Investigating the influence of standardisation media on the physicochemical and functional changes of skim milk during evaporation
Loading...
Files
Date
2024
Authors
Long, Tom
Journal Title
Journal ISSN
Volume Title
Publisher
University College Cork
Published Version
Abstract
Evaporation and spray drying are two fundamental processes used across the dairy industry to produce high value ingredients. Seasonality induced changes in milk composition particularly prevalent in seasonal calving pasture based dairy systems like Ireland, can pose a series of challenges to processors with changing milk constituents that affect the functionality. In the production of skim milk powder, it is desirable for dairy processers to produce a powder that consistently adheres to the required protein concentration, as excessive levels of protein, which becomes a particular challenge in late lactation, will have a negative effect on process yield, efficiency, and overall profitability for the company.
The aim of this research project was to simulate at lab scale, the effects of utilising lactose versus permeate for protein standardisation in skimmed milk, on the physiochemical and functional properties observed during evaporation. The first experimental chapter investigates the effects of permeate and lactose for standardisation of skim milk concentrate by varying total solids concentrations material on addition at 20% vs 50% and characterises the changes to physio-chemical properties during evaporation to ~50% solids. Results from this study indicate that standardisation of protein content can limit the increase of viscosity during the evaporation of skim milk concentrate, whereby the addition of lactose had a more potent effect in offsetting the increase in viscosity compared to permeate addition, and resulted in a lower viscosity overall. Heat stability and acid buffering capacity of the permeate standardised skim milk samples were higher when compared to the lactose standardised samples, offering insights into dynamics of pH changes during concentration. The second experimental chapter examines the effect of thermal treatment using a microthermics unit to simulate preheating of standardised materials prior to evaporation and if subsequent readjustment of pH back to native pH, after preheating and prior to evaporation has an effect on in process performance. After heat treatment, lactose standardised samples observed heat-induced changes such as a reduced pH, which was irreversible upon increasing the pH of the high heat skim milk prior to evaporation, highlighting the complexity of the casein micelle under varying processing conditions. The data from this study highlights the influence of thermal treatments on the pH of skim milk and its effects on concentrate viscosity, whereby the lactose standardised samples showed a greater increase in viscosity after the heat treatment was applied. The work from this research MSc. gives insight into the effects that standardisation media has on the physiochemical and functional properties of skim milk concentrate during production. These learnings may provide useful data to industry and manufacturers, whereby evaporating to a target viscosity rather than target milk solids would offer greater control and consistency during processing and therefore preventing product downtime with reduced C.I.P times and a reduced quantity of effluent being processed through treatment plants.
Description
Controlled Access
Keywords
Dairy science , Concentrate viscosity , Protein standardisation
Citation
Long, T. 2024. Investigating the influence of standardisation media on the physicochemical and functional changes of skim milk during evaporation. MSc Thesis, University College Cork.