MTJ-skabelon

The ultimate objective of our research is to show how tasty meat and dairy products can be produced.

What is aroma?
The aroma experience of foods originates from the release of volatile components in the mouth during eating and drinking. The volatile compounds (the aroma compounds) are flushed by the retro-nasal air flow to the upper part of the nose, where a special organ is located. This organ is composed of a lot of sensory cells, each of which is reacting to a specific aroma compound. As foods may contain hundreds of different aroma compounds, there is a corresponding number of different sensory cells each reacting to specific aroma compounds. To make the whole thing even more complicated, people perceive the compounds differently. For instance, some people are unable to smell the boar taint compound androsterone (which smells as sweat or urine). This is why taste differs! By the way, the aroma of food must not to be confused with the taste sensed by the tongue if the food is sour, alkaline, salt or sweet.

How is aroma produced?
The aroma of food may originate from two sources: the aroma of the food itself and the aroma produced during cooking. The aroma of uncooked meat is very weak. The well-known aroma of meat is not released until cooking, when the meat is heated. The heating initiates a lot of complex chemical reactions producing the aroma compounds. These compounds are a complex mixture of indoles, phenols, sulphur compounds, organic acids, pyrazines and many more. The aroma of dairy products is quite different. The aroma of milk has a more pronounced aroma itself, e.g. originating from the feed given to the cow. The aroma of cheese originates both from the milk used for the cheese, and from the metabolites and degradation products of the bacteria and fungi added during production.

How is aroma measured?
Aroma can be measured by instruments or by sensory judgement. At the Dept. of Animal Product Quality we focus on the objective measurement by instruments. Before measuring the aroma compounds, these must be isolated and identified. To do this we use a gas chromatograph coupled to a mass spectrometer (GC-MS) or GC-olfactometry, where we, instead of a detector at the end of the column, have placed an outlet making it possible to smell each component originating from the column. By using this technique it is possible to obtain a direct smell-impression of each aroma compound in a given food object, and correlate these observations with the measurements by GC-MS.

How can the aroma of a given food object be manipulated?
The aroma formation in products as meat and milk is influenced by several factors. The genetics, feeding, housing conditions and the treatment of the animals just before slaughter affect the aroma of the products. Furthermore, the treatment of the meat after slaughter (ripening) is also of importance. A more special factor in the development of aroma is the fermentation in the intestine of pigs. It is here one of the other boar taint compounds, skatole, is produced by fermentation of undigested protein. The question is then whether other compounds influencing the aroma of pig meat are produced by fermentation in the intestine? To elucidate this question we have started to study all the volatile compounds being produced by fermentation in the intestine. We measure which volatile compounds are present in the intestine and which are present in the meat from the same pigs. By correlating these observations we might be able to see a correlation for other compounds than skatole.

			Mogens T. Jensen Scientist Dept. of Animal Product Quality Danish Institute of Agricultural Sciences Postbox 50, DK- 8830 Tjele, Denmark Tel: +45 8999 1218 - Fax: +45 8999 1564 E-mail: MogensT.Jensen @agrsci.dk
	Research group: Oxidation and aroma development in animal products SPME-references Private homepage Publication database Dept. of Animal Product Quality		The ultimate objective of our research is to show how tasty meat and dairy products can be produced. What is aroma? The aroma experience of foods originates from the release of volatile components in the mouth during eating and drinking. The volatile compounds (the aroma compounds) are flushed by the retro-nasal air flow to the upper part of the nose, where a special organ is located. This organ is composed of a lot of sensory cells, each of which is reacting to a specific aroma compound. As foods may contain hundreds of different aroma compounds, there is a corresponding number of different sensory cells each reacting to specific aroma compounds. To make the whole thing even more complicated, people perceive the compounds differently. For instance, some people are unable to smell the boar taint compound androsterone (which smells as sweat or urine). This is why taste differs! By the way, the aroma of food must not to be confused with the taste sensed by the tongue if the food is sour, alkaline, salt or sweet. How is aroma produced? The aroma of food may originate from two sources: the aroma of the food itself and the aroma produced during cooking. The aroma of uncooked meat is very weak. The well-known aroma of meat is not released until cooking, when the meat is heated. The heating initiates a lot of complex chemical reactions producing the aroma compounds. These compounds are a complex mixture of indoles, phenols, sulphur compounds, organic acids, pyrazines and many more. The aroma of dairy products is quite different. The aroma of milk has a more pronounced aroma itself, e.g. originating from the feed given to the cow. The aroma of cheese originates both from the milk used for the cheese, and from the metabolites and degradation products of the bacteria and fungi added during production. How is aroma measured? Aroma can be measured by instruments or by sensory judgement. At the Dept. of Animal Product Quality we focus on the objective measurement by instruments. Before measuring the aroma compounds, these must be isolated and identified. To do this we use a gas chromatograph coupled to a mass spectrometer (GC-MS) or GC-olfactometry, where we, instead of a detector at the end of the column, have placed an outlet making it possible to smell each component originating from the column. By using this technique it is possible to obtain a direct smell-impression of each aroma compound in a given food object, and correlate these observations with the measurements by GC-MS. How can the aroma of a given food object be manipulated? The aroma formation in products as meat and milk is influenced by several factors. The genetics, feeding, housing conditions and the treatment of the animals just before slaughter affect the aroma of the products. Furthermore, the treatment of the meat after slaughter (ripening) is also of importance. A more special factor in the development of aroma is the fermentation in the intestine of pigs. It is here one of the other boar taint compounds, skatole, is produced by fermentation of undigested protein. The question is then whether other compounds influencing the aroma of pig meat are produced by fermentation in the intestine? To elucidate this question we have started to study all the volatile compounds being produced by fermentation in the intestine. We measure which volatile compounds are present in the intestine and which are present in the meat from the same pigs. By correlating these observations we might be able to see a correlation for other compounds than skatole.