Aim:
To investigate how volume of green tea ( 0ml, 2ml, 4ml, 6ml, 8ml) affects the breakdown of
fats by lipase in a whole milk in a given time period.
Introduction:
The lifestyle in the 21st century has dramatically changed due to abandonment of daily
physical activity caused by technology development and tendency of people to make life
effortless. More and more people switch from raw and natural food to processed,
ready-to-eat meals which contributed to 20% of deaths in the US in 2016 ("Why Good
Nutrition is Important", n.d.). The reason for that is diet containing excessive amount of
saturated fats, sodium and added sugars as well as in
sufficient level of essential macronutrients and micronutrients abundant in fruits, vegetables,
whole grains and fibers. As a result, the overall health gets deteriorated due to a built-up of
fatty tissue and cholesterol leading to an increased risk of coronary heart disease, stroke,
type 2 diabetes mellitus, obesity, cancer and high blood pressure (Center for Science in the
Public Interest, n.d.). Nowadays, society tends to look for the easiest ways to solve problems
thus we can find many products such as fat burners on the market. One thing that especially
sparked my curiosity was the presence of green tea as an ingredient in many fat burners. I
found out that certain properties of green tea result in reduced level of body fat (Koo & Noh,
2007). Green tea is considered to be the healthiest beverage worldwide and can at least
partially reduce the negative effects of unhealthy diet due to the presence of catechins that
indirectly act as antioxidants through their enzyme activities (US National Library of
Medicine National Institutes of Health, 2003). As I learned during my biology classes the
main enzyme responsible for fat metabolism is lipase so I decided to investigate if there is a
change of lipase activity when green tea is added. In order to examine the lipase’s ability to
catalyse the breakdown of fats I used the whole milk, as milk fat is one of the most complex
of all natural fats containing 400 different fatty acid (Healthline, 2019). The breakdown of fats
in the milk is monitored by measuring the pH of solution containing green tea. The change in
the pH value refers to the level of fatty acids that make up the milk fat.
Research Question: What is the effect of increasing the volume of green tea (0ml, 2ml, 4ml,
6ml, 8ml) on the breakdown of fats by lipase in the whole milk?
Background: Human body carries out a countless number of reactions daily. Some of them
require enzymes to catalyse and speed up the rate of reactions. Enzymes are globular
proteins which are highly specific in their action. They have an active site which is a binding
site for a substrate molecule that selectively fits to the shape of the site and undergoes
catalysis into a product. The relationship between a substrate and the enzyme’s active site is
often compared to a key which suits into the keyhole of the lock. However, this model was
later improved and called an induced fit model which states that substrate stimulates a
change in shape of the enzyme leading to a perfect match between each other. Enzymatic
reactions typically occur in aqueous solutions where the substrate and enzyme randomly
move, which is called the Brownian motion, and collide between each other in the solution.
Lipase is one out of the three main enzymes secreted by the pancreas into the lumen of
duodenum in the intestine. It is responsible for chemical digestion of fats from large organic
macromolecules into small monomers that can be easily absorbed by the microvilli in the
1
, small intestine and then enter the bloodstream. Lipase breaks down triglycerides into
glycerol and fatty acids in the process of hydrolysis that utilises water (Gopinath et al., 2013).
Image showing the simplified hydrolysis of triglyceride carried out by lipase (applied from
Research gate):
Diagrams 1 and 2: The diagrams showing effects of temperature on lipase activity and
effects of pH on lipase activity respectively (applied from researchgate)
According to the diagrams above the optimum temperature for the lipase activity is equal to
40 °C and the optimal pH value is 9. It suggests that under such conditions collisions
between the enzyme and substrate molecules occur most frequently so the rate of reaction
is the highest.
Daily consumption of green tea may have an incredibly beneficial effect on the whole body.
The major polyphenols in green tea are catechins which are the micronutrients packed with
antioxidants from certain plant-based food. They possess the abilities of interfering with or
inhibiting the luminal emulsification, hydrolysis, and micellar solubilization of lipids. It is
possible that catechins hinder access to the substrate by lipase or directly modify enzyme’s
conformation and its catalytic activity. Considerable evidence suggests that green tea and its
catechins may reduce the risk of coronary heart disease by lowering the plasma levels of
cholesterol and triglyceride (US National Library of Medicine National Institutes of Health,
2003).
Milk is one of the most commonly consumed liquids with highly complex nutritional
composition. Whole milk is very high in saturated fats, which make up about 70% of its fatty
acid content, rest constitutes mono and polyunsaturated fatty acids (Healthline, 2019). In the
investigation the whole milk of Coop brand has been used. It contains 3.6g of fat, of which
2.3 saturated ( around 63.89%)
2
To investigate how volume of green tea ( 0ml, 2ml, 4ml, 6ml, 8ml) affects the breakdown of
fats by lipase in a whole milk in a given time period.
