Hygienic Design PART A PDF

HYGIENE DESIGN Aim Knowledge the hygienic designing of the food processing plant. Purpose/Importance of hygienic designing of the food processing plant Food processing hygienic design of equipment. Purpose/Importance of hygienic designing of processing equipment. Cleaning and sanitation o...

HYGIENE DESIGN Aim Knowledge the hygienic designing of the food processing plant. Purpose/Importance of hygienic designing of the food processing plant Food processing hygienic design of equipment. Purpose/Importance of hygienic designing of processing equipment. Cleaning and sanitation of food processing plant. Content Introduction and purpose of Hygienic Design Of Food processing plant. Plant location and construction. Facility layout. Equipment design. Cleaning and Sanitation of food processing plant. Introduction and Purpose of Hygienic Design Hygienic factory design is concerned with protecting ingredients, packaging, intermediate and finished products from contamination may result processing environment. Hygiene considerations affect all the phases of food processing, including decisions in plant and process design, equipment selection, specification and handling of raw materials and packaging, maintenance of the physical plant and its environment, selection and training of the personnel at all levels, the overall conduct of activities and the ‘ culture ’ in a food processing plant. Successfully attain/achieve hygienic plant design the building necessitates a series of barriers to protect the product from the external environment and non-food manufacturing activities and, within the food manufacturing environment, the segregation of incompatible ingredients, packaging, intermediate and finished products and other activities, e.g. cleaning rooms, maintenance and quality/testing activities. Hygienic factory design also focuses on the building elements (floors, walls, ceilings, windows, doors, roofs) and the service provisions (water, lighting, ventilation, electrical installations, steam, compressed air, etc.) to ensure that such structures neither form hazards themselves (e.g. foreign bodies, chemicals) nor give rise to harbourage sites for other hazards (e.g. pests or microorganisms). The importance attributed to hygiene in a food processing company is reflected in the quality and safety of the products. FOOD PLANT LOCATION AND CONSTRUCTION Smoke, dust, odours and other contaminants are a concern to nearby food manufacturing facilities, thus whenever possible, factories should be located away from; Environmentally polluted areas and industrial activities that pose a serious threat of contaminating food (e.g. objectionable odours, smoke, dust or other contaminants); Areas subject to flooding unless sufficient safeguards are provided; Areas prone to infestations of pests; Areas prone to excessive levels of airborne bacteria, yeasts and moulds; Areas where wastes, either solid or liquid, cannot be removed effectively. At the site level, a number of steps can be taken to control hazards including the following: Have clearly defined boundaries, e.g. a perimeter fence or wall, with controlled access to the factory grounds to keep out animals or unauthorised persons. Measures to maintain site security, including the use of gate houses, security patrols and maintenance schedules for barrier fencing or other protection measures. FOOD PLANT LOCATION AND CONSTRUCTION Usage of two lines of rodent baits, one against the external fence and one against the factory walls, located every 15–21 m (45–65 ft) along the perimeter boundary fencing and at the foundation walls of the factory, together with a few mouse traps near building entrances. Have adequately draining areas or installed external drainage that should not pass under processing areas. The drainage system must be sufficient to handle peak volumes of rainwater without the possibility of leakage from manhole covers, etc. Entrances that have to be lit at night should be lit from a distance with the light directed to the entrance, rather than lit from directly above. This prevents flying insects being attracted directly to the entrance. Equipment necessary to connect transport devices to outside storage facilities (e.g. pumps, pipes, augers, conveyors, discharge tubing and fittings between tankers and silos) should be locked away when notin use. Parking areas for visitors and staff should not be close to factory entrances and external food storage areas.  Facility layout:Food factory/Plant Layout Factories should be constructed as a series of barriers that aim to limit the challenge of contaminants. The number of barriers created will be dependent on the nature of the food product and each barrier should reduce the challenge of a hazard to the subsequent barrier. There are four common levels of segregation that are for food plants/factory. Level 1: Represents the siting of the factory, the outer fence and the area up to the factory wall. This level seeks to control the degree of challenge of a hazard to the factory interior. (i.e. controlling pest access to waste material, control of unauthorized public access). Level 2: Represents the factory wall and other processes (e.g. UV flytraps) that should separate the factory from the external environment. Also includes all internal barriers designed to separate production stages (raw materials, intermediate product), incompatible materials (wet, dry, chilled, frozen, allergenic) and non-food production areas (engineering, boiler rooms, cleaning stores, changing areas etc.). The