Acid hydrolysis of kappa‐carrageenan as a way of gaining new substances for freezing process modification and protection from excessive recrystallisation of ice

Summary The effects of κ‐carrageenan and its hydrolysates on modification of the freezing process and also on inhibition of excessive recrystallisation of ice in sucrose solutions during storage were compared. Acid hydrolysis of κ‐carrageenan was carried out using sulphuric (H2SO4) and hydrochloric acid (HCl). Most effective in the hydrolysis process turned out to be H2SO4, which degraded κ‐carrageenan to a molecular mass of around 3 × 106 Da, after 1.5 h of hydrolysis. Addition of 0.005% of the new poligeenan (degraded carrageenan), to a sucrose solution (30%), frozen at −20 °C, caused a nearly 50% reduction in the phase‐change stages, and consequently, the total time of freezing was shorter. Significant retardation of recrystallisation was observed for both types of poligeenan, but a stronger effect was observed for the oligosaccharides obtained after HCl hydrolysis, and after 96 h of storage at −8 °C, the equivalent diameter of ice crystals was not greater than 11 μm.