Moshe Rosenberg

Current and future applications for membrane processes in the dairy industry

Abstract Technological advances related to the development of new membranes, improvements in process engineering and better understanding of the functionality of milk constituents have extended the range of membrane separation processes to cover the entire compositional spectrum of milk. Advanced membrane processes allow the recovery and purification of valuable milk constituents and have become an integral part of an increasing number of dairy processes. Current applications are aimed at enhancing the manifestation of desired functional properties of milk proteins, fractionating caseins and whey proteins, enhancing the microbial quality of dairy fluids, upgrading the quality of low-quality whey, and standardizing milk. Combinations of membrane processes with traditional milk-processing practices are being used to enhance the quality attributes of various dairy products.

Preparation and properties of glutaraldehyde cross-linked whey protein-based microcapsules containing theophylline

Whey protein-based microcapsules containing a model drug, theophylline, were prepared in organic phase, using glutaraldehyde-saturated toluene. In all cases, spherical microcapsules, ranging from <400 to 1000 microm in diameter, were obtained. Results indicated that core crystals were embedded throughout the wall matrix. In all cases, retention efficiency of theophylline was higher than 74% and was not affected by cross-linking conditions. Results of theophylline release in simulated intestinal and gastric fluids at 37 degrees C indicated that the diffusion-governed core release was significantly affected by size of microcapsules, cross-linking conditions, and by type of dissolution medium. In all cases, core release in simulated intestinal fluid was faster than in simulated gastric fluid.

Preparation and some properties of water-insoluble, whey protein-based microcapsules.

A method, consisting of double emulsification and chemical cross-linking with glutaraldehyde was used to prepare whey protein-based microcapsules containing anhydrous milk fat as a model core. Effects of emulsion composition and pH on core retention, microstructure, and water-solubility of microcapsules were investigated. In all cases, core retention higher than 88% was accomplished and, in most cases, was not significantly affected by emulsion composition. In all cases, spherical microcapsules, 10-80 microm in diameter, were obtained. Outer topography and the inner structure of microcapsules were significantly affected by the pH of the emulsion. In all cases, microcapsules were practically water-insoluble. Microcapsules similar to the developed prototype may be suitable for controlled core release in application fields where chemical cross-linking is acceptable.A method, consisting of double emulsification and chemical cross-linking with glutaraldehyde was used to prepare whey protein-based microcapsules containing anhydrous milk fat as a model core. Effects of emulsion composition and pH on core retention, microstructure, and water-solubility of microcapsules were investigated. In all cases, core retention higher than 88% was accomplished and, in most cases, was not significantly affected by emulsion composition. In all cases, spherical microcapsules, 10-80 mum in diameter, were obtained. Outer topography and the inner structure of microcapsules were significantly affected by the pH of the emulsion. In all cases, microcapsules were practically waterinsoluble. Microcapsules similar to the developed prototype may be suitable for controlled core release in application fields where chemical cross-linking is acceptable.

Microencapsulation of theophylline in whey proteins: effects of core-to-wall ratio

Effects of core-to-wall ratio ranging from 1:1.5 to 5:1.5 on formation, properties and core release from whey protein-based microcapsules containing theophylline were investigated. Microcapsules were cross-linked by glutaraldehyde-saturated toluene (GAST) in an organic phase. Size distribution of microcapsules, core content and core retention were affected by core-to-wall ratio. Proportion of small capsules was inversely related to core-to-wall ratio. Core content in microcapsules ranged from 6.7 to 65.7% (w/w) and core retention ranged from 16.8 to 85.4%. Outer topography and inner structure of microcapsules were influenced by core-to-wall ratio. Core release into simulated intestinal- and gastric-fluids was influenced by a combined effect of type of dissolution medium and core-to-wall ratio, through its influence on size, core content and structure of microcapsules. Results indicated that in order to attain a desired core content and release profile, the ratio of core-to-wall components, in suspensions consisting of whey proteins and theophylline, has to be carefully considered and adjusted.

Mechanical properties of composite gels consisting of fractionated whey proteins and fractionated milk fat

Abstract Properties of composite gels with 13% protein consisting of 0:1-to-1:0 α-lactalbumin (α-Lac) to β-lactoglobulin (β-Lg) and 10 or 30% filler consisting of fractionated milk fat as well as properties of matrix-only gels with 10–15% proteins were investigated at 4–50 °C. Maximum compressive force and elastic modulus of the composites were proportionately related to the proportion of β-Lg and proportion of solid lipids included in the matrix and filler, respectively. Details of the compressive behavior, microstructure and extent to which filler affected the mechanical properties were significantly influenced by protein composition. Results obtained with matrix-only gels indicated a protein composition-specific power law relationship ( n =2) between protein content and mechanical properties of the gels.

