Grape pomace high-methoxyl pectin: A new prebiotic stabilizer for low-fat synbiotic yogurt gels – Optimization and characterization

• Published in: International journal of biological macromolecules Vol. 282; no. Pt 5; p. 137139
• Main Authors: Mobasserfar, Reza, Shiri, Azam, Mofid, Vahid, Shahidi Noghabi, Mostafa, Gharibzahedi, Seyed Mohammad Taghi
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2024
• Subjects: Functional properties; High methoxyl pectin; Prebiotic polysaccharides; Probiotic viability; Rheology; Synbiotic yogurt; Functional properties; Prebiotic polysaccharides; High methoxyl pectin; Probiotic viability; Rheology; Synbiotic yogurt
• ISSN: 0141-8130; 1879-0003; 1879-0003
• DOI: 10.1016/j.ijbiomac.2024.137139

High-methoxyl pectin (HMP, 72.5 % esterification degree and galacturonic acid content of 67.9 %) was extracted from grape pomace using a sequential ultrasound-microwave extraction. The extracted HMP was used to develop low-fat synbiotic set yogurts containing probiotic cells. Higher grape pomace pectin (GPP) concentrations (0.5–2 %) increased the probiotic bacterial population of Lactobacillus acidophilus LA-5 and Bifidobacterium bifidum BB-12. Higher cell viability was observed for L. acidophilus LA-5 compared to B. bifidum BB-12. A response surface optimization showed that the presence of 8.08 Log CFU mL−1L. acidophilus LA-5 and 1.88 % HMP experimentally resulted in the best probiotic viability (10.83 ± 0.11 Log CFU mL−1), overall acceptability (8.03 ± 0.06), and pH (4.25 ± 0.05) values. Compared to pectin-free probiotic yogurts, the optimal yogurt gels presented higher probiotic survivability, lower syneresis, and superior storage-dependent sensory attributes during 21 days of storage. However, a 14-day storage period was generally deemed suitable. The GPP-containing yogurt compared to the pectin-free sample exhibited higher colloidal stability with a larger particle size (433.8 nm vs. 272.5 nm) and lower zeta potential (−20.4 mV vs. −10.6 mV). Field emission-scanning electron (FE-SEM) and fluorescent (FLM) microscopy images confirmed a denser microstructure for GPP-enriched yogurts. The chemical interactions in the yogurt were not affected by enriching with GPP as investigated by FTIR, whereas the steady and dynamic rheological properties were significantly improved. GPP-enriched yogurt had a firmer gel structure with a larger linear region and lower G′ compared to the control, indicating a semi-solid state. The GPP as a multi-functional prebiotic ingredient would be promising in designing healthier food products. [Display omitted] •Successful use of pectin (GPP) extracted from grape pomace in synbiotic yogurts•High prebiotic activity and colloidal stability of yogurts with GPP•More probiotic survival, lower syneresis, and better sensory attributes in GPP-yogurts•GPP enhances yogurt's microstructure and rheological properties for improved quality.•No notable change in yogurt's chemical interactions with GPP incorporation