viii
Lively Features
The Metric System and Foreign Trade
The U.S. federal
government is promoting
metrication. This means
changing from the English
to the metric system of
measurement. The metric
system includes product standards and
preferred sizes that are now being used by
industries and governments worldwide.
Economics is a key reason the government
is urging the switch. Products not measured
in metric units are becoming increasingly
unacceptable in world markets. The govern-
ment realizes that switching to the metric
system will improve U.S. standings in the
global marketplace. Companies that switched
to metric units have increased their ability to
sell products all over the world. U.S. industries
that have made this switch include the auto
and beverage industries. For example, most
people in the United States now buy soft
drinks in 1- and 2-liter bottles.
Congress fi rst encouraged the change
through the Metric Conversion Act of 1975.
This act made switching to the metric system
voluntary. In 1988, Congress passed amendments
to the act. These amendments required any
government function related to trade, industry,
or commerce to use the metric system. Federal
agencies are also required to seek ways to
educate the public about the metric system.
A number of factors make the complete
change to the metric system diffi cult. One
factor is reluctance of consumers to adopt
the new system. Teaching the metric system
in schools will gradually help the public
feel more comfortable with metric terms
and units. A second factor is the need to
rewrite many legal defi nitions. Some state
and federal regulations would also need to
be rewritten. A third factor is the cost. Most
businesses that use the English system are
not willing to make expensive changes in
production lines and equipment. However,
many of these businesses plan to make the
switch when they replace old equipment or
build new plants.
Experimental
Errors
Research by different
scientists on the same hypothesis
will often result in confl icting
evidence. As a result, multiple trials are
done and the results examined. When results
differ, it may be because of experimental error.
There are two basic types of experimental
error. Small differences, especially in mea-
surements, can be the result of variations in
the environment, equipment, timing, or basic
properties of nature. When this is the case,
scientists conduct multiple trials and analyze
the results. The simplest statistical analysis is
to take an average.
The other type of error is in the design
or execution of the experiment. This is known
as systematic error. In these cases, the results
are not valid. Some examples include
• too many variables
• personal bias
• a poorly designed experiment
that does not measure what
is intended
Sometimes it is diffi cult to see these errors.
The possibility of a fl awed experiment is one
reason scientists share or publish their work.
It is also the reason that scientists require
other teams be able to repeat the experiment
with the same results before the results are
accepted.
The possibility of experimental error
means scientists must be careful throughout
every part of an experiment. This is why, for
example, it takes years for a new drug to be
approved by the FDA. The more complex the
system being studied, the more factors there
are to examine.
STEM
Measuring Fat
Content
USDA research chemists
have developed a way to measure
fat content in cereal products with
near infrared refl ectance readings.
Traditional methods of measuring fat content
require 10 hours and the use of chemical
solvents. When perfected, this method
will require 10 minutes and a
spectrometer with a spectral
resolution of 10 nm. The FDA and
USDA’s Food Safety and Inspection
Service must certify the technique, and
near-IR-refl ectance models will have to
be developed for each application.
STEM
Calorie Density
Calorie density is a simple
way to examine the ratio of
calories to the weight of food.
Some research indicates that people
will eat until they have consumed a certain
mass or volume of food. Calorie density is
calculated by dividing the total weight
of the food by the total calories
the food provides. Select fi ve of
your favorite foods at home that
have a nutrition label. Calculate their
calorie density. Rank them from lowest to
highest calorie density. As a class, compare
and discuss your results.
STEM
Enzymes and Insulin Production
In 1955, a team of chemists made a
breakthrough for diabetics who need insulin
injections. The team identifi ed the order of
amino acids in the protein insulin. This team
was led by the English chemist Frederick
Sanger. He studied insulin’s chemical makeup
in different species of animals. This allowed
him to determine the structure of insulin.
Sanger’s work led to the development of
a method to mass-produce insulin. The
gene that produces the
enzyme that makes
insulin can be inserted
into single-celled
organisms. The organisms
multiply rapidly and produce
large volumes of pure insulin. This insulin
is cheaper to produce and easier to obtain
than the previous sources, which were oxen,
sheep, and pigs.
Obesity and Corn Syrup
As concerns about
obesity have increased
over the last decade,
the idea that corn syrup
causes obesity has become
widespread. The alarm over
high-fructose corn syrups began with data
that showed a sharp increase in obesity in the
United States at the same time high-fructose
corn syrup replaced much of the sugar in
sodas. However, most nutritionists and
scientists agree that there is no substantial
evidence to support the idea that high-fructose
corn syrup is responsible for obesity.
The issue of obesity is complex. There are
many potential contributing factors, including
sugars and corn syrups.
Deals with food topics that impact
global awareness and international
politics and economics.
D l ith f d t i th
Global Issues
Expands on scientifi c principles
and procedures.
E d i tifi i i
Science Matters
Highlights technology tools and
techniques used in nutrient analysis
and food production and processing.
Hi hli ht t h l t l d
Technology Matters
Explains chapter content related
to math principles.
E l i h t t
Math Matters
Discusses current research or
recent fi ndings that relate to
chapter content.
Di t h
Recent Research
Gives insight into the history of
important food discoveries and the
scientifi c understanding of food.
Gi i i ht i t t h hi t f
Historical Highlight