第35卷，第12期 2015年12月
光谱学与光谱分析 Spectroscopy and Spectral Analysis
Vol. 35 ,No. 12 -pp3555-3559
December, 2015
LipidCompositionofNativeMilkFatGlobulesby
ConfocalRamanMicroscopy
LUO Jie, WANG Yu-han,LI Yi-qi, ZOU Yu-ning, LU Xin, REN Fa-zheng
Beijing Laboratory of Food Quality and Safety , Key Laboratory of Funetional Dairy -
College of Food Science and Nutritional Engineering , Beijing Higher Institution Engineering Research Center of Animal Product , Beijing100083, China
Abstract Native fat globules composed mainly of triglycerides are secreted as droplets of variable size . The size of fat globules affects the form of fat in dairy products and final functionality , which depends mainly on the composition of the globules and membrane . However, the relation between the composition and size of fat globules has not been studied in detail . In this study , differences in the lipid content and fatty acid composition related to the size of native fat globules were investigated using confocal Raman spectroscopy which offers the possibility of acquisition and analysis of the Raman signal without disruption of a single fat globule in natural suspension . The results showed small fat globules (SFG) had a higher ratio of band intensities at 2 885 /2 850 cm , indicating SFG tend to have a triglyceride core in a fluid state with a milk fat globule membrane in a crystalline state . In addition , the SFG had a higher level of unsaturation compared to large fat globules , shown by a lower ratio at 1 655 /1 443 cm1 . Using cream with selected SFG would allow a harder and more costly churning process but lead to a softer butter .
KeywordsMilk fat ; Size ; Confocal Raman spectrosoopy ; Composition
中图分类号：0657.3
Introduction
文献标识码：A
DOI:10. 3964/j issn.1000-0593(2015)12-3555-05
ulations of milk fat globules , which are related to the origin of these globules in the lactating cell].
Cheese made from LFG and SFG has different physico-
Milk fat is very important because it confers distinctive nutritional, textural and organoleptic properties on dairy products . Bovine milk contains 3% ~5% (w /) fat in the form of spherical droplets or globules , which naturally vary in diameter from 0. 2~~15 μm and exist in at least two distinct size distributions . The majority (~90% ) of globules in milk are small fat globules (SFG ; diameter ~O. 4 μm ); however , virtually all the fat is carried in large fat globules (LFG ; di-sdosssaesosaa tional and/or functional significance between the two size pop
chemical characteristics and aroma , It is suggested the differ-ences in fat globule size/shape could be responsible for the difference in functionality of cheesec-. Regardless of the difference in surface area + globule coalescence and aggregation properties of milk might be affected by fat globule size-de-pendent lipid composition's
Many different approaches have been considered as offi-cial methods for milk fat determination , as well as chromato-graphie teehniques , including gas chromatography and liquid chromatography+} . These techniques , which include ex trac-tion and separation steps , are costly in terms of time and rea-
Received : 2014-07-11 ; aceepted : 2014-12-10
Foundation item: Chinese Universities Seientifie Fund (2015SP001); National "Twelfth Five-Year~ Plan for Science & Technology Support
(2012BAD12B08 ); Beijing outstanding Ph . D. Thesis & guidance teachers of science and technology projeet funding(20131001904 )
Biography : LUO Jie, (1987—), doctoral candidate of China Agricultural University
Corresponding author
e-mail : renfazheng@ 263 .net
e-mail : lizzyj925@ hotmail .com