Calcium-alginate coated, whey protein-based microspheres: preparation, some properties and opportunities

An ‘all aqueous’ encapsulation process followed by a heat treatment was used to prepare calcium-alginate-coated, whey protein-based, water insoluble microspheres containing micronized calcium carbonate as a model core. Results obtained with this process were compared to those obtained with a similar process in which chemical cross-linking was utilized. At an initial core load of 25 or 50% (w/w), core retention ranged from 84.2–95.12% and was not significantly affected by the initial core load or by the cross-linking method. Regardless of the cross-linking method, protein retention during the process was high and ranged from 78.2–87.5%. Outer topography of the microspheres was not influenced by the cross-linking method, however, at a given composition, the inner structure of heat treated microspheres differed from that obtained with chemically-cross-linked microspheres. Swelling properties of denovo microspheres were affected by pH. Results indicated that the micronized calcium carbonate could be used as a porogenic core. Removal of the core, by an acid treatment, allowed preparing microporous delivery devices. In addition to offer opportunities for encapsulation and delivery of crystalline core, the investigated process can provide means to prepare ‘ghost’ microporous delivery systems that can, in potential, be loaded, following their preparation, with sensitive core materials at conditions that favour the stability and functionality of this core.

Encapsulation of chlorothiazide in whey proteins: Effects of wall-to-core ratio and cross-linking conditions on microcapsule properties and drug release

A model drug with limited water-solubility, chlorothiazide, was successfully encapsulated in whey protein-based wall systems cross-linked by glutaralde-hyde-saturated toluene via an organic phase. The effects of drug content of the core-in-wall suspension and of cross-linking conditions on core retention and on microcapsule size, structure and core release properties were investigated. Spherical, surface cracks-free microcapsules ranging in diameter from ∼ 200–1300 μm were obtained. Particle size distribution of microcapsules was affected by core content and cross-linking conditions. Core retention in microcapsules prepared at different cross-linking conditions and different wall-to-core ratios ranged from 48.9–81%, from 42.2–76.1% and from 37.3–67.2% in large (L), medium-size (M) and small (S) microcapsules, respectively. In all cases, drug crystals were physically entrapped and embedded throughout the cross-linked protein matrix. Core release from the microcapsules into enzyme-free simulated gastric fluid was governed by a diffusion-controlled mechanism and did not involve erosion or softening of the wall matrix. Rate of core release was significantly affected by a combined influence of core content, microcapsule size and cross-linking density. Complete core release from L, M and S microcapsule prepared at different wall-to-core ratios and cross-linking conditions ranged from 28.6–81.2 h, from 16.8–28.6 h and from 7.2–15.9 h, respectively. Results suggested that whey protein-based wall matrix cross-linked by GAST may provide significant opportunities in modulating the release of an encapsulated core with a limited water solubility.

Cold-set whey protein microgels containing immobilised lipid phases to modulate matrix digestion and release of a water-soluble bioactive

Abstract This study investigated the in-vitro digestibility of cold-set whey protein (WP) microgels prepared by two gelation methods (external and internal) containing lipids (0%, 10% or 20% w/w). The incorporation of lipids into these matrices achieved higher entrapment of the bioactive vitamin riboflavin, as well as significant reductions in rates of both the digestion of the protein matrix, and the subsequent diffusion of the water-soluble bioactive. A biexponential model accounted for the contribution of digestion- and diffusion-driven mechanisms in describing the release of riboflavin into enzyme containing simulated gastrointestinal fluids. In particular, for external gelation microgels, as the lipid load within the matrices increased, the contribution of a faster diffusion-driven release was almost completely negated by a slower digestion-assisted release. Lipid loads provided a composite matrix capable of alternating from a burst to a sustained release of bioactive.

A biorefinery for efficient processing and utilization of spent pulp of Colombian Andes Berry (Rubus glaucus Benth.): Experimental, techno-economic and environmental assessment

This work investigated a model biorefinery for producing phenolic compounds extract, ethanol and xylitol from spent blackberry pulp (SBP). The biorefinery was investigated according to four potential scenarios including mass and heat integrations as well as cogeneration system for supplying part of the energy requirements in the biorefinery. The investigated SBP had 61.54% holocellulose; its total phenolic compounds was equivalent to 2700mg of gallic acid/100g SBP, its anthocyanins content was 126.41mg/kg of SBP and its total antioxidant activity was 174.8μmol TE/g of SBP. The economic analysis revealed that the level of integration in the biorefinery significantly affected the total production cost. The sale-to-total-production-cost ratio indicated that both, mass and heat integrations are of importance relevance. The cost of supplies (enzymes and reagents) had the most significant impact on the total production cost and accounted between 46.72 and 58.95% of the total cost of the biorefinery.

A model biorefinery for avocado (Persea americana mill.) processing

This research investigated and evaluated a biorefinery for processing avocado Hass variety into microencapsulated phenolic compounds extract, ethanol, oil and xylitol. Avocado was first characterized for its potential valuable compounds; then, the techno-economic and environmental aspects of the biorefinery were developed and finally the total production costs and potential environmental impact of the proposed biorefinery were investigated. Four scenarios of the biorefinery were evaluated with different extent of mass and energy integration as well as the incorporation of a cogeneration system. Results indicated that the main fatty acid in the pulp of the investigated avocado variety was oleic acid (50.96%) and that this fruit contained significant amount of holocellulose (52.88% and 54.36% in the peel and seed, respectively). Techno-economic and environmental assessment suggested an attractive opportunity for a biorefinery for complete utilization of the avocado fruit as well the importance of the level of integration.