Synbiotic yoghurts are fermented using a probiotic starter culture and prebiotics, which are claimed to promote health benefits. We have previously shown that new prebiotic oligosaccharides derived from lactulose (OsLu) are chemically stable during fermentation and cold storage. This study tested how physical properties are affected when adding OsLu and lactulose at concentrations reasonable for fermented milks' consumption (2% and 4%). Sixty six stirred yoghurts were produced from skimmed milk (<0.1% fat), as high-heated (95 °C, 256 s) after prebiotic supplementation. Protein content was standardized (4.5–5.2%) by skim milk powder (SMP) or total milk protein (TMP). Lactose and maltodextrin served as inert carbohydrate controls. Fermentation was significantly slowed by OsLu or lactulose, regardless of concentration, indicating substrate inhibition. Such gels were softer and resulted in less viscous yoghurt. Multivariate analysis revealed clustering into samples containing OsLu, lactulose, or the inert carbohydrates, with acidification rate being the most prominent feature.

This work was supported by the Spanish Danone Institute and Spanish Ministry of Economy, Industry and Competitiveness (project AGL2017-84614-C2-1-R). Paloma Delgado-Fernández thanks her contract from Spanish Danone, as well as the scholarship from German Academic Exchange Device (DAAD).

Peer reviewed