Sucrose cryoprotective effect

Organic Compounds. Sucrose, glucose, other sugars, and sorbitol have cryoprotective effects on frozen mince of Alaska pollack (60,118) and carp actomyosin (117,119,120). Furthermore, ethylene glycol, glycerol (121,122), and citrate (123) have cryoprotective effects on the proteins in muscles of Alaska pollack and cod. 

Sucrose and sorbitol are commonly used in frozen surimi processing. However, sucrose imparts a sweet taste to surimi products, which is undesirable to the consumer (Sych et al., 1990 Auh et al., 1999 Sultanbawa and Li-Chan, 2001). Thus, the use of other cryoprotectants to reduce sweetness but exhibit the equivalent cryoprotective effect is required. Auh et al. (1999) used highly concentrated branched oligosaccharide mixture (HBOS) as cryoprotectant in fish protein. An addition of HBOS resulted in the remainder Ca -ATPase activity of actomyosin extracted from Alaska pollock after freeze-thawing the best stabilization effect of HBOS was observed at a concentration of 8%. Sych et al. (1990) studied the cryoprotective effects of lactitol dehydrate, polydextrose, and palitinit at 8% (w/w) in cod surimi in comparison with an industrial control (sucrose/sorbitol, 1 1). The... 

Initially, glucose was used as cryoprotectant however, colour problems were encountered due to the initiation of Maillard-type non-enzymic browning reactions. Sucrose was effective at the 8% level, but the resultant surimi was found to be too sweet. Currently, a combination of sucrose... 

This argument does indeed support the contention that on a per-mole basis PEG is much more effective than sucrose at increasing protein chemical potential. And for cases where relatively high concentrations of PEG (e.g., >1% wt/vol) are needed to confer cryoprotection, the Timasheff mechanism may be applicable. However, it seems unlikely that a PEG concentration of 0.01% (wt/vol) would have a significant effect on the thermodynamics of the system. This is because the actual parameter of interest is the transfer free energy of the native versus denatured protein from water into cryoprotectant solution. The difference between the values for the two states determines the magnitude of the effect on the free energy... 

Figure 2. Effect of temperature on inactivation of thylakoids in the presence of NaCl. Washed thylakoids were suspended in a solution containing 100 mM sucrose and NaCl and were kept for 3 hours at 0°C, —6°C and —12°C. Freezing and thawing were fairly rapid and final temperatures were reached within less than 2 minutes. Sucrose served as cryoprotectant and was added to prevent freeze-inactivation of the membranes in the presence of low salt concentrations. After thawing, the activity of cyclic photophosphorylation was measured. Experimental conditions have been described previously (5, 20, 21).

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