A new study, published in the European Journal of Lipid Science and Technology, proposes a three step process to enrich the levels of diacylglycerols (DAG) – which are associated with improved appetite control and better energy balance – in milk fat; creating a nutritionally beneficial analogue of the ingredient which could be used in food formulation.
“Our results set the basis for the development of a simple process for the production of a DAG-rich milk fat analogue,” said the researchers, led by Dr Marta Lubary, from Delft University of Technology, The Netherlands.
The research was funded by SenterNovem – a department of the Dutch Ministry of Economic Affairs.
Milk fats
Diacylglycerols are esters of glycerol and two fatty acids that naturally present as minor components in edible fats and oils.
Recently studies have indicated a positive metabolic effect for diacylglycerols; with substitution of triglyceride based lipids to diglyceride based lipids shown to promote the decrease of postprandial plasma lipid levels, and to increase fat oxidation in humans.
Diacylglycerol -based cooking oils, containing around 80 per cent DAG, are currently manufactured and marketed in Japan and USA, however such oils are unsuitable for use in food production.
Oils or fats containing saturated fatty acids, for example milk fat, have a higher melting point, being partially solid at room temperature. This property makes them of use for adding structure to food products.
Milk fat is the most varied among all fats in terms of its physical and chemical properties and possesses a uniquely pleasing flavour not found in other fat ingredients.
They have applications in confectionary and bakery and pastry products, as well as being used to produce ‘spreadable’ butters and other dairy products including ice cream. They are also used as bloom inhibitors in dark chocolate and texture and flavoring agents in milk chocolate.
As well as performing functional roles within in the products, such as adding texture, flavor, milk fat also potentials offers added nutritive value to products it is used in.
Dr Lubary and colleagues said that milk fat is a valuable natural fat, which acts as a source of bioactive lipids and fat-soluble vitamins.
“The modification of milk fat by increasing its content in DAG has the potential of improving further its nutritional properties,” they added.
They said that the new study aimed to develop a suitable method for the production of a DAG-rich acylglycerol mixture from milk fat, without degrading its natural flavour and appearance.
Additional advantages of this product may be related to a higher-content in short chain fatty acids in relation to the original milk fat, they added.
Enriching process
Lubary and co workers said that the experimental process consisted of three steps: a lipase-catalysed partial break down of milk fat, followed by extraction of by-product fatty acid ethyl esters (FAEEs), and transformation of diacylglycerols.
They reported that several lipases were tested for maximizing the percentage of DAG in the acylglycerol mixture. The lipase (P. fluorescens) was reported to produce the maximum amount of diglyceride, whilst releasing minimum amounts of short chain fatty acids in the form of fatty acid ethyl esters.
Optimal temperature conditions for the reaction were found to be 40°C, whilst the use of CO2 at elevated pressures, for expanding the reaction mixture, was reported to have a negative effect on lipase activity.
The authors said that the experimental investigation of the three process steps “demonstrates the technical feasibility of the proposed process.”
They added that their results set the basis for the further development of a process for the synthesis of a DAG-rich milk fat – which may also be enriched in short chain fatty acids.
Source: European Journal of Lipid Science and Technology
Published online ahead of print, doi: 10.1002/ejlt.201000406
“A process for the production of a diacylglycerol-based milk fat analogue”
Authors: M. Lubary, G.W. Hofland, J.H. ter Horst