food production area may be split into a ‘dirty’ area, e.g. where animals are slaughtered or the soil is washed from vegetables and a ‘clean’ area, handling prepared food ingredients. Facility layout: Food factory/Plant Layout Level 3: Represents the internal barriers that are used to separate manufacturing processes of different microbiological risk, e.g. pre- and post heat treatment. Includes simple decontamination process (e.g. produce washing and final rinsing) or a pasteurisation treatment (e.g. an oven, cooker, fryer or heat exchanger). Level 4: Represents a product enclosure zone.. A product enclose zone encompassess true aseptic filling or ‘ultra-clean’ processing and packing areas such as glove boxes or the use of highly filtered air as a barrier around the process line. Equipment Design: Open Processing Equipment Design of food processing equipment aims to reduce the buildup of food material (microorganisms) in individual items of equipment and to ensure that all detectable soil is removed after cleaning. Food processing equipment should at least meet the following basic hygienic requirements: To avoid bimetallic corrosion, the right combination of steels, alloys or metals in the assembly of food processing equipment and food processing support systems must be used. So, piping and components should be constructed out of the same materials to prevent contact corrosion between dissimilar metals. Product contact surfaces (including the welds) must be smooth, enabling them to be easily cleaned. The design of food processing equipment must prevent bacterial ingress, survival, growth and reproduction on both product and nonproduct contact surfaces. The food processing equipment also must be constructed so as to ensure effective and efficient cleaning over the lifetime of the equipment. Equipment Design: Open Processing Equipment All equipment surfaces in the product zone must be so arranged that they are self-draining to minimize contamination and corrosion risks when liquid food, cleaning and disinfection solutions, and rinsing water are retained during idle periods. Microbes can flourish in stagnant pools of water, especially when nutrients are trapped in the internal pockets. Cleaning and disinfection solutions may contaminate food products , as a result of accumulation and pooling Equipment design must ensure hygienic compatibility with other equipment and systems (hydraulics and electrical, steam, air, and water systems). Equipment surfaces must be readily accessible for manual cleaning and disinfection, unless it can be demonstrated that the result of in place cleaning and disinfection procedures without dismantling is equivalent to the result of dismantled and manual cleaning procedures.  Equipment Design: Open Processing Equipment All parts of the equipment shall be readily accessible for inspection to facilitate the detection of all potential contaminants on representative surfaces throughout the product contact zone. All surfaces in the product zone must be immediately visible for inspection, or the design of the equipment shall allow easy dismantling without use of any tools. Food grade lubricant should be used, otherwise leaking of lubricant onto food product must be prevented. To protect the product zone, a drip pan should be used, or motors driving equipment components such as belt drives should be placed outside the product area. Open vessels, containers, and bins with bottom outlets must have their discharge outlet at the lowest level and their bottom shall be sloped (more than 3 degrees toward the outlet). Their corners shall be well rounded, with a radius equal to or larger than 3 mm Tank Designs Product cannot be drained : Poorly designed tank Easily drained Product: Good Tank Design Equipment Design: Open Processing Equipment Welding or continuous bonding is preferred over fastenings. Welds must be continuous and smooth, free of pits and cracks. Fastening of nameplates on the equipment should be avoided in favor of direct continuous welding. As a further improvement, direct application of graphics on equipment components by laser engraving is ideal. All inaccessible horizontal flat areas, ledges, edges, etc. where product residues can accumulate should be eliminated. The exterior of indirect product contact surfaces should be so arranged that harboring of contamination in and on the equipment itself, as well as in its contact with other equipment, floors, walls, or hanging supports, is prevented.  Equipment Design: Closed Processing Equipment Food processing equipment should at least meet the following basic hygienic requirements; Piping and components should be constructed from the same materials, so as to prevent contact corrosion (bimetallic corrosion) between dissimilar metals. Smooth product contact surfaces must minimize the adhesion and colonization of microorganisms, so as to prevent the formation of biofilms. Food processing equipment design and construction may not allow bacterial ingress, survival, growth and reproduction on both product and nonproduct contact surfaces. Equipment must be designed and constructed so as to prevent the ingress of liquids and living creatures (e.g., insects) into any areas that cannot be cleaned. In addition, organic matter must not be permitted to accumulate in such areas. Retained product residues or cleaning fluids may subsequently contaminate the product on rejoining the product stream. Equipment Design: Closed Processing Equipment Bearings should be either of the “sealed-for-life” or “double- sealed” variety and should