Course:FNH200/2014w Team08 Bread

Introduction

Brioche bread is a pastry which originates from French. It’s very popular and is usually served as bread pudding, French toast, hamburger bun, panini sandwich and so on. The dough of making brioche is enriched in butter and egg yolks and sometimes milk and oil are added to increase its richness and that’s the reason why it’s very high in fat.The high proportion of fat gives the bread an extremely soft crumb and a flaky rich texture as well as the attractive golden brown color with a buttery smell after baking. However, the richness of fat may have adverse effect on health that cannot be ignored. Although the brioche bread gives people a very classic taste, it’s actually not very difficult to make. Do you know the food chemistry behind it that contributes to its classic taste? Do you know why consuming too much brioche bread is not good for your health? Do you know why bread staling for brioche bread happens so fast? This wiki page will explore the mystery behind the lovely brioche bread and there’s an awesome video guiding you through the baking process step by step. Let's start the adventure of the brioche bread!

Freshly made brioche bread

History

Brioche is derived from the French word “broyer” which means to knead. Some etymologists say that the word might have actually come from a combination of hocher (to stir) and bris (to break). Other etymologists argue that the name actually derived from a French district that was famous for making Brioche pastry with Brie cheese. There have been references to brioche throughout history, but the most famous one was from Marie Antoinette’s famous quote “let them eat cake” which was interpreted to reference to brioche. It’s worthy to note, however, that the brioche mentioned by Marie Antionette is probably not the same as the brioche we know today as the brioche mentioned by her is more akin to a white loaf of bread that has been lightly enriched with butter and eggs .

Baker's yeast

Chemical Interactions

In the making of brioche, baker's yeast (Saccharomyces cerevisiae) is added. Baker's yeast are single-celled aerobic fungi that grow optimally between 27-35c and can undergo either meiosis or mitosis every 100 minutes or so. They reproduce either asexually (haploid cells) through budding, or sexually (diploid cells) through sporulation. Sporulation only occurs when resources are abundant enough to support the four daughter cells that are produced.

Most bread products follow a similar recipe: high-protein flour, water, salt, and yeast, either added or developed naturally from wild yeasts found in the air and flour (ie naturally leavened). Using these ingredients, the final bread product is made by alternating periods of work (kneading) and rest (fermentation). The first mixing and subsequent rest of water, salt, yeast, and flour is called the autolyse step, and is necessary to allow the flour to absorb water. After the autolyse, the dough is kneaded to develop the gluten structure that will form the crumb of the final product. The gluten that is developed through the kneading process traps the carbon dioxide gas within the bread structure, leading to the development of air pockets, or 'cells'. After kneading, the dough is allowed to rest in a period called bulk fermentation. Bulk fermentation is essential as it allows the yeast to begin fermenting the sugars found in the dough into alcohol. Initially, starch found in the flour is broken down into maltose sugar by diastase. The maltose is then broken down further into glucose by the yeast, using the enzyme maltase. Any sugar (sucrose) that is added will be broken down by invertase into fructose and glucose. The glucose and fructose are then used by the yeast for energy using the enzyme zymase, forming ethanol and carbon dioxide as a by-product. Bulk fermentation times can be adjusted to change the flavour of the final product. Longer fermentation times mean stronger, more acidic flavours. After the fermentation stage, the dough can go through the final shaping process, which deflates the carbon dioxide pockets that formed during fermentation. A final rest stage, called proofing, allows for further fermentation and gluten development before the final product goes into the oven.

Gluten function

Bread flour (flour that is relatively high in protein) mixed with water and kneaded will form gluten, which is a compound made up of two smaller proteins: gliadin and glutenin. Gliadin functions to promote viscosity and stretch, while glutenin is thought to affect bread volume and stability. The addition of fats will inhibit gluten development, as is found in the crumb of brioche: the addition of butter prevents the cellular structure inside the brioche from becoming airy, stretchy and chewy, leading to a softer, more substantial product. Added fats also increase the shelf-life of the final product. Some added sugar encourages fermentation, but the addition of too much will bind any free water and halt ethanol production.

Maillard Reaction

Maillard process

The Maillard browning reaction occurs when a nucleophilic amino group attached to an amino acid reacts with a carbonyl group of a reducing sugar. It is named after the French chemist Louis-Camille Maillard. This reaction can only take place at high temperatures (140-165C) and, because of the many different available combinations of amino acids and reducing sugars, is responsible for a wide array of flavours and smells. The egg wash used on top of the brioche provides the amino acids necessary for the Maillard reaction to occur.

