CHEM 101 ASSIGNMENT

1. Chemical Reactions During Cooking

Cooking involves numerous complex chemical reactions that transform raw ingredients into palatable and digestible food. Heat is the primary condition driving these changes.

1.1. Cooking of Carbohydrates (Spaghetti, Pounded Yam)

These foods are rich in starch, a complex carbohydrate.

Reactants: Starch (polysaccharide) and water.
Reaction: Starch gelatinization and some dextrinization.
- How it happens: When starch granules are heated in the presence of water (e.g., boiling spaghetti or yam), they absorb water and swell, leading to the rupture of the granules and the release of amylose and amylopectin. This process, called gelatinization, increases the viscosity and makes the food softer and more digestible. Prolonged heating can lead to some dextrinization, breaking starch into smaller dextrins.
Products: Gelatinized starch, dextrins.
Conditions: High temperature (e.g., $100^ ext{o}C$ for boiling water), presence of water.
Catalyst: None in the traditional sense; heat is the energy input.

1.2. Cooking of Proteins (Chicken, Egusi)

Chicken is primarily protein and fat, while egusi contains significant protein and fat from melon seeds.

Reactants: Proteins.
Reaction: Protein denaturation and coagulation, Maillard reaction.
- How it happens: Heat causes proteins to denature, meaning their complex three-dimensional structure unravels. This unfolding exposes hydrophobic regions and leads to the coagulation of proteins, changing the texture from raw (e.g., liquid egg white) to solid (e.g., cooked chicken breast). Denaturation also makes proteins more accessible to digestive enzymes. If dry heat is applied (e.g., frying chicken) or sufficient heat is applied to amino acids and reducing sugars, the Maillard reaction occurs, producing brown pigments and desirable flavor compounds.
Products: Denatured and coagulated proteins, various Maillard reaction products.
Conditions: Elevated temperature (ranging from $60^ ext{o}C$ to over $150^ ext{o}C$ depending on method), often dry or moist heat.
Catalyst: None.

1.3. Cooking of Fats (Chicken, Egusi Soup Ingredients)

Fats are present in chicken, egusi seeds, and other soup ingredients.

Reactants: Triglycerides (fats).
Reaction: Melting, and at higher temperatures, thermal degradation or oxidation.
- How it happens: When heated, solid fats melt into liquid form. Excessive heating can lead to thermal degradation (e.g., breaking down into free fatty acids and glycerol) or oxidation, which can produce undesirable flavors and aromas (rancidity) and potentially harmful compounds (e.g., acrolein at smoke point).
Products: Melted fats, potentially breakdown products like free fatty acids.
Conditions: Elevated temperature (melting points vary, degradation occurs at higher temperatures).
Catalyst: None, though certain metal ions can catalyze oxidation.

2. Chemical Reactions During Digestion

After consumption, food undergoes a series of enzymatic hydrolysis reactions in the digestive system. The body maintains a constant core temperature of approximately $37^ ext{o}C$ at which these enzymatic reactions are optimized.

2.1. Digestion of Carbohydrates (Spaghetti, Pounded Yam)

Reactant: Starch (a polysaccharide).
Product: Glucose (monosaccharide).
Reaction: Hydrolysis.
How it happens and Conditions:
1. Mouth: Saliva contains salivary amylase (ptyalin). This enzyme begins to break down long chains of starch into smaller polysaccharides (dextrins) and disaccharides (maltose).
  - Condition: Neutral to slightly alkaline pH ( $6.7-7.0$ ), body temperature ( $37^ ext{o}C$ ).
  - Catalyst: Salivary amylase.
2. Stomach: The highly acidic environment of the stomach denatures salivary amylase, halting starch digestion.
  - Condition: Acidic pH ( $1.5-3.5$ ), body temperature ( $37^ ext{o}C$ ).
3. Small Intestine: As chyme enters the small intestine, it is neutralized. The pancreas releases pancreatic amylase, which continues to hydrolyze starch into maltose (a disaccharide).
  - Condition: Slightly alkaline pH ( $7-8$ ), body temperature ( $37^ ext{o}C$ ).
  - Catalyst: Pancreatic amylase.
4. Small Intestine (Brush Border): Enzymes located on the brush border (inner lining) of the small intestine, such as maltase, break down maltose into two glucose molecules. Other disaccharidases like sucrase and lactase break down sucrose and lactose, respectively, into monosaccharides.
  - Condition: Slightly alkaline pH, body temperature ( $37^ ext{o}C$ ).
  - Catalysts: Maltase, sucrase, lactase.
Overall Products: Glucose, fructose, galactose (absorbed into the bloodstream).

2.2. Digestion of Proteins (Chicken, Egusi)

Reactant: Proteins.
Product: Amino acids.
Reaction: Hydrolysis.
How it happens and Conditions:
1. Stomach: Hydrochloric acid (HCl) denatures proteins, unfolding them and making them more accessible to enzymes. HCl also activates pepsinogen to pepsin, a protease that begins to hydrolyze proteins into smaller polypeptides.
  - Condition: Highly acidic pH ( $1.5-3.5$ ), body temperature ( $37^ ext{o}C$ ).
  - Catalyst: Pepsin (activated by HCl).
2. Small Intestine: The pancreas releases inactive proteases like trypsinogen and chymotrypsinogen, which are activated into trypsin and chymotrypsin (respectively) by enteropeptidase. These enzymes further break down large polypeptides into smaller peptides.
  - Condition: Slightly alkaline pH ( $7-8$ ), body temperature ( $37^ ext{o}C$ ).
  - Catalysts: Trypsin, chymotrypsin.
3. Small Intestine (Brush Border): Various peptidases (e.g., aminopeptidases, dipeptidases) on the brush border and within intestinal cells break down small peptides into individual amino acids.
  - Condition: Slightly alkaline pH, body temperature ( $37^ ext{o}C$ ).
  - Catalysts: Peptidases.
Overall Products: Amino acids (absorbed into the bloodstream).

