Werribee, Australia
Werribee, Australia

Time filter

Source Type

Fang Y.,Monash University | Selomulya C.,Monash University | Ainsworth S.,Dairy Innovation Australia Ltd. | Palmer M.,Dairy Innovation Australia Ltd. | Chen X.D.,Monash University
Food Hydrocolloids | Year: 2011

Milk protein concentrate (MPC) is a newly developed dairy powder with wide range of applications as ingredients in the food industry, such as cheese, yogurt, and beverage. MPC has relatively poor solubility as a result of their high protein content (40-90wt%), with distinct dissolution behaviour in comparison to skim milk or whole milk powders. Here, a focused beam reflectance measurement (FBRM) was used to monitor the dissolution process of an MPC powder, with the data used to develop a kinetic dissolution model based on the Noyes-Whitney equation. The model was used to estimate the dissolution rate constant k and the final particle size in suspension d∞, describing dynamic dissolution behaviours and final solubility respectively of a particular powder. In this work, the effects of dissolution temperature, storage duration and storage temperature on dissolution properties of an MPC powder were also investigated. A quantitative understanding of relationship between process and storage conditions with powder functionality could be achieved from k and d∞ profiles. This approach can potentially be applied to predict the dissolution behaviour of specific dairy powders in a more robust manner than conventional solubility tests. © 2010 Elsevier Ltd.

Ghandi A.,University of Ballarat | Powell I.,Dairy Innovation Australia Ltd. | Chen X.D.,Xiamen University | Adhikari B.,University of Ballarat
Journal of Food Engineering | Year: 2012

The drying and survival kinetics of Lactococcus lactis ssp. cremoris in a convective air drying environment were measured using single droplet drying experiments. Tests were carried out at five different drying temperatures (45-95°C) at a constant air velocity (0.5 m/s) and within 2.4-11% relative humidity. The effect of protective agents (10% w/w) of lactose, sodium caseinate and lactose:sodium caseinate (3:1) was also evaluated. The thermal inactivation kinetics parameters in convective air drying and isothermal water bath heating were determined and compared. The results showed that the final temperature attained by the droplet affected the survival of the bacteria significantly, however, most of the bacterial death occurred in early stage of drying while evaporative cooling kept the drop temperature relatively low. At higher droplet temperatures (≥65°C) the bacterial cultures were inactivated by both dehydration and thermal stresses. At lower droplet temperatures (≤55°C) the rate of change in droplet moisture content had much stronger effect on the bacterial survival. Lactose and sodium caseinate, as protective agents, enhanced the survival of bacterial cells significantly at all the test conditions. The lactose:sodium caseinate (3:1) mixture synergistically enhanced the survival of the bacterial cultures. The death of these bacteria followed first-order kinetics during convective single droplet drying as well as during isothermal water-bath heating. However, the inactivation energy in convective single droplet drying (181.3 kJ/mol) was much higher than the inactivation energy in isothermal water bath heating (16.8 kJ/mol) within the medium temperature of 45-95°C. © 2012 Elsevier Ltd. All rights reserved.

Dissanayake M.,RMIT University | Kasapis S.,RMIT University | George P.,RMIT University | Adhikari B.,University of Ballarat | And 2 more authors.
Food Hydrocolloids | Year: 2013

Hydrostatic pressure effects on whey protein/lactose mixtures were recorded with subsequent analysis of their structural, molecular and glass transition properties in comparison to thermal effects at atmospheric pressure. Experimental techniques used were small deformation dynamic oscillation in shear, modulated differential scanning calorimetry, Fourier transform infrared spectroscopy, and theoretical modelling of glass transition phenomena. Levels of solids ranged from 30 to 80% (w/w) in formulations with a protein/co-solute ratio of four-to-one. Addition of lactose protects the secondary conformation of the protein under application of high hydrostatic pressure. Nevertheless, pressurized protein systems are able to form three-dimensional structures due to the reduction in polymeric free volume and the development of an efficient friction coefficient amongst tightly packed particles. Systems can be seen as developing a " molten globular state", where the structural knots of pressure-treated networks remain in the native conformation but achieve intermolecular cross-linking owing to frictional contact. Furthermore, pressure treated assemblies of condensed whey protein preparations could match the viscoelasticity of the thermally treated counterparts upon cooling below ambient temperatures. That allowed examination of the physical state and morphology of a condensed preparation at 80% solids by the combined framework of reduced variables and free volume theory thus affording derivation of glass transition temperatures for pressurized and atmospheric samples. © 2012.

