Ch 2 Scientific Evaluation

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Scientific Evaluation:

Being Objective

Chapter 2

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Learning
Outcomes

After studying this chapter, you will be able to:

●

Describe the role of science in the development
of new food products.

●

Identify the function of measuring equipment
used in the science laboratory.

●

Demonstrate proper measurement techniques.

●

List the steps of the scientific method.

●

Use proper safety procedures in the food
science lab.

Poll

Which objective are you most interested in?

• Being able to describe the role of science in the development of new food products. 

• Identifing the function of measuring equipment used in the science laboratory.

• Demonstrating proper measurement techniques.

• Listing the steps of the scientific method.

• Using proper safety procedures in the food science lab. 

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● Science is the use of evidence to construct testable explanations

and predictions of natural phenomena, as well as knowledge
generated through this process.

● A phenomenon is a fact, occurrence, circumstance, or process that can be observed.

● Scientists watch what occurs, usually under controlled conditions,

to determine why things happen the way they do.

● From study and observation, scientists discover the natural world

has predictable patterns of behavior.

Multiple Choice

A ______________is a fact, occurrence, circumstance, or process that can be observed.

• Science

• Phenomenon

• Predictable

• Conditions

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● The process of putting scientific knowledge to practical use is called

applied science. Food science is an applied science.

● Food scientists apply basic laws of chemistry, physics, biology, and

nutrition to the production, processing, and packaging of the food supply.

● Developing food products involves the application of scientific principles.
● Food scientists experiment to learn what will work.

○ An experiment is a controlled situation that allows a scientist or

researcher to determine what causes a change to occur.

○ The results of food experiments are called recipes.
○ In the food industry, recipes are called formulations.

Word Cloud

True or False: Food science is an applied science?

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● For an experiment to be scientific, it must be replicable, or repeatable.
● To be successful in your food science investigations, you will need to

follow some basic guidelines. You must:

○ Avoid biases, which can skew your results.
○ Base your conclusions on what your careful observations

reveal, not on what you expect to see.

○ Take accurate measurements and investigate previous

studies for helpful ideas.

○ Keep detailed records of the steps you follow and design a

study’s procedure to observe only one change at a time.

Multiple Choice

For an experiment to be scientific, it must be replicable, or __________.

• completed at a lab

• done by a professional

• repeatable

• respectable

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Measurements

●

One guideline all researchers must follow is to take accurate measurement
readings.

●

To measure anything successfully, you must meet three requirements.

1.

Identify which system of measurement or standard you are using.

2.

Determine what you are trying to measure.

3.

Decide what method of measurement will give you the most consistent
results.

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Measurements

●

Because scientists working all over the world share information, they need a system of
measurement that everyone can use.

●

An international system has been developed that is based on the metric system.

●

The metric system is a decimal system of measurement.

●

The international accepted version of the metric system is called the International System of
Units (SI).

●

In this class, you will use basic metric units to measure mass, length, volume, time, and
temperature.

●

To achieve success when preparing a recipe, you must use the specified amount of each
ingredient.

●

When conducting an experiment, you need to use the specified amount of each substance.

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Metric Base Units

Type

Name

Symbol

Mass

gram

g

Length

meter

m

Volume

liter

L

Time

second

s

Temperature

Celsius degree

℃

Draw

Metric Base Units

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Measurements

● Prefixes make it easier to work with larger and smaller amounts of

substances in the metric system.

● You must know these prefixes to follow the experiments in this class.
● You must also know the types of measurements you need and how to take

accurate measurements.

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Metric Prefixes Greater Than 1

Prefix

Symbol

Meaning

Multiplier

kilo

k

thousand

1,000

hecto

h

hundred

100

deka

da

ten

10

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Metric Prefixes Less Than 1

Prefix

Symbol

Meaning

Multiplier

deci

d

tenth

0.1

centi

c

hundredth

0.01

milli

m

thousandth

0.001

micro

µ

millionth

0.000001

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Mass

● Mass is a measure of the quantity of matter.
● When conducting food science experiments, you will often be measuring the

mass of solid and liquid substances.

● Most of the time, you will be massing substances between 0 and 300 g.

○ A gram is the mass of 1 cubic centimeter (㎤) of water at 4℃.
○ A kilogram (kg) is the mass of 1 liter of water at 4℃.

■ One kilogram equals 1,000 grams.

● Mass is often confused with weight.

○ Weight is the measure of the force of gravity between two objects.

Weight changes with location.

Poll

Are mass and weight the same?