2.3. Digestion of Fats (Chicken, Egusi Soup Ingredients)

Reactant: Triglycerides.
Product: Monoglycerides and free fatty acids.
Reaction: Hydrolysis.
How it happens and Conditions:
1. Mouth and Stomach: Minor digestion by lingual lipase (mouth) and gastric lipase (stomach), primarily acting on short and medium-chain fatty acids.
  - Condition: Mouth (neutral pH), Stomach (acidic pH), body temperature ( $37^ ext{o}C$ ).
  - Catalysts: Lingual lipase, gastric lipase.
2. Small Intestine: The most significant fat digestion occurs here. Bile salts, produced by the liver and stored in the gallbladder, emulsify large fat globules into smaller droplets, increasing the surface area for enzyme action. Then, pancreatic lipase hydrolyzes triglycerides into monoglycerides and free fatty acids.
  - Condition: Slightly alkaline pH ( $7-8$ ), body temperature ( $37^ ext{o}C$ ), presence of bile salts.
  - Catalyst: Pancreatic lipase (with the help of co-lipase).
Overall Products: Monoglycerides and free fatty acids (absorbed and re-packaged).

In summary, both cooking and digestion involve complex chemical reactions essential for nutrient utilization and food safety, driven by heat during cooking and specific enzymes, pH, and temperature during digestion.

1. Chemical Reactions During Cooking

Cooking involves numerous complex chemical reactions that transform raw ingredients into palatable and digestible food. Heat is the primary condition driving these changes.

1.1. Cooking of Carbohydrates

1.1.1. Spaghetti

Spaghetti is rich in starch, a complex carbohydrate.

Reactants: Starch (polysaccharide) and water.
Reaction: Starch gelatinization and some dextrinization.
How it happens: When starch granules in spaghetti are heated in the presence of water (e.g., boiling spaghetti), they absorb water and swell, leading to the rupture of the granules and the release of amylose and amylopectin. This process, called gelatinization, increases the viscosity and makes the food softer and more digestible. Prolonged heating can lead to some dextrinization, breaking starch into smaller dextrins.
Products: Gelatinized starch, dextrins.
Conditions: High temperature (e.g., $100^\text{o}C$ for boiling water), presence of water.
Catalyst: None in the traditional sense; heat is the energy input.

1.1.2. Pounded Yam

Pounded yam is rich in starch, a complex carbohydrate.

Reactants: Starch (polysaccharide) and water.
Reaction: Starch gelatinization and some dextrinization.
How it happens: When starch granules in pounded yam are heated in the presence of water (e.g., boiling yam), they absorb water and swell, leading to the rupture of the granules and the release of amylose and amylopectin. This process, called gelatinization, increases the viscosity and makes the food softer and more digestible. Prolonged heating can lead to some dextrinization, breaking starch into smaller dextrins.
Products: Gelatinized starch, dextrins.
Conditions: High temperature (e.g., $100^\text{o}C$ for boiling water), presence of water.
Catalyst: None in the traditional sense; heat is the energy input.

1.2. Cooking of Proteins

1.2.1. Chicken

Chicken is primarily protein and fat.

Reactants: Proteins.
Reaction: Protein denaturation and coagulation, Maillard reaction.
How it happens: Heat causes proteins in chicken to denature, meaning their complex three-dimensional structure unravels. This unfolding exposes hydrophobic regions and leads to the coagulation of proteins, changing the texture from raw to solid (e.g., cooked chicken breast). Denaturation also makes proteins more accessible to digestive enzymes. If dry heat is applied (e.g., frying chicken) or sufficient heat is applied to amino acids and reducing sugars, the Maillard reaction occurs, producing brown pigments and desirable flavor compounds.
Products: Denatured and coagulated proteins, various Maillard reaction products.
Conditions: Elevated temperature (ranging from $60^\text{o}C$ to over $150^\text{o}C$ depending on method), often dry or moist heat.
Catalyst: None.

1.2.2. Egusi

Egusi contains significant protein and fat from melon seeds.

Reactants: Proteins.
Reaction: Protein denaturation and coagulation, Maillard reaction.
How it happens: Heat causes proteins in egusi to denature, meaning their complex three-dimensional structure unravels. This unfolding exposes hydrophobic regions and leads to the coagulation of proteins, changing the texture from raw to solid. Denaturation also makes proteins more accessible to digestive enzymes. If dry heat is applied or sufficient heat is applied to amino acids and reducing sugars, the Maillard reaction occurs, producing brown pigments and desirable flavor compounds.
Products: Denatured and coagulated proteins, various Maillard reaction products.
Conditions: Elevated temperature (ranging from $60^\text{o}C$ to over $150^\text{o}C$ depending on method), often dry or moist heat.
Catalyst: None.

