[Milk Bread Project Proposal] How does the ratio of milk to water affect the softness and appearance of bread?

How does the ratio of milk to water affect the softness and appearance of bread?

Background

The origin of milk bread is relatively unknown, but it is believed to be based on a Chinese technique for making soft, sweet buns which have air bubbles inside. The Japanese adopted the technique in the 20th century, but milk bread was not popular until the end of WWII when rice supply was limited and the influx of American ingredients was rising.  Today, Japanese milk bread has taken the world by storm, becoming many’s favourites.

Experiment (5Ws)

What?

To investigate the effect of the ratio of milk to water on the softness and appearance of milk bread

Who?

Fung Sing Yi, Zoe

When?

Observe instantly after cooling the milk bread

Where?

Home kitchen

Why?

To find out the best ratio of milk to water for the most cottony and velvety milk bread

How?

Follow the recipe except changing the ratio of milk to water. Compare the colour of the crust after cooling. Slice the bread to observe the softness.

Recipe

Yield: 9x5-inch loaf (4 servings)

Estimated preparation time: 1 hour and 45 minutes

Estimated cooking time: 40 minutes

Estimated total time: 2 hours and 30 minutes

Ingredients:
- 370g bread flour
- 240mL whole milk
- 120mL water
- 60g granulated sugar
- 7g active dry yeast
- 1 tablespoon non-fat dry milk powder
- 1 teaspoon fine sea salt
- 1 large egg (lightly whisked)
- 60g softened unsalted butter
- Heavy cream (for brushing)

Variables

Independent Variable	Dependent Variables	Controlled Variables
The ratio of milk to water - 360mL milk - 300mL milk and 60mL water (5:1) - 240mL milk and 120mL water (2:1) - 120mL milk and 240mL water (1:2)	The softness of milk bread - Number and size of air bubbles - Thickness of bread after compression with the same strength The appearance of milk bread - Colour of the crust	- Brand of all ingredients (Including flour, milk, yeast, sugar, butter, milk powder, egg and heavy cream) - Amount of all ingredients (Including flour, yeast, sugar, butter, milk powder, egg and heavy cream) - Time and speed used for kneading the dough - Size and shape of milk bread - Fermentation time - Baking time - Baking temperature - Cooling time

Science Behind

Lactose is found in milk, which has little sweetening power and is not fermentable. It will caramelize quickly in the oven and form a darker colour crust. The bread crust dries and turns brown due to the Maillard reaction. Maillard reaction takes place when sugar and protein-containing formulations are subjected to heat processing in the presence of adequate amounts of free water, alkaline pH and some metals. It is a common process to produce desired colours and flavours in bakery products.

Milk fats account for 3-4% of a bread recipe. During fermentation, milk fats will then melt and form an extensible thin film, further stabilizing the gas bubble. Upon further heating,  shortening fats melt completely and form an elastic film with gluten along cell walls. The newly established film can also stabilize gas bubbles. As a result, solid fat-incorporated bread exhibit increased porosity, loaf volume, and softness.

Source:

1. https://www.mdpi.com/2304-8158/8/9/383/pdf

2. https://opentextbc.ca/ingredients/chapter/milk-in-bread-baking/

3. https://redstaryeast.com/yeast-baking-lessons/common-baking-ingredients/liquids/