1.3: Water - Temperature and Dispersions
- Page ID
- 29355
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)
\( \newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\)
( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\)
\( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)
\( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\)
\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)
\( \newcommand{\Span}{\mathrm{span}}\)
\( \newcommand{\id}{\mathrm{id}}\)
\( \newcommand{\Span}{\mathrm{span}}\)
\( \newcommand{\kernel}{\mathrm{null}\,}\)
\( \newcommand{\range}{\mathrm{range}\,}\)
\( \newcommand{\RealPart}{\mathrm{Re}}\)
\( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)
\( \newcommand{\Argument}{\mathrm{Arg}}\)
\( \newcommand{\norm}[1]{\| #1 \|}\)
\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)
\( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\AA}{\unicode[.8,0]{x212B}}\)
\( \newcommand{\vectorA}[1]{\vec{#1}} % arrow\)
\( \newcommand{\vectorAt}[1]{\vec{\text{#1}}} % arrow\)
\( \newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vectorC}[1]{\textbf{#1}} \)
\( \newcommand{\vectorD}[1]{\overrightarrow{#1}} \)
\( \newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}} \)
\( \newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}} \)
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)
\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)- Relate descriptive temperature terms to the observable changes in water at various temperatures.
- Demonstrate correct operation of various range-top cooking utensils using water as a medium of heat transfer.
- Differentiate among true solutions, colloidal dispersions, and suspensions according to their various behavior characteristics determined by the size of the dispersed particles.
- Observe water appearance at temperatures used in food preparation.
- Change state of dispersion by common food preparation techniques.
- Determine effect of dispersed phase on boiling point of dispersion.
Observe commonly used water temperatures in an open saucepan:
- Calibrate the thermometer with boiling water.
- Heat a saucepan of tap water; observe the water at the following temperatures:
Lukewarm temperature (30-37ºC; ºF)
Does lukewarm water feel warm or cool to the touch?
What is normal body temperature? ºC; ºF.
Simmering temperature (85-99ºC; ºF)
Describe the surface appearance of simmering water:
Boiling temperature (100ºC; ºF)
Describe the surface appearance of water at:
a slow boil ( = actual recorded temperature)
a rapid (rolling or fast) boil ( = actual recorded temperature)
- What are the advantages of cooking foods at a slow boil rather than at a fast boil?
- When might a fast boil be advantageous?
Determine maximum water temperatures of other range-top utensils:
Double boiler
Heat 3 cups of water in upper part of a double boiler over 3 cups boiling water in the lower part. (Water in the lower pan should not touch the upper pan.)
Record the highest temperature reached: ______ºC; 190-198 ºF.
- Will the water in the upper part boil if boiling water in the lower part touches the top part of the double boiler?
- List appropriate uses for a double boiler:
Steamer
Put 3 cups water in the bottom part of a steamer, and a maximum temperature thermometer in a custard cup filled with water in the top part.
Record highest temperature reached: 91 ºC; _____ºF.
- How would the rate at which foods cook in a steamer compare to the rate in a saucepan? Explain.
- List appropriate uses for a steamer:
Pressure saucepan
Put 1 cup water in a pressure saucepan and place maximum thermometer in custard cup filled with water on rack. Following directions for the saucepan, hold at 10 lbs. pressure for 5 minutes.
Record highest temperature reached at 10 lbs. pressure: _____ºC; 240 ºF.
- At what temperature does water boil under
5 lbs. pressure 109 ºC; ____ºF.
10 lbs. pressure ____ ºC; 240 ºF.
15 lbs. pressure 121 ºC; ____ ºF.
- Temperature decreases 1°C for each 960 foot increase in altitude.
At what temperature would water boil in Denver, Colorado (altitude approximately 5,000 feet above sea level) under 10 lb. pressure?
____ºC; ____ ºF.
- How would the rate at which foods cook in a pressure saucepan compare to the rate at which they cook in a regular saucepan? Explain.
- List appropriate uses for a pressure saucepan.
Measure effect of dispersed phase on boiling point using sugar, salt, gelatin, or bran:
- Pour 2 cups of water into a saucepan. Throughout the exercise, add boiling water as needed to maintain this level.
- Bring water to a boil. Record boiling temperature in the table; then add 2 tbsp. assigned ingredient (sugar, salt, hydrated gelatin*, or bran) and stir.
* Hydrate gelatin by sprinkling 3 tbsp. dry gelatin over ¾ cup cold water. Use 2 tbsp. of the hydrated gelatin for each addition.
- Bring water to a boil again and measure the boiling point.
(Record results on the basis of a 100°C boiling point of water.)
- Repeat steps 2 and 3 until five additions of 2 tbsp. each have been made.
| Boiling temperature for | ||||
|---|---|---|---|---|
| Number of additions | Sugar
state of dispersion |
Salt
state of dispersion |
Gelatin
state of dispersion |
Bran
state of dispersion |
| 0 | ||||
| 1 | ||||
| 2 | ||||
| 3 | ||||
| 4 | ||||