Dairy and Food Engineering 3(2+1)

Lesson 16. Dairy plant design and layout-II

16.1.1 Location

Suitable location for the establishment and equipment should include following considerations:

16.1.1.1 Establishments

• To prevent potential sources of contamination to food.

• No food establishment should be located in the hazard prone site.

• Location should be away from environmentally polluted area that can contaminate food, such as, flooded, waste and infestations of pest prone area

16.1.1.2 Equipment

• Equipment should be properly located to permit adequate maintenance and cleaning.

• The location facilitates good hygienic practices and effective monitoring.

16.1.2 Premises and rooms

Suitable consideration should be given depending upon requirement and nature of equipment:

16.1.2.1 Design and layout:

Where appropriate /applicable, the internal design and layout of food establishments should permit good food hygienic practices including protection against cross-contamination during manufacturing and storage.

16.1.2.2 Internal structure and fittings:

Structures within dairy establishment should be soundly built of durable materials and be easy to maintain, clean and /or disinfect. To achieve this, the surfaces of wall, ceiling and floor should be impervious and of non- food toxic materials. The surfaces should be smooth and allow proper removing of water, dirt and germs. The material of facilities or fittings coming in the direct contact of milk should be non-reactive type.

16.1.2.3 Temporary /mobile premises and vending machines:

• Premises and structures like stalls, mobile sales and street vending points as temporary housing should be sited, designed and constructed to avoid, as far as reasonably practicable, contaminating food and harboring pests.

16.1.3 Equipment and containers

The design and construction of equipment and containers handling milk and milk products should be given adequate consideration for cleaning, disinfecting and preventing food contamination. The contact surfaces should be made of materials with no toxic effect in the intended use of food. Design of equipment should facilitate easy movement and capability of disassembling to allow maintenance, cleaning, disinfecting, monitoring and inspecting pest. Other important requirement of processing equipment is to withstand processing condition without affecting food safety aspect. The equipment should have provision and capability for monitoring and control of process parameters. Containers for waste, by-products and inedible or dangerous substances should have specific identification, safe design and placement at appropriate location. Required safeguard should be made to prevent cross contamination from these containers or their contents.

16.1.4 Design of facilities

Dairy plant has to be provided with required facilities for water supply, drainage/waste disposal, cleaning system, personal hygiene, toilets, humidity, air and temperature control, lighting and storage of various materials. These are discussed below:

16.1.4.1 Water supply:

An adequate and potable water supply with appropriate storage, distribution and temperature control, should be available whenever necessary to ensure the safety and suitability of food. Supply and storage line for non-potable water should be separate with proper identification. This requires proper selection of source of supply, pumping, storage and treatment units.

16.1.4.2 Drainage and disposal system:

Adequate sanitary condition in and around plant can be maintained by proper arrangement for types of drains with cleaning and dis-infection arrangement. Slope of floor and drains is of equal importance to let-out the spillage and washings.

16.1.4.3 Cleaning:

Cleaning of plant premises and equipment should have provision in the planning stage itself. Proper clearance and facilities need to be considered.

When manual cleaning is either not possible or less effective, then alternative methods like cleaning –in-place should be employed.

16.1.4.4 Facilities for personnel hygiene:

In order to prevent cross contamination from machine and materials to man and vice versa, required arrangements should be thought for necessary equipment, space and water supply. Good dairy plants have provisions of cloth changing and hand washing and drying. Other requirement relates to minimizing human contact with product. For this, most of the works are done by equipment and tools like trolley and shovel etc.

16.1.4.5 Temperature control:

Most of the dairy operations are temperature dependent. Heating, cooling or holding at certain temperature is required to obtain product of good microbial quality, flavor and texture. For this steam supply unit, refrigeration unit and temperature recording, monitoring and controlling mechanism are provided.

16.1.4.6 Air supply system:

Adequate air supply system should include compressor, inter-cooler, oil separator, air filters and drier /humidity controller. Air pipeline is provided to meet operation requirements of agitation, oxidation, control and / or conveying function. If air comes in direct contact of product, then its proper hygienic quality should be ensured.

16.1.4.7 Lighting:

Design should consider availability of adequate natural light. However provision of artificial light needs to be made according to the requirement of operation. A minimum illumination requirement in lumen per square meter for functions like reception, processing, cleaning is approximately 500 to 600, monitoring places like weighing, equipment with gauges, filling & inspection, laboratory and accounting is approx. 1000 and for common places like corridor and utility section is 200 to 300.

16.1.4.8 Storage:

Adequate facilities should be provided for the storage of food, ingredients and non-food chemicals (e.g. cleaning materials, lubricant fuels).Appropriate, food storage facilities should be designed and constructed to permit adequate cleaning and maintenance, avoid pest access and harborage, enable food to be effectively protected from contamination, and provide proper environment that minimizes the deterioration. Storage of edible, non-edible and hazardous materials should be separate.