• YES

• NO

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Equipment for Measuring Mass

● The two most common tools for measuring mass are the triple beam balance

and the electronic scale.

● We will be using the electronic scale in this class because it is faster and

easier to use than a triple beam balance.

● When you turn on an electronic scale, you need to calibrate it.

○ To calibrate is to adjust a measuring instrument to a standard.
○ This ensures the scale is measuring correctly.

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How to Measure Mass

●

You will often have to put substances in some kind of lightweight container
before massing them.

●

In this class, we will be using muffin cup liners or coffee filters.

●

You must first mass the empty container and record the result. This mass is
called the tare.

●

Then you mass the container with the substance in it and record the result.

●

Subtract the first result from the second result.

●

The difference is the mass of the substance.

●

Luckily, electronic scales do this work for you when you press the zero
button.

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Chewing
Gum Lab

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Objectives

● Demonstrate how to calibrate and tare an

electronic scale.

● Determine the mass of chewing gum and

compare how much mass is lost after chewing.

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Important Reminders

● Do not swallow your gum. It is unhealthy and you need to mass

the gum after you chew it.

● Save your wrapper to mass the chewed gum.
● Remove as much saliva from the chewing gum as possible before

massing the gum.

● Chew each type of gum for exactly 5 minutes.
● Don’t forget to record your data on your worksheet AND on the

class worksheet.

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How to Measure Mass

1. Turn the scale on.
2. Place the weighing paper or container on the scale.
3. Press the ZERO button to erase the weight of the paper. This ensures you

only have the weight of the ingredients you are massing.

4. Place the ingredient to be measured on the weighing paper or in the

weighing container.

5. Place on the scale and record the data.

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How to Measure Mass

1. Turn the scale on.
2. Place the gum wrapper on the scale.
3. Press the ZERO button to erase the weight of the gum wrapper. This

ensures you will only have the weight of the gum you are massing.

4. Place the gum to be measured on the wrapper
5. Place on the scale and record the data.

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1.

Which type of gum had a greater loss of mass after chewing. Why?

2.

What substance caused the loss of mass during chewing?

3.

Was there a difference in texture between the two types of gum? If so, why?

4.

Given that sugar has 4 kilocalories per gram, how many kilocalories would you estimate
are in a stick of gum?

How does your estimate compare with the nutrition label on the gum package?

5.

How would you determine the mass of 10 mL of milk?

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Questions

1.

Which type of gum had a greater loss of mass after chewing. Why?

The regular chewing gum should have lost more mass because sugar has a
greater mass than the artificial sweeteners used in sugar-free gum.

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2. What substance caused the loss of mass during chewing?

Sugar and artificial sweeteners

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3. Was there a difference in texture between the two types of gum? If so, why?

Regular gum was gritty because of sugar. Sugar-free was smoother.
Sugar-free got tougher faster.

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4. Given that sugar has 4 kilocalories per gram, how many kilocalories would you estimate are
in a stick of gum?

How does your estimate compare with the nutrition label on the gum package?

our estimate of 4 kilocalories for a stick of gum from its sugar content alone
is close to what is typically found on nutrition labels, which usually report
5-10 kilocalories per stick.

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Nutrition Information

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5. How would you determine the mass of 10 mL of milk?

Place a beaker on the scale. Press the zero button. Add 10 mL of milk. The
mass shown will be the mass of the milk.

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Length

● Length is the distance between two points.
● This measurement allows you to evaluate the size of objects.
● The standard unit of length in the metric system is the meter (m).
● One meter is equal to 39.37 inches.
● Most objects you will measure in this class are much shorter than a meter.
● You will usually record length measurements in centimeters (cm) and

millimeters (mm).

● You will usually measure length with a ruler.

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Volume

● Volume is a measurement derived from length.
● Volume is the amount of space occupied by an object.

○ For example, the volume of a box is calculated by multiplying the length

times the width times the height.

○ Equation: v = l x w x h

● The metric unit for measuring fluid volume is the liter (L).
● A liter is slightly more than 4 cups.
● In this class, you will often use milliliters as well as liters to measure volume.

○ 1 L equals 1,000 mL.

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Equipment for Measuring Volume

● You will usually measure liquids by their volume.
● You will use containers made of clear glass or plastic that have a graduated

scale on the side.

● Containers are measured against a standard, and then marks are carefully

placed on the side to show various volumes.

● Generally, the smaller the divisions on the container are, the more

accurately the container will measure volume.

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Equipment for Measuring Volume

●

Several types of containers are used for measuring volume in the food science
lab.
○

A beaker is a deep, wide-mouthed container with a pouring lip used to hold
substances during experiments and to measure approximate volume.