be located external to the equipment in order to minimize contact with product. When bearings are mounted outside the product area, contamination of food products by lubricants is avoided, as well as the ingress of bacteria. There is also less chance that the bearing gets damaged due to ingress of product. Where possible the bearings should be self-lubricating. Bearing covers should be fitted where possible (however, that seals ultimately wear and leak). When the bearing is within the product area (e.g., slide bearings, such as bottom bearings of top-driven stirrers or bearings in scraped-surface heat exchangers), it should be self- or product- lubricated. It is advisable to avoid steam cleaning of lubricated bearings. After contact with fluids or steam (where essential), bearings should be allowed to dry out before they are relubricated. [Applicable to bearings manually lubricated]  Equipment Design: Pipping systems Pipes must ensure minimum resistance to flow, and therefore there should be no sudden changes in cross-sectional area or obstructions that are likely to hinder the flow. Pipework must be so designed that as far as possible a minimum velocity of 1.5 m/s is achieved over the whole trajection of pipes, unless data for the specific soil indicate otherwise. As a consequence, substantial flowrates for larger- diameter pipework are required. To avoid the formation of standing “pools” of liquid that can support the growth of microorganisms, process and utility piping runs should be sloped to at least 3% in the direction of flow and should be properly supported to prevent sagging. Sagging of piping must be avoided because standing “pools” of liquid can support the growth of microorganisms. Where plastic piping is installed, special care should be taken to avoid sagging by increasing the frequency of support. Pipelines and valves should be supported independently of other equipment to reduce the chance of strain and damage to the equipment, pipework, and joints.  Equipment Design: Pipping systems A properly designed food processing line must not have dead legs, as blanked-off tees constitute a hazard. A dead space, being an area outside the product flow where liquid or gas can become stagnant and where water is not exchanged during flushing, is formed. An air pocket may be present if the branch of a blanked-off tee is pointing vertically upwards(Fig A). Hence it will prevent liquids (cleaning solutions, disinfectant solutions, or hot water) from reaching all surfaces to be treated, with the result that CIP and decontamination processes will be unsatisfactory. Drain points pointing downwards (B) act as a dead leg and are not acceptable because they provide an area of entrapment that may not be reached by cleaning or sterilization procedures.  Equipment Design: Pipping systems During a hot water treatment, the hot water also will stagnate in the downwards pointing pocket, so that the temperature of the surfaces in the dead area as a consequence of heat loss may be lower than required. A downwards pointing dead area also will collect condensate during steam sterilization (C), with the result that again the temperature of the surfaces in the dead area may be lower than required. As a consequence, the thermal disinfection or sterilization of the dead space is compromised.  Equipment Design: Pipping systems The direction of the flow of food product has a significant influence on the residence time in the dead leg. When the food product flows in the direction as indicated in Fig. A, B and C, part of the product will stand still in the dead leg, especially if the length or depth of the T- section is too long. If the length of the T-section is equivalent to the diameter of the main pipe, a flow velocity of 2 m/s in the main pipe will already result in a reduced velocity of 0.3 m/s in the T-section. This decrease in flow velocity provides a relatively stable pocket or dead leg in which product residues can accumulate and microorganisms begin to multiply. Long T-sections outside of the main flow of cleaning solutions are also very difficult to clean. During cleaning there is much less transfer of thermal (heat), chemical (detergent and disinfectant chemicals) and mechanical energy (action of turbulent flow) to the food residues in the T-sections (outside the main flow of cleaning liquids).  Equipment Design: Pipping systems Note that flow away from the dead leg such as in Fig. A and C further gives rise to more contamination problems and worse cleaning, as velocities in these dead legs are even much lower. For most liquids, the dead leg should be positioned as shown in Fig. D, E and F. If the dead leg is very short, configuration Fig. D is acceptable. Configuration Fig E may not be suitable, if products contain any particulate matter, which may accumulate in the dead leg. The configuration in Fig. F is the most acceptable, because the flow directed into the short dead leg provides sufficiently high velocities for proper cleaning. For pipe diameters of 25 mm or larger, T-sections should have a depth/ length of preferably under 28 mm, while for smaller pipe diameters this length should be smaller than the diameter. Blanked-off tees should be positioned such that they are a few degrees above the horizontal. The dead leg will then be drainable but not necessarily cleanable even if made as short as possible. A sensor must be installed in a process line, it should be installed in a bend on a shortened tee in a position that the flow of cleaning fluid should be directed into the tee (Fig. E and F).