the mixture and of the fraction containing the lipid free agent compared an increase in the nucleating point of 3 u00b0 c is observed consequently lipids contribute to the production of a high nucleating activity the effect of mercaptoethanol and of 0 01m sds is measured at various ph values on crude berry extracts mercaptoethanol has no effect on the nucleating point which indicates that disulphide bridges are not essential for the nucleation and the effect of sds on the nucleating point is relatively limited 0 u00b0 to 1 u00b0 c according to the ph which indicates that the positive charges at the surface of the agent are not essential for the nucleating activity sds adds an excess of negative charge to the protein and thereby masks the positive charges present at the surface of the protein likewise the ph appears not to influence the behaviour of the nucleating agent finally the action of n bromosuccinimide nbs on the nucleating point of the agent is analyzed the mixture of purified nucleating agent and nbs final concentration 0 001m is adjusted to ph 3 0 by adding small quantities of 2m hcl and it is then left for 30 minutes at 25 u00b0 c before being readjusted to ph 7 5 by adding small quantities of a tris buffer the determination of the nucleating point before and after treatment reveals a decrease of 2 8 u00b0 c in this point this indicates that aromatic amino acids are important for the nucleating activity nbs oxidizes the indole groups and the tyrosines the following examples are presented by way of illustration of the various industrial applications of the nucleating agent according to the present.