As by request by everyone to have access to the pictures for the current Food Chemistry Lab on 8th October 2007.

Red is the red cabbage, whilst green is the spinach

Any problems recieving them email me at kelvins@hotmail.com or MSN.

Food molecules are modified by a large number of reactions which occur in small steps, each catalysed by an enzyme.
These are the basis of metabolism. Notice that all three types of food molecules (carbohydrates, lipids and proteins) pass through a common pathway to make ATP called the citric acid cycle (tricarboxylic acid, Krebs cycle) and electron transport chain.
These 2 processes occur in the mitochondria.

Process of making ATP in the mitochondria is called oxidative phosphorylation.
Making ATP outside the mitochondria are relatively small without the presence of air and occurs via glycolysis and fermentation which is also called substrate-level phosphorylation.
(Oxygen is needed to make ATP in the respiratory chain and carbon from the food is released in the form of carbon dioxide. This is why we breath oxygen and breathe out carbon dioxide)

Metabolism also allows the inter-conversion of different types of food molecules. For example if proteins are low in a diet they can be made from carbohydrates or lipids and vice versa. Interconversion between carbohydrates, lipids and proteins occur via the key molecules pyruvic acid and acetyl CoA.

Citric Acid Cycle

The citric acid cycle is a cyclic series of enzyme catalysed reactions that are of fundamental important to metabolism of aerobic organisms. Enzymes for the citric acid cycle are found in the mitochondrion.

2 carbon acetyl-CoA, react with four carbon oxaloacetate to form 6 carbon citrate. In a series of seven reactions, this is reconverted to oxaloacetate and produces 2 molecules of carbon dioxide. But more importantly, the cycle produces 3 molecules of NADH and 1 mole of FADH2, which are subsequently used in electron transport chain to generate ATP.

Refers to true viscous flow, where the shear rate is directly proportional to shear stress applied. Most foods are non-Newtonian and deviate strongly from Newtonian behaviour.

Newtonian fluids has its shear rate directly proportional to shear stress begins at origin. Therefore slope of the line (viscosity) at any shear rate is the same.But the slopes of the lines differ at points along a plastic curve. This would mean change in viscosity.

Plastic flow
Occurs when minimum shear stress exceeded before flow begins. This is very common in foods. For each food that displays this property, there is a point at which flow starts the plastic yield stress. (does not start from 0 and must start above 0 in order for shearing to occur)

Pseudoplastic
Starts at origin and is Newtonian for a while but eventually flattens. (Curves then reaches back to the same gradient as the beginning)

Dilatant
Characterized by escalating viscosity with shear rate. Only occurs in high concentration suspensions, such as raw starch and chocolate syrups which contain insoluble rigid particles. For dilatancy to occur, the particles have to exist in close packed form. When this is disturbed by shear, viscosity increases.

Just some basic terminology, if you can imagine molecules in parrallel and molecules which are juttered out. Parrallel can be like pringles and molecules with ends or kinks could be a generic brand of chip. Being parallel enables shear rate to reach a point where shearing does not effect it as the force is just allowed through due to the parallel arrangement of molecules whilst molecule with kinks will create friction(resistance).Quicky summery on viscosity, may update it. (Most likely not)