FERMENTATION PROPERTIES OF INTESTINAL STRAINS OF LACTOBACILLUS, OF A SOUR DOUGH AND OF A YOGURT STARTER CULTURE IN AN OAT-BASED NUTRITIVE SOLUTION

Fermented oatmeal soup containing viable lactic acid bacteria is a product which can be used as a base for a nutritive solution in enteral feeding. Oatmeal soups were individually inoculated with 18 strains of Lactobacillus, isolated from the intestinal mucosa of humans and rat, and with two kinds of commercial starter cultures L. plantarum strain A1 (sour dough) and a mixture of L. bulgaricus and S. thermophilus (yoghurt), and fermented at 37 °C for 15 h. The rate at which the pH decreased depended on the strains used, and the time taken for pH 4·0 to be reached in the soups varied from 6 to 15 h. The viable counts of lactobacilli varied in the final soups, from 1·0×108 to 4·7×109 cfu ml-1. The amount of lactate varied between 0·3 to 0·9 g/100 ml soup and L. plantarum strain A1 produced the highest proportion of D-lactate of the total amount of lactate. 53% of the tested strains produced 0·05 g acetate/100 ml soup, or more. L. plantarum (299, A1) and L. reuteri (108) were shown to have different requirements for amino acids during the fermentation process in the oatmeal soup. L. acidophilus (308) showed the slowest rate of pH decrease, which also gave a low amount of viable cells in the final soup (1×108 cfu ml-1) after 15 h fermentation. There were distinct differences in the aroma among the soups fermented by homofermentative and heterofermentative bacteria. For instance, the aroma of the soups fermented byL. plantarum (299 and A1) was more appetizing than of the soup fermented by L. reuteri (108). © 1992 Academic Press Limited.