Pang Z.,University of Queensland | Deeth H.,University of Queensland | Sopade P.,University of Queensland | Sharma R.,Dairy Innovation Australia Ltd | Bansal N.,University of Queensland
Food Hydrocolloids | Year: 2014

The effects of gelatin concentration, pH and addition of milk proteins on the physical and microstructural properties of type B gelatin gels were studied by small deformation rheology, texture analysis and scanning electron microscopy. Whey protein isolate (WPI), milk protein concentrate (MPC) and skim milk powder (SMP) were used as sources of milk proteins. The elasticity of gelatin gels was significantly affected by the concentration of gelatin. Higher gelatin concentrations led to a stronger gel, and higher gelling and melting temperatures. However, all the gelatin gels at concentrations from 1.0 to 5.0% melted below human body temperature. Rheological properties of gelatin gels were independent of pH in the range pH 4.6-8.0. At pH 3.0 gelation of gelatin was significantly inhibited. Addition of SMP and MPC significantly enhanced the rheological properties of gelatin gels, while addition of WPI had a negative effect on them. However, the effect of addition of milk proteins was dependent on the gelatin concentration. Textural results showed that addition of all milk powders increased the hardness of gelatin gels at high gelatin concentration (5.0%). The fracturability of the gels was greatly influenced by pH. Addition of milk proteins and high gelatin concentration (5.0%) both caused loss of gel fracturability. Microstructural results showed that gelatin concentration and pH had a marked influence on the gel structure, and the addition of MPC and SMP changed the structure of the gelatin gels; a structure similar to pure gelatin gel was observed after addition of WPI. © 2013 Elsevier Ltd.

Truong T.,University of Queensland | Bansal N.,University of Queensland | Sharma R.,Dairy Innovation Australia Ltd | Palmer M.,Dairy Innovation Australia Ltd | Bhandari B.,University of Queensland
Food Chemistry | Year: 2014

The crystallisation properties of milk fat emulsions containing dairy-based ingredients as functions of emulsion droplet size, cooling rate, and emulsifier type were investigated using a differential scanning calorimeter (DSC). Anhydrous milk fat and its fractions (stearin and olein) were emulsified with whey protein concentrate, sodium caseinate, and Tween80 by homogenisation to produce emulsions in various size ranges (0.13-3.10 μm). Particle size, cooling rate, and types of emulsifier all had an influence on the crystallisation properties of fat in the emulsions. In general, the crystallisation temperature of emulsified fats decreased with decreasing average droplet size and was of an exponent function of size, indicating that the influence of particle size on crystallisation temperature is more pronounced in the sub-micron range. This particle size effect was also verified by electron microscopy. © 2013 Elsevier Ltd. All rights reserved.

Liu D.Z.,University of Melbourne | Weeks M.G.,Dairy Innovation Australia Ltd | Dunstan D.E.,University of Melbourne | Martin G.J.O.,University of Melbourne
Food Chemistry | Year: 2013

Milk is a complex colloidal system that responds to changes in temperature imposed during processing. Whilst much has been learned about the effects of temperature on milk, little is known about the dynamic response of casein micelles to changes in temperature. In this study, a comprehensive physico-chemical study of casein micelles in skim milk was performed between 10 and 40 °C. When fully equilibrated, the amount of soluble casein, soluble calcium and the pH of skim milk all decreased as a function of increasing temperature, whilst the hydration and volume fraction of the casein micelles decreased. The effect of temperature on casein micelle size, as determined by dynamic light scattering and differential centrifugation, was less straightforward. Real-time measurements of turbidity and pH were used to investigate the dynamics of the system during warming and cooling of milk in the range 10-40 °C. Changes in pH are indicative of changes to the mineral system and the turbidity is a measure of alterations to the casein micelles. The pH and turbidity showed that alterations to both the casein micelles and the mineral system occurred very rapidly on warming. However, whilst mineral re-equilibration occurred very rapidly on cooling, changes to the casein micelle structure continued after 40 min of measurement, returning to equilibrium after 16 h equilibration. Casein micelle structure and the mineral system of milk were both dependent on temperature in the range 10-40 °C. The dynamic response of the mineral system to changes in temperature appeared almost instantaneous whereas equilibration of casein was considerably slower, particularly upon cooling. © 2013 Elsevier Ltd.

Zisu B.,Dairy Innovation Australia Ltd. | Schleyer M.,Dairy Innovation Australia Ltd. | Chandrapala J.,University of Melbourne
International Dairy Journal | Year: 2013

Concentrated skim milk was treated with high intensity low frequency ultrasound (20 kHz) to lower viscosity through a process of acoustic cavitation. Batch sonication for 1 min at 40-80 W, and continuous treatment delivering an applied energy density of 4-7 J mL-1, reduced the viscosity of medium-heat skim milk concentrates containing 50-60% solids. Viscosity was reduced by approximately 10%, but this improved to >17% in highly viscous age thickened material. Sonication also changed the shear thinning behaviour at shear rates below 150 s-1. Although ultrasound lowered the viscosity of skim milk concentrated to ≥50% solids, the treatment could only delay the rate of thickening once the ageing process was established. It was only when ultrasound was activated during concentration that sonication prevented the viscosity of skim milk concentrates from increasing rapidly. © 2012 Elsevier Ltd.

