Ginger Milk Curd
Daughters of Mary Help of Christians Siu Ming Catholic Secondary School
Cherry Choi, Vivian Chau, Grace Chim, Iris Lau and Ivy Wong
Hong Kong Student Science Project Competition 2006
Introduction: Making ginger milk curd
2) Heat the milk1) Grate ginger 3) Stretch milk ()
4) Pour the milk into 5) Measure the 6) Ginger milk curdginger juice () product temp.
Introduction: Our research questions
Question 1
Hot milk
Enzymes denatured ?Enzymes in
ginger juiceMilk
coagulates+
Question 2
Many recipes are not successful
How does milk coagulate in ginger milk curd?
Part I: Studies on mechanismof milk coagulation
Part I: Studies on mechanism of milk coagulation
Factor
Optimum range pH 3 - pH 6
Adjust pH values of ginger juice by NaOH, HCl and citric acidpH
Optimum range 62 - 67 Use milk with different temp.Temp.
Boiled ginger juice did not coagulateBoiled / un-boiled ginger juice
Ginger juice
ResultMethod
Enzymatic reaction
Part I: Where is the enzyme in ginger juice?
Result:1) supernatant contains the
enzyme2) white powder contains starch
Control
Iodine test
Upper supernatant
+/-
Middle supernatant
+
White powder
-
To make ginger milk curd
Part II: Determining hardness ofginger milk curd
Distribution of coin test results
0
5
10
15
20
25
30
35
0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000
Time measured in the coin test (s)
Num
ber o
f coa
gula
ted
prod
uct
Aim: Compare and categorize the hardness of productPart II: Coin test
Soft (0-50s)
Medium (51-230s)
Hard (231-900s)
Part III: Other factors affectingmilk coagulation
Part III: Procedures
Grate ginger Boil milk pH
Extract ginger juice pH Stretch milk
Pour the milk into ginger juice Temp. and pH
Coin test Time
Part III: Other factors affecting milk coagulation
Factor Method ResultBoiling Boiled / un-boiled milk Boiling of milk is needed
Stretching Stretched / un-stretched milk
Lower the temp.
Fat HCSM milk()HCLF milk()
Necessary for a stable coagulation
Calcium Add calcium into milk before heating
Lumps formed:cannot be determined
Protein Soybean milk Milk protein is necessary
Part III: Other factors affecting milk coagulation
Factor Method ResultBoiling Boiled / un-boiled milk Boiling of milk is needed
Stretching Stretched / un-stretched milk
Lower the temp.
Fat HCSM milk()HCLF milk()
Necessary for a stable coagulation
Calcium Add calcium into milk before heating
Lumps formed:cannot be determined
Protein Soybean milk Milk protein is necessary
Part III: Other factors affecting milk coagulation
Factor Method ResultBoiling Boiled / un-boiled milk Boiling of milk is needed
Stretching Stretched / un-stretched milk
Lower the temp.
Fat HCSM milk()HCLF milk()
Necessary for a stable coagulation
Calcium Add calcium into milk before heating
Lumps formed:cannot be determined
Protein Soybean milk Milk protein is necessary
Part III: Other factors affecting milk coagulation
Factor Method ResultBoiling Boiled / un-boiled milk Boiling of milk is needed
Stretching Stretched / un-stretched milk
Lower the temp.
