Dairy Research at Wageningen University can be characterized by an integrative approach: quality of dairy products is influenced by all parts of the dairy chain. Many products can be made from milk and milk components are frequently used as ingredients in other non-dairy foods. This requires knowledge on properties of the raw material on a molecular level (dairy chemistry, physics, and microbiology) and about the interaction of milk components during processing and storage of dairy products.
Current research projects:
Gao Ran
Ion speciation in milk-like systems
Some dairy products contain a fruit layer with a neutral gelled dairy layer on top. Such products are subject to diffusion phenomena of acids and salts, resulting in protein aggregation in the neutral gelled dairy layer. The mechanisms of dairy protein gelation are complex, but the role of salts has been clearly demonstrated to be important in determining the onset pH of aggregation and gelation. Recent literatures also report that control of specific ion equilibria in dairy systems provides a way to control the onset and structure of protein gels. The objective is to understand the role of ion transport phenomena, the resulting ion activities and pH changes, and their consequences for protein gelations. A combination of measurements of ion activities, ion transport and modeling of these phenomena, and physical characterization of protein aggregation will shed light on the complex ion equilibria and lead to improved control of gelation phenomena.
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Etske Bijl
The influence of genetic variants, degree of phosphorylation and environmental conditions on casein micelle characteristics
This project is part of the Milk Genomics Initiative.
The objective is to determine the influence of genetic variants, degree of phosphorylation and environmental conditions on casein micelle characteristics. Gaining more insight in these characteristics will open up possibilities to improve milk composition by breeding strategies and to design high quality dairy products.
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Kasper Hettinga
Rapid headspace analysis of farm milk
Kasper Hettinga is working on the development of a fast chemical analytical method (headspace combined with GC/MS) for detection of quality deficits in fresh raw milk. I mainly focus on cow feed (detection of feeding strange by-products to cows) and cow health (detection of ketosis and mastitis). The information of these analyses could be used by farmers as management tool and by dairy factories for quality control of their milk supply.
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Milk Proteomics
Milk contains a few proteins in relatively high concentration. This are the 4 different casein, α- lactalbumin, and β-lactoglobulin. Next to these 6 proteins, a wide range of hundreds of minor proteins occur. The minor proteins have a wide range of activities: immune-related (e.g. immunoglobulins, complement factors, lactoferrin), enzymes (e.g. lactoperoxidase, lysozyme), growth-factors (e.g. IGF), bio-active peptides (e.g. break-down products of caseins having a blood-pressure lowering effect). With the help of the latest advances in proteomics techniques, we will investigate the variability of minor proteins in raw milk. Samples with a special composition, or from cows with a specific genetic background, will be investigated to finds the enzymes/proteins which may help in explaining the differences found.
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Esther de Kort
Protein-mineral interactions in dairy drinks
The general aim of this project is to obtain a better understanding of the interaction of minerals with calcium and casein proteins for the development of (concentrated) dairy products with respect to heat stability and shelf life.
The main aim can be divided into four sub aims:
- Study and unravel the physical/chemical interactions of organic and anorganic phosphates with calcium and casein
proteins.
- Study the effect of varying ionic environments on the hydrodynamic volume of casein proteins.
- Develop, with the obtained protein-mineral interaction knowledge, compact protein particles for concentrated dairy
products.
- Relate the physico-chemical properties of the casein micelles to the sensory perception of dairy products.
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Ellen Wemmenhove
Risk assessment of Listeria monocytogenes in (semi) hard cheeses
For accurate prediction of the relevance of L. monocytogenes, in semi-hard cheeses, more information about the occurrence, growth and survival of this organism in products and processing environment is required. In case of contamination of semi-hard cheeses with this organism, model calculations predict growth of the organism while this risk is very limited in practice.
The aim of the project is to identify critical points that determine contamination and/or growth of Listeria monocytogenes in semi-hard cheeses. Relevant growth data of Listeria for different product and storage conditions will be collected and generated. The overall aim is to improve predictive models for Listeria in semi-hard cheeses
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Lu Jing
Explaining the variation in milk composition by analyzing the milk production related proteins
The composition of milk, and its variability, depends on the synthesis of the major components of milk (fat, protein, lactose) in the udder in several metabolic pathways. Also, some components may be transported unchanged from the blood through the secretory cells into the milk. Many proteins/enzymes are involved in these metabolic pathways and in the transport of components. These proteins/enzymes can be detected in the milk using proteomic techniques.
Using proteomic techniques to analyse the minor proteins and enzymes in the milk, explanations for the variation in composition may be found.
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Sarn Settachaimongkon
Simultaneous growth of yoghurt starter cultures and probiotic bacteria
Yoghurt quality comprises a wide range of bacterial fermentation and sensory features such as composition and pre-treatments of base milk, varieties of starter cultures, fermentation conditions, flavour and texture of final product. This project aims at studying the simultaneous growth between traditional yoghurt starter cultures and three different strains of probiotic bacteria. Understanding the impacts of these different cultures on fermentation is essential in order to promote the growth and viability of probiotic strains as well as their potential for providing a good organoleptic properties yielding in significant higher quality products.
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