Probiotic yoghurt bars: exploring gelatine concentration effects on chemical composition, rheological and textural properties.

Abstract

Yoghurt is a food product with strong sensory acceptance and health appeal, making its matrix a target for various innovative presentations and modifications. This study aimed to develop a yoghurt bar with the addition of probiotic microcapsules and to evaluate the effect of gelatine concentration on its chemical composition, microbiological stability, rheological properties and texture profile. Three formulations were developed: YB6 (6.66% gelatine dispersion), YB9 (9.33% gelatine dispersion) and YB12 (12% gelatine dispersion) Probiotics were microencapsulated by ionic gelation, achieving 93.46% encapsulation efficiency. Gelatine concentration influenced protein (YB6/YB9: 6.95 g.100 g^-1; YB12: 7.65 g.100 g^-1) and sodium content (YB6/YB9: 56.00 mg.100 g^-1; YB12: 57.50 mg.100 g^-1) but did not significantly alter other compositional parameters. Probiotic counts (log CFU.g^-1) for Lactobacillus delbrueckii subsp. bulgaricus (YB6 = 7.08; YB9 = 7.34; YB12 = 7.4), Streptococcus thermophilus (YB6 = 9.20; YB9 = 9.08; YB12 = 9.18) and Lactobacillus acidophilus NCFM® (YB6 = 7.32; YB9 = 7.3; YB12 = 7.0) remained stable over 30 days at 5 °C, meeting regulatory standards for yoghurt classification. Gelatine concentration and temperature influenced rheological properties. At 10 °C, formulations exhibited no structural failure up to 1000 Pa of shear stress, whereas at 25 °C, YB9 and YB12 demonstrated higher structural integrity than YB6. YB12 presented the highest values of firmness, adhesiveness, cohesiveness, gumminess and elasticity. The yoghurt bar represents an innovative product that expands the range of fermented dairy options. The use of 9% or 12% gelatine dispersion in yoghurt bar production ensures good storage stability, protein enrichment and a suitable texture for handheld consumption, thereby expanding the scope of yoghurt-based offerings.