Study on the physicochemical/ microbial properties and gas chromatography profile of synbiotic yogurt

A synbiotic yogurt was provided by adding aerobic (Lactobacillus acidophilus) and anaerobic (Bifidobacterium bifidum) probiotics and inulin to the yogurt. The effects of aerobic and anaerobic probiotics, storage time, and inulin on the physicochemical/microbial properties of synbiotic yogurt in terms of acidity, viscosity, syneresis, and microbial count were studied. A head-space solid phase microextraction-gas chromatography (HS-SPME-GC) method was used to extract and detect of VOCs profile (total peak area and total peak height) of yogurt sample by nano-sized polyaniline fiber. The D-Optimal Combined Design (DOCD) was used to analyze the effect of probiotics type (aerobic and anaerobic), inulin percent (W/W %), and storage time of yogurt (day) on the physicochemical/microbial properties of synbiotic yogurt. Results showed that the aerobic and anaerobic probiotics, inulin, and storage time of yogurt affect the yogurt physicochemical/microbial property and there were relations between the physicochemical/microbial properties of yogurt and VOCs gas chromatography profile (total peak area and total peak height). The current research also enables us to obtain microbial count by total peak area and total peak height of the VOCs GC-profile of yogurt sample.