Bifidobacterium Bb-12 microencapsulated by spray drying with whey: Survival under simulated gastrointestinal conditions,tolerance to NaCl,and viability during storage

Bifidobacterium Bb-12 was microencapsulated by spray drying with whey. This present work investigated the survival of these microcapsules under simulated gastrointestinal conditions, as well as their tolerance to NaCl and their viability during storage. The results showed a small decrease in the viability of microencapsulated Bifidobacterium at low pH. In relation to the exposure of Bifidobacterium to bile, microencapsulation with whey did not protect the probiotic cells; however, the viability of the microcapsules remained >6 log cfu/g, even after 24 h of incubation at the highest bile concentration analyzed. No growth was noted with either the free cells or the microencapsulated cells on MRS-LP with NaCl. The viability of the microcapsules stored at 4 °C remained high and constant for 12 weeks. When the microcapsules were added to a dairy dessert, the probiotic count remained above 7 log cfu/g for 6 weeks. Therefore, whey is a promising encapsulating agent for Bifidobacterium Bb-12.     

Dynamic light scattering and atomic force microscopy techniques for size determination of polyurethane nanoparticles

Nanoparticles have applications in various industrial fields principally in drug delivery. Nowadays, there are several processes for manufacturing colloidal polymeric systems and methods of preparation as well as of characterization. In this work, Dynamic Light Scattering and Atomic Force Microscopy techniques were used to characterize polyurethane nanoparticles. The nanoparticles were prepared by miniemulsion technique. The lipophilic monomers, isophorone diisocyanate (IPDI) and natural triol, were emulsified in water containing surfactant. In some formulations the poly(ethylene glycol) was used as co-monomer to obtain the hydrophilic and pegylated nanoparticles. Polyurethane nanoparticles observed by atomic force microscopy (AFM) were spherical with diameter around 209 nm for nanoparticles prepared without PEG. From AFM imaging two populations of nanoparticles were observed in the formulation prepared with PEG (218 and 127 nm) while dynamic light scattering (DLS) measurements showed a monodisperse size distribution around 250 nm of diameters for both formulations. The polydispersity index of the formulations and the experimental procedures could influence the particle size determination with these techniques.     

Microencapsulation of bifidobacteria by spray drying in the presence of prebiotics

This study was conducted to evaluate the viability and the physical properties of Bifidobacterium BB-12 microencapsulated by spray drying with partial replacement of reconstituted skim milk (RSM), as encapsulating agent, with the prebiotics inulin, oligofructose, and oligofructose-enriched inulin (at a ratio of 1:1, 200 g L^?1 total concentrations). The viable cell counts of the microcapsules were determined during storage for 180 days at 4 °C and at ? 18 °C. The physical characterization included analysis of morphology, particle size, moisture content, water activity, dissolution, hygroscopicity, color, and thermal properties. All the microcapsules produced in this study showed a high survival rate of bifidobacteria during storage at the temperatures evaluated. The microcapsules produced with inulin and those produced with oligofructose-enriched inulin showed higher initial counts. However, blending oligofructose-enriched inulin with RSM and blending oligofructose with RSM resulted in better protection of bifidobacteria during storage. All microcapsules showed similar morphologies and particle sizes, between 14.45 and 18.78 μm. The partial replacement with prebiotics decreased moisture content and water activity of the microcapsules. The time of dissolution in water was higher for the microcapsules produced with inulin, while the microcapsules produced with oligofructose were more hygroscopic. The value of a* increased in the microcapsules produced with prebiotics. The results of the thermal analysis suggest a higher stability of the microcapsules produced with prebiotics than those produced with RSM only.     

Effects of the addition of microencapsulated Bifidobacterium BB-12 on the properties of frozen yogurt

Samples of frozen yogurt were added with microcapsules containing Bifidobacterium BB-12 produced with different contents of carrier agents (reconstituted skim milk and inulin). The viability of this probiotic culture was evaluated, as well as the effect of addition of microcapsules on the chemical and rheological properties of frozen yogurt during 90 days of storage. The counts of bifidobacteria maintained practically constant in the samples added with the microcapsules, while the frozen yogurt added with free bacteria showed a decrease of about 34% after 90 days. The addition of the microcapsules increased the total solids content and the overrun values. The highest pH values were noted in the samples containing microcapsules produced with reconstituted skim milk. All the melted frozen yogurts showed non-Newtonian behavior with shear thinning characteristics. The samples added with microcapsules had greater apparent viscosity and those added with microcapsules produced with inulin showed a larger hysteresis area at the end of storage period.     

