Prescribed task: Factors affecting the rising of bread dough Ms Mancy Chan Pui Tak Canossian College
Prescribed task: Factors affecting the rising of bread dough Introducing the task (version A) Modifying the task to investigate temperature effect (version C) Adapting the task for school s use
Introducing the task (version A) Background 酵母的發酵作用 CO2 expands the gluten network and causes the bread dough to rise Observe and measure depends on the growth and activity of the yeast
Introducing the task (version A) Factors affecting the rising of bread dough Temperature (Cup B) Additives Salt (Cup C) Sugar (Cup D) Vinegar (Cup E / optional) Control (Cup A)
Introducing the task (version A) Cup (Beaker) Step 1 A B C D Step 2 20 g bread flour 1 tsp yeast 20 g bread flour 1 tsp yeast 20 g bread flour 1 tsp yeast 20 g bread flour 1 tsp yeast -- -- ¼ tsp salt ¼ tsp sugar Stir the mixture Step 3-6 30 ml distilled water 30 ml cold distilled water 30 ml distilled water 30 ml distilled water Stir the mixture Step 4-6 Step 7 Measure and record the initial height of the dough (h i ). Wait for 25 minutes Record the final height of the dough (h f ) in each cup. Note and record the texture of the dough in each cup.
Introducing the task (version A) Initial height of the dough (h i ) A C D E
Introducing the task (version A) Final height of the dough (h f ) A B C D E
Introducing the task (version A) Texture of the dough [Hint: You may indicate the size of bubbles observed in the dough using + signs. The greater the number of + signs (maximum being 5), the larger is the size of bubbles observed in the dough.] A B C D E
Introducing the task (version A) Results Cup (Beaker) Substance added Fermentation temperature ( C) Height of the dough h i (cm) h f (cm) Rise of dough (cm) Appearance A -- ~25 1.7 4 2.3 +++ B -- ~4 1.7 2 0.3 / C salt ~25 1.8 2.5 0.7 + D sugar ~25 1.8 6 4.2 +++++ E vinegar ~25 1.8 3.6 1.8 ++ Another way of describing the appearance (will be mentioned by Eva)
Cup (Beaker) Substance added Fermentation temperature ( C) Height of the dough h i (cm) h f (cm) Rise of dough (cm) Appearance A -- ~25 1.7 4 2.3 +++ B -- ~4 1.7 2 0.3 / C salt ~25 1.8 2.5 0.7 + D sugar ~25 1.8 6 4.2 +++++ Discussion 1. Based on the results of this experiment, state and explain which of the investigated factors favour(s) yeast fermentation. 2. Based on the results of this experiment, state and explain which of the investigated factors inhibit(s) yeast fermentation. 3. Discuss the applications of your findings in bread making.
Modifying the task to investigate temperature effect (version C) Background Similar to Version A But To study the effect of temperature on the rising of bread dough Different fermentation temperatures: 25 C 4-8 C 40-65 C 80-100 C
Modifying the task to investigate temperature effect (version C) Cup (Beaker) Step 1 A B C D Step 2 Step 3 Step 4-8 Step 4-8 Step 9 Measure and record the temperatures of the distilled water and the cold distilled water 20 g bread 20 g bread 20 g bread 20 g bread flour flour flour flour 1 tsp yeast 1 tsp yeast 1 tsp yeast 1 tsp yeast ¼ tsp sugar ¼ tsp sugar ¼ tsp sugar ¼ tsp sugar Stir the mixture 30 ml distilled water 30 ml cold distilled water 30 ml distilled water 30 ml distilled water Stir the mixture Measure and record the initial height of the dough (h i ). Room temperature 4 C 40-65 C 80-100 C Wait for 25 minutes Record the final height of the dough (h f ) in each cup. Note and record the texture of the dough in each cup. Check the surrounding temperature of cup C and cup D every 5 minutes.
Results Modifying the task to investigate temperature effect (version C) A B C D
Modifying the task to investigate temperature effect (version C) Texture of the dough [Hint: You may indicate the size of bubbles observed in the dough using + signs. The greater the number of + signs (maximum being 5), the larger is the size of bubbles observed in the dough.] A B C D
Cup (Beaker) Results Modifying the task to investigate temperature effect (version C) Temperature of distilled water ( C) Fermentation temperature ( C) Height of the dough h i (cm) h f (cm) Rise of dough (cm) Appearance A ~25 (27 C) ~25 (27 C) 1.8 4.5 2.7 +++ B 4 8 4 8 1.9 1.9 0 / C ~25 40 65 1.7 4.5 2.8 D ~25 80 100 1.9 2.8 0.9 ++ (Shrink after few minutes) + (fully cooked)
Height of the Cup Temperature of Fermentation Rise of dough (Beaker) distilled water ( C) temperature ( C) dough (cm) h i (cm) h f (cm) Appearance A ~25 (27 C) ~25 (27 C) 1.8 4.5 2.7 +++ B 4 8 4 8 1.9 1.9 0 / C ~25 40 65 1.7 4.5 2.8 ++ (Shrink after few minutes) D ~25 80 100 1.9 2.8 0.9 + (fully cooked) Discussion 1. Based on the results of this experiment, state and explain which temperature(s) favour(s) yeast fermentation. 2. Based on the results of this experiment, state and explain which temperature(s) inhibit(s) yeast fermentation. 3. Discuss the applications of your findings in bread making.
