Measurement of eutectic and co-melting point in freeze-drying foods

Based on the electric resistivity method,the eutectic and melting point of 2% 5% mannitol solution and 2% NaCl solution(mass fraction) were measured respectively.The results showed that: for the same kind of material,the eutectic point is lower than the co-melting was.The higher concentration of solution,the lower temperature of eutectic and co-melting was.Different solutes of solution have different eutectic and co-melting point.The curves of temperature-resistance will be different if the solutes and kinds of solution are different.According to the feature of measurement curves,proposed different methods to determine the eutectic and co-melting point: use temperature of mutation point as eutectic piont if the resistance mutated.Otherwise,combine the change rate and value of resistance to determine the eutectic and co-melting point.