Ginger Milk Curd 薑汁撞奶

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1 Ginger Milk Curd 薑汁撞奶 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

2 Introduction: Making ginger milk curd 1) Grate ginger 2) Heat the milk 3) Stretch milk ( 拉奶 ) 4) Pour the milk into 5) Measure the 6) Ginger milk curd ginger juice ( 撞奶 ) product temp.

3 Introduction: Our research questions Question 1 Enzymes in ginger juice + Hot milk Enzymes denatured? Milk coagulates Question 2 Many recipes are not successful How does milk coagulate in ginger milk curd?

4 Part I: Studies on mechanism of milk coagulation

5 Part I: Studies on mechanism of milk coagulation Factor Ginger juice Temp. Method Boiled / un-boiled ginger juice Use milk with different temp. Result Boiled ginger juice did not coagulate Optimum range ph Adjust ph values of ginger juice by NaOH, HCl and citric acid Optimum range ph 3 - ph 6 Enzymatic reaction

6 Part I: Where is the enzyme in ginger juice? Upper supernatant Middle supernatant White powder To make ginger milk curd +/- + - Iodine test Control Result: 1) supernatant contains the enzyme 2) white powder contains starch

7 Part II: Determining hardness of ginger milk curd

test results 0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800

8 Part II: Coin test Aim: Compare and categorize the hardness of product Number of coagulated product Soft (0-50s) Distribution of coin test results Medium (51-230s) Hard ( s) Time measured in the coin test (s)

9 Part III: Other factors affecting milk coagulation

10 Part III: Procedures Grate ginger Boil milk ph ph Extract ginger juice Stretch milk Pour the milk into ginger juice Temp. and ph Coin test Time

11 Part III: Other factors affecting milk coagulation Factor Method Result Boiling Boiled / un-boiled milk Boiling of milk is needed Stretching Stretched / un-stretched milk Fat HCSM milk( 高鈣脫脂奶 ) Calcium HCLF milk( 高鈣低脂奶 ) Add calcium into milk before heating Lower the temp. Necessary for a stable coagulation Lumps formed: cannot be determined Protein Soybean milk Milk protein is necessary

12 Part III: Other factors affecting milk coagulation Factor Method Result Boiling Boiled / un-boiled milk Boiling of milk is needed Stretching Stretched / un-stretched milk Fat HCSM milk( 高鈣脫脂奶 ) Calcium HCLF milk( 高鈣低脂奶 ) Add calcium into milk before heating Lower the temp. Necessary for a stable coagulation Lumps formed: cannot be determined Protein Soybean milk Milk protein is necessary

13 Part III: Other factors affecting milk coagulation Factor Method Result Boiling Boiled / un-boiled milk Boiling of milk is needed Stretching Stretched / un-stretched milk Fat HCSM milk( 高鈣脫脂奶 ) Calcium HCLF milk( 高鈣低脂奶 ) Add calcium into milk before heating Lower the temp. Necessary for a stable coagulation Lumps formed: cannot be determined Protein Soybean milk Milk protein is necessary

14 Part III: Other factors affecting milk coagulation Factor Method Result Boiling Boiled / un-boiled milk Boiling of milk is needed Stretching Stretched / un-stretched milk Fat HCSM milk( 高鈣脫脂奶 ) Calcium HCLF milk( 高鈣低脂奶 ) Add calcium into milk before heating Lower the temp. Necessary for a stable coagulation Lumps formed: cannot be determined Protein Soybean milk Milk protein is necessary

15 Part IV: The refined recipe

16 Part IV: The refined recipe Aim: To design an easy and effective recipe 1) Peel off the ginger 2) Extract 1 tbsp (15ml) ginger juice Vinegar / orange juice (optional) 3) Boil 1 box (236ml) 4) 6 times stretching 5) Ginger milk curd of HCLF milk and pour milk into ginger juice

17 Part V: New tastes of milk curd

18 Part V: New tastes of milk curd Aim: Develop new tastes Method: Using different food to replace ginger juice Food Pineapple juice Kiwi fruit juice Papaya juice Orange juice Water chestnut juice ( 荸薺 / 馬蹄汁 ) Rich in enzymes Reasons Contains citric acid Underground stem of the plant like the ginger

19 Part V: New tastes of milk curd Food Coagulation Remarks Pineapple juice + Bitter and rough product Kiwi fruit juice + Bitter and rough product Papaya juice - Orange juice - Water chestnut juice -

20 Part V: New recipe Traditional way in consuming pineapple: Pineapple + Salt solution Enzyme inhibited Bitter taste removed Our experiment: Pineapple juice Kiwi fruit juice + Salt solution and boiled milk Still bitter

21 Key references 1. Hong Kong Examination Authority. HKCEE Biology 2002 I Q4c 2. Wikipedia-Ginger, 3. 維基百科 - 薑汁撞奶, B6 4. University of Guelph, Dairy Science and Technology Dairy Chemistry and physics, Professor Arthur R. Hill, 5. University of Guelph, Dairy Science and Technology - UHT Processing, Professor Arthur R. Hill, 6. Dept. of Food Science, University of Guelph, Canada -8.1 Milk structure, 8.2 Enzymic Coagulation of Milk, Professor Arthur R. Hill, 7. Wikipedia-milk, Why milk expands on heating,

22 Acknowledgement Prof. LAM H.M., Advisor of the competition for his advice in the Sharing Session with advisors Mr. LO S.K., Teacher advisor Ms. CHAN L.K., Laboratory technician The 28 schoolmates that tested our refined recipe The Organizing Committee and Our School for their generous financial support

