Denaturation and Coagulation

Hey guys! welcome back to my blog. This week in class we made two delicious recipes, mini quiches and chocolate meringue kisses. In class we learned about the functional properties of proteins, which are Denaturation and Coagulation.

For the mini quiche, here is the recipe:

For the bacon and tomato filling:

- 20g butter


-  ½  brown onion, finely chopped


-  1 garlic clove, finely chopped

-  ½ tomato, sliced

-1 rasher bacon, diced

- 50g cheese, grated

- 2 eggs

- 90ml cream

-Salt and pepper to season

For the shortcut pastry:

-1 cup flour

- 75g butter, chilled, chopped

-1  egg yolk


-Pinch of salt

-1-3 tbs ice water


Method:
For Pastry:

1. Preheat oven to 220C. Grease a mini quiche baking tray with butter.

2. Sift together the flour and salt

3. Rub butter into flour using fingertips until the mixture resembles fine breadcrumbs. Add water gradually to make stiff dough.


4. Wrap in plastic film and refrigerate for at least 15 minutes

5. Roll out dough 2mm thick between 2 sheets of baking paper. Use a large cookie cutter to cut pastry cases. Place into well-greased quiche baking tray. Cover each case with baking paper and blind bake (bake with cooking weights) for 10 minutes. Remove weights and cook for a further 5 minutes.


For Filling:


1. Melt butter in a small frying pan over medium heat. Add onion and garlic (and bacon). Cook, stirring, for 5 minutes until onion has softened (and bacon is crispy) (add spinach and cook for 1 minute).  Transfer mixture to a bowl. Set aside for 10 minutes to cool (once cool mix through crumbled feta or tomato).

2. Beat together egg and cream.  Season with salt and pepper. Transfer to a pouring jug. Evenly spoon either bacon or spinach mixture into your pastry cases and then pour egg mixture into each case. Sprinkle with grated cheese and bake for 15-20 minutes or until set. Stand for 5 minutes. Serve with salad.

For the chocolate meringue kisses:

 - 1 eggwhite

-  1/4 cup caster sugar

- 45g dark chocolate

- 30g sour cream

- Cocoa powder to dust

Method:

1. Preheat oven to 150°C/130°C fan-forced. Line 2 baking trays with baking paper.

2. Using an electric mixer, beat eggwhites until stiff peaks form. Add caster sugar. Beat for 8 minutes or until sugar has dissolved.

3. Place mixture into a piping bag fitted with a 5mm fluted or plain nozzle. Pipe 2cm wide swirls of mixture onto prepared trays, allowing 2cm between each for spreading. Bake for 20 minutes or until meringues are firm. Turn off oven. Allow to cool in oven with door slightly ajar.

4. When meringues are cool, place the chocolate and sour cream in a heatproof bowl. Place bowl over a saucepan of simmering water; stir until chocolate melts.

5. Dip the base of a meringue in the chocolate and sandwich with another meringue. Repeat with remaining meringues and chocolate. Dust with cocoa powder.

The physical changes that occurred throughout the making of the quiche is the mixing ingredients for both the filling and the pastry. The physical change that occurred in the filling were the dicing of the bacon, onion, garlic and tomato. For the pastry, the rolling out of the dough to make it thin and smooth was a physical change.

In the making of the mini quiche and the chocolate meringue kisses, the process of denaturation and coagulation occurred. Egg was the protein that was mainly responsible of the chemical changes that occurred for both the quiche and meringue. When denaturation occur the strands of the helix separate and unravel and the bonds that holds the helix shape breaks. In coagulation, it occurs when protein strands that were unravelled begins to re-join with other strands which forms a solid mass.

There are several chemical changes that occurred in both recipes. There are 4 factors that allow these chemical changes to occur. They include temperature, agitation, acidity and enzyme action. For The higher the temperature is the quicker proteins will coagulate. Heat also causes proteins to unravel. But, different temperatures will affect the process properties of different food. Denaturation occurs when the bonds between strands of amino acids begins to break. Acid is also used to help thicken dairy products.The function of the food can be affected if there is too much mixing and if its mixed too much the strands will be stretched too much to the point where the protein is denatured, that factor is called Agitation. And lastly, enzyme action can also affect denaturation and coagulation.

