Abstract
With the increase in the proportion of older people in the population, the development of foods especially suitable for this segment of the population is eagerly expected. We produced a soft, sticky variety of natto that is easy for older people to masticate and to swallow, using a bacterial strain improved by mixed culture. By screening natto bacilli for their ability to make soft Itohiki-natto, we selected the strain Bacillus subtilis (natto) KFP 897, but the stickiness of the natto produced with this strain was very weak. Using a mixed culture of KFP 897 with Micrococcus luteus IAM1056, we obtained strain KFP 89711, which produced a soft, sticky natto. At approximately 5.2 times that of KFP 897-natto, the relative viscosity of KFP 89711-natto was close to that of marketed natto. Similarly, the activity of the γ-glutamyl-transpeptidase of KFP 897 natto was approximately six times that of KFP 89711-natto. Analysis by capillary column gas chromatography detected the ten volatile substances that are responsible for the flavor of natto, showing that the flavor of KFP 89711-natto was similar to that of Japanese Itohiki-natto. Organoleptic tests were conducted on elderly subjects concerning the taste of the new soft, sticky natto at three official centers for the elderly in Chiyodaku, Tokyo. The participants viewed the new soft, sticky natto as being slightly better than their generally held opinion of natto. Consequently, the newly developed soft, sticky natto proved to be a useful food for older people.
