Preservation of moist grain anaerobically by so-called crimping has many advantages. Generally, preservation has been successfully performed when grain is harvested at 30–40% moisture content (MC). However, there is a trend towards using drier than the optimal MC of the raw material. This leads to an increasing need to control aerobic spoilage of the material and also to experimental challenges in assessing the quality and stability of low-MC crimped grain. The objective of the current work was to evaluate fermentation quality, microbial composition and aerobic stability (AS) of drier than the optimal crimped grain ensiled with different additives and to use these materials to compare three different AS evaluation methods. Crimped wheat grain with 28% MC was ensiled using eight additive treatments based mainly on formic and propionic acids including a control without any additive. The low MC resulted in no lactic acid fermentation, but significant ethanol formation occurred in the control. The treatments used resulted in clear differences in microbial quality and AS of the feeds, and use of formic and propionic acid-based additives provided a clear benefit in improving the AS of crimped wheat grain. The correlation between increasing temperature and carbon dioxide (CO2) production under aerobic conditions was very close, indicating that CO2 produced by aerobic bacteria can be used as a method of evaluating AS. Visual inspection of mould growth resulted in somewhat different ranking of the treatments.

Psychrotrophs, particularly Pseudomonas spp. are known to be the main determinants of the shelf-life of pasteurized milk and refrigerated raw milk. It is presumed that they mainly cause spoilage through the elaboration of proteinase and lipase enzymes. At the time of this research, under the relevant European Directive, one of the means of determining the quality of pasteurized milk was the pre-incubated count, which involves incubating the milk sample for 5 d at 6°C followed by a plate count. Examination of numerous pre-incubated counts revealed a bimodal rather than a normal distribution indicating that the types of contaminants in pasteurized milk may be as important as their initial concentration. Pseudomonads that gave particularly high (>5×106 cfu/ml) and low (<103 cfu/ml) pre-incubated counts were isolated (high and low count isolates respectively). After the organisms had been subjected to a cold shock no consistent trend between the groups of isolates was detected with respect to lag phase duration. However, the high count isolates consistently had a faster exponential growth rate. Unexpectedly, with the exception of one isolate, the low count isolates produced detectable proteinase and lipase earlier. In addition, with one exception, maximal proteinase and lipase production was observed with the low count isolates. These findings indicate that there is no causal relationship between selective growth advantage and ability to produce proteinase and lipase. It also indicates that the spoilage of pasteurized milk is a complex phenomenon and is worthy of further research.

The reason for the reported difference in spoilage behaviour of skim and whole pasteurised milks was investigated. The rates of growth of psychrotrophic bacteria were not significantly different in the two milks and the bacterial types, all pseudomonads, present at spoilage were also similar. However, when representative spoilage organisms were cultured into freshly pasteurised skim and whole milks, skim milks exhibited predominantly bitter flavours while whole milk showed mostly sour flavours. The different spoilage behaviours can be largely explained by greater proteolysis in skim milk than in whole milk, caused by higher production of protease and greater susceptibility of the protein to protease attack. In addition, lipolysis in whole milk, caused by the substantial quantities of lipase produced by spoilage pseudomonads in this milk, also contributes to the different flavours produced during cold storage of these milk types.

The method elaborated by Working Group 5 involves standard procedures for poultry meat sampling, sample preparation, inoculation of a selective isolation medium, counting of colonies and interpretation of results. These are described, together with full details of media preparation. Widespread adoption of the method in processing plants would help considerably in the establishment of more uniform quality control standards. In turn there could be significant benefits to international trade and to the image of the products of the poultry meat industry among consumers.