For eggs to coagulate it requires temperature. Egg whites begin to thicken when it reaches 63 degrees Celsius, at 65 degrees Celsius egg whites become tender solid and the yolk protein starts to thicken, this is when coagulation occurs. The egg yolk sets at 70 degrees Celsius. When it hits 73 degrees Celsius the whole egg sets. If eggs are left in the heat for too long it will continue to coagulate and water is pushed out from between protein molecule, the egg will get rubbery.

There are two types of denaturation of proteins, reversible and irreversible. In many proteins (unlike egg whites), denaturation is reversible when the proteins regain their native state when the denaturing influenced is removed, this process can be called renaturation. In under certain conditions, the process coagulation may be reversible. The characteristics of a protein change when coagulated, among which is loss of solubility in water and dilute salt solutions.

There are many different types of protein. Proteins enable foods to set. These properties are useful to commercial food processing. The two processes are denaturation and coagulation. To denature means to change properties; once a protein has denatured, it cannot return to its original form. An example of this is when heat is applied to an egg. Coagulation helps thicken and changes into a semisolid mass. Examples of denaturation and coagulation are scrambled egg, baked custard and beaten egg white. The process of denaturation and coagulation is affected by the application of acid, alkalis, sugar and salt.

That is the end of my blog. I hope you that helped you understood more about denaturation and coagulation!

Thanks, Kae :)

Bibliography:

EndInformatics 1999, Science project ideas using eggs, viewed 17 March 2016, http://www.edinformatics.com/science_projects/egg_proteins.htm


Florina 2014, Kkkjjm, viewed 18 March 2016, http://www.slideshare.net/priyankaflorina/denaturation-of-proteins


StasoSphere 2007, Coagulation of proteins, viewed 18 March 2016, http://chestofbooks.com/food/science/Experimental-Cookery/Coagulation-Of-Proteins.html

Chemistry of Lipids

Hey guys! welcome back to my blog. This week we made a delicious recipe, homemade sausage rolls with sweet chilli aioli. In class we learned about saturated and unsaturated fatty acids and we also started looking at chemistry of fat. 

Even though we didn't actually do this experiment in class, we talked through about what happens when you add bromine water solution to saturated fat or unsaturated fat, then we talked about the different results it impacted between the two fatty acids. When you add bromine solution to olive oil, the oil will turn into a colourless colour, this happened because it is an unsaturated fat. When you add bromine solution to animal fat it will turn into a brown/orangey colour because animal fat is saturated fat. Both vegetable oil and vegetable shortening also works for this experiment. If you do the same thing as before with vegetable oil, your result would be a colourless colour because vegetable oil is unsaturated. As vegetable shortening is unsaturated, the colour will turn into a brown/orangey colour when you add bromine solution but even though vegetable shortening is from a plant, which is unsaturated, it has gone through a process called hydrogenation making it a saturated fat. Double bonds are converted to single bonds in the reaction. In this way unsaturated fats can be made into saturated fats.

Unsaturated fats contains double carbon-carbon bonds, which means it reacts to bromine solution. Polyunsaturated fats has double carbon-carbon bonds, whilst monounsaturated fats have one carbon-carbon bond. Therefore, polyunsaturated fat will react more because it has more double bonds, and the more double bonds there are in the fat, the more the bromine will react.

Saturated fats and unsaturated fats have different chemical structures. As shown in the picture below, the saturated fat structure has no double bond between molecules, which means there are no gaps and the fat is saturated with hydrogen molecules. Instead of a single bond, unsaturated fats have double bonds, which break up the chains, leaving hydrogen molecules missing and create gaps.

With the sausage rolls here is the recipe for it:

- 300g sausage mince
- 75g fresh breadcrumbs
- 1/2 brown onion, coarsely grated
- ½ carrot, grated
- 1 garlic cloves, crushed
- 2 tsp Moroccan spice mix
- ¼  cup coarsely chopped coriander
- 1.5 sheets (25cm) ready -rolled puff pastry, thawed, halved
- ½  egg, lightly whisked
- 2 tsp sesame seeds
- 1 tsp cumin seeds

Method:
1. Preheat oven to 220°C. Line 2 oven trays with baking paper. Combine the mince, breadcrumbs, onion, garlic, Moroccan spice and coriander in a large bowl.

