Trans Fat Lab to Label
Mar 31, 2015
Trans Fat
Lab to Label
What is trans fat?
Chemically: Geometric isomers of the natural cis form of unsaturated fatty acids
Physically: Fatty acids modified to have a higher melting point by changing their configuration from bent to straight.
What is a Trans Fat?
Oleic (9-cis-C18:1)mp: 13-14C
Elaidic (9-trans-C18:1)mp: 44-45C
Where Does Trans Fat Come From?
Chemical Hydrogenation of Vegetable Oils (may be >50%)
Biochemical Hydrogenation by Rumen Bacteria (5% or less)
Some Food Labeling History
Nutrition Labeling & Education Act 1990Major Change in Fat DefinitionNew Fat Methodologies RequiredOnly “cis” fats included in unsaturatesCall for Trans Fat LabelingDecision Delayed Pending Better Data
Trans Added to Label
Amended to Include TransRequired by Jan 2006
Why Trans Fat?
Trans Fat Raises LDL Cholesterol/Lowers HDLTrans Fat Increases Plasma TGsMay Be Stronger CHD Factor than Saturated FatUp to 100,000 Premature Deaths/yr in USAverage US Consumer Gets 2% of Calories from Trans Fat
What Foods Contain Trans Fat?
Margarines (Hard varieties are higher)Shortenings and Frying FatsFried FoodsBeef and Dairy FatsBakery Products
But . . . . Changing Rapidly
How Are They Measured?
Usually complex mixturesPHVO can have >40 isomers of 18 Carbon FAMore than 15 isomers of linoleic acids
Hydrogenation Increases Complexity
Salad Oil – no hydrogenation
C18:0
C18:1 C18:2
Hydrogenation Increases Complexity
Margarine C18 region only
C18:1 C18:2
Trans C18:1
How Are They Measured?
FTIR for Process Control of Fats and Oils(high levels, not for complex foods, specific)
HRGC for Products and Ingredients(low levels, complex foods, not specific)
Ag+ Chromatography/GC(Not practical at present, but may be useful in future)
Accurate Measurement ofTrans Fat in Foods
Specialized GC Capillary ColumnsVery Long Columns (100 meters)Optimized Separation of Trans Fats
Overview of Methodfor Measuring Fat
Crude Extract
Saponify with KOH
Esterify with Acid/MeOH
Separate and Measure by GCCriti
cal step fo
r trans fa
t
Optimized Trans Analysis
Standard Separation(Could underestimateTrans by up to 25%)
Optimized Separation
Optimized Trans Fat Separation
100 Meter Capillary ColumnSpecialized Stationary PhasesIsothermal Column TemperatureSplit Injection
US and Canadian Food Labels
US Canada
List Separately
List Sum
Trans Fat Label Requirements
USLabel trans fat >0.5 g per servingIf total fat < 0.5 g per serving, not required, but“Not a significant source of trans fat”No fat or cholesterol claims allowed
No nutrient content claims for trans fat
CanadaBoth sat fat and trans fat <0.2 g per serving to list as “zero”Limited use of “Not a significant source”
Future
Other Label Changes Being StudiedMay Add a %DV for Trans FatMay Allow Nutrient Content Claims for Trans Fat
Trans Fats Rapidly Disappearing from Food Products
Online Resources
Harvard School of Public Health Trans Fat Report:http://www.hsph.harvard.edu/reviews/transfats.html
FDA Trans Fat Labeling Q&A Siteshttp://www.cfsan.fda.gov/label.htmlhttp://www.cfsan.fda.gov/~dms/qatrans2.html