The research team of Stefanie Bruckner, Antonia Albrecht, Brigitte Petersen and Judith Kreyenschmidt of the University of Bonn and the University of Applied Science in Münster looked at the influence of fluctuations of the cold chain on the growth of Pseudomonas spp. on fresh pork and poultry.

Through this research, they were able to establish the shelf-life of the product.

In each trial, the shelf life at the control scenario of 4°C (constant) was compared with shelf-life at two dynamic scenarios including temperature shifts from 4° to 7° and to 15°C, respectively.

Overall, fresh pork and fresh poultry showed similar spoilage patterns at dynamic temperature conditions with remarkable reductions in the shelf-life when short temperature upshifts occurred at the beginning of the storage.

The reduction in shelf-life was up to two days or more than 30 per cent, although the storage time with an abusive temperature was less than five per cent of the total storage time.

In another study, besides the extrinsic factor, temperature, the intrinsic factors, pH-value, aw-value, Warner-Bratzler shear force (WBSF), d-glucose, L-lactic acid, fat and protein content were analysed.

The team found that the growth of Pseudomonas spp. was clearly dependent on temperature, with faster growth at higher temperatures.

The research team said that the growth was faster on fresh poultry than on fresh pork resulting in shorter shelf lives at constant temperatures from 2° to 15°C. Almost all of the investigated intrinsic factors were significantly different (P<0.05) for fresh pork and poultry (except aw-value and L-lactic acid).

As expected, scenarios with shifts to 15°C led to higher shelf life reductions than scenarios with shifts to 7°C for both meat types.

The research team said that early spoilage of fresh meat can lead to food waste and thereby economic losses as well as the loss of consumer confidence.

Until now, there have been no detailed studies describing and comparing different intrinsic and extrinsic parameters and their influence on the growth of Pseudomonas spp. as specific spoilage organism in different types of meat.

Understanding the main impact factors on shelf-life of fresh pork and poultry is a prerequisite for the development of methods and tools for improving processes in meat supply chains.

In particular, the results can serve as a basis for the development of mathematical models that can predict the shelf life and remaining shelf life of both meat types.

The studies have been published in the International Journal of Food Science and Technology and the Journal of Food Quality.

August 2012