Lactase is an enzyme that breaks down the milk sugar lactose into glucose and galactose. This enzyme is produced in the small intestine of humans and other mammals, and has an optimum pH of 6.5. Lacking lactase, a person consuming dairy products may experience the symptoms of lactose intolerance.Lactase can be purchased as a food supplement, or can be added to milk to produce "lactose-free" milk products. Industrial production of lactase can be achieved by fermentation of soybean with Aspergillus oryzae.

A fermented soybean medium containing 70 mg per litre of lactase and 104cells per litre of Aspergillus oryzaeneeds to be sterilised at 121 C before subsequent separation and purification processes. While the sterilisation is a crucial step to kill the Aspergillus oryzaecells, this unavoidable thermal treatment also denatures some of the enzyme molecules.

The values of the Arrhenius constant and Edfor the Aspergillus oryzaecells are:

A(cells)= 11036min-1

Ed(cells)= 65 kcal mol-1

The values of the Arrhenius constant and Edfor the lactase are:

A(lactase)= 1104min-1

Ed(lactase)= 10 kcal mol-1

(a)Calculate the amount of active lactase in the sterilised medium when using a10 litrefermenter and a10000 litre fermenter, if the sterility assurance level (SAL) should be 10-3in both cases. Ignore the effects of the heat-up and cool-down periods.Based on these results, which of the two fermenters is more suitable for the productionof lactase? Why?[20marks]

(b)After adequate separation and purification, lactase is being sold by your company as food supplement pills, for people with lactose intolerance. Marketing surveys indicated that many consumers did not likethe hard-to-swallow gastro-resistant shell of the pills. In response to these observations, and in order to reduce costs, your boss decided to change the current shell for a soft and acid-soluble gelatine coating, much cheaper, easier to swallow and gentle on the stomach.

After a few weeks in the market, the new easy-to-swallow gelatine capsules have received very negative feedback, with consumers claiming that the pills are not as effective at reducing the lactose intolerance symptoms as they usedto be.What could be the reason for this negative feedback? Justify your answer.