2. Fit a large piping bag with a 2cm plain nozzle. Place the sausage mixture into the piping bag. Pipe the mixture down the edge of a pastry sheet. Roll to enclose. Brush a little egg on the end to secure. Use a sharp knife to cut the roll into 4cm lengths. Place on the tray. Continue with remaining mince and pastry sheets. Brush with remaining egg and sprinkle with sesame and cumin seeds. Place in the fridge for 15 minutes to rest.

3. Bake for 15-20 minutes or until pastry is puffed and golden and centre is cooked through. Serve warm or at room temperature

For the Puff Pastry recipe:

- 150g plain flour
- Pinch of salt
- 20g butter, chopped
- 85ml iced water
- 133g butter

Method:1. Place the flour and salt in food processor. Add butter and mix until it resembles breadcrumbs.

2. Add water and pulse until a ball forms. Turn dough onto a lightly floured surface and gently knead until just smooth. Cover with plastic wrap and place in the fridge for 10 minutes to rest.

3. Use a lightly floured rolling pin to roll out the dough to a 10 x 30cm rectangle. Place butter between 2 sheets of plastic wrap and tap with a rolling pin to make a 8 x 9cm rectangle. Lay dough on a lightly floured surface with a short edge closest to you. Remove the plastic wrap from the butter and place in the centre of the dough. Fold the end closest to you over the butter, and then fold the opposite end over the top (the butter should now be enclosed in the dough).

4. Turn dough 90° clockwise and gently press edges together. Use a lightly floured rolling pin to gently tap to flatten butter. Roll out dough to a 10 x 30cm rectangle and repeat folding process as before. Cover with plastic wrap and place in the fridge for 5-10 minutes to rest.

5. Remove dough from the fridge and repeat rolling and folding process 2 more times. Cover with plastic wrap and place in the fridge for 5-10 minutes to rest. Repeat rolling and folding process a further 2 times and place in the fridge for 5-10 minutes to rest. (Dough should have been folded and rolled 6 times altogether.)

The sausage rolls we cooked in class were delicious. It was also big, so it was very filling. They had a golden brown colour to them when they came out of the oven. The texture was flaky but also soft when you bite into it. They are a lot more different then the ones we buy from a grocery store. The sausage rolls we made were homemade, therefore they are fresher and you can taste the flavour more like the herbs and spices which gave it a great taste. The ones we buy at the grocery stores are frozen, which means it loses its flavour and its freshness. The puff pastry we buy from the grocery stores are also frozen. The texture will not be as good and flaky compared to homemade puff pastry. The taste of the sausage roll can also differ from the ones at the grocery stores due to its ingredients and seasonings that were added to the filling.

The purpose of rolling butter into pastry more than once was to create the flaky texture and the flaky layers of the pastry. This develops strong two-dimensional glutinous layers and traps air between them. This air then expands on heating, giving height to your pastry.

The purpose of putting the dough in the fridge was to rest it. It gives the gluten time to rest to prevent the pastry from shirking while cooking it. It also keeps the butter cool. If its not refrigerated, the butter would melt, making the pastry soggy and wet.

The sources of fats in the recipe were:
- the meat (sausage mince) : contains saturated and unsaturated fats
- butter: contains saturated and unsaturated fats
- olive oil: unsaturated fats
- egg: Contains monounsaturated, polyunsaturated and saturated fats
- Dijon mustard: only has roughly 0.19g of fat per teaspoon, but contains all three types of fats.

In this recipe, we used emulsification and shortening. We used emulsification when were making the sweet chilli aioli. We used it to combine the oil to the egg while slowing adding the oil in while whisking at a fast motion. This functional property is used to make sauces such as mayonnaise and other salad dressings. For shortening, we used this functional property to make the pastry. Its process is to incorporate air when we rub the butter into the flour. It also stops gluten from becoming tough. This functional property is mostly used to make pastries, cakes and cookies.