1.3. Cooking of Fats

1.3.1. Chicken

Fats are present in chicken.

Reactants: Triglycerides (fats).
Reaction: Melting, and at higher temperatures, thermal degradation or oxidation.
How it happens: When heated, solid fats in chicken melt into liquid form. Excessive heating can lead to thermal degradation (e.g., breaking down into free fatty acids and glycerol) or oxidation, which can produce undesirable flavors and aromas (rancidity) and potentially harmful compounds (e.g., acrolein at smoke point).
Products: Melted fats, potentially breakdown products like free fatty acids.
Conditions: Elevated temperature (melting points vary, degradation occurs at higher temperatures).
Catalyst: None, though certain metal ions can catalyze oxidation.

1.3.2. Egusi Soup Ingredients

Fats are present in egusi seeds and other soup ingredients.

Reactants: Triglycerides (fats).
Reaction: Melting, and at higher temperatures, thermal degradation or oxidation.
How it happens: When heated, solid fats in egusi soup ingredients melt into liquid form. Excessive heating can lead to thermal degradation (e.g., breaking down into free fatty acids and glycerol) or oxidation, which can produce undesirable flavors and aromas (rancidity) and potentially harmful compounds (e.g., acrolein at smoke point).
Products: Melted fats, potentially breakdown products like free fatty acids.
Conditions: Elevated temperature (melting points vary, degradation occurs at higher temperatures).
Catalyst: None, though certain metal ions can catalyze oxidation.

2. Chemical Reactions During Digestion

After consumption, food undergoes a series of enzymatic hydrolysis reactions in the digestive system. The body maintains a constant core temperature of approximately $37^\text{o}C$ at which these enzymatic reactions are optimized.

2.1. Digestion of Carbohydrates

2.1.1. Spaghetti

Reactant: Starch (a polysaccharide).
Product: Glucose (monosaccharide).
Reaction: Hydrolysis.
How it happens and Conditions:
1. Mouth: Saliva contains salivary amylase (ptyalin). This enzyme begins to break down long chains of starch from spaghetti into smaller polysaccharides (dextrins) and disaccharides (maltose).
- Condition: Neutral to slightly alkaline pH ( $6.7-7.0$ ), body temperature ( $37^\text{o}C$ ).
- Catalyst: Salivary amylase.
1. Stomach: The highly acidic environment of the stomach denatures salivary amylase, halting starch digestion.
- Condition: Acidic pH ( $1.5-3.5$ ), body temperature ( $37^\text{o}C$ ).
1. Small Intestine: As chyme enters the small intestine, it is neutralized. The pancreas releases pancreatic amylase, which continues to hydrolyze starch from spaghetti into maltose (a disaccharide).
- Condition: Slightly alkaline pH ( $7-8$ ), body temperature ( $37^\text{o}C$ ).
- Catalyst: Pancreatic amylase.
1. Small Intestine (Brush Border): Enzymes located on the brush border (inner lining) of the small intestine, such as maltase, break down maltose into two glucose molecules. Other disaccharidases like sucrase and lactase break down sucrose and lactose, respectively, into monosaccharides.
- Condition: Slightly alkaline pH, body temperature ( $37^\text{o}C$ ).
- Catalysts: Maltase, sucrase, lactase.
Overall Products: Glucose, fructose, galactose (absorbed into the bloodstream).

2.1.2. Pounded Yam

Reactant: Starch (a polysaccharide).
Product: Glucose (monosaccharide).
Reaction: Hydrolysis.
How it happens and Conditions:
1. Mouth: Saliva contains salivary amylase (ptyalin). This enzyme begins to break down long chains of starch from pounded yam into smaller polysaccharides (dextrins) and disaccharides (maltose).
- Condition: Neutral to slightly alkaline pH ( $6.7-7.0$ ), body temperature ( $37^\text{o}C$ ).
- Catalyst: Salivary amylase.
1. Stomach: The highly acidic environment of the stomach denatures salivary amylase, halting starch digestion.
- Condition: Acidic pH ( $1.5-3.5$ ), body temperature ( $37^\text{o}C$ ).
1. Small Intestine: As chyme enters the small intestine, it is neutralized. The pancreas releases pancreatic amylase, which continues to hydrolyze starch from pounded yam into maltose (a disaccharide).
- Condition: Slightly alkaline pH ( $7-8$ ), body temperature ( $37^\text{o}C$ ).
- Catalyst: Pancreatic amylase.
1. Small Intestine (Brush Border): Enzymes located on the brush border (inner lining) of the small intestine, such as maltase, break down maltose into two glucose molecules. Other disaccharidases like sucrase and lactase break down sucrose and lactose, respectively, into monosaccharides.
- Condition: Slightly alkaline pH, body temperature ( $37^\text{o}C$ ).
- Catalysts: Maltase, sucrase, lactase.
Overall Products: Glucose, fructose, galactose (absorbed into the bloodstream).