Fat HCSM milk()HCLF milk()
Necessary for a stable coagulation
Calcium Add calcium into milk before heating
Lumps formed:cannot be determined
Protein Soybean milk Milk protein is necessary
Part IV: The refined recipe
Part IV: The refined recipeAim: To design an easy and effective recipe
Vinegar / orange juice (optional)
1) Peel off the ginger 2) Extract 1 tbsp (15ml)ginger juice
4) 6 times stretching3) Boil 1 box (236ml) 5) Ginger milk curdand pour milkinto ginger juice
of HCLF milk
Part V: New tastes of milk curd
Part V: New tastes of milk curd
Aim: Develop new tastes
Method: Using different food to replace ginger juice
Food ReasonsPineapple juiceKiwi fruit juicePapaya juice
Rich in enzymes
Orange juice Contains citric acidWater chestnut juice(/)
Underground stem of the plant like the ginger
Food Coagulation RemarksPineapple juice + Bitter and rough productKiwi fruit juice + Bitter and rough productPapaya juice -Orange juice -
Water chestnut juice -
Part V: New tastes of milk curd
Part V: New recipeTraditional way in consuming pineapple:
Enzyme inhibitedSalt
solutionBitter taste removed
Pineapple +
Our experiment:
Pineapple juice
Kiwi fruit juice+ Salt solution and boiled milk Still bitter
Key references
1. Hong Kong Examination Authority. HKCEE Biology 2002 I Q4c
2. Wikipedia-Ginger , http://en.wikipedia.org/wiki/Ginger
3. -, http://zh.wikipedia.org/wiki/%E8%96%91%E6%B1%81%E6%92%9E%E5%A5%B6
4. University of Guelph , Dairy Science and Technology Dairy Chemistry and physics, Professor Arthur R. Hill, http://www.foodsci.uoguelph.ca/dairyedu/chem.html
5. University of Guelph , Dairy Science and Technology - UHT Processing, Professor Arthur R. Hill, http://www.foodsci.uoguelph.ca/dairyedu/uht.html
6. Dept. of Food Science, University of Guelph, Canada -8.1 Milk structure, 8.2 Enzymic Coagulation of Milk, Professor Arthur R. Hill, http://www.foodsci.uoguelph.ca/cheese/sectiond.htm#coagulation
7. Wikipedia-milk, Why milk expands on heating, http://en.wikipedia.org/wiki/Milk
Acknowledgement
Prof. LAM H.M., Advisor of the competition for his advice in the Sharing Session with advisors
Mr. LO S.K., Teacher advisorMs. CHAN L.K., Laboratory technician
The 28 schoolmates that tested our refined recipe
The Organizing Committee and Our School for their generous financial support
Enzymes in the supernatant of
ginger juice
Boiled milk protein
Summary (concluded from 130 experiments)
Stretching (temp. dropped)
Enzymatic reaction supported
Optimal conditions investigated
Recipe refined
New tastes of milk curd
Ginger milk curd
enhance
Suitable temp. + Low pH + Fat (62 - 67 ) (pH3-pH6)
spareBackground information
1) Kiwi Actinidin
Milk coagulation bitter taste
2) Pineapple Bromelin
Anti-coagulatant
3) Bongkrekic acid
Inhibit papain / bromelin / ficin
Nutrition content of different milks spare
Content
Types of milk
Calories
(Kcal)
Protein
(g)
Fats
(g)
Carbohydrates
(g)
Calcium
(mg)
F (Nestle) 62 3.1 3.5 4.6 110
HCLF (Nestle) 63 4.6 2.0 6.7 238
HCSM (Nestle)
F (Kowloon Dairy)
HCLF (Kowloon Dairy)
HCSM (Kowloon Dairy)
Soybean milk
40 3.6 0.2 5.4 215
62.0 3.1 3.5
4.6
110
57.0
38.8
63
4.0
3.7
3.3
2.0
0.3
1.9
5.6
5.1
8.4
165
160
-
Method - Acid coagulation of milk spare
Boil milk
Stretch milk Add Ethanoic acid
pH 2 pH 3 pH 4 pH 6 pH 5
Result - Acid coagulation of milk spare
pH value
Ethanoic acid pH 2 pH 3 pH 4 pH 5 pH 6
Boiled milk + + ++ + -
Un-boiled milk + + ++ + -
Method - Temperature spare
Grate ginger Boil milk
Stretch milk
Reheat milkExtract ginger
juice
Pour the milk into ginger juice
Result - Temperature
IndexCoagulationtemp. ()
Coagulation Hardness
6040107 45 -
6031815 57 + S
6040803 60 + M
6041513 62 + H
6041509 67 + H
6022803 73 -
spare
Method - Ginger juice spare
Grate ginger
Extract ginger juice
Pour the milk into ginger juice
Stretch milk
Boil milk
Centrifuge into 3 parts
Middle layer
Upper supernatant +/-
Middle supernatant +
White powder -
Result - Ginger juice
Index Coagulation temp. () Coagulation Hardness Remarks
6052004 57 - White powder was used instead of ginger juice
6052007 61 + SUpper supernatant from ginger juice was used instead of ginger juiceOnly the bottom part coagulated
6052012 61 + H Middle supernatant from ginger juice was used instead of ginger juice
spare
1 - Control2 - Paper which wrapped the powder with iodine solution3 and 4 Powder with iodine solutionResult: 1) turns from brown to blue-black
2) white powder contains starch
Iodine test of the white powder
1 2 3 4
spare
Method pH condition spareGrate ginger
Boil milk
Extract ginger juice
Add citric acid/ HCl / NaOH
Stretch milk
Pour the milk into ginger juice
- pH of milk and ginger juice : 8
Result pH condition (ginger juice)
pHIndex
Coagulationtemp. () Ginger
juice MilkMilk curd
6041516 55 8 8 8 + S
Ginger juice
6041505 56 3 8 7 + H Citric acid was added
6041504 56.5 4 8 8 + H Citric acid was added
6040118 56 9 8 8 + SSodium hydroxide was added.
