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