○

An Erlenmeyer flask is a flat-bottomed, cone-shaped container used to mix
and hold liquids and to measure approximate volume measurements.
■

You can use beakers and Erlenmeyer flasks to measure volume when
accuracy is not important.

○

A graduated cylinder is a tall container used to accurately measure the
volume of liquid to the nearest millimeter.

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How to Measure Volume

●

The surface of a liquid in a measuring container does not appear to be flat. It
appears to curve.

●

This curve at the surface of the liquids is called the meniscus.

●

The narrower the container is, the more obvious the curve will be.

●

The meniscus is caused by liquid clinging to the sides of a container.

●

To accurately measure liquid volume, place the container on a flat surface. Read
the volume at eye level from the bottom of the meniscus.

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Time

●

A fourth type of measurement is time.

●

In most food science experiments, you will measure time in seconds.

●

Whenever an experiment calls for time measurements, it will be critical to have
someone act as a timer.

●

Record start and stop times using a clock, watch, or phone.

●

Failure to accurately monitor time can make your entire experiment invalid.

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Temperature

●

Temperature is a measure of heat intensity.

●

When you describe the temperature of a food, you probably think of words like
hot, warm, cool, and cold.

●

These terms give the general description of the heat intensity in an object.

●

In food science experiments, you will need more exact measurements of heat
intensity.

●

The most commonly used unit of temperature in the lab is the Celsius degree
(℃).

○

A Celsius degree is 0.01 of the difference between the boiling and
freezing points of water.

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Recording Measurements

●

When recording any type of measurements, be sure to list the units in which you
are measuring.

●

Simply writing numbers does not provide enough information to anyone who is
referring to your data table.

●

It is important to clarify whether you measured items in metric or English units.

●

You also must specify which units of a measuring system you used.

●

Remember that taking accurate measurements is only one aspect of scientific
experiments. Scientists also use a process that helps guide the way they conduct
experiments.

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The Scientific Method

●

The scientific method is a system of steps used to solve problems.

●

This method is used by scientists throughout the world.

●

Solving problems using the scientific method is a useful skill no matter what
your career choice may be.

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Step One: Ask Questions

●

The scientific method begins when a questions arises.

●

To approach a problem from a scientific angle, start by asking yourself such
questions as what, why, and how.
○

Example: Why do plants in a certain area grow taller than plants in another
area?

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Step Two: Define the Problem

●

The second step of the scientific method is to define what the problem is.

●

In class experiments, the problem is the purpose of the experiment.

●

This information is given in the introductory paragraph of each experiment.

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Step Three: Conduct Research

●

After defining the problem, you must list possible causes.

●

This requires gathering as much information about the problem as possible.

●

First you list all the ideas that come to mind.

●

Once you have listed ideas, it is time to do research.

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Step Four: State the Hypothesis

●

From your research, you should be able to narrow your list of possible causes of
the problem.

●

Select the cause that seems to be most likely and state a hypothesis about this
cause.

●

A hypothesis is a possible or tentative solution to a problem.

●

It is an educated guess based on available evidence; an “if, then” statement.

●

It is okay to be wrong!
○

Example: If plants receive more sunlight, then they will grow taller.

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Step Four: State the Hypothesis

●

When a hypothesis has been tested repeatedly and found to fit the known facts
over a variety of conditions, it becomes a theory.
○

A theory is an established explanation that accounts for known facts or
phenomena.

○

Scientific theories are established and highly reliable explanations that may
be tested by many independent researchers.

●

Laws are theories that are widely accepted as explaining and predicting
phenomena in the same way under the same circumstances.
○

In science, laws are known facts.

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Step Five: Design the Experiment

●

The next step of the scientific method is to design an experiment to see if your
hypothesis was correct.

●

A well-designed experiment will have a control and a variable.
○

A variable is a factor that is being changed.
■

When designing an experiment, you must control the number of
variables.

○

The control is the standard against which you measure all changes.

○

Each change in an experiment is called a variation.

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Step Five: Design the Experiment

●

An independent variable is the variable that the scientist changes or
manipulates in the experiment. It is the "cause" that is being tested.
○

For the plant growth scenario, the amount of sunlight could be the
independent variable, as it's being deliberately altered.

●

A dependent variable is the outcome or result that is measured in response to
the changes in the independent variable. It's the "effect" that is being observed.
○

In the plant growth scenario, the height of the plants would be the
dependent variable.

●

The dependent variable changes in response to the independent variable.

