Physiological Activity of Deep‐Frozen Concentrates ofLeuconostocStrains

摘要

Abstract11 strains ofLeuconostoc cremorisand 1 strain ofLeuconostoc lactiswere the subject of investigations. Basing on the evaluation of growth parameters in the different cultivation media and on the diacetyl production ability in milk 2 strains ofLeuconostoc cremorisand 1 strain ofLeuconostoc lactiswere chosen for preparing frozen concentrated biomass. Sterile milk or cream (18 fat) were used as protecting agents. Concentrated biomass was frozen at −70 °C and stored at −30 °C for 3 months. The prepared concentrates contained from 1.6 × 1011to 2.8 × 1011colony forming units (CFU)/g. Except for one (strain “S”) the strains retained 100 survival. All the strains showed high growth activity after their recovery in milk (3.3 × 108‐ 8.4 × 108CFU/ml). Both protecting agents applied proved to be equally good for preserving viability of the cells and for their acidifying activity. In spite of the protecting agent a decrease in the aroma activity by 25–50 was observed after one month of the biomass storage. Nevertheless, concentrated frozen multicomponent starters containingLeuconostocstrains retained the ability to produce diacetyl and acetoin on the unchanged level during the three mont