© 2006
Ralph Lane
Virtual Lab Rules
•Follow on-screen
Procedure by
clicking the mouse.
•Each bulleted step
represents one click.
•WAIT at least 3 seconds
between clicks
to ensure
that
. .(steps)
. and read
the rules
operation is complete.
(i.e., don’t get trigger-happy!)
STOP
© 2006
Ralph Lane
Moisture Content of Foods
Procedure:
•
Weigh (click) the
apple slice and
record weight.
•
Place (click) in
drying oven
•
Dry overnight at
100oC to constant
weight.
•
Remove and
reweigh; record
weight.
•
Compute %
Moisture
Objects not drawn to scale
100oC
Oven
0.0g
10.0g
1.3g
© 2006
Ralph Lane
© 2006
Ralph Lane
•
Slice the
strawberry
• Sprinkle sugar
on the slices
• Let stand for 30
min
29. What is the
liquid that
formed on the
strawberry
slices?
30. Explain how it
formed.
31. What is this
process called?
Osmosis and
Syrup Formation
Objects not drawn to scale
30
10
20
0
min
© 2006
Ralph Lane
© 2006
Ralph Lane
Experiment 2
Measuring Liquids
(Milk, Water, juices, Syrups, etc.)
Fill the liquid measure to the ½
cup line. Note the surface
of the milk in the cup.
9. Is it level?
a. Yes
b. No
10. Why or why not?
a. Milk fat sticks to sides of
glass container
b. Capillary action of liquid for
glass container
c. Attraction of milk solubles
(proteins, lactose, watersoluble vitamins) for glass
container
1 Cup
3/4
2/3
1/2
1/3
1/4
© 2006
Ralph Lane
© 2006
Ralph Lane
Standards of Identity,
Quality & Fill
• Open can
• Express contents into
strainer
(Allow contents to
drain. Reserve
packing medium for
sugar analysis)
Mrs. Kirby’s
Fruit Cocktail
In
Heavy Syrup
15oz (426g)
© 2006
Ralph Lane
Refractometer, handheld
Determination of
Syrup Strength
• Place some of the
packing medium
on the
refractometer
prism
• Close prism lid
• Read scale in %
sugar at line
between light and
dark areas.
Record.
%
32
30
28
26
24
22
20
18
Eyepiece
16
14
12
10
8
6
4
2
0
© 2006
Ralph Lane
Determination of
Syrup Strength
• Place some of the
packing medium
on the
refractometer
prism
• Close prism lid
• Read scale in %
sugar at line
between light and
dark areas.
Record.
%
32
30
28
26
24
22
20
18
Eyepiece
16
14
12
10
8
6
4
2
0
© 2006
Ralph Lane
© 2006
Ralph Lane
•Remove container
Standards of Identity, Quality &
Fill of Container
•Separate each fruit
variety
•Weigh each variety
& record.
•
•
•
•
•
Fruit legend
Peach
Pear
Grape
Pineapple
Cherry
114.0g
0.0g
© 2006
Ralph Lane
Based on your findings, enter appropriate data in Tables 1 & 2 on your Data Sheet.
Table 1
Standards of Identity and Quality Analyses of Canned Fruit
Cocktail
Brand
Standard
%
Peaches
30-50*
%
Pears
25-45*
%
Grapes
6-20*
%
Pineapple
6-16*
%
Cherries
2-6*
%
Solute**
Mrs. Kirby’s
* 21 CFR 145: Std of Quality range each fruit variety
**21 CFR 145: Std of Quality for packing medium (sugar content): Lite, 10-14%; Medium, 14-18%; Heavy, 18-22%
Table 2
Standards of Identity and Quality Analyses of Canned Fruit
Cocktail
Brand
Net Wt. of Contents
gm
Label
Mrs.
Kirby’s
426
Actual
Drained Wt. of Fruit
gm
Label
277
Actual
% Fill
Standard
Actual
65
© 2006
Ralph Lane
•
•
•
•
•
4.
5.
Principles of Cooking: Direct Heat
Use of Broiling Element
Turn on broiler
element
Open door
Insert pan
containing two
cups of water
Insert temperature
probe into water
(record ambient
temp.)
Partially close oven
door & monitor &
record water
temperature and
time until 180oF
endpoint is
reached.
How was heat
transferred from
element to water in
container?
Why was the door
left ajar during the
broiling period?
179
159
93
73
80
86
72oooFF
104
122
129
138
145
152
163
168
172
176
177
180
111
1
2
3
5
10
12
11
0
4
6
7
8
9
19
13
14
15
16
17
18
min
© 2006
Ralph Lane
© 2006
Ralph Lane
•
•
•
•
•
6.
7.
Principles of Cooking: Direct Heat
Turn on broiler Use of Broiling Element
element
Open door
Insert pan
containing two
cups of water on
top shelf
Insert temperature
probe into water
(record ambient
temp.)
Partially close oven
door & monitor &
record water
temperature and
time until 180oF
endpoint is reached
Why did this water
sample heat faster
than the previous
one?
How is broiling
temperature
controlled?
180
100
125
138
149
159
168
177
113
72oF
87
1
2
3
5
10
0
4
6
7
8
9
min
© 2006
Ralph Lane
© 2006
Ralph Lane
Factors Affecting Enzymatic Browning: Acid
•
•
•
12.
Dip apple slice 1 in water and note browning
Dip apple slice 2 in acid at pH 5 and note browning
Dip apple slice 3 in acid at pH 2 and note browning
Which medium inhibited enzymatic browning best?
Why?
13. Explain how pH inhibits enzyme function.
1
2
3
Water
pH 7
Acid
pH 5
Acid
pH 2
© 2006
Ralph Lane
© 2006
Ralph Lane
Crude Protein Analysis of Red Beans:
Kjeldahl Method
• Add 1.4g homogenized
red bean sample to
Kjeldahl flask
• Heat Kjeldahl flask until
sample is digested
(disappears)
• Add NaOH pellet to make
digest alkaline (pink).
• Connect water-cooled
condenser
• Distill NH3 into
Erlenmeyer flask
Objects not drawn to scale
© 2006
Ralph Lane
Crude Protein Analysis of Red Beans
Kjeldahl Method
0.0mL
Red bean distillate
from Kjeldahl digestion
(previous) step
• Titrate with 0.1 M HCl
to clear endpoint
• Read burette and
record
12.5mL
© 2006
Ralph Lane
© 2006
Ralph Lane
% Crude Protein Content of Red Beans
Kjeldahl Method
4. Based on titration data, compute % crude
protein for the red bean sample using the
formula:
% Nitrogen = MHCl x VHCl x 14 x 100
Sample wt. X 1000
% Protein = % N x 6.25
© 2006
Ralph Lane
Objective Determination
of Texture of Raw Beef Roast
Side View
Front View
Objects not drawn to scale
• Remove a 1” core
sample of raw roast
• Place in triangular
opening of shear
tester.
• Activate shear
tester and record
maximum shear
result in pounds.
• Read maximum
deflection pointer
value of raw sample
and reset shear
tester.
20 lb
Capacity
Capacity
10.7
lb
© 2006
Ralph Lane
© 2006
Ralph Lane