Preparation

Ingredients

• 500g bread flour
• 70g milk
• 15g fresh yeast /or 7.5g of dry yeast
• 15g salt
• 50g sugar
• 250g/5 medium eggs
• 300g unsalted butter

Bread flour compared to all purpose flour:bread flour contains more gluten protein than all purpose flour, which is structurally crucial for bread making. All purpose flour or cake flour has less gluten protein, making it suitable for baked goods which are not as dense, such as cakes, sponges, muffins, etc.

Salted butter compared to unsalted butter: unsalted butter has a faster expiry date compared to salted butter, and we have learned that salt is a common preservation method which slows down certain spoilage causing bacteria. In almost all commercial bakeries around the world, unsalted butter is used because it is crucial that chefs and bakers alike be able to have control over the sodium content of their goods. Aalt is an inhibitor of yeast, which will negatively impact bread and other baked goods. Salted butter is the cheaper variety, and most often the one found in households. It is used primarily for cooking in which fat and seasoning are required, such as steaks and saute.

Procedure

Begin by adding all the dry ingredients (flour, salt, sugar) together in a bowl. Using lukewarm tap water, mix the dry yeast in a small bowl. Have butter, milk, eggs at room temperature. On a large surface, create a well within the mixed flour, and pour in all the wet ingredients. Roughly mix the dough into a solid mass, and begin adding chunks of butter into the dough while kneading. Continue kneading until the dough begins to dry and separate from your hands. Shape the dough into a boule (ball) and let it rest for 10-20 minutes. Resting the dough allows the yeast cells to feed and grow in strength, and allows the gluten strands to rest before portioning and proofing.

After being rested, the dough is punched down and folded over to develop the gluten just alittle bit more. After the folds, we can being to scale our dough out into desired portions. The dough must rest after portioning to allow the gluten to relax again, otherwise the product will become tough. A relaxed dough will make shaping much easier, after which they can be put into molds or baking trays for proofing.

Proofing is a method of applying moisture and warm heat, similar to a sauna, to re-enable the yeast to ferment, this time for good until they enter the oven. The product, in this case brioche, is very delicate and will deflate if not handled properly. Ideally, the brioche should double in size during the proofing process. Before entering the oven, the product is given an egg wash to aid in appearance and protect the tops from burning.

Nutrition and Health

Health Influence

Approximate nutrition facts for brioche

Since brioche is bread with a significant addition of butter and eggs, it’s bound to have a relatively high amount of fats, protein, and carbs. Brioche’s nutritional values are as follows: Brioche has a high amount of saturated fat and cholesterol which, when taken in excess, have negative effects on the body. Saturated fats increase risk of heart disease, stroke, and atherosclerosis. Similarly, excess cholesterol also increases risk of atherosclerosis and other heart-related diseases by causing a buildup of plaque.

Diets affected by consuming brioche

• Celiac/Coeliac Disease
• Lactose Intolerance
• Vegan
• Allergies
• Kosher
• Diabetes
• High Cholesterol/Fat Diet.

Characteristics

Internal Characteristics

The inside of brioche is very similar to those white breads we see on the shelf of bakery section in any stores. Although it has uniform air pockets like regular white breads, the size of the bubbles are rather small. This is due to the amount of butter used. When kneading the dough, unlike the white breads, excessive amount of butter is well mixed into the air bubble, leaving no space between the strands of the flour mixture. However, during baking, the butter is melted and that makes the air pockets.

External Characteristics

The outer part of the bread resembles croissant. It has very thin crust-like layer which breaks very easily when sliced. Depending on how the baker shapes the dough, it can have white bread-like external structure. However, it is not as dense or thick as the regular bread. If egg wash is applied to the top of the dough before baking, it has very delicious-looking golden brown color to it.

Flavor

Compared to white bread, it has very heavy taste to it when consumed. It gives very strong butter flavor. To imagine the taste of brioche, combine the flavor of croissant and texture of very soft white bread. If brioche is used to make sandwich, it may not be a good combination as the taste of the bread itself is very overwhelming. It goes well with fruity jams, or can be eaten with tea or coffee, something that is light in flavor for the balance.

Stability

Just like any other bread, the shelf-life of brioche falls in the short-side. However, it can be lengthened by making few changes to the environment the brioche is stored in. Due to the amount of butter it has, the oxidative rancidity easily develops and quickens when exposed to light. Level of moisture and the temperature also affect the self-life. The starch within the bread starts to retrograde. Packing of linear starch molecules will exclude moisture, making the bread dry and tough. The temperature affects the rate of enzymatic reaction. To avoid negative changes that will shorten the shelf life of brioche, wrap the freshly baked brioche into aluminium foil to block the light. Then place it in a plastic bag to avoid any contact with air. After, place it in a refrigerator to keep the temperature low, which will also decrease the rate of enzymatic reaction.