2.2. Digestion of Proteins

2.2.1. Chicken

Reactant: Proteins.
Product: Amino acids.
Reaction: Hydrolysis.
How it happens and Conditions:
1. Stomach: Hydrochloric acid (HCl) denatures proteins from chicken, unfolding them and making them more accessible to enzymes. HCl also activates pepsinogen to pepsin, a protease that begins to hydrolyze proteins into smaller polypeptides.
- Condition: Highly acidic pH ( $1.5-3.5$ ), body temperature ( $37^\text{o}C$ ).
- Catalyst: Pepsin (activated by HCl).
1. Small Intestine: The pancreas releases inactive proteases like trypsinogen and chymotrypsinogen, which are activated into trypsin and chymotrypsin (respectively) by enteropeptidase. These enzymes further break down large polypeptides from chicken into smaller peptides.
- Condition: Slightly alkaline pH ( $7-8$ ), body temperature ( $37^\text{o}C$ ).
- Catalysts: Trypsin, chymotrypsin.
  3

1. Chemical Reactions During Cooking Cooking involves numerous complex chemical reactions that transform raw ingredients into palatable and digestible food. Heat is the primary condition driving these changes. ##### 1.1. Cooking of Carbohydrates These foods are rich in starch, a complex carbohydrate. ###### 1.1.1. Spaghetti Spaghetti is rich in starch, a complex carbohydrate. - Reactants: Starch (polysaccharide) and water. - Reaction: Starch gelatinization and some dextrinization. - How it happens: When starch granules in spaghetti are heated in the presence of water (e.g., boiling spaghetti), they absorb water and swell, leading to the rupture of the granules and the release of amylose and amylopectin. This process, called gelatinization, increases the viscosity and makes the food softer and more digestible. Prolonged heating can lead to some dextrinization, breaking starch into smaller dextrins. - Products: Gelatinized starch, dextrins. - Conditions: High temperature (e.g., $100^\text{o}C$ for boiling water), presence of water. - Catalyst: None in the traditional sense; heat is the energy input. ###### 1.1.2. Pounded Yam Pounded yam is rich in starch, a complex carbohydrate. - Reactants: Starch (polysaccharide) and water. - Reaction: Starch gelatinization and some dextrinization. - How it happens: When starch granules in pounded yam are heated in the presence of water (e.g., boiling yam), they absorb water and swell, leading to the rupture of the granules and the release of amylose and amylopectin. This process, called gelatinization, increases the viscosity and makes the food softer and more digestible. Prolonged heating can lead to some dextrinization, breaking starch into smaller dextrins. - Products: Gelatinized starch, dextrins. - Conditions: High temperature (e.g., $100^\text{o}C$ for boiling water), presence of water. - Catalyst: None in the traditional sense; heat is the energy input. ##### 1.2. Cooking of Proteins Chicken is primarily protein and fat, while egusi contains significant protein and fat from melon seeds. ###### 1.2.1. Chicken Chicken is primarily protein and fat. - Reactants: Proteins. - Reaction: Protein denaturation and coagulation, Maillard reaction. - How it happens: Heat causes proteins in chicken to denature, meaning their complex three-dimensional structure unravels. This unfolding exposes hydrophobic regions and leads to the coagulation of proteins, changing the texture from raw to solid (e.g., cooked chicken breast). Denaturation also makes proteins more accessible to digestive enzymes. If dry heat is applied (e.g., frying chicken) or sufficient heat is applied to amino acids and reducing sugars, the Maillard reaction occurs, producing brown pigments and desirable flavor compounds. - Products: Denatured and coagulated proteins, various Maillard reaction products. - Conditions: Elevated temperature (ranging from $60^\text{o}C$ to over $150^\text{o}C$ depending on method), often dry or moist heat. - Catalyst: None. ###### 1.2.2. Egusi Egusi contains significant protein and fat from melon seeds. - Reactants: Proteins. - Reaction: Protein denaturation and coagulation, Maillard reaction. - How it happens: Heat causes proteins in egusi to denature, meaning their complex three-dimensional structure unravels. This unfolding exposes hydrophobic regions and leads to the coagulation of proteins, changing the texture from raw to solid. Denaturation also makes proteins more accessible to digestive enzymes. If dry heat is applied or sufficient heat is applied to amino acids and reducing sugars, the Maillard reaction occurs, producing brown pigments and desirable flavor compounds. - Products: Denatured and coagulated proteins, various Maillard reaction products. - Conditions: Elevated temperature (ranging from $60^\text{o}C$ to over $150^\text{o}C$ depending on method), often dry or moist heat. - Catalyst: None. ##### 1.3. Cooking of Fats Fats are present in chicken, egusi seeds, and other soup ingredients. ###### 1.3.1. Chicken Fats are present in chicken. - Reactants: Triglycerides (fats). - Reaction: Melting, and at higher temperatures, thermal degradation or oxidation. - How it happens: When heated, solid fats in chicken melt into liquid form. Excessive heating can lead to thermal degradation (e.g., breaking down into free fatty acids and glycerol) or oxidation, which can produce undesirable flavors and aromas (rancidity) and potentially harmful compounds (e.g., acrolein at smoke point). - Products: Melted fats, potentially breakdown products like free fatty acids. - Conditions: Elevated temperature (melting points vary, degradation occurs at higher temperatures). - Catalyst: None, though certain metal ions can catalyze oxidation. ###### 1.3.2. Egusi Soup Ingredients Fats are present in egusi seeds and other soup ingredients. - Reactants: Triglycerides (fats). - Reaction: Melting, and at higher temperatures, thermal degradation or oxidation. - How it happens: When heated, solid fats in egusi soup ingredients melt into liquid form. Excessive heating can lead to thermal degradation (e.g., breaking down into free fatty acids and glycerol) or oxidation, which can produce undesirable flavors and aromas (rancidity) and potentially harmful compounds (e.g., acrolein at smoke point). - Products: Melted fats, potentially breakdown products like free fatty acids. - Conditions: Elevated temperature (melting points vary, degradation occurs at higher temperatures). - Catalyst: None, though certain metal ions can catalyze oxidation. #### 2. Chemical Reactions During Digestion After consumption, food undergoes a series of enzymatic hydrolysis reactions in the digestive system. The body maintains a constant core temperature of approximately $37^\text{o}C$ at which these enzymatic reactions are optimized. ##### 2.1. Digestion of Carbohydrates ###### 2.1.1. Spaghetti - Reactant: Starch (a polysaccharide). - Product: Glucose (monosaccharide). - Reaction: Hydrolysis. - How it happens and Conditions: 1. Mouth: Saliva contains salivary amylase (ptyalin). This enzyme begins to break down long chains of starch from spaghetti into smaller polysaccharides (dextrins) and disaccharides (maltose). - Condition: Neutral to slightly alkaline pH ( $6.7-7.0$ ), body temperature ( $37^\text{o}C$ ). - Catalyst: Salivary amylase. 