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
- 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.
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:
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
Kae, you demonstrated an excellent understanding of saturated and unsaturated fatty acids and their reaction to bromine solution. You did this by including a detailed response to the chemical structures of the different fatty acids and how these react to a bromine solution. Here you could have also talked about the fact that fatty acids with more C=C bonds are more susceptible to attack and therefore more readily break.
ReplyDeleteFor the second half of your response, you did not go into enough depth for the questions regarding rolling and refrigerating pastry, functional properties of fat and the chemistry of an emulsifying agent. Despite this, you included a number of examples of foods used in industry to help demonstrate the uses of fat in the food industry.
Overall grade for Practical Work and Post: B-