DOCTORAL DISSERTATION: The role of water in matrices stabilizing health promoting oils

Monday, 15 December 2008 17:41

Enrichment of processed foods with health promoting fatty acids (e.g. omega-3) would be a convenient way of ensuring their sufficient intake at population level. The challenge lies in the low oxidative stability of omega-3. VTT's Research Scientist Riitta Partanen, M. Sc. (Tech.), investigated in her doctoral thesis the importance of water in the preservation of omega-3 fatty acids containing triglycerides in food matrices. The results of this research could be exploited in the development of foods containing oxygen-sensitive bioactive compounds.

Unsaturated fatty acids are easily oxidized producing off-flavours in foods. Availability of oxygen is the rate limiting to oxidation in glassy food matrices. The role of water as a plasticizer for carbohydrate and protein matrices was investigated in the doctoral work of Riitta Partanen. In addition, the effects of water on mass transfer, and furthermore, on the preservation of oxygen sensitive and volatile compounds were investigated.

These studies revealed that the mobility of linear starch polymer, amylose was increased by both glycerol and water. Increased oxygen permeation was found with increasing polymer mobility. The influence of water on the oxygen permeability was explained, not only by increased diffusion due to plasticization of the matrix, but also by the role of water as a solvent for oxygen.

Oxygen transfer in carbohydrate and protein matrices was studied indirectly through oxidative stability of matrix-embedded oils. Again, the role of water was evaluated. The experiments showed that both whey protein and modified starch formed a matrix, which slowed down oxidation of oils rich in polyunsaturated fatty acids. Interestingly, the influence of water on the oxidation rate was markedly dependent on the matrix. Oxidation in carbohydrate matrices followed the hypothesis of increased oxygen transfer with increasing humidity, as oxidation rate was lowest at low humidity. On the contrary, whey protein matrix provided most protection at humid conditions, which implies the importance of reactivity of the functional groups.

Some guidelines could be suggested based on these results for designing novel food products, which contain nutritionally important but technologically challenging fats. The research is continued in cooperation with the University of Tottori, Japan.

Riitta Partasen defended her doctoral work: "Mobility and oxidative stability in plasticised food matrices. The role of water" in the Helsinki University of Technology, Espoo (Kemistintie 1), 5th December 2008 at 12 o'clock.

Suomenkielinen väitöstiedote: http://www.vtt.fi/vtt/01122008_partanen_vaitos.jsp?lang=fi
Download the thesis (Pdf, full-text): http://www.vtt.fi/inf/pdf/publications/2008/P697.pdf

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