Calcium binding and calcium-induced gelation of normal low-methoxyl pectin modified by low molecular-weight polyuronate fraction. (August 2017)

• Record Type: Journal Article
• Authors: Nakauma, Makoto; Funami, Takahiro; Fang, Yapeng; Nishinari, Katsuyoshi; Draget, Kurt I.; Phillips, Glyn O.
• Is Part Of: Food hydrocolloids. Volume 69(2017)
• Page Start: 318
• Page End: 328
• Publication Date: 2017-08
• Subjects: Calcium binding -- Egg-box dimer -- Gelation -- Low-methoxyl pectin -- Low molecular-weight fractions; Hydrocolloids -- Periodicals; Food additives -- Periodicals; Colloïdes -- Périodiques; Aliments -- Additifs -- Périodiques; Colloids; Food additives; Periodicals; Electronic journals; 664.06
• DOI: 10.1016/j.foodhyd.2016.12.035
• Languages: English
• ISSNs: 0268-005X

Abstract

Abstract: Functions of low molecular-weight polyuronate fractions in the calcium binding and calcium-induced gelation of normal low-methoxyl pectin (LMP) were investigated. The fractions from pectin with two different degrees of esterification (DE) and also from alginate with two different mannuronate/guluronate (M/G) ratios were prepared within the weight average molecular-weight range from ca. 40–65 kg/mol. In the mixtures of LMP and each polyuronate fraction, changes in the relative viscosity ( η r ) of dilute solutions and in rheological properties of gels were examined in the presence of calcium. Different results were indicated between the pectin and the alginate fractions. The addition of the pectin fractions, regardless of its DE, increased η r of dilute solutions and increased dynamic storage modulus ( G ′) of gels with showing greater effects at the lower DE. On the contrary, the addition of the alginate fractions, regardless of its M/G ratio, increased the critical threshold concentration of calcium required for the increase in η r of dilute solutions and decreased G ′ of gels with showing greater effects at the lower M/G ratio (i.e. guluronate rich). Based on the results, molecular associations of the mixtures were presented schematically to compare the functions between the pectin and the alginate fractions. Graphical abstract: Highlights: Ca-binding of normal LM pectin was modified by low M w polyuronate fractions. Ca-binding site plays an important role for either the pectin or the alginate fractions. The pectin fractions associate with LM pectin and increase the elasticity of Ca-induced pectin gel. The alginate fraction segregates from LM pectin and decrease the elasticity of Ca-induced pectin gel.