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Step Six: Conduct the Experiment

●

Carrying out your plan by conducting the experiment is the next step.

●

It is critical that everyone follows the directions exactly.

●

Besides following directions, you must take precise measurements.

●

Records of your observations are of two basic types: numerical and descriptive.
○

Numerical observations, also called quantitative observations, are expressed
in terms of numbers.

○

When you take a measurement, you are making a numerical observation.

○

Data is measurable facts that are collected during an experiment.

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Step Six: Conduct the Experiment

○

The second type of observation is descriptive observation, also called
qualitative observation.

○

Descriptions of what is happening that cannot be measured in numbers are
often as important as numerical data.

○

Descriptive observations may refer to such factors as color, texture, and
odor.

○

These factors can affect a person’s willingness to try a food product.

○

They can also indicate chemical and physical changes in a product.

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Step Seven: Evaluate the Results

●

Evaluating the results mainly requires thinking.

●

You must read through your data, observations, and notes.

●

Look for patterns, trends, common factors, changes, and questions.

●

Look for answers to support or disprove your hypothesis.

●

Reach a conclusion about the accuracy of the hypothesis.

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Step Eight: Report the Results

●

The final step is to report your results.

●

You must put your evaluation in writing so you can share it with others.

●

When writing conclusions, people often repeat their data and observations. This
is NOT drawing a conclusion.

●

A conclusion analyzes and applies data and will usually answer how, what, where,
when, and why.

●

It describes what the data and observations mean.

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Evaluating Scientific Studies

●

It is important to understand that scientific research is a process of discovery
and debate.

●

Because you are exploring the unknown, there will be uncertainty and
seemingly conflicting reports.

●

New research published in journals should be viewed as discussions that give
direction, not final answers.

●

Researchers often examine hundreds of studies on the same issue before
making recommendations to the public.

●

When the results of several individual studies are pooled to yield overall
conclusions, it is called meta-analysis.

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Writing a Hypothesis

● If dietary fiber is consumed regularly, then it will reduce the absorption of

cholesterol into the bloodstream.

● If baking soda is added to baked goods, then it will rise and become light and

fluffy due to the release of carbon dioxide gas during the baking process

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Your hypothesis can TELL you what your variables

are!

Example:

If I increase the amount of caffeine I drink before
bed, then I will decrease the minutes of sleep.

IV: Amount of caffeine consumed

DV: Minutes of sleep

Using the hypothesis to determine variables

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Identify the Variables

TrY to Use INcReAse anD/Or DEcReAse
wiTh YoUr VarIaBlES in YOur HyPotHEsiS

Use this hypothesis to identify the variables:
If I increase daily consumption of calcium,

then I will increase bone density.

IV: ______________________

DV: ______________________

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Terminology

VarIaBlE:

■
Factor that is
being changed

ConTrOL:

■
Standard against
which you measure
all changes

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vaRIabLE teRmINolOGy

InDepENdeNt VarIaBlE:
Variable that is changed
by the scientist-
the “I control” variable

DepENdeNt VarIaBlE:
The variable that might change because of what
the scientist changes – what is being measured

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Connecting Variables to Your Hypothesis

Use the independent variable to take an educated
guess to what will happen to the dependent
variable.
WriTE as AN “If…, tHen” StaTEmeNt

If “independent variable”

then “dependent variable”

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We know that a VarIaBlE:

■
is the factor that is being changed

■
compared to the control

VAriATiOnS:

■
The varieties used to be measured against the
control.

vaRIabLE veRsUS vaRIatIoN TerMInoLOgY

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Which fat is most palatable for cakes?
VarIaBlE: TyPe Of Fat USed

■
Determine coNtROl: butter

VAriATiOn PosSIbiLItiES:

▪

shortening

▪

lard

▪

vegetable oil

▪

coconut oil

▪

olive oil

vaRIabLE veRsUS vaRIatIoN ExaMpLE

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Which fat is most palatable for cakes?
VarIaBlE: TyPe Of Fat USed

■
Determine control: butter

■
Determine how you will measure results &
control the number of variations

■
Determine variations

shortening, lard, vegetable oil, coconut oil

vaRIabLE veRsUS vaRIatIoN ExaMpLE

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Which fat is most palatable for cakes?

FutURe vARiAbLe PosSIbiLItiES:
Use a different variable to see if that impacts the
results of each type of fat used:

▪ mixing method

▪ cooking time

▪ cooking temperature

vaRIabLE veRsUS vaRIatIoN ExaMpLE

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Scientific Method Relay Race