2. Stomach: The highly acidic environment of the stomach denatures salivary amylase, halting starch digestion. - Condition: Acidic pH ( $1.5-3.5$ ), body temperature ( $37^\text{o}C$ ). 3. Small Intestine: As chyme enters the small intestine, it is neutralized. The pancreas releases pancreatic amylase, which continues to hydrolyze starch from spaghetti into maltose (a disaccharide). - Condition: Slightly alkaline pH ( $7-8$ ), body temperature ( $37^\text{o}C$ ). - Catalyst: Pancreatic amylase. 4. Small Intestine (Brush Border): Enzymes located on the brush border (inner lining) of the small intestine, such as maltase, break down maltose into two glucose molecules. Other disaccharidases like sucrase and lactase break down sucrose and lactose, respectively, into monosaccharides. - Condition: Slightly alkaline pH, body temperature ( $37^\text{o}C$ ). - Catalysts: Maltase, sucrase, lactase. - Overall Products: Glucose, fructose, galactose (absorbed into the bloodstream). ###### 2.1.2. Pounded Yam - Reactant: Starch (a polysaccharide). - Product: Glucose (monosaccharide). - Reaction: Hydrolysis. - How it happens and Conditions: 1. Mouth: Saliva contains salivary amylase (ptyalin). This enzyme begins to break down long chains of starch from pounded yam into smaller polysaccharides (dextrins) and disaccharides (maltose). - Condition: Neutral to slightly alkaline pH ( $6.7-7.0$ ), body temperature ( $37^\text{o}C$ ). - Catalyst: Salivary amylase. 2. Stomach: The highly acidic environment of the stomach denatures salivary amylase, halting starch digestion. - Condition: Acidic pH ( $1.5-3.5$ ), body temperature ( $37^\text{o}C$ ). 3. Small Intestine: As chyme enters the small intestine, it is neutralized. The pancreas releases pancreatic amylase, which continues to hydrolyze starch from pounded yam into maltose (a disaccharide). - Condition: Slightly alkaline pH ( $7-8$ ), body temperature ( $37^\text{o}C$ ). - Catalyst: Pancreatic amylase. 4. Small Intestine (Brush Border): Enzymes located on the brush border (inner lining) of the small intestine, such as maltase, break down maltose into two glucose molecules. Other disaccharidases like sucrase and lactase break down sucrose and lactose, respectively, into monosaccharides. - Condition: Slightly alkaline pH, body temperature ( $37^\text{o}C$ ). - Catalysts: Maltase, sucrase, lactase. - Overall Products: Glucose, fructose, galactose (absorbed into the bloodstream). ##### 2.2. Digestion of Proteins ###### 2.2.1. Chicken - Reactant: Proteins. - Product: Amino acids. - Reaction: Hydrolysis. - How it happens and Conditions: 1. Stomach: Hydrochloric acid (HCl) denatures proteins from chicken, unfolding them and making them more accessible to enzymes. HCl also activates pepsinogen to pepsin, a protease that begins to hydrolyze proteins into smaller polypeptides. - Condition: Highly acidic pH ( $1.5-3.5$ ), body temperature ( $37^\text{o}C$ ). - Catalyst: Pepsin (activated by HCl). 2. Small Intestine: The pancreas releases inactive proteases like trypsinogen and chymotrypsinogen, which are activated into trypsin and chymotrypsin (respectively) by enteropeptidase. These enzymes further break down large polypeptides from chicken into smaller peptides. - Condition: Slightly alkaline pH ( $7-8$ ), body temperature ( $37^\text{o}C$ ). - Catalysts: Trypsin, chymotrypsin. 3. Small Intestine (Brush Border): Various peptidases (e.g., aminopeptidases, dipeptidases) on the brush border and within intestinal cells break down small peptides into individual amino acids. - Condition: Slightly alkaline pH, body temperature ( $37^\text{o}C$ ). - Catalysts: Peptidases. - Overall Products: Amino acids (absorbed into the bloodstream). ###### 2.2.2. Egusi - Reactant: Proteins. - Product: Amino acids. - Reaction: Hydrolysis. - How it happens and Conditions: 1. Stomach: Hydrochloric acid (HCl) denatures proteins from egusi, unfolding them and making them more accessible to enzymes. HCl also activates pepsinogen to pepsin, a protease that begins to hydrolyze proteins into smaller polypeptides. - Condition: Highly acidic pH ( $1.5-3.5$ ), body temperature ( $37^\text{o}C$ ). - Catalyst: Pepsin (activated by HCl). 2. Small Intestine: The pancreas releases inactive proteases like trypsinogen and chymotrypsinogen, which are activated into trypsin and chymotrypsin (respectively) by enteropeptidase. These enzymes further break down large polypeptides from egusi into smaller peptides. - Condition: Slightly alkaline pH ( $7-8$ ), body temperature ( $37^\text{o}C$ ). - Catalysts: Trypsin, chymotrypsin. 3. Small Intestine (Brush Border): Various peptidases (e.g., aminopeptidases, dipeptidases) on the brush border and within intestinal cells break down small peptides into individual amino acids. - Condition: Slightly alkaline pH, body temperature ( $37^\text{o}C$ ). - Catalysts: Peptidases. - Overall Products: Amino acids (absorbed into the bloodstream). ##### 2.3. Digestion of Fats ###### 2.3.1. Chicken - Reactant: Triglycerides. - Product: Monoglycerides and free fatty acids. - Reaction: Hydrolysis. - How it happens and Conditions: 1. Mouth and Stomach: Minor digestion by lingual lipase (mouth) and gastric lipase (stomach), primarily acting on short and medium-chain fatty acids from chicken. - Condition: Mouth (neutral pH), Stomach (acidic pH), body temperature ( $37^\text{o}C$ ). - Catalysts: Lingual lipase, gastric lipase. 2. Small Intestine: The most significant fat digestion occurs here. Bile salts, produced by the liver and stored in the gallbladder, emulsify large fat globules from chicken into smaller droplets, increasing the surface area for enzyme action. Then, pancreatic lipase hydrolyzes triglycerides from chicken into monoglycerides and free fatty acids. - Condition: Slightly alkaline pH ( $7-8$ ), body temperature ( $37^\text{o}C$ ), presence of bile salts. - Catalyst: Pancreatic lipase (with the help of co-lipase). - Overall Products: Monoglycerides and free fatty acids (absorbed and re-packaged). ###### 2.3.2. Egusi Soup Ingredients - Reactant: Triglycerides. - Product: Monoglycerides and free fatty acids. - Reaction: Hydrolysis. - How it happens and Conditions: 1. Mouth and Stomach: Minor digestion by lingual lipase (mouth) and gastric lipase (stomach), primarily acting on short and medium-chain fatty acids from egusi soup ingredients. - Condition: Mouth (neutral pH), Stomach (acidic pH), body temperature ( $37^\text{o}C$ ). - Catalysts: Lingual lipase, gastric lipase. 2. Small Intestine: The most significant fat digestion occurs here. Bile salts, produced by the liver and stored in the gallbladder, emulsify large fat globules from egusi soup ingredients into smaller droplets, increasing the surface area for enzyme action. Then, pancreatic lipase hydrolyzes triglycerides from egusi soup ingredients into monoglycerides and free fatty acids. - Condition: Slightly alkaline pH ( $7-8$ ), body temperature ( $37^\text{o}C$ ), presence of bile salts. - Catalyst: Pancreatic lipase (with the help of co-lipase). - Overall Products: Monoglycerides and free fatty acids (absorbed and re-packaged). In summary, both cooking and digestion involve complex chemical reactions essential for nutrient utilization and food safety, driven by heat during cooking and specific enzymes, pH, and temperature during digestion.

