Ginger Milk Curd 薑汁撞奶 - PDF Free Download

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

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.

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?

Part I: Studies on mechanism of milk coagulation

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 62-67 ph Adjust ph values of ginger juice by NaOH, HCl and citric acid Optimum range ph 3 - ph 6 Enzymatic reaction

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

Part II: Determining hardness of ginger milk curd

Part II: Coin test Aim: Compare and categorize the hardness of product Number of coagulated product 35 30 25 20 15 10 5 0 Soft (0-50s) Distribution of coin test results 0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 Medium (51-230s) Hard (231-900s) Time measured in the coin test (s)

Part III: Other factors affecting milk coagulation

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

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

Part IV: The refined recipe

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

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 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

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 -

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

Key references 1. Hong Kong Examination Authority. HKCEE Biology 2002 I Q4c 2. Wikipedia-Ginger, http://en.wikipedia.org/wiki/ginger 3. 維基百科 - 薑汁撞奶, 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 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

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)

Background 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 Content Calories Protein Fats Types of milk (Kcal) (g) (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) 40 3.6 0.2 5.4 215 F (Kowloon Dairy) 62.0 3.1 3.5 5.6 110 HCLF (Kowloon Dairy) 57.0 4.0 2.0 4.6 165 HCSM (Kowloon Dairy) 38.8 3.7 0.3 5.1 160 Soybean milk 63 3.3 1.9 8.4 -

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

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

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

Result - Temperature Index Coagulation temp. ( ) Coagulation Hardness 6040107 45-6031815 57 + S 6040803 60 + M 6041513 62 + H 6041509 67 + H 6022803 73 -

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 -

Result - Ginger juice Index Coagulation temp. ( ) 6052004 57-6052007 61 + S 6052012 61 + 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 and 4 Powder with iodine solution Result: 1) turns from brown to blue-black 2) white powder contains starch

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

Result ph condition (ginger juice) Index Coagulation temp. ( ) Ginger juice ph Milk Milk curd Coagulation Hardness Remarks 6041516 55 8 8 8 + S Ginger juice 6041505 56 3 8 7 + H 6041504 56.5 4 8 8 + H 6040118 56 9 8 8 + S Citric acid was added Citric acid was added Sodium hydroxide was added.

Result ph condition (milk) Index Coagulation temp. ( ) Ginger juice ph Milk Milk curd Coagulation Hardness Remarks Milk 6040802 57.5 7.5 6 6.5-6040806 56 7.5 10 8 - Sodium hydroxide was added

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

Result Boiling effect Index Coagulation temp. ( ) Boiling Coagulation Hardness 6040102 51 - - 6040103 56 - - 6040808 51 + + S 6040807 56 + + S

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

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

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

Result - Stretching of milk Index Coagulation temp. ( ) stretching Hardness 6040811 51 - M 6040803 60 + M 6052009 68 - S 6041509 67 + S

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

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 54.5 + 1020 H 6041514 HCLF 55 + 900 H smooth 6040816 HCSM 58 + 72 M Control-milk 6052002 HCSM 58 + 265 H Control 6031804 HCSM 57 + 8 S Remarks

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

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

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 10-15 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