Properties of Low-Moisture Viscoplastic Materials Consisting of oil droplets dispersed in a Protein-Carbohydrate-Glycerol Matrix: Effect of Oil Concentration

The influence of oil concentration and baking on the properties of low-moisture composites consisting of oil droplets dispersed in a protein–carbohydrate–glycerol matrix was investigated. These composites were produced by blending canola oil, whey protein concentrate (WPC), corn syrup, and glycerol together using a high-speed mixer. The resulting system consisted of oil droplets dispersed in a polar matrix. Some composites were analyzed directly after preparation, while others were analyzed after being heated at 176 °C for 10 min to simulate baking. The “lightness” of the composites was greater before baking (higher L value), but the color was more intense after baking (higher a and b values). The lightness and color intensity of the composites decreased as the oil concentration increased, with the effects being more pronounced in the baked samples. The ζ potential of the oil droplets (measured after dilution at pH 6) was highly negative (approximately −40 mV), indicating that whey protein was adsorbed to the droplet surfaces. The mean particle diameter (measured after dilution at pH 6) increased appreciably after baking, which was attributed to droplet flocculation. The rheological properties of the unbaked and baked materials were characterized by squeezing flow viscometry, which showed that the measurements associated with consistency and yield stress increased with increasing oil concentration and with baking

Influence of Environmental Stresses on Stability of Oil-in-Water Emulsions Containing Droplets Stabilized by Beta-Lactoglobulin-Iota-Carrageenan Membranes

An oil-in-water emulsion (5 wt% corn oil, 0.5 wt% β-lactoglobulin (β-Lg), 0.1 wt% ι-carrageenan, 5 mM phosphate buffer, pH 6.0) containing anionic droplets stabilized by interfacial membranes comprising of β-lactoglobulin and ι-carrageenan was produced using a two-stage process. A primary emulsion containing anionic β-Lg coated droplets was prepared by homogenizing oil and emulsifier solution together using a high-pressure valve homogenizer. A secondary emulsion containing β-Lg–ι-carrageenan coated droplets was formed by mixing the primary emulsion with an aqueous ι-carrageenan solution. The stability of primary and secondary emulsions to sodium chloride (0–500 mM), calcium chloride (0–12 mM), and thermal processing (30–90 °C) were analyzed using ζ-potential, particle size and creaming stability measurements. The secondary emulsion had better stability to droplet aggregation than the primary emulsion at NaCl ⩽ 500 mM, CaCl2 ⩽ 2 mM, and holding temperatures ⩽60 °C for 20 min. The interfacial engineering technology used in the study could therefore lead to the creation of food emulsions with improved stability to environmental stresses

Irreversible Thermal Denaturation of Beta-Lactoglobulin Retards Adsorption of Carrageenan onto Beta-Lactoglobulin-Coated Droplets

The influence of isothermal heat treatments on the adsorption of anionic carrageenan molecules to the surfaces of anionic β-lactoglobulin-coated droplets has been investigated. The ζ-potential, mean particle diameter, microstructure, and creaming stability of emulsions containing β-lactoglobulin-coated droplets and/or carrageenan molecules that had previously been heat treated at temperatures ranging from 30 to 90 °C for 20 min were measured (pH 6.0, 150 mM NaCl). Three different heat treatments were used to establish the physicochemical origin of the influence of thermal history on the adsorption of carrageenan molecules to the protein coated droplets:  (i) droplets and carrageenan were mixed at room temperature, then heated together; (ii) droplets were heated, cooled to room temperature, then mixed with carrageenan; (iii) carrageenan was heated, cooled to room temperature, then mixed with droplets. For treatments i and ii appreciably more carrageenan adsorbed to the protein-coated droplet surfaces at temperatures ≤ 60 °C than at higher temperatures. For treatment iii, carrageenan adsorbed to the droplet surfaces across the whole temperature range. These results suggest that an irreversible thermal denaturation of the adsorbed β-lactoglobulin molecules inhibited the adsorption of carrageenan molecules to the droplet surfaces. We postulate that there is a patch of positive charge on the surface of the native globular protein molecules which becomes more diffuse upon thermal denaturation. We found that the carrageenan molecules were unable to protect the β-lactoglobulin-coated droplets at high temperatures (T \u3e 60 °C) because they desorbed from the droplet surfaces. Nevertheless, adsorption of ι-carrageenan was capable of protecting the droplets against flocculation caused by surface denaturation of the adsorbed proteins at lower temperatures (T ≤ 50 °C)

Influence of pH and Carrageenan Type on Properties of β-Lactoglobulin Stabilized Oil-in-Water Emulsions

The influence of pH and carrageenan type (ι, κ, and λ) on the properties of β-lactoglobulin (β-Lg) stabilized oil-in-water emulsions was investigated by particle charge, particle size distribution, creaming stability, and optical microscopy measurements. Emulsions containing droplets stabilized by β-Lg were produced by homogenization, and then adjusted to a particular pH (3, 5 or 6) before carrageenan solution (0 to 0.15 wt%) of the same pH was added. At pH 3 and 5, there was a pronounced decrease in droplet charge with increasing polysaccharide concentration for all carrageenan types, suggesting adsorption of carrageenan to the droplet surfaces. Extensive droplet aggregation and creaming were observed in these emulsions when the carrageenan concentration exceeded a particular level, indicating that carrageenan destabilized the emulsions. At pH 6, the droplet charge decreased when ι- or λ-carrageenan were added to the emulsions suggesting surface adsorption, but did not significantly change when κ-carrageenan was added. The mean particle diameter remained relatively small in all emulsions at pH 6 indicating no strong flocculation or coalescence occurred, however only the emulsions containing ι-carrageenan were stable to creaming after 1 week storage. We propose that ι-carrageenan, which had the most densely charged helix structure, was most effective at creating highly charged interfacial membranes, thereby reducing the tendency for depletion flocculation to occur

