Maribel Jiménez

Effect of wall material on the antioxidant activity and physicochemical properties of Rubus fruticosus juice microcapsules

Abstract Blackberry (Rubus fruticosus) juice possesses compounds with antioxidant activity, which can be protected by different biopolymers used in the microencapsulation. Therefore, the effects of cell wall material including maltodextrin (MD), Arabic gum (GA) and whey protein concentrate (WPC) were evaluated on the physicochemical and antioxidant properties of encapsulated blackberries using a spray-drying technique. Anthocyanin concentration, polymeric colour, total polyphenols, radical scavenging activity of the 1,1-diphenyl-2-picrilhydrazil radical, reducing power and the stability at different storage conditions were evaluated. GA and MD conferred a similar protection to the antioxidant compounds when the microcapsules were stored at low water activities (aw < 0.515) in contrast to at a high moisture content (aw > 0.902), whereas WPC presented a high protection. Therefore, the selection of the best wall material for blackberry juice encapsulation depends of the conditions of storage of the powder.

Physicochemical and antioxidant properties of honey from Scaptotrigona mexicana bee

The physicochemical properties of honey from the stingless bee Scaptotrigona mexicana harvested at four, three, two, and actual years did not show significant differences in most of their physicochemical and antioxidant properties. Some properties, such as: color, pH, and titratable acidity were affected by storage temperature, being most affected at 45 °C. The concentration of polyphenols was correlated with the percentage of radical 2,2′-diphenyl-1-picrylhydrazyl scavenging activity (R2 = 0.930). Honey showed an antibacterial activity against gram (+) and gram (–) bacteria, not showing inhibition of yeast and mold tested. The sensory evaluation showed that this honey had a high level of preference by consumers. Honey from S. mexicana bee can be stored for at least three years without being significantly affected by their physicochemical and antioxidant properties, and this is acceptable for marketing.

Characterization of O/W emulsions of carotenes in blackberry juice performed by ultrasound and high-pressure homogenization

ABSTRACT Carotene compounds are a group of natural pigments with potential applications in the food industry for their antioxidant activity, but due to their physicochemical instability and incompatibility with many food matrices, different technologies have been employed, such as emulsification, to improve stability and compatibility. Therefore, the physicochemical stability and antioxidant activity of carotene oil-in-water (O/W) emulsions were studied, using carotene compounds extracted from carrot as the oil phase and blackberry juice as the continuous phase. The effect of different factors on the stability of the emulsion – the relative concentration of the dispersed phase, the hydrophilic-lipophilic balance (HLB), the surfactant concentration, and the emulsification method – was assessed using surface response analysis. The emulsion with the best properties was obtained in the phase ratio 2:8 (v/v) with 6% surfactant and an HLB of 16.7. The ultrasound method produced emulsions with higher antioxidant stability and lower carotene degradation rates than those prepared by high pressure, when compared after 60 days of storage at 25°C. This study allowed the development of a stable emulsion with antioxidants in each of the phases of the emulsion that could be incorporated into several types of food products to produce functional foods. GRAPHICAL ABSTRACT