Abstract
This study evaluated the physicochemical characteristics of Gracilaria birdiae and the effects of aqueous extract of this seaweed on the physicochemical, microbiological and textural features of milk fermented with a mixed culture of Streptococcus thermophilus, Lactobacillus acidophilus and Bifidobacterium animalis subsp. lactis. The seaweed powder contained 68.61 g 100 g−1 dietary fibre and the seaweed aqueous extract was composed of 2.44 g 100 g−1 total solids. The seaweed did not inhibit the growth of cultured microorganisms and all fermented milk assays achieved similar microbial viability and acid production after 5 h at 37 °C. Nonetheless, the microbial viability tended to be above 9 log cfu ml−1 in the assays added to G. birdiae even after 2 h of fermentation, with increased acid production at this period compared to the products without seaweed. When the seaweed extract was compared to gelatin as a texture modifier, the effect of G. birdiae was higher than the animal hydrocolloid. Moreover, the interaction effect of these two ingredients was about a half that of the seaweed alone. The desirability function showed that similar texture parameters obtained for the final product prepared using gelatin at 0.4 g 100 g−1 would be obtained using only G. birdiae at 0.3 g 100 g−1.
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