For many hetrogenous catalytic reactions, the rate behavior is characterized by:
• Surface reaction and adsorption controls the reaction rate at 100°C.
• Rates increases as H2 pressure increases (at the max 7 atm gage)
• At 180°C, mass transfer for solution of H2 and diffusion to and from catalyst are rate controlling steps.
2. What is Rancidity ?
Ans: The moisture and oxygen cause deterioration of fats. The combine action of both moisture and oxygen causes rancidity which is characterised by bad smell, development of red colour, increase in acidity and increase in viscosity. During frying, cooking, baking etc, oil undergo hydrolytic and polymerization reaction. These reactions are undesirable in edible oils. Prolonged exposure to air yield undesirable resinous products causing rancidity.
3. What is winterising ?
Ans: When oils are cooled slowly to a lower temperature, then less soluble glycerides rich in fatty acid crystallizes out. These crystals can be separated by centrifuge or by filter. This separation of solid fats by chilling is called winterising.