Abstract

Bifidobacteria strains (BLR, BLE, Bbv-1 and Bbv-2) were investigated throughout changes in their growth and acidifying activity in the presence of yogurt starters (Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus) on reconstituted skimmed milk (10% w/v) supplemented with 5 or 10% (w/v) polyfloral or unifloral honey as a sweetener. A positive association (P>0.05) between S. thermophilus and each one of the four Bifidobacterium strains was observed and acidity of milk containing (5 or 10%)polyfloral or unifloral honey was acceptable (P>0.05). In associated cultures between oneBifidobacterium strain and Lactobacillus bulgaricus, only 10% of honey stimulated (P>0.05) growth and acid production of both organisms. However, the level of 5% has at the same time both stimulatory (P>0.05) and inhibitory effect (P>0.05) on bifidobacteriaand lactobacilli, respectively. A significant (P<0.05) improvement in bifidobacteria biomass (1.51 to 9.55%) co-cultivated with both lactic acid bacteria was observed in milk containing 5 or 10% honey.  However, only 10% honey seems to stimulate (P<0.05) lactic acid bacteria growth in this co-culture. Viability of all bacteria was improved (P<0.05) in the presence of honey, and acidity of fermented milks during storage was regulated, which is probably the cause of the good sensory properties of all honey-added yogurts.

Key words: Bifidobacteria, Streptococcus thermophilus, Lactobacillus delbrueckii subsp.bulgaricus, honey, sensory properties, acidification, viability