Fresh acid-curd (Quarg) cheese-based on ultrafiltration
Quarg is a soft cheese with a mildly acidic flavor which can be prepared from full-fat or skimmed milk. The milk is coagulated by inoculation with lactic acid bacteria ( a small amount of chymosin may be added) to form a gel. Whey is usually removed by centrifugation or ultrafiltration techniques. It is generally sola as a chilled product with a shelf-life of 2-4 weeks. It is available at a range of fat levels (up to 40% fat in dry matter). Further processing (e.g. hydrocllloid, addition, heating, homogenization, aeration) may be carried out and various materials (e.g. spices, herbs, fruit purees, cream, sugar etc) may be added to give a wide range of sweet and savoury products.

A soft cheese plant is designed to process 500 tonne/day milk to produce approximately equal amounts of full fat and skim milk quarg. The main elements of the process are:
1. Incoming raw milk is stored at <4? in 200 tonne silos
2. Fat removal (if skimmed milk required)
3. Pasteurisation / heating treatment
4. Manufacture of quarg
5. Further processing (if required)
6. Packaging and distribution
The average composition of the incoming milk is
Component concentration (% w/w)
Water 87.0
Fat 3.9
Protein 3.5
Lactose 4.9
Minerals 0.7

Question:
1. Investigate the alternative processing methods for the manufacture of quarg. Ensure that you understand the acid coagulation process and the implications of different heat teanments.

2. Prepare a process flowsheet for the plant showing the principal operations and process streams

3. Investigate the available types of processing equipment you would use and briefly discuss your choice where an alternative exists. Whey removal can be achieved by centrifugation or ultrafiltration. Discuss the relative of each, but base your manufacture methods on ultrafiltration

4. Develop a mass balance for the plant for the manufacture of:
1. Low-fat qurag
2. Full-fat quarg
Include the daily output of all process streams (tonnes per day). Include the yields of products and waste streams in the flow diagram too.

5. Calculate the total massed of water, fat, protein, lactose and minerals in the milk, and total outputs of these components in the whey, and hence calculate the composition of the finished cheese. Also calculate the composition of the whey or permeate produced in each case. And calculate the composition and weight of cream separated from milk to make skimmed quarg.

6. Investigate how milk composition varies throughout the year in the UK. Use this information to predict how the mass balance data above would change throughout the year.

7. Discuss the waste management of the plant. Suggest uses for co-product and bi-products

8. Consider the main packaging requirement for your products

9. Investigate how further processing can be used to increase the product range and discuss the range of quarg-based products available to consumers?

carry out some work in the Pilot plant to verify some of the assumption you have made, for example you may like to validate the estimates of yields/loses etc. By experimentation.