A nutritional composition obtainable by fermenting a mixture comprising protein, carbohydrate and fat, wherein the major source of protein is potato protein, and wherein the mixture is fermented by lactic acid-producing bacteria.

A method of fixating and stabilizing nitric oxide metabolites within fermented natural substance according to an embodiment of the present disclosure includes adding a fermentative strain to nitrogen-containing natural substance and carrying out fermentation. The fermentation efficiency is maximized by optimizing the fermentation conditions so that the productivity of nitric oxide metabolites is significantly improved. Thus, eating a fermented natural substance in which nitric oxide metabolites are fixated and stabilized by the method of the present invention would be helpful for maintaining the homeostasis of human body, in which nitric oxide synthase is either absent or insufficient, based on vasodilation and activation of a neurotransmitter and immune function as medical efficacy of nitric oxide.

The present invention provides novel Lactococcus lactis lactic acid bacterium strains having improved texturing properties and methods of using the strains for producing food products.

An object of the present invention is to provide a method for efficiently obtaining a lactic acid bacterium that is made to contain a large amount of double-stranded RNA; and a lactic acid bacterium having a high double-stranded RNA content obtained by the method. The object is achieved by: (1) a method for producing a double-stranded RNA-containing lactic acid bacterium, including a step of culturing a lactic acid bacterium under at least one condition of an aeration condition and a low-temperature condition lower than an optimum temperature, thereby obtaining the double-stranded RNA-containing lactic acid bacterium; (2) a double-stranded RNA-containing lactic acid bacterium, in which the content of double-stranded RNA is 2.0 times or more as compared with the content of double-stranded RNA when a bacterium of the same strain is cultured for the same culture time under an optimum temperature and non-aeration condition; or the like.