Hydrolysates from Sorghum Crude Kafirin Extract Exhibit Ice Recrystallization Inhibition Activity

Ice recrystallization can damage the microstructure of food products, and one potential solution is the use of molecules with demonstrated ice recrystallization inhibition (IRI) activity. The objective was to determine the IRI activity of sorghum kafirin hydrolysates as affected by succinylation and the dispersing medium. The IRI activity of the sorghum kafirin hydrolysates was analyzed by the splat assay in phosphate-buffered saline (PBS) and 10 mM NaCl. At 2% concentration, sorghum kafirin hydrolyzed by bromelain for 1 h resulted in 55% reduction in ice crystal size in 10 mM NaCl, while this was not observed when the dispersing medium is PBS. Succinylation at 0.25:1 molar ratio (succinic anhydride: amine group of the peptides) yielded modified hydrolysates that were slightly more IRI active in PBS, but the difference was not significant. The data showed the potential application of sorghum kafirin hydrolysates to act as antifreeze molecules to preserve the quality of frozen materials.