Introduction:
The lifestyle in the 21st century has dramatically changed due to abandonment of daily
physical activity caused by technology development and tendency of people to make life
effortless. More and more people switch from raw and natural food to processed,
ready-to-eat meals which contributed to 20% of deaths in the US in 2016 ("Why Good
Nutrition is Important", n.d.). The reason for that is diet containing excessive amount of
saturated fats, sodium and added sugars as well as in
sufficient level of essential macronutrients and micronutrients abundant in fruits, vegetables,
whole grains and fibers. As a result, the overall health gets deteriorated due to a built-up of
fatty tissue and cholesterol leading to an increased risk of coronary heart disease, stroke,
type 2 diabetes mellitus, obesity, cancer and high blood pressure (Center for Science in the
Public Interest, n.d.). Nowadays, society tends to look for the easiest ways to solve problems
thus we can find many products such as fat burners on the market. One thing that especially
sparked my curiosity was the presence of green tea as an ingredient in many fat burners. I
found out that certain properties of green tea result in reduced level of body fat (Koo & Noh,
2007). Green tea is considered to be the healthiest beverage worldwide and can at least
partially reduce the negative effects of unhealthy diet due to the presence of catechins that
indirectly act as antioxidants through their enzyme activities (US National Library of
Medicine National Institutes of Health, 2003). As I learned during my biology classes the
main enzyme responsible for fat metabolism is lipase so I decided to investigate if there is a
change of lipase activity when green tea is added. In order to examine the lipase’s ability to
catalyse the breakdown of fats I used the whole milk, as milk fat is one of the most complex
of all natural fats containing 400 different fatty acid (Healthline, 2019). The breakdown of fats
in the milk is monitored by measuring the pH of solution containing green tea. The change in
the pH value refers to the level of fatty acids that make up the milk fat.
Research Question: What is the effect of increasing the volume of green tea (0ml, 2ml, 4ml,
6ml, 8ml) on the breakdown of fats by lipase in the whole milk?
Background: Human body carries out a countless number of reactions daily. Some of them
require enzymes to catalyse and speed up the rate of reactions. Enzymes are globular
proteins which are highly specific in their action. They have an active site which is a binding
site for a substrate molecule that selectively fits to the shape of the site and undergoes
catalysis into a product. The relationship between a substrate and the enzyme’s active site is
often compared to a key which suits into the keyhole of the lock. However, this model was
later improved and called an induced fit model which states that substrate stimulates a
change in shape of the enzyme leading to a perfect match between each other. Enzymatic
reactions typically occur in aqueous solutions where the substrate and enzyme randomly
move, which is called the Brownian motion, and collide between each other in the solution.
Lipase is one out of the three main enzymes secreted by the pancreas into the lumen of
duodenum in the intestine. It is responsible for chemical digestion of fats from large organic
macromolecules into small monomers that can be easily absorbed by the microvilli in the
1
, small intestine and then enter the bloodstream. Lipase breaks down triglycerides into
glycerol and fatty acids in the process of hydrolysis that utilises water (Gopinath et al., 2013).
Image showing the simplified hydrolysis of triglyceride carried out by lipase (applied from
Research gate):
Diagrams 1 and 2: The diagrams showing effects of temperature on lipase activity and
effects of pH on lipase activity respectively (applied from researchgate)
According to the diagrams above the optimum temperature for the lipase activity is equal to
40 °C and the optimal pH value is 9. It suggests that under such conditions collisions
between the enzyme and substrate molecules occur most frequently so the rate of reaction
is the highest.
Daily consumption of green tea may have an incredibly beneficial effect on the whole body.
The major polyphenols in green tea are catechins which are the micronutrients packed with
antioxidants from certain plant-based food. They possess the abilities of interfering with or
inhibiting the luminal emulsification, hydrolysis, and micellar solubilization of lipids. It is
possible that catechins hinder access to the substrate by lipase or directly modify enzyme’s
conformation and its catalytic activity. Considerable evidence suggests that green tea and its
catechins may reduce the risk of coronary heart disease by lowering the plasma levels of
cholesterol and triglyceride (US National Library of Medicine National Institutes of Health,
2003).
Milk is one of the most commonly consumed liquids with highly complex nutritional
composition. Whole milk is very high in saturated fats, which make up about 70% of its fatty
acid content, rest constitutes mono and polyunsaturated fatty acids (Healthline, 2019). In the
investigation the whole milk of Coop brand has been used. It contains 3.6g of fat, of which
2.3 saturated ( around 63.89%)
2