1. Chemical Reactions During Cooking

Cooking involves numerous complex chemical reactions that transform raw ingredients into palatable and digestible food. Heat is the primary condition driving these changes.

1.1. Cooking of Carbohydrates

These foods are rich in starch, a complex carbohydrate.

1.1.1. Spaghetti

Spaghetti is rich in starch, a complex carbohydrate. The reactants are starch (polysaccharide) and water, undergoing gelatinization and some dextrinization. When starch granules in spaghetti are heated in the presence of water (e.g., boiling spaghetti), they absorb water and swell, leading to the rupture of the granules and the release of amylose and amylopectin. This process, called gelatinization, increases the viscosity and makes the food softer and more digestible. Prolonged heating can lead to some dextrinization, breaking starch into smaller dextrins. The products are gelatinized starch and dextrins, occurring under high temperature (e.g., $100^\text{o}C$ for boiling water) and in the presence of water. There is no catalyst in the traditional sense; heat is the energy input.

1.1.2. Pounded Yam

Pounded yam is rich in starch, a complex carbohydrate. The reactants are starch (polysaccharide) and water, undergoing gelatinization and some dextrinization. When starch granules in pounded yam are heated in the presence of water (e.g., boiling yam), they absorb water and swell, leading to the rupture of the granules and the release of amylose and amylopectin. This process, called gelatinization, increases the viscosity and makes the food softer and more digestible. Prolonged heating can lead to some dextrinization, breaking starch into smaller dextrins. The products are gelatinized starch and dextrins, occurring under high temperature (e.g., $100^\text{o}C$ for boiling water) and in the presence of water. There is no catalyst in the traditional sense; heat is the energy input.

