Abstract
Screening various food yeast strains revealed the growth capabililty of Candida utilis NBRC1086 on the medium of locust bean gum (LBG) . The composition of the LBG medium (pH 5.0) was 0.5% (w/v) LBG, 0.3% (w/v) (NH4) 2SO4, 0.02% (w/v) MgSO4⋅7H2O, 0.01% (w/v) Yeast extract, 0.15% (w/ v) NaH2PO4, 0.1% (w/v) KH2PO4. C. utilis has been cultivated for 24 hours, degraded by producing the β-mannosidase into the culture broth when transferred to shorten LBG (120 kDa) from LBG (300 kDa) . Each LBG could be separated by gel filtration chromatography. The homogeneity of shortened LBG was confirmed by paper chromatography and gel permeation chromatography (GPC) . The mannose / galactose ratio in the acid hydrolysate in shortened LBG was found to be 2.8: 1 using HPLC. The purified shortened LBG had a high level of cryoprotective activity (100%) at a concentration of 50μg⋅m1-1. Furthermore, the activity of the purified shortened LBG was higher than those of LBG, mannan and other sugars. This cryoprotective activity was specified for lactate dehydrogenase (LDH) and alcohol dehydrogenase (ADH) . The CP50 of purified shortened LBG was 8.3×10nM, which was almost one-fifth of the CP50 of BSA. The cryoprotective activity of shortened LBG against a freeze-labile enzyme, had the possibility of protecting protein component in food materials, e.g. eggs, meats etc. from freezing damage, then shortened LBG could provide for various frozen foods such as good appetite feelings. The shortened LBG is expected to be more effective as a cryprotectant than LBG for various frozen foods.
