Evaluation of arabinoxylan isolated from sorghum bran, biomass, and bagasse for film formation.

Arabinoxylans (AX) are potential agricultural co-products for material applications. Sorghum has seen increased production as a bioenergy crop for biofuel and co-product generation. AX from three sorghum fractions (bran, bagasse, and biomass) were isolated to study film formation. All three AX fractions exhibited high moisture sensitivity. Sorghum biomass AX produced low water vapor permeability compared to sorghum bran or sorghum bagasse AX films. Glycerol addition to sorghum bran AX films reduced tensile strength from 34.8 to 16.0 MPa at 0% and 10% (w/w) glycerol, respectively; reduced the storage and loss moduli during dynamic mechanical analyses at 50% relative humidity (RH) and decreased the rubber-to-plastic material transition temperature at 50% RH, from 78.1 °C to 38.4 °C at 0 and 10% (w/w) glycerol, respectively. Sorghum bran AX, while sensitive to water absorption at high RH, produced favorable strength performance compared to AX from other cereal grains indicating potential utilization as a renewable material.

Effect of heat and homogenization on in vitro digestion of milk.

Central to commercial fluid milk processing is the use of high temperature, short time (HTST) pasteurization to ensure the safety and quality of milk, and homogenization to prevent creaming of fat-containing milk. Ultra-high-temperature sterilization is also applied to milk and is typically used to extend the shelf life of refrigerated, specialty milk products or to provide shelf-stable milk. The structures of the milk proteins and lipids are affected by processing but little information is available on the effects of the individual processes or sequences of processes on digestibility. In this study, raw whole milk was subjected to homogenization, HTST pasteurization, and homogenization followed by HTST or UHT processing. Raw skim milk was subjected to the same heating regimens. In vitro gastrointestinal digestion using a fasting model was then used to detect the processing-induced changes in the proteins and lipids. Using sodium dodecyl sulfate-PAGE, gastric pepsin digestion of the milk samples showed rapid elimination of the casein and α-lactalbumin bands, persistence of the ß-lactoglobulin bands, and appearance of casein and whey peptide bands. The bands for ß-lactoglobulin were eliminated within the first 15min of intestinal pancreatin digestion. The remaining proteins and peptides of raw, HTST, and UHT skim samples were digested rapidly within the first 15min of intestinal digestion, but intestinal digestion of raw and HTST pasteurized whole milk showed some persistence of the peptides throughout digestion. The availability of more lipid droplets upon homogenization, with greater surface area available for interaction with the peptides, led to persistence of the smaller peptide bands and thus slower intestinal digestion when followed by HTST pasteurization but not by UHT processing, in which the denatured proteins may be more accessible to the digestive enzymes. Homogenization and heat processing also affected the ζ-potential and free fatty acid release during intestinal digestion. Stearic and oleic acids were broken down faster than other fatty acids due to their positions on the outside of the triglyceride molecule. Five different casein phosphopeptide sequences were observed after gastric digestion, and 31 sequences were found after intestinal digestion, with activities yet to be explored. Processing affects milk structure and thus digestion and is an important factor to consider in design of foods that affect health and nutrition.

Enrichment and Purification of Casein Glycomacropeptide from Whey Protein Isolate Using Supercritical Carbon Dioxide Processing and Membrane Ultrafiltration.

Whey protein concentrates (WPC) and isolates (WPI), comprised mainly of ß-lactoglobulin (ß-LG), α-lactalbumin (α-LA) and casein glycomacropeptide (GMP), are added to foods to boost nutritional and functional properties. Supercritical carbon dioxide (SCO2) has been shown to effectively fractionate WPC and WPI to obtain enriched fractions of α-LA and ß-LG, thus creating new whey ingredients that exploit the properties of the individual component proteins. In this study, we used SCO2 to further fractionate WPI via acid precipitation of α-LA, ß-LG and the minor whey proteins to obtain GMP-enriched solutions. The process was optimized and α-LA precipitation maximized at low pH and a temperature (T) ≥65 °C, where ß-LG with 84% purity and GMP with 58% purity were obtained, after ultrafiltration and diafiltration to separate ß-LG from the GMP solution. At 70 °C, ß-LG also precipitated with α-LA, leaving a GMP-rich solution with up to 94% purity after ultrafiltration. The different protein fractions produced with the SCO2 process will permit the design of new foods and beverages to target specific nutritional needs.

