1. Cured Meat Discolouration
Influence of minor components on colour changes and oxygen uptake
Nadine Böhner, Wolfgang Danzl
Fraunhofer Institute for Process Engineering and Packaging IVV, Freising, Germany
Introduction
Discolouration and oxygen uptake are the major causes of quality deterioration of cured, boiled sausage. Fresh cut cured sausage turns grey within a few hours if it is exposed to oxygen and light. Especially the colour of the sausage influences the retail consumers´ acceptance. Even in MAP (modified atmosphere packaging) the residual oxygen content in the headspace of packaged sausages is up to 2 % because of oxygenation during slicing and packaging. This leads to a destruction of the characteristically pink colour during illumination. In the AiF funded Cornet-Project CureColour (49 EN/1) the influences of minor components like chlorophyll, carotenoids, tocopherol and nitrite on the sausages colour and oxygen uptake are investigated.
Fig. 1: a*-value of exposed sausage with green bell pepper, red bell
pepper, different nitrite contents (90, 130, 170 mg NO2/kg) as a function
of time with 2% O2 in the headspace of the measuring unit [5].
Material and Methods
In this study, the sausages were sliced and packed into an oxygen measuring unit. Afterwards the samples were illuminated in a cooling cabinet with 1200 lx at 7 °C. The colour changes during storage were measured as L*a*b*-values. The most interesting value was the a*-value which shows the redness of a product. Also the oxygen uptake of the sausage during illuminated storage was measured by a non-destructive fluorescence measurement method.
Results and Discussion
The bright red colour of cured sausages is formed by the reaction of muscle myoglobin with nitrite to nitrosomyoglobin [1]. Fig. 1 shows the a*-value of sausages with low (90 mg/kg), standard (130 mg/kg) and high (170 mg/kg) nitrite contents. The loss of the typically red colour is particularly high during the first 2 days. No difference in a*-value during the whole storage period is seen between the samples with different nitrite contents. Another batch of sausages was produced with small red (antioxidant) and green (photosensitizer) dried bell pepper pieces. The a*-value of the sausages with bell pepper is higher after 2 days of storage compared with the samples with varying nitrite contents. The higher a*-value of the red bell pepper sausage might be explained by the colouring of the sausage by the red bell peppers itself. The rapid loss of colour of all samples might be explained by the photosensitizing effect of the nitrosomyoglobin itself [2].
The oxygen uptake of the sausage with green bell pepper during exposed storage of 22 days with an oxygen concentration of 2‮‮‮ ‮% in the headspace, is significantly higher compared to the varying nitrite contents and the red bell pepper sausage (Fig 2). This might also be a result of the photosensitizing effect of the chlorophyll [2;4].
In addition the influence of supplemented vitamin E in the pig fodder and therefore the antioxidant effect of tocopherol in meat [3], which is used for cured sausage production, was analyzed. There was no significant effect of feeding 250 or 500 mg Vitamin E / kg fodder. This is right in line with the low recovery-rate of the tocopherol found in the sausage.
Fig. 2: Oxygen uptake of exposed sausage with green bell pepper, red bell
pepper, different nitrite contents (90, 130, 170 mg NO2/kg) as a function
of time with 2% O2 in the headspace of the measuring unit [5].
Conclusion
Minor components can influence the oxidative stability of cured meat products. Under illumination green herbs showed a prooxidative effect. The amount of nitrite and red bell pepper or feeding of tocopherol had no significant influence on both, discolouration and oxygen uptake. By stabilizing the colour of cured sausage with natural additives during transport, storage and in the retail outlets, it is possible to create a high potential for reduced economic loss and less discarded food.
References:
[1] Andersen, H. J., et al. (1988). Meat Science, 22(4),
[2] Sandmeier, D. (1996). Lipid / Fett, 98(6),
[3] Harms C, et al. (2003).Meat Science, 63(1),
[4] Björn, L. O. (2008). Photobiology - the science of life and light (2. ed. ed.). New York: Springer.
[5] Fraunhofer Institute for process engineering and packaging, Freising, Germany.
Poster presentation at 2012 EFFoST Annual Meeting,
20-23 November 2012, Monpellier, France
Contact person:
Nadine Böhner
Phone: +49 (0) /