To make a sweet chilli aioli, we need an emulsifying agent. We would need an egg as the emulsifying agent for this recipe to help the oil and water mix together. This is because egg yolk contains an ingredient called lecithin. Lecithin has the ability to stabilize oil and water, making it a great emulsifier.

Trans fatty acid is an unsaturated fatty acid but act like saturated fat. They occur naturally in food or be formed or added to food during manufacture. They are commonly found in animal products including meat, cheese and margarine. They are formed when a liquid, such as vegetable oil, goes through a process of 'hydrogenation' to create spreads such as margarine, cooking fats for deep frying and shortening for baking. A high amount of trans fatty acids can increase your bad (LDL) cholesterol levels and decrease your good (HDL) cholesterol. (Food Standards Australia and New Zealand, 2015).

I hope that helped you understand more about saturated and unsaturated fats!

Will be posting another blog next week :)

Thanks, Kae

Reference:

BBC 2006, GCSE Bitesize: Double bonds and hydrogenation, viewed 8 March 2016, http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/plantoilsanduses/vegoilsrev4.shtml

BBC 2013, GCSE Bitesize science - natural fats and oils: Revision, page 2, viewed 10 March 2016,  http://www.bbc.co.uk/schools/gcsebitesize/science/triple_ocr_gateway/chemistry_out_there/natural_fats_oils/revision/2/

Demand Media n.d, How to distinguish between saturated & unsaturated fats, viewed 10 March 2016, http://healthyeating.sfgate.com/distinguish-between-saturated-unsaturated-fats-7667.html

Food Standards Australia and New Zealand 2015, viewed 11 March 2016, http://www.foodstandards.gov.au/consumer/nutrition/transfat/pages/default.aspx

picture: http://healthyeating.sfgate.com/distinguish-between-saturated-unsaturated-fats-7667.html

Functional Properties of Gelatinisation

Hey guys! welcome back. For this weeks blog post we will be discovering the functional properties of gelatinisation and how the chemical reactions occur when used in cooking.

For this week, I cooked two recipes that involves gelatinisation. The first recipe was the White Sauce, second recipe was the Risotto.

Gelatinisation is the process in which starch granules are heated in a liquid, causing the starch granules to swell.
The heat breaks down the starch molecules allowing it to absorb the liquid. Any type of starch can be used. Gelatinisation is used as a thickening agent of food systems. The ratio of amylopectin and amylose and the method used determines the physical qualities of the gel that is produced.

Starches contain around 25% amylose and 75% amylopectin. Starches that contain more amounts of Amylose are more useful in food preparation. Starches that contain a higher amount of amylopectin creates clearer gels and thick liquid, while starches that contain 25% amylose creates opaque gels that are quite solid. Amylose and Amylopectin have a few differences, such as that amylose are more soluble in water, while amylopectin is less soluble. However, amylose does not form starch gel or paste, while amylopectin does. Although, amylose is soluble in hot water without even swelling, while amylopectin swells up in soluble hot water. Amylose is a part of 20% of the starch, while amylopectin is a part of 80% of the starch.


For the White sauce:
The equipment's we will be needing for this recipe are:
-1/2 cup of milk
- Either: 2 tsp plain flour, corn flour or rice flour
- 10g butter
- 1 tbs cheese
- 1/2 tsp dried parsley
- 2-3 tsp frozen corn
- 1/8 Turkish roll, roasted

For the Method:
1. Melt butter in a small saucepan on a medium heat. Remove from the heat. Stir in flour to absorb butter. Return to heat (this help to break open the starch molecules in the flour) for 1 minute. Remove from heat.
2. Slowly whisk in milk, until all lumps have been removed. Return to heat until sauce thickens.
3. Allow to cool for 2 minutes, and stir through cheese, corn and parsley. Season with salt and pepper.
4. Serve with torn, toasted Turkish bread.

