Preventive Effect of Oligosaccharides against Denaturation of Carp Myofibrillar Protein Caused by Freeze-Drying

Abstract

The preventive effect of oligosaccharides against denaturation of carp myofibrillar protein during freeze-drying was studied by measuring the inactivation of Ca²⁺-ATPase . In the presence of oligosaccharides, the activity of Ca²⁺-ATPase decreased fast at the stage of initial several hours and then remained the same level during subsequent freeze-drying period . The preventive effect was estimated by the following epuation : e=Δlog k_D/a, where k_D is the first order rate constant for inactivation of Ca²⁺-ATPase at the early stage, and a is the concentration (%, g/100 ml) of oligosaccharide. The e values of various oligosaccharide-containing syrups examined were observed to become lower in the order of #360, #470, #350, #450. It was also found that a values were high when syrups containing large amounts of maltotetraose or oligosaccharides of higher polymerization degree and only small amounts of glucose and maltose were used. Another preventive effect was investigated for the minimum concentration (%, g/100 ml) of oligosaccharide to keep the full activity of myofibrillar Ca²⁺-ATPase . The concentration was estimated by extrapolation of the linear relation between the logarithm of remaining myofibrillar Ca²⁺-ATPase activity and oligosaccharide concentration . The minimum concentrations of every oligosaccharide-containing syrup to prevent perfectly the activity of myofibrillar Ca²⁺-ATPase from the inactivation during freeze-drying were within the limits of 5-9% .