Adapting the task for school s use List of ingredients Choice of cups Plastic cups 250ml Beakers / Glass cups Ways to maintain different temperatures
List of ingredients Strong flour Yeast (Small pack)
Distilled water List of ingredients
Choice of cups (Plastic cups)
Choice of cups (Plastic cups) Requirements: Volume (~250ml) Cylindrical cup Heat resistance (for Version C)
Choice of cups Plastic cups (285ml) Cheap ($32 for 25) Reusable Beakers (250ml) Expensive (~@$15) (Can be borrowed from Science Lab) Reusable A little bit fragile (broken 10 out of 25 after student trial) Need to handle with care (But students are aware of it) Cannot be used in Version C Can be used in all 3 versions
Ways to maintain different temperatures Dangerous when students pour in or out hot water Water bath Need to have an oven thermometer to monitor the temperature inside the oven Oven (Electric)
Result Ways to maintain different temperatures Cup (Beaker) Temperature of distilled water ( C) D ~25 D2 ~25 Fermentation temperature ( C) 80 100 (Steamer with lid) 80 100 (Electric oven) Height of the dough h i (cm) h f (cm) Rise of dough (cm) 1.9 2.8 0.9 1.9 3.1 1.2 Appearance + (fully cooked) + (fully cooked)
Ways to maintain different temperatures Check the temperature every 5 minutes. Steamer (40-65 C) Steamer (80-100 C)
Prescribed task: Investigating Ways to Prevent Enzymatic Browning
Prescribed task: Investigating Ways to Prevent Enzymatic Browning Introducing the task Adapting the task for school s use
Introducing the task Investigate the effectiveness of three ways of preventing enzymatic browning: immersing the food in lemon juice 1% salt solution blanching for a short period of time
Introducing the task Procedures Steps 1-3 Making lemon juice, 1% salt solution and boiling water Step 4 Making apple slices or balls (will be mentioned later) Dissolve 1 g of salt completely in 100 ml distilled water.
Introducing the task Steps 5-6 Different treatments of apple slices or balls Step 7 No treatment Immersed in lemon juice for 30 seconds Immersed in 1% salt solution for 30 seconds Blanching (Immersed in boiling water for 30 seconds and cool it in icy distilled water) Determine and record the degree of browning every 5 minutes for 30 minutes. Tabulate the results.
Introducing the task Results (Apple balls) No treatment Lemon juice 1% salt solution Blanching 0 min 5 min 10 min 15 min 20 min 25 min 30 min
Introducing the task Results (Apple balls) Treatment Degree of browning at 0 min 5 min 10 min 15 min 20 min 25 min 30 min No treatment + +++ +++ ++++ +++++ +++++ +++++ Immersed in lemon juice - - - - - - - Immersed in 1% salt solution - - - + + + + Blanching - + + ++ ++ ++ ++
Introducing the task Results (Apple slices) No treatment Lemon juice 1% salt solution Blanching 0 min 5 min 10 min 15 min 20 min 25 min 30 min
Introducing the task Results (Apple slices) Degree of browning at Treatment 0 min 5 min 10 min 15 min 20 min 25 min 30 min No treatment + ++ ++ +++ ++++ ++++ +++++ Immersed in lemon juice - - - - - - - Immersed in 1% salt solution - - - - - - + (edge) Blanching - + + + + + +
Remarks Prefer to use Red Delicious Apple (Medium to large size) Red Delicious apple is easier to undergo browning. More obvious results can be obtained.
Adapting the task for school s use Apple corer Using the corer: 1. Push an apple corer down into the flesh of the apple. 2. Twist the corer. 3. Remove the apple flesh from the corer. 4. Cut the cylindrical apple flesh into 0.5cm thick slices.
Adapting the task for school s use Using melon baller : 1. Cut the apple into half. Melon baller 2. Use the melon baller to scoop out the balls. More obvious results can be obtained. * Easier to turn brown.
Adapting the task for school s use White tiles (Bought it from 磁磚店 ) White plates