Test Science of Steaming

This study looked at the effect of steaming on micro-organisms in hay, comparing decent hay to hay that had been badly stored, and had “spoiled”. They also followed the change in microbiota after holding for 24 hours post-steaming. They prepared the compromised hay by wetting some hay and holding at room temperature for 6 days. The work was carried out on a laboratory scale, using 750 g portions of hay held in nets within a small steam chamber. They investigated several time intervals for steaming, along with several temperatures, spanning from 50 deg C for 90 minutes through to 100 deg C for 20 minutes. The subtleties of the mathematical methods used for comparison mean that differences focus on the median values, rather than the arthmetic mean values. For the normal (i.e., uncompromised) hay, steaming caused a reduction of the total count by an average 96% irrespective of the steaming conditions. Additional storage of the steamed hays at room temperature for 24 hours did not affect the microbial counts compared with the samples that were immediately analyzed after steaming. In the normal hay, the impact of steaming on mould was not statistically significant, although the baseline levels were notably low, and the yeast levels were too low to be measured. The compromised hay had much higher levels of microorganisms, so it was a useful testing ground for assessing the impact of various steaming conditions. They found that the count for total moulds was controlled effectively by all steaming conditions tested (nearly 100% reduction on average) . There was a similar trend for reduction in yeasts, but this was reported as being less statistically significant within the data analysis, generally a sign that some samples will have contradicted this trend. The results for were interesting. Inm highly bacteriallyu contaminated hay, steaming was fairly ineffective in reductng bacterial numbers. The exception was for Bacillus species, which were controlled by on average 88% by steaming at 100 deg C. They also examined the effect of steaming on the nutrient levels in hay. They tested the nutrients in the uncompromised hay, which were largely unchanged by steaming, except for some minerals, such as sodium and copper, which were lowered.