Fractionation of whey protein isolate with supercritical carbon dioxide to produce enriched α-lactalbumin and ß-lactoglobulin food ingredients.

An environmentally friendly protein fractionation process using supercritical carbon dioxide (SCO(2)) as an acid was developed to produce enriched α-lactalbumin (α-LA) and ß-lactoglobulin (ß-LG) fractions from whey protein isolate solutions containing from 2 to 10% WPI. This study investigated the effects of pH, temperature, WPI concentration, and residence time on the precipitation kinetics and recovery yields of individual whey proteins and the relative enrichment and composition of both protein fractions. At 5.5-34 MPa and 60-65 °C, solubilized SCO(2) decreased solution pH and induced the formation and precipitation of α-LA aggregates. Gel electrophoresis and HPLC of the enriched fractions demonstrated the production of ≥ 60% pure α-LA, and ≥ 70% pure ß-LG, under various operating conditions, from WPI containing ∼57% ß-LG and 21% α-LA. The enriched fractions are ready-to-use food ingredients with neutral pH, untainted by acids and contaminants.

Fractionation of whey protein isolate with supercritical carbon dioxide-process modeling and cost estimation.

An economical and environmentally friendly whey protein fractionation process was developed using supercritical carbon dioxide (sCO(2)) as an acid to produce enriched fractions of α-lactalbumin (α-LA) and ß-lactoglobulin (ß-LG) from a commercial whey protein isolate (WPI) containing 20% α-LA and 55% ß-LG, through selective precipitation of α-LA. Pilot-scale experiments were performed around the optimal parameter range (T = 60 to 65 °C, P = 8 to 31 MPa, C = 5 to 15% (w/w) WPI) to quantify the recovery rates of the individual proteins and the compositions of both fractions as a function of processing conditions. Mass balances were calculated in a process flow-sheet to design a large-scale, semi-continuous process model using SuperproDesigner® software. Total startup and production costs were estimated as a function of processing parameters, product yield and purity. Temperature, T, pressure, P, and concentration, C, showed conflicting effects on equipment costs and the individual precipitation rates of the two proteins, affecting the quantity, quality, and production cost of the fractions considerably. The highest α-LA purity, 61%, with 80% α-LA recovery in the solid fraction, was obtained at T = 60 °C, C = 5% WPI, P = 8.3 MPa, with a production cost of $8.65 per kilogram of WPI treated. The most profitable conditions resulted in 57%-pure α-LA, with 71% α-LA recovery in the solid fraction and 89% ß-LG recovery in the soluble fraction, and production cost of $5.43 per kilogram of WPI treated at T = 62 °C, C = 10% WPI and P = 5.5 MPa. The two fractions are ready-to-use, new food ingredients with a pH of 6.7 and contain no residual acid or chemical contaminants.

A novel biocompatible adhesive incorporating plant-derived monomers.

We describe a new class of biomaterials with potential for a variety of applications in tissue engineering, wound healing, and transdermal drug delivery. These materials are based on oleic methyl ester (OME), which is derived from various plant oils including soybean oil. The OME was acrylated (AOME) and subsequently copolymerized with methyl methacrylate (MMA) and ethylene glycol dimethacrylate (EGDMA) to form pressure sensitive adhesives (PSAs). We assessed the cytocompatibility of each PSA product using Alamar Blue and Live/Dead assays. It was found that after 2 h, human fibroblast cells attached on all four of the PSA polymers tested. After 24 h, cell spreading was seen on all materials with the exception of the polymerized AOME product (PAOME). Cells attached to the copolymer PSA products continued to proliferate for up to 2 weeks, as shown by fluorescent confocal microscopy imaging. Finally, a mechanical analysis of each of the copolymers is presented demonstrating that they have a range of mechanical properties and cell adhesiveness depending on the formulation, making them attractive candidates for use as bioactive adhesives.