

Electrospinning was used to produce fibrous membranes, in single and multiple layers, from poly(ε-caprolactone), pullulan, and from mixtures of poly(ε-caprolactone) with potato modified starch and β-glucan. It was possible to obtain single-layer membranes from solutions of pullulan in water, poly(ε-caprolactone) in chloroform, and from mixtures of poly(ε-caprolactone)/β-glucan and poly(ε-caprolactone)/potato modified starch in chloroform. Scanning electron microscopy images showed the formation of ultrathin homogeneous fibers from electrospun poly(ε-caprolactone) and pullulan, whereas the fibers obtained from mixtures of poly(ε-caprolactone)/ β -glucan and poly(ε-caprolactone)/potato modified starch had different sizes and morphologies, as well as irregular microstructures, characterized by the presence of beads. Contact angle analyses showed that pullulan membranes were extremely hydrophilic, while poly(ε-caprolactone) membranes were predominantly hydrophobic. Subsequently, poly(ε-caprolactone)-pullulan-poly(ε-caprolactone) multilayer membranes, with intermediate wettability, were prepared by successive electrospinning steps. Infrared spectroscopy and calorimetric analyses showed the presence of both polymers and the absence of changes in their structure and stability due to electrospinning, indicating adequate compatibility between the two polymers. We foresee that the polyester-polysaccharide multilayer membrane might be used as a biodegradable vehicle for active agents with different hydrophobicity, with applications as food packaging and biocompatible scaffold materials.