Now for the Risotto,
The equipment's that are needed are:
- 2 3/4 cups hot chicken stock
- 1/2 chicken breast, sliced
- 2 Tbs oil
- 1/2 onion, chopped
- 1 cup (440g) Arborio rice
- 1 tsp lemon rind, finely grated
- 2 rashers of bacon, diced
- 1/4 cup white wine
- 1 garlic clove, finely chopped
- 1/4 cup (40g) finely grated parmesan
- Salt and Pepper to season
- 1/2 cup fresh basil leaves, roughly torn

For the Method:
1. Heat 1tbs oil in a small fry pan over a medium heat. Add chicken and cook until golden. Transfer to a bowl and cover with foil. Add bacon and fry for 1-2 minutes. Add to bowl.
2. Meanwhile, in a separate medium size fry pan, sweat (without browning) onion and garlic in remainder of the oil for 2-3 minutes or until soft (cook on medium heat with lid on.) Add the rice and stir until well coated in oil. Add white wine and allow to reduce.
3. Add 1 cup of the hot stock and cook, stirring often, until the stock is absorbed. Continue adding the hot stock, 1 cup at a time, stirring until the stock is absorbed and the rice is just tender.
4. Stir the lemon rind and grated parmesan through the risotto and then season to taste. Fold 3/4 of the basil through the risotto. Divide among the serving dishes. Top with the remaining basil and shaved parmesan. Serve immediately.

We were able to tell that the gelatinisation in the white sauce and risotto was occurred by the consistency and look. The longer it was in the heat the thicker and more gel like it gets. The risotto rice went from being hard and nutty ,to becoming a thick gel consistency, it was because of the rice absorbing the liquid which caused the rice to break down. In the white sauce, the sauce became thicker and thicker the longer it was in the presence of the heat, it went from a runny, watery like consistency to a thick sauce. The observations showed us that gelatinisation had occurred on both recipes.

My observations of the rice before and after cooking it was;
Rice before: White, Hard, Grainy, Nutty, Thin shape 
Rice After: Almost transparent, Soft, Smooth, Slightly thicker shape

When starch is in the presence of heat, it softens, giving it the chance to absorb the liquid. When the temperature reaches 86 degrees - 90 degrees, the starch granule bursts and the amylose and amylopectin is released which absorbs the liquid, giving us a thick gel like product. Without heat, the molecules wont burst therefore the amylose and amylopectin are not released.

Starch is a polysaccharide, which means it is able to break down. Polysaccharide are found in plants, starchy vegetables and grains such as rise and wheat. When the molecule breaks down, it processes chemical changes like gelatinisation and dextrinization. Corn starch and plain flour are most commonly used to help thicken liquid such as water. For potato starch, it used with things like potato soup and mashed potato, it is also commonly used in fast food restaurants. Also, corn starch and rice starch are commonly used to make edible sweets and lollies (Hegenbart,1996).

Arborio rice is commonly used to make risotto because it contains a high level of starch, while brown rice or long grain rice has lower levels and does not produce a sticky creamy texture like Arborio rice.  Long grain rice cooks up fluffy and doesn't clump together, therefore it will not make the required texture for a risotto (Tamarkin, 2015). Also, long grain rice and brown rice wont absorb as much liquid compared to Arborio rice,  therefore they both don't have that sticky and thick result. They both have more levels of amylose then amylopectin, and like I said before in the previous paragraphs, it is the amylopectin that thickens the liquid, whilst amylose gives the product more of a solid opaque gel end result.

It is important to add acid such as lemon in the risotto after it was cooked because gelatinisation can be affected by additives such as sugar and acid, the pH level can be altered which gives it different results. Acids like lemon juice can affect the thickness of the mixture, while for sugar, it affects the temperature of gelatinisation.

Here are my resources:

Diana Maricruz Perez Santos, n.d., Science Meet Food, viewed 1 March 2016, http://sciencemeetsfood.org/starch-gelatinization/

Major Differences 2015, Major Differences, viewed 1 March 2016, http://www.majordifferences.com/2013/02/difference-between-amylose-and_17.html#.VtaQ249OLIV

Scott Hegenbart 1996, Understanding Starch Functionality, viewed 3 March 2016, http://www.naturalproductsinsider.com/articles/1996/01/understanding-starch-functionality.aspx

David Tamarkin 2015, When to Use Long-Grain, Medium-Grain and Short-Grain Rice, viewed 3 March, http://www.epicurious.com/ingredients/rice-guide-long-grain-short-medium-article

I hope you enjoyed this weeks blog and learned things!

Thanks, Kae