The recently published WHO/FAO guidelines on the assessment of allergenicity of 
novel food proteins provide a strategy with which to approach the determination 
of the potential of novel proteins in foods to be allergens. Key to this 
strategy are the assessment of sequence similarity to known allergens and the 
assessment of the resistance to pepsin hydrolysis. Ice structuring proteins 
(also commonly referred to as anti-freeze or thermal hysteresis proteins) are a 
group of naturally occurring proteins that bind to ice and structure ice crystal 
formation. The amino acid sequence of the ice structuring protein (ISP) type III 
HPLC 12 (ISP type III) was compared in silico with the sequences of known 
allergens. Secondly, the resistance to pepsin hydrolysis of ISP type III and its 
glycoconjugates (produced in recombinant baker's yeast) was assessed. The 
results indicate that ISP type III has no sequence similarity with known 
allergenic proteins. Both ISP type III and ISP type III glycoconjugates 
contained within the fermentation product were hydrolysed readily by pepsin (50% 
loss in <10 min at pH 1.5) to give peptide fragments that were too small to be 
allergenic or to trigger cross-linking to IgE. In an accompanying study, we 
demonstrated that IgE from fish-allergic individuals did not bind ISP Type III. 
Therefore, in accordance with the WHO/FAO strategy, the assessment of ISP type 
III and ISP type III glycoconjugates by sequence analysis together with lack of 
resistance to pepsin hydrolysis and the absence of IgE binding supports the 
conclusion that both are unlikely to present a potential sensitisation hazard.