ON-LINE MEASUREMENT OF THE MICROBIAL IMPACTS ON THE GERMINATION OF BARLEY DURING MALTING

During germination, the metabolic activity of sterile barley was more pronounced than the activity of barley contaminated by its endogenous microbial population. CO₂ and heat production profiles showed higher peak values when microbial activity was eliminated. Moreover, the maxima in the profiles appeared sooner than with barley in the presence of its natural microflora. More intensive growth of the acrospire was observed with sterile barley and a malt was obtained with a higher and more homogeneous modification. Reverse effects were noticed when sterile barley was inoculated with an Erwinia sp. strain and germination was evaluated. The results provide clear evidence for the strong interaction between microbial and plant metabolism, even for non dormant and non water sensitive barley. The ratio of CO₂ production to heat production levels was a useful tool for on-line monitoring of microbial activity during germination. In this way, the effects of the microbial activity can be taken into account in the development of a more effective control of the malting process. All experiments were performed using a specially designed solid-state reactor.