The influence of Bifidobacterium Bb-12 and lactic acid incorporation on the properties of Minas Frescal cheese

The effects of a probiotic bacterium (Bifidobacterium Bb-12) and lactic acid on the microbiological, physicochemical, rheological and microstructural proprieties of Minas Frescal cheese were evaluated after 1 day and after 28 days of storage (5 ± 1 °C). The cheese was produced with four different treatments: with no lactic acid (C1 and C2), with lactic acid (C3 and C4) and with bifidobacteria (C2 and C3). The cheese formulations containing bifidobacteria were classified as probiotic. The addition of bifidobacteria to the cheese did not influence its yield, protein or lipid levels one day after production. Moreover, after 28 days of storage, the cheese samples with no lactic acid showed lower moisture levels compared to the samples containing lactic acid (P < 0.05). The absence of lactic acid had an influence on the rheological and microstructural behavior, making them more elastic, firm and compact, however all the cheese samples evaluated showed a higher tendency to viscosity than to elasticity. The Minas Frescal cheese with Bifidobacterium Bb-12 and lactic acid showed great potential as a functional food, with possible industrial and commercial application.     

Concentration of biologically active compounds extracted from Ilex paraguariensis St. Hil. by nanofiltration

The aim of this study was to characterise the bioactive compounds in mate (Ilex paraguariensis St. Hil) extract and in concentrated mate extract obtained by nanofiltration (NF). Also, the impact of NF on the antioxidant activity of both mate extracts was evaluated in vitro and using eukaryotic cells of Saccharomyces cerevisiae (yeast assay). The results showed a significant increase in the contents of total phenolics (338%), chlorogenic acid (483%), theobromine (323%), caffeine (251%), chlorophyll (321%), condensed tannins (278%) and saponins (211%) in the concentrated mate extract. The concentrated mate extract showed higher in vitro antioxidant activity than the mate extract. According to the results obtained, it can be stated that the use of nanofiltration membrane is a valid approach for the concentration of biologically active compounds in aqueous extract of mate.     

A coma-corrected multibeam shaped lens antenna, part II: Experiments

A dielectric lens based on the shaping technique described in Part I of this communication was fabricated and tested. This lens was shaped to control the sidelobes and zoned for improved scanning characteristics. Basic antenna measurements were conducted and excellent performance results have been observed. In the prototype lens system with unmatched surfaces, a 4 dB crossover between adjacent beams of -30 dB sidelobes was obtained. The beam was scanned up topm 12degwithout significant coma degradations. This coma-corrected zoned lens was developed for satellite multibeam applications. The multibeam antenna so designed not only reduces the total costs and the payload burden, but also enhances the system reliability and the overall gain compared to a conventional design because no complex feed network is required.     

Stevia‐fortified yoghurt: Stability,antioxidant activity and in vitro digestion behaviour

In this study, yoghurt samples were fortified with 0.25% and 0.5% freeze‐dried stevia extract (FSE). The control and stevia‐fortified yoghurts were evaluated and compared for the viability of the starter cultures, physicochemical properties, total phenolic content (TPC) and antioxidant activity throughout 30 days of storage. In addition, TPC and antioxidant activity were evaluated during in vitro gastrointestinal digestion. The results showed that the yoghurt matrix preserved the TPC, antioxidant capacity and total solids during storage, while the acidity, synaeresis and counts of the starter cultures of the final product were not significantly affected. However, addition of 0.5% FSE exerted a buffering effect on the system. After simulated digestion, the values of TPC and antioxidant activity of the fortified yoghurts increased in relation to the undigested fractions. These findings showed the feasibility of employing FSE as a functional ingredient in the manufacture of yoghurts with potential antioxidant properties.