1.2. Cooking of Proteins

Chicken is primarily protein and fat, while egusi contains significant protein and fat from melon seeds.

1.2.1. Chicken

Chicken is primarily protein and fat. The reactant is protein, undergoing protein denaturation and coagulation, and the Maillard reaction. Heat causes proteins in chicken to denature, meaning their complex three-dimensional structure unravels. This unfolding exposes hydrophobic regions and leads to the coagulation of proteins, changing the texture from raw to solid (e.g., cooked chicken breast). Denaturation also makes proteins more accessible to digestive enzymes. If dry heat is applied (e.g., frying chicken) or sufficient heat is applied to amino acids and reducing sugars, the Maillard reaction occurs, producing brown pigments and desirable flavor compounds. The products are denatured and coagulated proteins, and various Maillard reaction products. These reactions occur at elevated temperatures (ranging from $60^\text{o}C$ to over $150^\text{o}C$ depending on the method), often with dry or moist heat. There is no catalyst.

1.2.2. Egusi

Egusi contains significant protein and fat from melon seeds. The reactant is protein, undergoing protein denaturation and coagulation, and the Maillard reaction. Heat causes proteins in egusi to denature, meaning their complex three-dimensional structure unravels. This unfolding exposes hydrophobic regions and leads to the coagulation of proteins, changing the texture from raw to solid. Denaturation also makes proteins more accessible to digestive enzymes. If dry heat is applied or sufficient heat is applied to amino acids and reducing sugars, the Maillard reaction occurs, producing brown pigments and desirable flavor compounds. The products are denatured and coagulated proteins, and various Maillard reaction products. These reactions occur at elevated temperatures (ranging from $60^\text{o}C$ to over $150^\text{o}C$ depending on the method), often with dry or moist heat. There is no catalyst.

1.3. Cooking of Fats

Fats are present in chicken, egusi seeds, and other soup ingredients.

1.3.1. Chicken

Fats are present in chicken. The reactants are triglycerides (fats), undergoing melting, and at higher temperatures, thermal degradation or oxidation. When heated, solid fats in chicken melt into liquid form. Excessive heating can lead to thermal degradation (e.g., breaking down into free fatty acids and glycerol) or oxidation, which can produce undesirable flavors and aromas (rancidity) and potentially harmful compounds (e.g., acrolein at smoke point). The products are melted fats and potentially breakdown products like free fatty acids. These reactions occur at elevated temperatures (melting points vary, degradation occurs at higher temperatures). There is no catalyst, though certain metal ions can catalyze oxidation.

1.3.2. Egusi Soup Ingredients

Fats are present in egusi seeds and other soup ingredients. The reactants are triglycerides (fats), undergoing melting, and at higher temperatures, thermal degradation or oxidation. When heated, solid fats in egusi soup ingredients melt into liquid form. Excessive heating can lead to thermal degradation (e.g., breaking down into free fatty acids and glycerol) or oxidation, which can produce undesirable flavors and aromas (rancidity) and potentially harmful compounds (e.g., acrolein at smoke point). The products are melted fats and potentially breakdown products like free fatty acids. These reactions occur at elevated temperatures (melting points vary, degradation occurs at higher temperatures). There is no catalyst, though certain metal ions can catalyze oxidation.

2. Chemical Reactions During Digestion

2.1. Digestion of Carbohydrates

2.1.1. Spaghetti

For spaghetti, the reactant is starch (a polysaccharide), and the overall product is glucose (a monosaccharide) through hydrolysis. Digestion begins in the mouth where saliva contains salivary amylase (ptyalin), which breaks down long chains of starch from spaghetti into smaller polysaccharides (dextrins) and disaccharides (maltose). This occurs at a neutral to slightly alkaline pH ( $6.7-7.0$ ) and body temperature ( $37^\text{o}C$ ), catalyzed by salivary amylase. In the stomach, the highly acidic environment (pH $1.5-3.5$ ) denatures salivary amylase, halting starch digestion. As chyme enters the small intestine, it is neutralized, and the pancreas releases pancreatic amylase, which continues to hydrolyze starch from spaghetti into maltose. This takes place at a slightly alkaline pH ( $7-8$ ) and body temperature ( $37^\text{o}C$ ), with pancreatic amylase as the catalyst. Finally, at the small intestine (brush border), enzymes such as maltase break down maltose into two glucose molecules. Other disaccharidases like sucrase and lactase break down sucrose and lactose, respectively, into monosaccharides, all at a slightly alkaline pH and body temperature ( $37^\text{o}C$ ). The overall products of digestion are glucose, fructose, and galactose, which are then absorbed into the bloodstream.

