Effect of starch- and lipid-based encapsulation on the culturability of two Bifidobacterium longum strains.

AIMS: To assess the applicability of starch- and lipid-based encapsulation methods for improving the viability and culturability of two Bifidobacterium longum strains stored in fermented and nonfermented foods. MATERIALS AND RESULTS: Cells were encapsulated with partially hydrolysed potato starch granules combined with amylose coating, or entrapped in cocoa butter matrix. The tested B. longum strains were not adherent to the starch granules, and the culturability of the cells stored in fermented and nonfermented foods was not improved by starch-based encapsulation. Encapsulation of the cells in cocoa butter was found to increase the plate counts during storage. In addition to plate counts, viability of the cells was measured by fluorescent microscopy using LIVE/DEAD BacLight viability assay. Microscopic counts of the viable cells did not change significantly during storage, suggesting that the cells remained alive despite becoming unable to grow on nutrient agar plates. CONCLUSIONS: Encapsulation with cocoa butter increased the culturability of the cells, but encapsulation with hydrolysed potato starch had no effect. Culture-independent viability assay suggested that cells remained viable despite being unable to grow on agar plates. SIGNIFICANCE AND THE IMPACT OF THE STUDY: This study indicates that encapsulation techniques may be useful in improving the culturability of bacteria, but the plate counts may yield insufficient data on the actual viability of the cells.

Corn starches as film formers in aqueous-based film coating.

The purpose of this study was to evaluate the film formation ability and mechanical stress-strain properties of aqueous native corn starches, using free films and film coatings applied to tablets. Free films were prepared from high-amylose corn (Hylon VII), corn and waxy corn starches, using sorbitol and glycerol as plasticizers. The tablets and pellets were film-coated using an air-suspension coater, and characterized with respect to the film coating surface topography, cross-sectional structure and thickness (SEM), and dissolution in vitro. The amylose content of the starch film formers affected both the tensile strength and the elongation. The elongations were under 5% for even the plasticized starches, and in most cases, no plasticization effect was seen by either of the plasticizers. Dissolution of native corn starch film-coated tablets (weight gain 1%) did not differ from uncoated ones. A notable delay in dissolution of the drug was found by increasing Hylon VII film coating thickness, suggesting controlled-release characteristics.

Adhesion of bifidobacteria to granular starch and its implications in probiotic technologies.

Adhesion of 19 Bifidobacterium strains to native maize, potato, oat, and barley starch granules was examined to investigate links between adhesion and substrate utilization and to determine if adhesion to starch could be exploited in probiotic food technologies. Starch adhesion was not characteristic of all the bifidobacteria tested. Adherent bacteria bound similarly to the different types of starch, and the binding capacity of the starch (number of bacteria per gram) correlated to the surface area of the granules. Highly adherent strains were able to hydrolyze the granular starches, but not all amylolytic strains were adherent, indicating that starch adhesion is not a prerequisite for efficient substrate utilization for all bifidobacteria. Adhesion was mediated by a cell surface protein(s). For the model organisms tested (Bifidobacterium adolescentis VTT E-001561 and Bifidobacterium pseudolongum ATCC 25526), adhesion appeared to be specific for alpha-1,4-linked glucose sugars, since adhesion was inhibited by maltose, maltodextrin, amylose, and soluble starch but not by trehalose, cellobiose, or lactose. In an in vitro gastric model, adhesion was inhibited both by the action of protease and at pH values of < or =3. Adhesion was not affected by bile, but the binding capacity of the starch was reduced by exposure to pancreatin. It may be possible to exploit adhesion of probiotic bifidobacteria to starch granules in microencapsulation technology and for synbiotic food applications.

Waxy corn starch: a potent cofiller in pellets produced by extrusion-spheronization.

The purpose of this study was to assess the usefulness of waxy corn (maize) starch as a cofiller and diluent in pellets produced by aqueous extrusion-spheronization. Waxy corn starch was combined with microcrystalline cellulose (MCC) in the range of 20-50% of the entire composition. Pellets containing ordinary corn starch or lactose with MCC were used as reference. The shape of pellets was characterized using an optical microscopic image analysis system. The surface and cross-sectional structure were investigated by means of scanning electron microscopy (SEM). The replacement of ordinary corn starch by waxy corn starch made it possible to increase the amount of starch from 20 to 40%. The pellets containing 50% waxy corn starch were of poorer quality but superior to those containing 30% corn starch. The surface structure became slightly more irregular with respect to the amount of either starch, and a cavity was formed inside the pellet during the spheronization. The origin of starch did not affect the surface structure of the pellets. Waxy corn starch is a potential cofiller: the amount of MCC can be reduced in pellets produced by extrusion-spheronization by using waxy corn starch as a cofiller. This enables the reduction of the manufacturing cost of pellets with low drug load.

Applications of immobilized lipases to transesterification and esterification reactions in nonaqueous systems.

Lipases from Candida cylindracea, Aspergillus niger, and Pseudomonas fluorescens were immobilized by adsorption on anion-exchange resin and diatomaceous earth using buffer or hexane as a reaction medium. The enzyme preparations were tested in the transesterification of triolein with lauric acid and the esterification of lauric acid with different alcohols. Immobilized C. cylindracea preparations were more active when hexane was used as the reaction medium, and anion-exchange resin was a better support than diatomaceous earth. Hexane was also a better immobilization medium for A. niger lipase. No difference was observed in the lipase activity of P. fluorescens lipase immobilized in different ways. The synthetic activities of the immobilized enzymes could be predicted from their hydrolytic activities: the higher the hydrolytic activity, the higher the synthetic activity. There was no direct correlation, however, between the lipolytic and the transesterification activities.

Intrahepatic hematoma after aspiration liver biopsy. A prospective randomized trial using two different needles.

The purpose of this study was twofold: (1) to determine the incidence of intrahepatic hematoma after liver biopsy by the aspiration technique and (2) to compare the incidence of hematoma after biopsy with a needle of 1.6 mm vs 1.9 mm OD. Fifty-one patients were randomly assigned to be biopsied with the smaller needle and 46 with the larger. Hematomas, diagnosed by development of characteristic transient defects on liver scans done shortly after biopsy, occurred in two (4%) of those biopsied with the smaller needle and in none of those biopsied with the larger. This difference is not statistically significant. Neither patient who developed a hematoma had changes in vital signs, CBC, or serum alkaline phosphatase. One had a fivefold rise in SGOT; n the other, the SGOT remained normal. If these results are considered with those of other prospective trials of similar design, the overall incidence of intrahepatic hematoma after aspiration biopsy may be estimated to be 2.3% when needles of 1.6-2.0 mm (OD) are used. Many of these go undetected because, justifiably, scans are not routinely done shortly after biopsies.