23 Summary (concluded from 130 experiments) Enzymatic reaction supported Optimal conditions investigated Recipe refined New tastes of milk curd Enzymes in the supernatant of ginger juice Boiled milk protein Stretching (temp. dropped) Ginger milk curd enhance Suitable temp. + Low ph + Fat (62-67 ) (ph3-ph6)

24 Background information 1) Kiwi Actinidin Milk coagulation bitter taste 2) Pineapple Bromelin Anti-coagulatant 3) Bongkrekic acid Inhibit papain / bromelin / ficin

25 Nutrition content of different milks Content Calories Protein Fats Types of milk (Kcal) (g) (g) Carbohydrates (g) Calcium (mg) F (Nestle) HCLF (Nestle) HCSM (Nestle) F (Kowloon Dairy) HCLF (Kowloon Dairy) HCSM (Kowloon Dairy) Soybean milk

26 Method - Acid coagulation of milk Boil milk Stretch milk Add Ethanoic acid ph 2 ph 3 ph 4 ph 6 ph 5

27 Result - Acid coagulation of milk ph value Ethanoic acid ph 2 ph 3 ph 4 ph 5 ph 6 Boiled milk Un-boiled milk

28 Method - Temperature Grate ginger Boil milk Stretch milk Extract ginger juice Reheat milk Pour the milk into ginger juice

29 Result - Temperature Index Coagulation temp. ( ) Coagulation Hardness S M H H

30 Method - Ginger juice Grate ginger Boil milk Extract ginger juice Stretch milk Centrifuge into 3 parts Pour the milk into ginger juice Upper supernatant Middle layer Middle supernatant +/- + White powder -

31 Result - Ginger juice Index Coagulation temp. ( ) S H Coagulation Hardness Remarks White powder was used instead of ginger juice Upper supernatant from ginger juice was used instead of ginger juice Only the bottom part coagulated Middle supernatant from ginger juice was used instead of ginger juice

Iodine test of the white powder 1 2 3 4 1-Control 2 - Paper which wrapped the powder with iodine solution 3

32 Iodine test of the white powder Control 2 - Paper which wrapped the powder with iodine solution 3 and 4 Powder with iodine solution Result: 1) turns from brown to blue-black 2) white powder contains starch

33 Method ph condition Grate ginger Extract ginger juice Boil milk Add citric acid/ HCl / NaOH Stretch milk Pour the milk into ginger juice - ph of milk and ginger juice : 8

34 Result ph condition (ginger juice) Index Coagulation temp. ( ) Ginger juice ph Milk Milk curd Coagulation Hardness Remarks S Ginger juice H H S Citric acid was added Citric acid was added Sodium hydroxide was added.

35 Result ph condition (milk) Index Coagulation temp. ( ) Ginger juice ph Milk Milk curd Coagulation Hardness Remarks Milk Sodium hydroxide was added

36 Method Boiling effect Grate ginger Expt. 1 heat milk Compare with Expt. 2 Boil milk Extract ginger juice Cool down Cool down Pour the milk into ginger juice

37 Result Boiling effect Index Coagulation temp. ( ) Boiling Coagulation Hardness S S

38 Method Milk protein Grate ginger Boil soybean milk Extract ginger juice Stretch milk Pour the milk into ginger juice

39 Result Milk protein Ginger-soybean milk Coagulation. temp.: 58

40 Method Stretching of milk Grate ginger Boil milk Boil milk Extract ginger juice Cool down Compare with Stretch milk Pour the milk into ginger juice

41 Result - Stretching of milk Index Coagulation temp. ( ) stretching Hardness M M S S

42 Method 1 Milk-Fats Grate ginger Add butter Extract ginger juice Boil milk Stretch milk Milk and butter could not be well-mixed Pour the milk into ginger juice

43 Method 2 Milk Fats Grate ginger Boil HCSM / HCLF Extract ginger juice Stretch milk Pour the milk into ginger juice

Result 2 Milk-Fats Index Milk Coagulation temp. ( ) Coagulation Hardness Time (s) Class 6031805 HCLF 54 + 945 H 6031810 HCLF 54.

44 Result 2 Milk-Fats Index Milk Coagulation temp. ( ) Coagulation Hardness Time (s) Class HCLF H HCLF H HCLF H smooth HCSM M Control-milk HCSM H Control HCSM S Remarks

45 Method - Calcium Grate ginger Add calcium [Ca, Ca(NO 3 ) 2, CaCl 2 ] Boil milk Extract ginger juice Stretch milk Pour the milk into ginger juice

46 Result- Calcium Lumps formed Reason: Ca 2+ coagulates the milk upon heating

47 Application- refined recipe Ingredients: 2 tablespoon (30 ml) Fresh ginger juice Ginger milk curd 1 box (236ml) High Calcium Low Fat milk 2 teaspoons Sugar 1/2 teaspoon (2.5 ml) Vinegar *(optional) Utensils: 1 no. Small bowl 1 no. Small saucepan 1 no. Big bowl Method: 1) Peel the skin of ginger, grate the ginger and press the ginger juice 2) 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 milk 7) Pour the milk into the ginger juice with cm apart vertically 8) 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

Islamic Kasim Tuet Memorial Secondary School. Chun Suk Kwan 6S (6)

Islamic Kasim Tuet Memorial Secondary School Chun Suk Kwan 6S (6) Introduction Aim Principal of experiment Apparatus and Chemicals Procedure Precaution Result Discussion Conclusion References Acknowledgement