Here is a simple table on the whiteboard to record predicted and actual water activity (Aw) values for different foods/solutions: Food/Solution Predicted Aw Actual Aw

1. Food Chemistry Lab
FSTC 313

2. Teaching Instructors
• Eric Casteneda: efrankiec@tamu.edu
• Helen Sarbazi: zahra74@tamu.edu
• Mehdi Hashemi: mehdihashemi666@tamu.edu
• Emma Link (lab coordinator): e.link@tamu.edu
•

3. Rules and Regs
Students are expected to be on time and attend all
laboratory exercises. Anticipated and/or emergency
absences should be notified to the instructor as early as
possible. Students are expected to be familiar with the
topic to be covered prior to entering the lab and to
participate in class discussion. Make-up work will only be
allowed under strict University guidelines.
Lab Safety and General Procedures:
• General laboratory safety will be covered prior to the
first laboratory exercise.
• Lab coats and closed toe shoes are mandatory for all
labs

4. Rules and Regs
Late Policy and Missed Lab Policy
• Labs are due one week after completion of experiments.
• Late reports will be penalized 20% per day
• Unexcused absences = 0
• Excused absences will be required to write a 500-word
(1” margin, single spaced, 12-pt font) technical literature
review (minimum of 5 peer-reviewed references) on the
missed lab topic and will be additionally turned in with
your lab group to enhance the quality of your lab group’s
work. Clearly indicate the author of this review and its
purpose.

5. Rules and Regs
Food Industry Application Note: Total = 5
• All data reports will have an “Application Note”
(AppNote) associated with it. Since all
experiments will be conducted in groups, your lab
group must come to a consensus on what
segment of the food industry you will write your
AppNote to.
• All are group AppNotes except the last one of the
semester (individual).
• So work together, divide the work, and come to a
mutual agreement on this information.

6. Rules and Regs
Technical Abstracts: Total = 3
• An abstract is a written summary of your work/data, so the entirety of your lab
procedures must be expressed in writing. Abstracts will not include graphs, tables,
or references but rather a written data description of methods and results.
• Abstracts will be a minimum of 400 words and a maximum of 500 words using the
MSWord word counter. So chose your words carefully.
• All abstracts will be individual work, and will inherently be unique from the work
of your lab group
• 50% of your total grade is individual abstracts and 50% is AppNotes
•
• 1. Justification (~1-2 sentences)
• 2. Objective (~2-3 sentences)
• 3. Methods (~3-5 sentences)
• 4. Results (~5-10 sentences)
• 5. Significance of your data (~2-3 sentences)

7. Rules and Regs
Notebook and Laboratory Exam:
• You will keep a formal lab notebook for this lab.
• Any BOUND lab book format is fine.
• Lab books will be checked periodically
throughout the semester.
• A mid-term lab exam will be given covering
material up to and including that day’s lab. Take
good notes and be organized throughout the
semester to aid you in preparation.

8. Rules and Regs
To write a good abstract, you need good notes. Take
notes in your lab book and write about the following 5
points:
1. Motivation. Why do we care about the problem?
2. Problem statement. What problem are you trying to
solve or understand?
3. Approach. How did you go about solving the
problem?
4. Results. What's the conclusion of your experiments?
5. Conclusions. What are the implications of your data?

9. What to Turn In
• Each written assignment will have a cover page.
– Title of the assignment
– Names of everyone in the lab group.
– Signature of each lab group member next to your name.
– Your signature indicates you are in agreement with the
work turned in.
– Assignments will not be accepted without the signature
of all lab group members.
• Staple all pages together and turn in as a lab group.

10. Grades
• Application Notes (2 @ 50 pts each) = 100 pts
• Abstract/AppNote (3 @ 100 pts each) = 300 pts
• Laboratory notebook = 50 pts
• Lab Exam = 50 pts
• Total = 500 pts

11. Lab Safety and Procedures
• Your safety and those around you are our #1
concern.
• Watch out for yourself and others.
• The instructors will show you how equipment
works, but if you don’t know…don’t assume.
– Ask…take your time…we will show you how.

12. This is a “W-Course”
• Up to 70% of your grade will be based on how
your write about your experiments and results.
• Your AppNotes and Abstracts will be graded on
clarity of thought and technical interpretation.
• We will cover writing techniques before labs.
• You will not be able to write well, if you don’t read
literature in your field.

13. Find a Lab Partner
• I can choose your lab partner.
• I reserve the right to change lab partners at ANY
time for ANY reason.
• If you have an issue with your lab partner, first try
to resolve, try again, and then let a TA know.
• There are times when it may be advantageous to
combine lab groups to run larger, more
complicated experiments.
• Exchange contact information.

14. What is Food Chem Lab?
• We will study reactions in foods.
• Getting “the right answer” is not a
requirement of this class.
• You must critically think about your lab.
• You must come prepared for the lab.
• Many labs you will have experimental options
that require thought followed by action.
• You will need time to evaluate your results
and re-test your experiment to confirm.

15. Questions?

16. Water Activity of Foods

17. 1) Adsorbed water
is water that associates in layers via intermolecular
bonds around hydrophilic food molecules, monolayer
2) Bound water
is tightly bound water, does not exhibit colligative
properties
3) Free water
is lightly trapped and easily removed from food
material

18. Water activity
Important in food preservation and safety
Definitions
-”Availability” of water to enter chemical and
enzymatic reactions.
-Represents the degree to which the bound water
in a food is “tied up” and “unavailable” for chemical
reactions or microbial growth
-Relationship between loss of quality and moisture
content

19. A general rule of thumb:
As the percentage of bound water in a food increases,
the water activity decreases
Aw = P/ Po
P= Vapor pressure of a food
Po= Vapor pressure of pure water (1.0)
Aw scale is from (0.0 to 1.0)
All foods have a water activity less than 1.0; the higher the
water activity the more perishable the food item is likely to be

20. Desorption – wet material placed in a dry environment
Foods lose moisture, water activity decreases
Important in drying or concentration food processing
Adsorption- Dry material placed in a wet environment
Foods gain moisture, water activity increases
Hygroscopic foods absorb moisture

21. “BOUND”
“ADSORBED”
“FREE”

23. Someone make a simple table
on the white board
Food/Solution Predicted Aw Actual Aw