第34卷，第1期 2014年1月
光谱学与光谱分析 Spectroscopy and Spectral Analysis
Spectroscopic Investigation of the Influence of
Vol. 34,No. 1 -pp92-97
January.2014
Calcium Ion on the Structures of Casein Micelles WANG Peng-jie', WU Jian-ping",ZHANG Hao', GUO Hui-yuan'
LIU Hong-na",REN Fa-zheng
1 . Beijing Laboratory for Food Quality and Safety , College of Food Science and Nutritional
Engineering , China Agricultural University , Beijing100083 , China 2. University of Alberta, Edmonton , Canada
3 , College of Food Science and Technology , Gansu Agricultural University , Lanzhou 630070 , China
Abstract The effects of calcium ion on the structural properties of casein micelles in the course of heat treat -ment were synthetically examined by non-structure-invasive spectrometry . The hydrophobicity , reflected by extrinsic fluorescence (ANS fluorescence ), was positively correlated with the concentration of the calcium ion within the range of O to 12 mmol - L1 . Meanw hile , the turbidity and stability of casein micelles also increased with the growth of calcium concentrations . However , opposite results were observed for hydrodynamic diame-ter and polydispersity index . Compared with the calcium ion , the calcium-chelator (citrate ) has an opposite effect on the structural characteristics of casein micelles . Within the calcium concentrations range of O to 12 mmol - L1 , the hydrophobicity - stability and turbidity were negatively correlated with the conentration of the calcium ion , nevertheless , opposite results were observed for hydrodynamic diameter and polydispersity in -dex . All the results indicate that the calcium ion could be used to modify the structures of casein micelles dur -ing heat heatment .
KeywordsCasein micelles ; Calcium ions; Structures; Spectroscopy
中图分类号：0657.3
Introduction
文献标识码：A
DOI: 10. 3964/j. issn. 1000-0593(2014)01-0092-06
sult in noticeable effects on milk stability[2]. Caseins are a group of unique milk-specific proteins , and represent 80% of the total protein in the milk of commercial dairy species . Ca-
In the dairy industry , various kinds of minerals are used to improve the quality of milk-based products, such as cheese + yoghurt and protein powders . These minerals play an important role in the process and the final quality of products , as they greatly influence the susceptibility of the products to sedimentation and gelation , rennet action , and fouling of heat exchangers . In general , all the minerals exist in dynamic e-quilibrium between the diffusible and the micellar phase in milk . Small changes in the distribution of minerals would re-
Received : 2013-04-10 , accepted : 2013-07-11
seins , the most important parts of milk , together with miner-als, exist mainly in the form of colloidal particles , i.e., the casein micelles(a) . The physicochemical characteristics of al-most all milk-based products mainly depend on the casein mi-celles[4]
The functional and chemical properties of casein micelles are determined by their structures , which can be altered by the modification of the microenvironment of milk . These al terations in the structures can be reflected in the hydrophobic-
Foundation item: International Science & Technology Cooperation Program of China (2011DFA32550 ), Ministry of Science and Technology of
China (2012BAD12B08)
Biography : WANG Peng-jie, (1986—), Doctoral Candidate of China Agricultural U niversity
Corresponding author
e-mail ; renfaxheng@ 263.net
e-mail : wpj1019@ 126 .com