16.1.5 Space consideration

Space requirement for facilities and equipment varies from make to make and model to model for a given capacity. Functional areas or rooms in a plant must not be crowded or sized far larger than necessary. Therefore, the structure and civil arrangement is made precisely, One has to either select specific model /make process /product line or has to approximate the requirements. In the first type of arrangement, selected supplier may be requested to detail the space requirement.

However, the planning of a dairy is done in advance before selection of particular equipment /model or manufactures; hence, for effective planning, one has to depend on certain guidelines, which are given below for general purpose:

1. For a medium size milk plant, the area should be 2 to 3 sq. m per 100 L of milk, whereas for small plant of less than 10000 L per day, space requirement will be approximately 6 to 7 sq. m per 100 L milk.

2. Approximately 75000 L milk can be stored in 200 sq. m area cold store.

3. Approx. 50 kg ghee or butter can be stored per sq. m area.

4. 750 kg milk powder in 25 kg bags would require approx. one sq. m storage space.

5. Dry storage area should constitute approx. 25% of the total plant area.

6. Refrigeration and steam boilers each requires approx. one fifth sq. m per 100 L milk

7. Processing area should be five times the size of equipments

8. At-least one meter space is considered good between two equipments.

9. If floor area available is insufficient, then vertical type of storage tanks /vessels should be preferred. Now for storage of chilled water, insulated silos are becoming popular, which requires less space and can be installed outside of plant. Similarly, milk storage tank can be kept outside of the constructed building.

10. While considering the requirement of hardening room, a minimum of five days production would be required.

11. Milk reception, storage tank and product sections require approximately10% of the plant area. CIP, laboratory, personal hygiene and rest room etc. require approx. 2 to 3 %, whereas processing, packaging and cold store would require 15 to 20% of the plant area.

16.2 Plant layout

Dairy functions and equipments require number of considerations. Therefore, best match of these considerations would give optimum layout to allow smooth plant operations without hindrance and cross contamination at economical cost. While finalizing the layout plan, future expansion of facilities and product line also need to be kept in mind. The ideal layout permits production of new product or modification in production system at the least possible expense and interruption in production schedule.

Good plant layout has short pipeline, least number of bends. As far as possible, sequencing of equipment should follow the process layout. Plant machinery should be placed apart at sufficient distance to allow movement for cleaning, operation and monitoring. Minimum holding of product during production is another aspect of consideration. Least possible stock of intermediary or in-process and finished item should be present on the production floor. The premises should allow use of the material handling equipment. Development of good layout should fulfill following objectives:

a) Improve or facilitate production operation,

b) Minimize material handling,

c) Have flexibility of operation for alterations and expansions,

d) Minimize investment in equipment,

e) Economize use of floor area,

f) Make labour utilization effective,

g) Make effective utilization of by-products,

h) Provide convenience and comfort for employees,

i) Ensure proper cleaning, operation and monitoring of processes, and

j) Prevent cross contamination.

The above points can be planned according to the type of layout. In multipurpose production system, product layout is preferred, whereas specialized production needs process oriented layout. Depending upon the requirement and nature of production, each function should have their optimized layout.

Some useful books

• Arthur W. Farrall, 1967, Engineering for Dairy and Food Products, Wiley Eastern Private Limited South Extension, New Delhi-3

• BIS, New Delhi. IS 115000:1998, Food Hygiene – General principles -Code of practice (second Revision),

• BIS, New Delhi. IS 21591:1998, Food Hygiene – Hazard Analysis and Critical Control point (HACCP) –system and guidelines for its application

• Buccola, S.T. and Corner, M.C. 1979. Least cost milk manufacturing plant locations for North Agrl. Econ.Council. 8(1):6

• Chander L., 2004, Textbook of Dairy Plant Layout and Design, Dir. of Information and Publication of Agriculture, ICAR, Pusa, New Delhi.

• Hall, H.S. and Helge, B. 1963. In milk plant Layout, FAO, Rome Hedric,T.I. and Chandan, R.C. 1980. Reducing dairy plant costs and improving efficiency. Indian Dairyman. 32(12): 873.

• Khorody, D.N.1978. Basic requirements in Planning and operating a milk undertaking. Indian Dairyman. 32(7): 7151

• Moore, James M., 1962, Plant Layout and Design, Macmillan Publ. Co.Inc, NewYork.

• Mudgil, V.D. and Prasad, S.R., 1994, Design Consideration in planning a dairy plant. Indian Dairyman. XLVI(II) 692-696