Collaboration between the partners in the LIPIDTEXT project has been further expanded in 2006. For example CTH is now collaborating with IFL on the volatile analysis of samples from the fish muscle model. Moreover, the joint work between IIM, Unilever, CTH and DIFRES on evaluation of the same antioxidants in different systems has shown some interesting results. Thus, while caffeic acid has a very clear antioxidative effect in fish muscle model and in fish mince, its effect in fish oil emulsions is less clear as it promotes the formation of certain volatiles while it prevents the formation of others. This shows that the efficacy of antioxidants is very dependent on the oxidation mechanisms in the actual food system and therefore results obtained in one system cannot be extrapolated to another food system.
The collaboration with other projects in pillar 4 (PROPEPHEALTH and CONSUMERPRODUCTS) has been continued. The data from the collaboration with CONSUMERPRODUCTS project show a clear antioxidative effect of the grape fibres used in that project when applied in the fish muscle model. In contrast, the protein hydrolysates from PROPEPHEALTH project did not show an antioxidative effect when evaluated in the fish muscle model and they could not be evaluated in the o/w emulsion system, because they were not able to form physically stable emulsions when applied as emulsifiers.
Finally LIPIDTEXT has also joined the cross pillar initiative ETHICOD with plans for analysis of oxidation and proteolytic enzyme activity.
The mathematical modelling of lipid oxidation in liposomes and emulsions including work on the kinetics and oxygen mass balances has progressed further. In 2006, an advanced method (LC-MS) has been included to study the compounds that are degraded and to identify the compounds that are formed as a result of lipid oxidation. Interesting results that will improve our understanding of the oxidation processes have been obtained.
Interestingly, the data obtained in the fish muscle model with different fish species show that the oxidation pattern is the same, but that the oxidation rates are different. This indicates that the underlying oxidation mechanisms are the same, but that intrinsic factors such as endogenous antioxidants, trace metal levels etc can affect the oxidation rate.
The emulsion experiments have shown that emulsifiers and antioxidants are interacting with each other and with iron in a complex manner. These interactions may be even more complicated in more food like systems.
Important data about the effect of caffeic acid on the level of endogenous antioxidants have been obtained. It is expecetd that these data in combination with data obtained from the planned experiments in the coming period will allow us to suggest the mechanisms behind the antioxidative effect of this antioxidant.
The work on the relationship between texture and proteolytic profile is progressing very well. The data obtained can be used to identify the proteins that most likely are degraded by the different cathepsins and this can be linked to texture changes. In this period, the MS identification of proteins that are linked to texture changes have been more successful than in the previous period and very satisfying results have been obtained.