Coagulation Hardness Remarks
spare
Result pH condition (milk)
pHIndex
Coagulationtemp. () Ginger
juice MilkMilk curdMilk
6040802 57.5 7.5 6 6.5 -
6040806 56 7.5 10 8 -Sodium hydroxide was added
Coagulation Hardness Remarks
spare
Method Boiling effect spare
Grate ginger
Extract ginger juice
Pour the milk into ginger juice
heat milkExpt. 1
Cool down
Boil milkExpt. 2
Compare with
Cool down
Result Boiling effect
Index Coagulation temp. () Boiling Coagulation Hardness
6040102 51 - -
6040103 56 - -
6040808 51 + + S
6040807 56 + + S
spare
Method Milk protein spare
Grate ginger
Extract ginger juice
Boil soybean milk
Stretch milk
Pour the milk into ginger juice
Result Milk protein spare
Ginger-soybean milk
Coagulation. temp.: 58
Method Stretching of milk spare
Grate ginger Boil milk Boil milk
Extract ginger juice
Pour the milk into ginger juice
Cool down Stretch milk
Compare with
Result - Stretching of milk
Index Coagulation temp. () stretching Hardness
6040811 51 - M
6040803 60 + M
6052009 68 - S
6041509 67 + S
spare
Method 1 Milk-Fats spare
Grate ginger
Extract ginger juice
Pour the milk into ginger juice
Stretch milk
Boil milk
Add butter
Milk and butter could not be well-mixed
Method 2 Milk Fats spare
Grate ginger
Boil HCSM / HCLF
Extract ginger juice Stretch milk
Pour the milk into ginger juice
Result 2 Milk-FatsHardnessIndex Milk Coagulation
temp. ()Coagulation
Time (s) Class6031805 HCLF 54 + 945 H6031810 HCLF 54.5 + 1020 H6041514 HCLF 55 + 900 H smooth6040816 HCSM 58 + 72 M Control-milk6052002 HCSM 58 + 265 H Control6031804 HCSM 57 + 8 S
Remarks
spare
Method - Calcium spare
Grate ginger
Add calcium [Ca, Ca(NO3)2 , CaCl2 ]
Boil milk
Extract ginger juice Stretch milk
Pour the milk into ginger juice
Result- Calcium
Lumpsformed
spare
Reason: Ca2+ coagulates the milk upon heating
Application- refined recipeGinger milk curd
Ingredients:2 tablespoon (30 ml) Fresh ginger juice1 box (236ml) High Calcium Low Fat milk2 teaspoons Sugar1/2 teaspoon (2.5 ml) Vinegar *(optional)Utensils:
1 no. Small bowl1 no. Small saucepan1 no. Big bowlMethod:1) Peel the skin of ginger, grate the ginger and press the ginger juice2) Filter the ginger juice and take 1 tablespoon of it
3) Mix ginger juice with vinegar* in small bowl 4) Boil the milk 5) Pour the milk into a big bowl and pour the milk back into the small saucepan for 6 times in a distance
10-15cm (from one container to another container is counted as once)6) Add sugar into the milk7) Pour the milk into the ginger juice with 10-15 cm apart vertically8) Wait the milk till set for 3-4 minutes *It is not necessary to add vinegar, the ginger milk curd will be harder and rough if vinegar is added
spare
Ginger Milk CurdIntroduction: Making ginger milk curdPart I: Where is the enzyme in ginger juice?Background informationNutrition content of different milksMethod - Acid coagulation of milkResult - Acid coagulation of milkMethod - TemperatureResult - TemperatureMethod - Ginger juiceResult - Ginger juiceMethod pH conditionResult pH condition (ginger juice)Result pH condition (milk)Method Boiling effectResult Boiling effectMethod Milk proteinResult Milk proteinMethod Stretching of milkResult - Stretching of milkMethod 1 Milk-FatsMethod 2 Milk FatsResult 2 Milk-FatsMethod - CalciumResult- Calcium