2.1.2. Pounded Yam

For pounded yam, the reactant is starch (a polysaccharide), and the overall product is glucose (a monosaccharide) through hydrolysis. Digestion begins in the mouth where saliva contains salivary amylase (ptyalin), which breaks down long chains of starch from pounded yam into smaller polysaccharides (dextrins) and disaccharides (maltose). This occurs at a neutral to slightly alkaline pH ( $6.7-7.0$ ) and body temperature ( $37^\text{o}C$ ), catalyzed by salivary amylase. In the stomach, the highly acidic environment (pH $1.5-3.5$ ) denatures salivary amylase, halting starch digestion. As chyme enters the small intestine, it is neutralized, and the pancreas releases pancreatic amylase, which continues to hydrolyze starch from pounded yam into maltose. This takes place at a slightly alkaline pH ( $7-8$ ) and body temperature ( $37^\text{o}C$ ), with pancreatic amylase as the catalyst. Finally, at the small intestine (brush border), enzymes such as maltase break down maltose into two glucose molecules. Other disaccharidases like sucrase and lactase break down sucrose and lactose, respectively, into monosaccharides, all at a slightly alkaline pH and body temperature ( $37^\text{o}C$ ). The overall products of digestion are glucose, fructose, and galactose, which are then absorbed into the bloodstream.

2.2. Digestion of Proteins

2.2.1. Chicken

For chicken, the reactant is protein, and the overall product is amino acids through hydrolysis. In the stomach, hydrochloric acid (HCl) denatures proteins from chicken, unfolding them and making them more accessible to enzymes. HCl also activates pepsinogen to pepsin, a protease that begins to hydrolyze proteins into smaller polypeptides. This occurs at a highly acidic pH ( $1.5-3.5$ ) and body temperature ( $37^\text{o}C$ ), with pepsin (activated by HCl) as the catalyst. In the small intestine, the pancreas releases inactive proteases like trypsinogen and chymotrypsinogen, which are activated into trypsin and chymotrypsin (respectively) by enteropeptidase. These enzymes further break down large polypeptides from chicken into smaller peptides. This process occurs at a slightly alkaline pH ( $7-8$ ) and body temperature ( $37^\text{o}C$ ), catalyzed by trypsin and chymotrypsin. At the small intestine (brush border), various peptidases (e.g., aminopeptidases, dipeptidases) on the brush border and within intestinal cells break down small peptides into individual amino acids. This occurs at a slightly alkaline pH and body temperature ( $37^\text{o}C$ ), catalyzed by peptidases. The overall products are amino acids, which are absorbed into the bloodstream.

2.2.2. Egusi

For egusi, the reactant is protein, and the overall product is amino acids through hydrolysis. In the stomach, hydrochloric acid (HCl) denatures proteins from egusi, unfolding them and making them more accessible to enzymes. HCl also activates pepsinogen to pepsin, a protease that begins to hydrolyze proteins into smaller polypeptides. This occurs at a highly acidic pH ( $1.5-3.5$ ) and body temperature ( $37^\text{o}C$ ), with pepsin (activated by HCl) as the catalyst. In the small intestine, the pancreas releases inactive proteases like trypsinogen and chymotrypsinogen, which are activated into trypsin and chymotrypsin (respectively) by enteropeptidase. These enzymes further break down large polypeptides from egusi into smaller peptides. This process occurs at a slightly alkaline pH ( $7-8$ ) and body temperature ( $37^\text{o}C$ ), catalyzed by trypsin and chymotrypsin. At the small intestine (brush border), various peptidases (e.g., aminopeptidases, dipeptidases) on the brush border and within intestinal cells break down small peptides into individual amino acids. This occurs at a slightly alkaline pH and body temperature ( $37^\text{o}C$ ), catalyzed by peptidases. The overall products are amino acids, which are absorbed into the bloodstream.

2.3. Digestion of Fats

2.3.1. Chicken

For chicken, the reactant is triglycerides, and the overall products are monoglycerides and free fatty acids through hydrolysis. Minor digestion by lingual lipase (in the mouth) and gastric lipase (in the stomach) primarily acts on short and medium-chain fatty acids from chicken. This occurs at neutral pH in the mouth and acidic pH in the stomach, both at body temperature ( $37^\text{o}C$ ), with lingual lipase and gastric lipase as catalysts. The most significant fat digestion occurs in the small intestine. Here, bile salts, produced by the liver and stored in the gallbladder, emulsify large fat globules from chicken into smaller droplets, increasing the surface area for enzyme action. Subsequently, pancreatic lipase hydrolyzes triglycerides from chicken into monoglycerides and free fatty acids. This process occurs at a slightly alkaline pH ( $7-8$ ) and body temperature ( $37^\text{o}C$ ), in the presence of bile salts, with pancreatic lipase (aided by co-lipase) as the catalyst. The overall products are monoglycerides and free fatty acids, which are absorbed and re-packaged.

2.3.2. Egusi Soup Ingredients

For egusi soup ingredients, the reactant is triglycerides, and the overall products are monoglycerides and free fatty acids through hydrolysis. Minor digestion by lingual lipase (in the mouth) and gastric lipase (in the stomach) primarily acts on short and medium-chain fatty acids from egusi soup ingredients. This occurs at neutral pH in the mouth and acidic pH in the stomach, both at body temperature ( $37^\text{o}C$ ), with lingual lipase and gastric lipase as catalysts. The most significant fat digestion occurs in the small intestine. Here, bile salts, produced by the liver and stored in the gallbladder, emulsify large fat globules from egusi soup ingredients into smaller droplets, increasing surface area for enzyme action. Subsequently, pancreatic lipase hydrolyzes triglycerides from egusi soup ingredients into monoglycerides and free fatty acids. This process occurs at a slightly alkaline pH ( $7-8$ ) and body temperature ( $37^\text{o}C$ ), in the presence of bile salts