2. Results and considerations

Fig.1 (see on the Cover) shows survival curves of yeast in control medium and in media with various toxin concentrations of 1 u, 2 u and 4 u, respectively (b-d). The number of yeast cells in wort medium was estimated as follows; 1.0-10^-5 ml of each cort culture was transplanted on to agar medium, and after incubation at 30C for 24-48 hours, the number of the colonies of yeast was counted. It is demonstrated in the figure that 1 unit is the static concentrations for yeast growth, while 2 or more units bring the death of almost all cells. But certain strains of staub yeast, for instance strain BH 12, were not killed by the toxin.

a. Toxic effect of various cereals:

The toxic effect of various cereals used as raw material for alcoholic beverages were examined by the above mentioned methods. The results are given in Table 1.

It is interesting to note that wheat and barley showed strong effect (+++) and barley malt showed about one third effect (+) while other grains showed no effect (-).

b. Toxin content of wheat species:

It is well known that wheat species are classified into three groups, namely einkorn wheat (genome constitution AA), emmer wheat (genome constitution AABB) and dinkel or bread wheat (genome constitution AABBDD). It has been established by KIHARA and others that Aegilops squarrosa is one of the ancestors which donated D genome to bread wheat. Consequently, a hexaploid wheat has been synthesized from the cross of emmer wheat with Ae. squarrosa. The toxin content of these materials were measured for the purpose of detecting the differences in toxin content among wheat species with different genome constitutions.

The results are shown in Table 2, in which nitrogen contents of these materials are also given.

As shown in the Table, emmer wheat gives a lower content of toxin, while bread wheat and synthesized hexaploid wheat give the higher content, but the further studies are now under way.

c. Toxin content of barley species:

From the studies by ABERG, WIEKE and TAKAHASHI⁴, H. spontaneum and H. agriocrithon were estimated as the primitive forms of the cultivated type. So the toxin content of above two species and four varieties were measured for the purpose of examining if there are any differences in toxin content among barley species.

The results are shown in Table 3, in which nitrogen contents of these materials are also given. The results indicate that the content of cultivated varieties was higher than that of wild types.