Study of the concentration of volatile compounds in synbiotic yogurt by polyaniline-ZnO fiber/gas chromatography

The chemical polymerization method was used to fabricate polyaniline-ZnO fiber at room temperature. The effects of aerobic (Lactobacillus acidophilus) and non-aerobic (Bifidobacterium bifidum) probiotics and inulin on the concentration of volatile organic compounds (VOCs) including acetone, acetic acid, acetaldehyde, diacetyl, lactic acid, ethanol and methanol in yogurt samples were studied. A head-space solid phase microextraction (HS-SPME) method by polyaniline-ZnO nanocomposite fiber was used to extract VOCs of yogurt samples. The extracted VOCs was detected and quantity determined by Gas chromatography-Flame Ionization detector (GC-FID). An experimental design based on D-Optimal Combined Design (DOCD) was used to study some factors effect on the concentration of VOCs. The type of probiotics (aerobic and non-aerobic), percent of inulin (W/W %), and storage time of yogurt (day) were studied as three variable factors that affect the concentration of VOCs. Results showed that 1- The fabricated polyaniline-ZnO fiber could extract VOCs and could be coupled with GC-FID, 2- The aerobic and non-aerobic probiotics, inulin, and storage time of yogurt affect the concentration of VOCs.