trans fat Flashcards
trans fatty acid:
an unsaturated fatty acid with a straighter chain than a cis fatty acid; usually results from partial hydrogenation; more solid than cis fatty acids; H atoms end up on different sides of the C chain.
Hydrogenation
Produces more solid fat Get isomerization (interconversion of cis and trans) during partial hydrogenation
TFA are solid fats produced artificially by heating liquid vegetable oils in the presence of metal catalysts and hydrogen. This process, partial hydrogenation, causes carbon atoms to bond in a straight configuration and remain in a solid state at room temperature.
iodine value- measure of trans fat
partially is the worst in that it has the most amount of trans fat
the higher the iodine value- zero tans and some saturated
the lower the value of iodine: zero trans sat but high in saturated
History of Hydrogenation
Began in early 20th century
1960’s—processed vegetable fats displaced animal fats; eliminated bad cholesterol
1980’s-1990’s–awareness of connection of saturated fat to heart disease; trans fat appeared to be good substitute
Commercial production of partially hydrogenated fats began in the early 20th century; 1911—cottonseed oil was hydrogenated to make shortening.
Increased steadily until about the 1960s as processed vegetable fats displaced animal fats in the diets of the U.S. and other Western countries.
Lower cost was the initial motivation.
Health benefits were later claimed for margarine as a replacement for butter.
The hydrogenation process became popular in the 1960s when it provided an alternative to frying and baking with saturated fat. Hydrogenated oils extended the shelf life and stability of the food, provided the same desirable characteristics in food without providing dietary cholesterol, and appeared to be the healthier alternative to saturated fat.
Consumption rose significantly in the 1980s and 1990s when the public embraced the connection between heart disease and saturated fats. Fast food restaurants replaced the beef fat in the fryers with partially hydrogenated oils. Food manufacturers began to market their products as free of saturated fats and cholesterol–but the substitute was partially hydrogenated oils.
Trans-free Not Always the Same
In some products, the removal of trans fat isn’t noticeable
Differences: texture, taste, and/or color
Trans-fat free Crisco: blends fully hydrogenated cottonseed oil with sunflower and soybean oil to give a pie crust that is more cracker-like
Triscuit—no noticeable difference
Wheat Thins—crispier
Keeble Wheat Crackers—consistently paler color; texture same
Oreo—different texture (not as crispy) and taste; cream filling not as creamy
crisco went to fully hydrogenated and is now much better
Strategies for Reducing Trans FA
Modification of the hydrogenation process
Use of interesterification
Use of fractions high in solids; fractionation
Use of trait-enhanced oils
Combination strategies
Modification of Hydrogenation
Pressure
Temperature
Catalyst
Affects FA composition, melting point, & solid fat content of the oil
Increases costs & production problems
Interesterification
Rearrangement (or randomization) of fatty acids on the glycerol backbone of triglyceride
Mix veg oil and “hardstock” (eg. lard or fully hydrogenated veg oil)
Chemical (heat and catalyst) or enzymatic (lipase) process
Modifies melting and crystallization temp
Trans-free (unless use partially hydrogenated)
Requires chemical catalyst (sodium methoxide) or enzyme.
Requires complex expensive to set up and operate.
Current interest for production of trans-free or low-trans-fats for margarines, spreads, and shortenings
Human studies—no significant effect of interesterified fats on blood lipid parameters
Use of Fractions High in Solids
Fractions high in solids derived from natural oils
Coconut
Palm
Palm kernel
May be used as single fractions or in combination with other fractions
Fractionation= Began in palm industry in mid 70’s
Historically, solvent and detergent processes used.
Today physical or dry fractionations is the standard industry method
Replace trans fat with highly saturated palm fractions? Increase sat fat content
Prepared by reducing temperature of oil sample more saturated fraction solidifies and more unsaturated fraction remains liquid
Separate solid/liquid fractions by filtration or centrifugation
Liquid fractions (olein fractions) high in oleic acid and good sources of antioxidants
Fractions From Palm Oil
For trans-free or low-trans shortenings/margarines
Palm olein
Palm midfractions
Palm kernel stearine
Blend with liquid oils such as soybean or canola = low saturated fats
Trait-Enhanced Oils
High-oleic acid oils
(High oleic sunflower & canola oils)
Midrange oleic acid oils
(Midoleic sunflower & soybean oils)
Low linoleic acid oils
(Low-linoleic canola & soybean oils)
Limitations:
Plant varieties not widely grown
More expensive
High oleic oils liquid at room temp
Obtained through traditional plant breeding or biotechnological methods
High range and midrange oleic acid oils are more stable to oxidation than traditional oils high in linoleic acid such as soybean, corn & sunflower oils.
Low-linoleic acid oils have significantly reduced levels of oxidatively unstable linoleic acid.
Trait enhanced oils have good oxidative stability (hi oleic acid, low linoleic and alpha-linolenic acid) making them suitable for frying, beverages, and some bakery applications.
Canada - How can a product be labelled as “trans-fat free”?
has to meet 2 conditions
As outlined in the Food and Drug Regulations, the amount of trans fats can be labelled as “0 g” in the Nutrition Facts Table and the product may be labelled as “trans-fat free” if the following conditions are met:
The food:
contains less than 0.2 g of trans fat per
reference amount and serving of stated size, or
serving of stated size, if the food is a prepackaged meal; and
meets the conditions set out for “low in saturated fats”.
The conditions set out for “low in saturated fats” state that:
The food contains 2 g or less of saturated fat and trans fat combined per
reference amount and serving of stated size; or
100 g, if the food is a prepackaged meal.
The food provides 15% or less energy from the sum of saturated fat and trans fats.
Canada’s Food Guide Messages
Include a small amount -
30 to 45 mL (2 to 3 Tbsp) -
of unsaturated fat each day.
Use vegetable oils such as canola, olive and soybean.
Choose soft margarines that are low in saturated and trans fats.
There are also four health claims on how diet affects health and the reduction of the risk of disease. This slide shows an example of one of these four claims.
“A healthy diet low in saturated and trans fats may reduce the risk of heart disease. (Naming the food) is free of saturated and trans fats.”
Federal government regulations specify the criteria a food must meet before a claim can be made, and the wording of the claim to ensure that they are consistent and not misleading.
A key feature of these claims is that they begin with the wording “A healthy diet…”. Because nutrition claims are optional and highlight a characteristic of a healthy diet, you may still need to refer to the Nutrition Facts table to make informed food choices.
The other disease risk reduction claims are:
a healthy diet with adequate calcium and vitamin D, and regular physical activity, help to achieve strong bones and may reduce the risk of osteoporosis;
a healthy diet rich in vegetables and fruit may help reduce the risk of some types of cancer; and
a healthy diet containing foods high in potassium and low in sodium may reduce the risk of high blood pressure, a risk factor for stroke and heart disease.
More information on health claims is posted on the Canadian Food Inspection Agency Web site:
http://www.inspection.gc.ca/english/fssa/labeti/guide/tab8e.shtml