Preservation and Deterioration

There are some factors that have influence on the taste of brioche bread as well as microbial growth, enzyme activity and chemical reaction which account for the food deterioration. Therefore, a proper preservation is needed for the maintenance of food quality.

Loss of moisture

The leftover of freshly baked brioche bread can be well wrapped and then put in the fridge for short-term storage or frozen for up to five weeks’ preservation. However, the texture of the brioche bread will be changed due to the retrogradation of starch. The brioche bread will become dry and tough which is caused by packing of linear starch molecules leading to the exclusion of water that was previously absorbed during gelatinization.

Water activity

The preservation of baked brioche bread or dough by low temperate will lead to the lowering water activity due to the loss of moisture. When the free water present in food is removed, multiplication of microbial cells will stop because there’s no free water available for the chemical and biological reactions to take place. Therefore, the lowering of water activity can inhibit the microbial growth and enzymatic reactions and thus the storage life of brioche bread is extended. Similarly, salt is added to the dough to remove water by binding water in dough which prevents the participation of free water in chemical and biological reactions.

Temperature

The storage of life can be extended by lowering the temperature which can reduce the rate of enzymatic, biological and chemical reactions. Although the microbial growth rate is reduced by low temperature, not all the microorganisms are killed. Therefore, raw brioche dough can be preserved by being placed in a freezer-safe container in the freezer for only up to ten days.

Oxygen

Oxygen is one of the effects contributing to food deterioration and the deterioration occurs frequently due to the oxidation of fats in food. Brioche bread has a very high proportion in fats and thus the oxidative rancidity can easily develop and accelerate with exposure to light. To reduce the oxidative rancidity, the exposure to oxygen should be reduced. So for preservation, brioche bread should be wrapped tightly in aluminum foil and then place the foil-wrapped brioche bread in a plastic bag and reduce the exposure of brioche bread to oxygen by tying the ends closed as well as pushing out as much air as possible. Lastly, use the adhesive tape to seal the brioche bread tightly.

Chemicals

For the sake of controlling the growth of microorganisms, some chemicals are added to food as preservatives. Sodium propionate is one of the antimicrobial agents that is usually added in bread for the mould inhibition purposes. Moreover, antioxidant such as ascorbic acid is usually added to the dough to decay the oxidative rancidity.

Reflection

Brioche bread is a very soft and filling bread. As previously stated, it is also high in saturated fat which, in excess amounts, can have negative effects on health. As that is the case, brioche bread is good every once in a while as it is enjoyable and delicious. Furthermore, brioche takes quite a bit of time to make even if everyone knows what they are doing. The process of making the bread requires effort and patience.

Our group would also recommend that brioche is eaten with jelly/jam as it helps to reduce the “sick” feeling that one gets from eating too much brioche in one occasion. Not only that, the addition of jelly/jam helps to give a contrast in texture and flavour. Overall, brioche, while it takes some work to make, is a delicious bread that is even tastier with the addition of other flavours and textures.

Final Exam Question

Question 1

What makes brioche unhealthy if eaten in excess?

a) High butter content

b) High unsaturated fat content

c) High saturated fat content

d) Both A and C

e) All of the above

Question 2

Describe the series of reactions that occur when yeast fully ferment the sugars found in flour. List all intermediates, enzymes, and end products.

Question 3

Why the brioche bread becomes tough and dry after a short-term storage?

Question 4

What are the proteins that make up Gluten, and what does Gluten do during kneading and baking.

Answer

Question 1

d

Question 2

During bulk fermentation, yeast use the enzyme diastase to break down starch found in the flour into maltose sugar, which is further broken down into glucose via the enzyme maltase. Any added table sugar (sucrose) is also broken down by the enzyme invertase into glucose and fructose. The yeast then use the glucose and fructose for cellular respiration, which creates ethanol and carbon dioxide as a by-product.

Question 3

The retrogradation of starch which is caused by packing of linear starch molecules leading to the exclusion of water that was previously absorbed during gelatinization. Therefore, the brioche bread is tough and dry.

Question 4

Gliadin & Glutenin. Gluten's main purpose during the kneading phase is to absorb all the moisture, all the while developing and tenderizing the strands of gluten formed. Gluten provides the structure for the bread to stand on itself once baked.

Video

https://www.youtube.com/watch?v=LUDWDkMCyXQ