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Jörg Hinrichs and the world of dairy products

What is the best way to bring together biology, chemistry, physics and the engineering sciences? Prof. Dr.-Ing. Jörg Hinrichs, director of the Department of Animal Foodstuff Technology and head of the Dairy for Research and Training at the Institute for Food Technology at the University of Hohenheim knows how: become a food technologist!

Prof. Dr.-Ing. Jörg Hinrichs has been the director of the Department of Animal Foodstuff Technology and the head of the Dairy for Research and Training at the University of Hohenheim since 2001. © Universität Hohenheim

Even a roundabout route can lead to the goal as Prof. Dr.-Ing. Jörg Hinrichs’ career clearly shows: back in the early 1980s, Hinrichs trained to become a dairy specialist at a company called Nordkontor in the city of Zeven in Lower Saxony. He was following in the footsteps of his ancestors – Hinrichs’ grandfather and his father were both dairy managers. After completing his training, however, Hinrichs pursued his academic ambitions by going on to study food technology at the Technical University of Munich. “I’ve always been interested in the natural sciences and in chemistry and physics in particular. I decided to study food technology because this gave me an excellent opportunity to combine my knowledge and interests. Food technology involves mechanical engineering as well as microbiology and process engineering. The role of food technologists is varied and depends on which area of industry they are working in. Activities can range from developing food production processes to inventing new recipes,” said Hinrichs.

Dairy technology has always remained central to his career: after his doctorate, he became a research associate in the Department of Food Process Engineering and Dairy Technology at the Technical University of Munich, and continued his scientific career as a senior academic councillor on the university’s Weihenstephan campus from 1997 to 1999. During this time, Hinrichs focussed on the high-pressure treatment of foods and more especially on the inactivation of microorganisms and the denaturation and structure of milk proteins. 

He is still working on the subject on which he habilitated. “The high-pressure treatment of food is an extremely efficient way to cause proteins to unfold and denature,” Hinrichs explained. He was appointed chair of the Department of Animal Foodstuff Technology at the University of Hohenheim in 2001 and has since focussed specifically on the texture and structure of food. “Structure relates to nano-, micro- and even macrostructures of food matrices. Texture is more summative and consists of anything that can be perceived with the eyes or mouth,” said Hinrichs explaining the terms structure and texture. His major centre of interest is the flow behaviour and gliding properties of orally consumed food with the aim of identifying the underlying chemical and physical phenomena.

The texture of dairy products determines their commercial success

The microstructure of mozzarella changes when it is heated (proteins are shown in red, fat in blue). Hinrichs’ research involves investigations into the structure of food and how it can be altered. © J. Hinrichs, Universität Hohenheim 2012

This knowledge about the structural and textural properties of food is of practical use for the food industry. A fat-free food product does not contain any fat globules. Its development requires the use of specific production processes and it also differs from fat-containing products in its microbiology, structure and taste. Hinrichs uses an example from dairy foam research, which is a relatively complex field, to explain what he means: “Whipped cream is essentially nothing more than balanced fat foam. Whipped cream that contains little fat collapses fairly quickly. In addition, fat absorbs and preserves flavours. The production of a low-fat product requires manufacturers to use special flavour mixtures as the distribution coefficients of the individual flavours between the gas phase and the matrix depend on the fat content of the product.”  Each flavour compound has its specific distribution coefficient, which is why the development and production of foamed, low-fat dairy products is rather complicated. Hinrichs’ team also focusses on the optimisation of apparatuses and processes for plastifying dairy products and giving them a specific structure. Mozzarella production is an excellent example of this. “Nowadays, mozzarella is mainly produced using semi-batch methods. We are working with a number of smaller companies in order to develop methods and tools that enable the efficient and continuous production of mozzarella,” Hinrichs says.

Hohenheim University membrane technologies modernise the dairy sector

Bacteriophages are viruses that infect bacteria, and bacteriophage specimens that infect dairy bacteria are the last thing that is required. The University of Hohenheim team is developing membrane technologies for separating bacteriophages from whey. © H. Neve, Max-Rubner-Institut 2012

Hinrichs’ team carries out numerous projects related to cheese production. One major focus is the development of innovative membrane technologies. The Hohenheim researchers have already developed an electrical membrane filtration method in which an electrical field is applied to a membrane in order to attempt to isolate small bioactive peptides from protein hydrolysates or to enrich large peptides that can be used as emulsifiers that stabilise interfaces.

Innovative membrane technologies are also an excellent means of separating bacteriophages from whey. Some bacteriophages are specific to bacteria that are required for making cheese. For example, Lactococcus bacteria give cheese a slightly sour taste and Leuconostoc species give cheeses a distinct flavour. The goal is therefore to prevent the bacteriophages from killing the bacteria. “Raw milk always contains phages of which around 90 percent are thermally so stable that they survive the pasteurisation process,” Hinrichs said. As a result, the bacteriophages are also found in whey that separates from milk after curdling. Whey is centrifuged to remove fat (whey cream), subsequently pasteurised, concentrated and further processed into cheese. Whey cream is returned to the cheese-making process.

“Amongst other things, we are investigating how and up to what temperature we need to heat whey cream in order to inactivate the phages and prevent them from compromising cheese quality. In addition, we are investigating how fat-free whey can be treated using our membrane technology to produce whey products with native proteins, but without bacteriophages,” said Hinrichs. The dairy industry is very interested in Hinrichs’ results, as such products are perfect as fermentation substrates and not associated with any health risk.

From research to application

As a cross-sectional scientist, Hinrichs is always interested in bringing together scientific and technical aspects, including in the broad field of enzymes. Enzymes have an effect on the formation of flavour or structure. Hinrichs is particularly focussed on the enzymatic formation of lactulose. It is a disaccharide (double-sugar) that forms naturally during the exposure of milk to intensive heat during which lactose isomerises. The lactulose content can therefore be used to characterise the thermal load of dairy products. However, Hinrichs is more interested in two other aspects. At a specific concentration, lactulose acts as a prebiotic within the colonic microflora, increasing the numbers of bifidobacteria and hence improving digestion. At higher concentrations, lactulose has a laxative effect. “The sugar’s properties can be used for making products that are specifically designed for the elderly or people in need of care. In order to make dairy products prebiotic, we are working with our partners to develop production methods that enable the enzymatic production of a defined amount of lactulose directly in the dairy product that is being manufactured,” said Hinrichs.

The application aspect of his research is an important incentive for Hinrichs: “Of course, our results are not always implemented directly, but I am always pleased to hear that a particular company has integrated our ideas and findings into the product development process.” In 2012, Hinrichs was awarded the German Dairy Industry Innovation Prize for his achievements, which underlines the practical benefit of his research. “Some projects were scientifically rather exciting, some dealt with an industrial aspect and others taught us something,” said Hinrichs summarising his research. His long-term experience with industrial projects is also beneficial for Hinrichs in his role as member of the scientific board of the Research Association of the German Food Industry (FEI), where he puts his engineering vision to good use. Hinrichs supports the FEI executive board in the evaluation of project proposals submitted to AiF (German Federation of Industrial Research Associations), thereby helping applying SMEs with the science behind their proposals without, however, losing sight of the projects’ economic importance. 

Further information:

University of Hohenheim
Institute of Food Science and Biotechnology
Prof. Dr.-Ing. Jörg Hinrichs
Garbenstr. 21
70599 Stuttgart
Tel.: +49 (0)711 459-23792
E-mail: jh-lth@uni-hohenheim.de

Website address: https://www.gesundheitsindustrie-bw.de/en/article/news/joerg-hinrichs-and-the-world-of-dairy-products