Influence of Environmental Stresses on Stability of O/W Emulsions Containing Cationic Droplets Stabilized by SDS-Fish Gelatin Membranes

Oil-in-water (O/W) emulsions containing small oil droplets (d32 ≈ 0.22 μm) stabilized by sodium dodecyl sulfate (SDS)−fish gelatin (FG) membranes were produced by an electrostatic deposition technique. A primary emulsion containing anionic SDS-coated droplets (ζ ≈ −40 mV) was prepared by homogenizing oil and emulsifier solution using a high-pressure valve homogenizer (20 wt % corn oil, 0.46 wt % SDS, 100 mM acetic acid, pH 3.0). A secondary emulsion containing cationic SDS−FG-coated droplets (ζ ≈ +30 mV) was formed by diluting the primary emulsion with an aqueous fish gelatin solution (10 wt % corn oil, 0.23 wt % SDS, 100 mM acetic acid, 2.00 wt % fish gelatin, pH 3.0). The stabilities of primary and secondary emulsions with the same oil concentration to thermal processing, ionic strength, and pH were assessed by measuring particle size distribution, ζ potential, microstructure, destabilized oil, and creaming stability. The droplets in secondary emulsions had good stability to droplet aggregation at holding temperatures from 30 to 90 °C for 30 min, [NaCl] ≤ 100 mM, and pH values from 3 to 8. This study shows that the ability to generate emulsions containing droplets stabilized by multilayer interfacial membranes comprised of two or more types of emulsifiers, rather than a single interfacial layer comprised of one type of emulsifier, may lead to the development of food products with improved stability to environmental stresses

Properties of Low Moisture Composite Materials Consisting of Oil Droplets Dispersed in a Protein-Carbohydrate-Glycerol Matrix: Effect of Continuous Phase Composition

The influence of continuous phase composition on the properties of low moisture (\u3c3% water) composite materials consisting of oil droplets dispersed in a protein−carbohydrate−glycerol matrix was investigated. These composites were produced by blending canola oil (62.3%), whey protein concentrate (1.7%, WPC), and corn syrup and glycerol together (36.0% combined) using a high speed mixer equipped with a whisk. The polyol composition was varied by changing the ratio of corn syrup to glycerol in the system while keeping the total concentration of these two polyol components constant. Some composites were analyzed directly after preparation (“unbaked”), while others were analyzed after heating at 176 °C for 10 min to simulate baking of a food product (“baked”). The “lightness” of the composites was greater before baking (higher L value), but the color intensity of the composites was greater after baking (higher b value), which was attributed to Maillard browning reactions. The brownness of the baked composites increased with increasing corn syrup concentration, which was attributed to Maillard browning reactions. Squeezing flow viscometry indicated that the consistency and yield stress of the composites increased with baking, which was attributed to whey protein unfolding and aggregation. These rheological parameters also increased with increasing corn syrup concentration, which was attributed to its influence on the continuous phase rheology and on the interactions between the whey proteins. This study shows that the continuous phase composition and thermal history of low moisture composite materials have a large impact on their final physicochemical properties

Potential Impact of the Involvement of Clinical Pharmacists in Antimicrobial Stewardship Programs on the Incidence of Antimicrobial-Related Adverse Events in Hospitalized Patients: A Multicenter Retrospective Study

Although specialized pharmacists have been suggested to be essential members of antimicrobial stewardship programs (ASPs), not all hospitals in Korea operate ASPs with pharmacists involved. We aimed to evaluate the association of involvement of clinical pharmacists as team members of multidisciplinary ASPs with the incidence of antimicrobial-related adverse drug events (ADEs). Five tertiary teaching hospitals participated in this retrospective cohort study. At each participating hospital, we randomly selected 1000 participants among patients who had received systemic antimicrobial agents for more than one day during the first quarter of 2017. We investigated five categories of antimicrobial-related ADEs: allergic reactions, hematologic toxicity, nephrotoxicity, hepatotoxicity, and antimicrobial-related diarrhea. Multivariate logistic regression analysis was used to evaluate the potential impact of pharmacist involvement in ASPs on the incidence of ADEs. A total of 1195 antimicrobial-related ADEs occurred in 618 (12.4%) of the 4995 patients included in the analysis. The overall rate of ADE occurrence was 17.4 per 1000 patient days. Hospitals operating ASPs with pharmacists showed significantly lower AE incidence proportions than other hospitals (8.9% vs. 14.7%; p < 0.001). Multidisciplinary ASPs that included clinical pharmacists reduced the risk of antimicrobial-related ADEs by 38% (adjusted odds ratio 0.62; 95% confidence interval 0.50–0.77). Our results suggest that the active involvement of clinical pharmacists in multidisciplinary ASPs may contribute to reduce the incidence of antimicrobial-related ADEs in hospitalized patients