Zisu B.,Dairy Innovation Australia Ltd. | Bhaskaracharya R.,University of Melbourne | Kentish S.,University of Melbourne | Ashokkumar M.,University of Melbourne
Ultrasonics Sonochemistry | Year: 2010

High intensity low frequency ultrasound was used to process dairy ingredients to improve functional properties. Based on a number of lab-scale experiments, several experimental parameters were optimised for processing large volumes of whey and casein-based dairy systems in pilot scale ultrasonic reactors. A continuous sonication process at 20 kHz capable of delivering up to 4 kW of power with a flow-through reactor design was used to treat dairy ingredients at flow rates ranging from 200 to 6000 mL/min. Dairy ingredients treated by ultrasound included reconstituted whey protein concentrate (WPC), whey protein and milk protein retentates and calcium caseinate. The sonication of solutions with a contact time of less than 1 min and up to 2.4 min led to a significant reduction in the viscosity of materials containing 18% to 54% (w/w) solids. The viscosity of aqueous dairy ingredients treated with ultrasound was reduced by between 6% and 50% depending greatly on the composition, processing history, acoustic power and contact time. A notable improvement in the gel strength of sonicated and heat coagulated dairy systems was also observed. When sonication was combined with a pre-heat treatment of 80 °C for 1 min or 85 °C for 30 s, the heat stability of the dairy ingredients containing whey proteins was significantly improved. The effect of sonication was attributed mainly to physical forces generated through acoustic cavitation as supported by particle size reduction in response to sonication. As a result, the gelling properties and heat stability aspects of sonicated dairy ingredients were maintained after spray drying and reconstitution. Overall, the sonication procedure for processing dairy systems may be used to improve process efficiency, improve throughput and develop value added ingredients with the potential to deliver economical benefits to the dairy industry. © 2009 Elsevier B.V. All rights reserved.

Truong T.,University of Queensland | Morgan G.P.,University of Queensland | Bansal N.,University of Queensland | Palmer M.,Dairy Innovation Australia Ltd | Bhandari B.,University of Queensland
Food Chemistry | Year: 2014

The triacylglycerol (TAG) crystal structures and morphologies of fractionated milk lipids in nanoemulsions were investigated at 4 °C. Droplet size (0.17 versus 1.20 μm), lipid composition (stearin versus olein) and cooling rate (1 versus 10 °C min-1) had an influence on the structural properties. Five crystal polymorphs (α, β′1, β′2, β1, and β2) were formed with either triple and/or double chain length structures in the solid phases of the emulsified systems. X-ray scattering peak intensities were reduced with the nanoemulsion particles. The internal structure of TAG exhibited stacking of individual lamellar layers (3.8-4.2 nm). Various anisometric shapes of fat nanoparticles were formed due to a highly sharp curvature of the nano-size droplets. The shape of olein nanoparticles was more polyhedral compared to the stearin. TAG crystals arranged in a planar-layered organisation at the slower cooling rate. These differences imply that the nanometric confinement of oil droplets modifies the fat crystal habit. © 2014 Elsevier Ltd. All rights reserved.

Hausmann A.,Victoria University of Melbourne | Sanciolo P.,Victoria University of Melbourne | Vasiljevic T.,Victoria University of Melbourne | Weeks M.,Dairy Innovation Australia Ltd. | And 3 more authors.
Journal of Membrane Science | Year: 2013

This study investigates fouling of membranes during membrane distillation (MD) of two model dairy feeds - skim milk and whey, as well as their major single components. Every MD experiment was conducted for 20. h at 54. °C feed inlet temperature and 5. °C permeate inlet temperature using PTFE membranes. Performance was assessed in terms of throughput (flux) and retention efficiency. Skim milk flux was found to be lower but stable over time compared to whey. The study using single components as well as combinations thereof revealed that fouling was primarily driven by proteins and calcium, but only in combination. Lactose also played a role to a lesser extent in the protein/membrane interactions, possibly due to preferential hydration, but did not interact with the membrane polymer directly. However lactose was found to deposit once an anchor point to the membrane was established by other components. Skim milk showed strong adhesion from its principle proteins, caseins; however salts were needed to form a thick and dense cake layer. Caseins seem to form a layer on the membrane surface that prevents other components from interacting with the membrane polymer. Whey proteins, on the other hand, deposited to a lesser extent. In general, membrane distillation was found to be a process that generates high quality water with retention of all tested components >99% while simultaneously concentrating whey or skim milk. © 2013 Elsevier B.V.

Loading Dairy Innovation Australia Ltd collaborators
Loading Dairy Innovation Australia Ltd collaborators