Associations between microstructural features and dispersion stability: A comparative study of orange and lemon...

The relationship between pectin structure and dispersion stability remains unclear. This study aimed to investigate the differences between citrus pectin (L1: lemon pectin, degree of esterification, DE: 72%; L2:lemon pectin, DE: 68%; O1: orange pectin, DE: 72%, O2: orange pectin, DE: 68%; CP150H: standardized pectin, DE: 69%). It indicated that lemon pectin and orange pectin differed in monosaccharide composition such as arabinose content, homogalacturonan (HG)/rhamnogalacturonan I (RG-I) ratio, and degree of branching. The standardized pectin CP150H exhibited the highest in acetyl content (1.48% ± 0.26%) and ferulic acid content (0.88 mg/g ± 0.02 mg/g) which resulted in its strong hydrophobicity in the situation of the similar apparent molecular weight and degree of esterification. Atomic force microscopy (AFM) revealed chain-like and entangled features for CP150H and orange pectin, which was rarely found in lemon pectin. Subsequently, L1, L2, O1, O2, CP150H were added to yogurt at a concentration of 0.4% (w/v). Confocal laser scanning microscopy (CLSM) suggested that yogurt prepared with lemon pectin had larger droplet sizes than orange pectin. Scanning electron microscopy (SEM) showed the morphological states of different pectin in yogurt system, which indicated that orange pectin had a smoother film structure than lemon pectin. Only through the combination of various factors like molecular structure and hydrophobic moieties, can pectin exhibit enhanced dispersion stability.