Chapter 3.2: Protein

Physical and Chemical reaction of Protein
Hydrolysis 

•  acid present
• able to enhance solubility and capability to form gel

Denaturation

• pressure needed [stirring, freezing or mild heating]
• decrease the solubility and loss ability to catalyze reaction

Coagulation

• breaking of linkage (peptide bond) - non reversible process
• factor: Heat, pH
• increase viscosity as denatured protein aligned themselves in clumps (if protein too high)

Differences between Starch & Flour

The type of flour can affect the gluten formation depends on the protein content in the flour.
Protein content [From high to low]:
Semolina flour → Bread flour ⟶ All purpose flour ⟶ Pastry flour ⟶ Cake flour
Batter vs Dough : the ratio of liquid & flour : technique to develop gluten
Batter has lower flour content than Dough ;
Batter use stirring/beating where Dough use kneading method to develop gluten.

Gluten Formation
How the gluten form? 
Why mixing process is needed?
Why kneading process is needed?
Why water is needed?
When the flour that contain protein (gliadin&glutenin) is mixed with water. The water will hydrate the flour. Mixing process is needed in order to form distribution of dry ingredients uniformly. Kneading process is needed to incorporate air and restructure the molecule. Both protein have different function to the product. Gliadin provides stickiness, extensibility and stretching. Glutenin provides the strength and elasticity. When the flour undergo fully hydration and proper agitation, gluten is able to form.
What happen if Overkneading?
The outcome of the product will be tough. why?
Overkneading will cause the gluten strength break and then will form sticky/lumpy. Then, the volume is unable to increase and give a dense result.

Function of flour in products
🎀Provide structure🎀
- prevent product from collapse once cooled and removed from heat
- help to hold the shape
- gluten formation provides strength,volume,structure & appearance
🎀Absorb lipids🎀
- important quality factor in bread production
- affected by several factors eg. protein content
🎀Contribute flavor🎀
- provide mild nutty flavor.
- higher protein & ash content contribute stronger flavor [Whole wheat flour > cake flour]
🎀Contribute color🎀
- through Maillard reaction

Example:
-🍞🥖 Bread : Yeast + sugar → alcohol + CO2
The rise of bread = [Heat + leavening agent] with gluten formation
Yeast is biological leavening agent commonly used in bread.
Gluten is formed when the flour + water with kneading.
Heat applied: The yeast undergo fermentation and produce CO2. The gluten membrane will be filled with CO2 and the steam generated during baking. The heat in air expand and stretch out with gluten. The protein coagulate when heating. ∴ The bread volume 🆗 & airy👌
Others Leavening agent :
Physical: Air & steam 
Chemical: Baking soda & baking powder
Baking powder - acidic
Baking soda - alkali; need to add acid & water to produce CO2
What if pastry flour is used to make bread❓
Pastry flour ➡ low protein content ➡ low gluten formation ➡ low volume & dense
🎂🍰Can cake flour be replaced in making cakes❓
Cake flour contain more starch than protein ⇾ starch tend to undergo gelatinization to give the structure. Making cake need lesser gluten formation in term of the texture.

- 🌾Whole wheat flour products
Dense texture,
Low volume,
Darker color,
Strong flavor,
Lower shelf-life. WHY❓ 
Because the presence of bran in whole wheat flour.  
Bran contain sharp edge so it will cut out and disrupt the gluten. Hence, less gluten formation which cant contribute the volume and give dense texture.
The oat flavor is because of the presence of germ and bran. 
The presence of germ give lower shelf-life. 
Because germ contain fat so it has the possibility to induce rancidity.

- 🍜🍝Noodle/ pasta products
Protein content ↠ gluten strength affect the pasta quality
Protein content ∝ firmness and elasticity of pasta (Structure)

-🍪 Cookies and pastry products like tarts
Control gluten formation by Absorb lipid👈
①Prevent gluten formation - incorporate fat into flour
Flour is covered/surrounded with fat so the water cant hydrate the flour.
Gluten cant form when the flour is not hydrated.
②Shortened gluten
Fat is added to cut the gluten that already developed in the product.
To provide tender/softer texture.

🥚Egg🍳
Egg: only Egg yolk contains Fat. Yolk contain more protein where egg white has higher water content.
💟Functional Role of Egg💟
Emulsifier
Foaming
Interfering agent
Others [Binder,clarifying agent]

What is emulsion? A colloidal dispersion of a liquid into another liquid which is immiscrible.
Oil in water emulsion ; eg: Mayonaise, milk
Water in oil emulsion ; eg: Butter, margarine
4 types of emulsion instability:
1. Creaming
2. Sedimentation
3. Flocculation
4. Coalescene
Emulsifier is needed to??
✔ form an stable emulsion
✔ lower interfacial tension
✔ form a protective film around droplets (short term stability to delay coalescene)

The function of ingredients in Mayonnaise

Function of Egg in Cake

Function of hydrocolloid in cake
1.Higher Cake Volume
2.Finer and Closer Texture
3.Improved Softness and Humidity
4.Simplicity and Flexibility
5.Formula Cost Reduction

Foaming -
🍥Making of Meringue cookies 🍥

Soft Meringue Challenge
Leaking - caused by failure to coagulate all the protein in the foam
Beading - formation of brown color on the surface of meringue

Interfering- egg control sugar crystallization & water molecule crystallization
outcome: smoother and more velvety texture
Example: Ice-cream 🍦

Binding&clarifying -
Egg protein coagulate and form binding // trap impurites
Example: Making consomme and meatball

Coagulation - temperature
68℃ Whole egg
60-65℃ Egg white
65-70℃ Egg yolk
To raise the coagulation temp.: add sugar / reduce amount of egg
To decrease the coagulation temp.: add salt/ acid/ increase amount of egg
Hence,
The factors affecting are.....❓
Temperature,
Duration of cooking,
Salt content and its concentration,
Sugar content

🥛🐄Milk & dairy products
Milk content 80% casein and 20% whey
Casein curd when added acid and the pH level closed to its isoelectric point.

Treatment/ Processing of Milk
Pasteurization - Kill microbes but benign microbes still alive ; Lacto Bacillus → Lactic acid
a) LTLT : 65℃ /30min – quick cool 7℃
b) HTST : 72℃/15s - cool 10℃
c) UHT : 138℃/2s - store sterile container; store in fridge once open.
UHT: ultra high temperature kill most of the microbes.
Homogenization - Creamy texture, prevent creaming, increase stability
Dispersed the fat globule to tiny globule
Skimming - No fat
Possible have to fortified Vitamin A & D, why?
Because vitamin A & D are fat soluble vitamin, so they tend to be removed during skimming process.
Evaporation - Concentrated milk ≽ 50% evaporate
Power milk also undergo evaporation
Drying - Powder milk
Drying will cause lumping because of lactose crystal
Prevent lumping = avoid from moisture

💌Function of milk in bakery products💌
1. Increase crust color - due to Maillard reaction
2. Increase crust softness - fat content increase
3. Delay staling - prevent starch retrogradation, increase shelf-life
4. Absorbs moisture - dough rise easily [milk contain sugar]
5. Aids in coagulation of egg protein - milk protein & salt strengthen gluten structure.

Scum Formation 

Dairy products - Cream
Milk undergo "Creaming" process to form cream & skimmed milk
The higher fat content, more thicker and heavier, more creamier and more yellowish (carotenoid content)
Whipping cream

Factors affect stability of milk foam - fat content, temperature, sugar & whipping time
Dairy products - Cheese
Acid / Enzyme is added to produce curd and whey
Cheese are categorized by the firmness and moisture content
Problems using cheese: