title: Characteristics of two calcium pectinates prepared from citrus pectin using either calcium chloride or calcium hydroxide.
abstract: Calcium pectinate (CaP) was prepared from citrus pectin using either calcium chloride (C-CaP) or calcium hydroxide (HO-CaP) as the source of calcium for the reaction. The production yields and the rates of decalcification for the two calcium pectinates were compared and both found to be lower for C-CaP than for HO-CaP. In an attempt to explain these differences, certain chemical and structural characteristics of the two products, including functional groups (-CH3, C═O, COO-), rheological properties, morphology, and egg-box junction zones, were investigated by Fourier transformation infrared (FTIR) spectroscopy, rheology, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results from FTIR showed that, with an increase in calcium content, the wavenumber values and peak areas of FTIR for -CH3, C═O, and COO- groups all changed dramatically for C-CaP, while they were virtually unchanged for HO-CaP. Rheological analysis of the CaP gel showed that C-CaP had a stronger cross-linked network structure and a greater range of elastic behavior as compared to HO-CaP. SEM images of two CaP gels showed irregular membranes. C-CaP maintained a tight structure and a smooth surface, whereas HO-CaP was loose and rough. The results from XRD revealed a higher degree of crystallinity within C-CaP than within HO-CaP, which indicated that C-CaP possessed compact, ordered, and stable egg-box junction zones while the junction zones in HO-CaP were metastable and loose.
authors.affiliation: Department of Food Science and Engineering, Jinan University , Guangzhou 510632, China.
authors.forename: Xiujun
authors.initials: X
authors.lastname: Guo
authors.forename: Hanying
authors.initials: H
authors.lastname: Duan
authors.forename: Chao
authors.initials: C
authors.lastname: Wang
authors.forename: Xuesong
authors.initials: X
authors.lastname: Huang
mesh_terms: D002122:Calcium Chloride / Q000737:chemistry; D002126:Calcium Hydroxide / Q000737:chemistry; D002957:Citrus / Q000737:chemistry*; D015394:Molecular Structure; D010368:Pectins / Q000737:chemistry* / Q000302:isolation & purification; D010936:Plant Extracts / Q000737:chemistry* / Q000302:isolation & purification; D012212:Rheology; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
chemical_list: D010936:Plant Extracts; D010368:Pectins; D002122:Calcium Chloride; D002126:Calcium Hydroxide