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Journal of Hygienic Engineering and Design Review paper UDC 664.013 BASIC FACTORS FOR FOOD PROCESSING EQUIPMENT HYGIENIC DESIGN AND ITS CLEANABILITIES WITH MINIMAL CONTAMINATION RISK Tadeusz Matuszek1* 1 Mechanical Engineering Faculty, Gdansk University of Technology, 11/12 G. Narutowicza St., 80-233 Gdansk, Poland * e-mail: tmatusze@pg.gda Abstract In this paper basic factors with respect to the manu- Key words: Equipment design factors, Hygiene surface facturing suitable for food processing equipment have clean abilities, Tools blunt and sharpness, Contamination been presented and considered for specific food pro- risk area. cessing lines. All of these factors have been graphically shown and 1. Introduction numbered in the figure one. They have to be specifi- Food production is one of the most complicated and cally taken into consideration for so call open food sophisticated engineering processing of raw materi- production productivity area, and for open process- als due to their sensitivity and chemical activity, and ing equipment as well. It is the most important at the because of the very high demand for the hygiene and area when raw food material is being prepared as food sanitation requirements for both processes parameters ready to eat. It can also be analysed through many oth- and machinery together with auxiliary technical outfit, er technological food production lines, but the particu- and the surroundings data where the food production lar importance have to be seen among food branches periodically or continuously is going on. Moreover, as following: fish fresh, frozen and meat processing, hygiene is the process of considerable importance in cheese, meat slices, meat raw or cooked dicer and strip all food industry branches, due to the increasing cost cutter, meat separation from bones and trimming, placed on both the food producers and for food equip- dray apple slices, confectionery, potato chips and slic- ment manufacturers. es, tomato, cucumbers and other vegetables cut out to The main reason for rising up the cost is the expect- pieces, bakery, many dairy final products. In general for ed safety and possible extension of the shelf life of the all cutting, slicing, sawing, mixing, grinding, injection, food products. It is also strictly related to the fouling, flow divider multiple processing track for fillings meat, cleaning and disinfection processes, usually accepted fish, cheese or vegetables products unit operations, as the cause creating potential impact on the product when that equipment should be dismantled every day quality, and food processing plant operational perfor- for cleaning. mance. The best concept for realising such a place for In conclusions it has been stated that all basic food food production is known as the closed food produc- processing equipment factors have to be verified and tion cycle. In another words it means that all what is assessed two times. For the first time at the beginning needed for the food productivity plant, i.e., energy, raw of the design machinery concept of all equipment materials and water, remain inside that area, and any types, together with building and surrounding plant kind of waste are not leaving the food production area, requirements, quality of raw materials, operations staff and not creating the waste problem for environment. qualification and expected from them demand to fulfil the GHP for any kind of final food products. For the sec- 2. Basic equipment food processing factors ond time, at the end of that food production needs as above pointed out, regarding the EU 96/IPPC Directive, The basic food processing factors influencing on the with respect to the level of waste like solids including equipment parameters during the unit processes in dust, gases and liquids in keeping the ongoing way food production under technological conditions are zero level waste campaign to safe environment. presented in Fig. 1. 38 Journal of Hygienic Engineering and Design these persons should possess specific medical health checking with respect to the zones at the production plant and for the described micro-organisms level there to avoid any of food contamination risk coming from human beings at the different region they will be working on. Details for such specific staff requirements are given in the EU Instruction No. 2073/2005 issued th st on 11 November 2005 which is in power form 1 Jan- uary 2006, with further amendments. The third factor include the water quality properties. In this case it is necessary to stress that hygiene and sanitation in the food industry is not simply concerned with cleaning. Hygienic requirements embraces the plant, equipment and buildings design, including both construction and layout, the supply of services such as bacteriological acceptable water supplies, including installation facilities for cleaning and sterilisation, and waste disposal facilities. The quality of water proper- ties can be varies. For instance, if the water is bacterio- logical acceptable and has been softened, only deter- gent need to be added, but if the mineral content of the water is high, water conditioners like sequestering Figure 1. Food processing equipment factors agents such as sodium polyphosphates must be add- ed to prevent precipitation on pipeline and equipment The first factor include the full information about raw surfaces. materials for instance meat, fish, fruit, vegetables, Water supplies to the food industry may be as either sweetness, bakery, and others to be cut out to pieces ground or surface waters. It is necessary to underline and further processed for specific kind of final food that micro-organism are commonly encountered in product. It means to possess all data based on trace- surface water, usually including diatoms, fungi, algae, ability continuing information process about the raw protozoa, and variety of non-pathogenic bacteria. If materials quality collected from their receiving area introduced into processing plant, living microorgan- up to the consumer, using micro and nano electron- isms and their decomposition products may give rise ic devices applied as it is described by the ISO 22519 to off-colours, tastes and odours in both foodstuffs standard. These traceability data have to contain the and food equipment. Even more, pathogenic bacte- compatibility between the local and international law ria may not cause spoilage of food products but also requirements regarding protected designation of or- food poisoning. Water used in food processing plant igin (PDO), protected graphical indication (PGI), and can be classified as: general purpose water, process traditional speciality guaranteed (TSG) of agricultural water, cooling and boiler feed water. Many food facto- and other raw products sources. It is also important be- ries purchase their water supplies direct from munic- cause food belongs to the very high complex system, ipal authorities, and for it use further treatment may and also is known as a very dissipative one. Therefore, be necessary. The ways of necessary treatments for the control of food material properties have a major the water satisfactory quality production, depends role in the processing behaviour, in growth of mi- on the use for which the water is required. The major cro-organisms, and is a key factor of many food quality impurities requiring removal are: suspended matter, aspects [7, 8]. micro-organisms, organic matter like colour, testes The second factor is related to the operations staff and odours, dissolved mineral matter, iron and manga- qualifications and to the specific demand expected nese, and dissolved gases. In general, organic matters, from them in any kind of supporting service during colours, tastes and odours are unacceptable in water the food engineering process for variety of unit oper- to be used for food processing, regarding all hygien- ation processes in the technological lines. In general, ic food production aspects. All natural waters contain basic requirements for personnel directly engaged to dissolved mineral common matter like sulphates, chlo- the equipment service are written in the GHP (Good rides and bicarbonates of sodium, magnesium and Hygienic Practice) standard. Among other things, it is calcium. For water treatment purposes and its quality necessary to wear clothing, the best made of natural needed in hygienic and safety food processing as well woven, with different colours that indicate the process- as to achieve minimal contamination risk after clean- ing place at the divided productivity area. In particular ing and sanitation processes, it is also convenient to 39 Journal of Hygienic Engineering and Design examine the effects of the following soluble impuri- following criteria are playing major role for its specif- ties: alkalinity, hardness, and iron and manganese. In ic parameters: temperature, air distribution, filtration, the EU Directives and Veterinary Medical Instructions time and spatial variations, relative humidity, cleaning EU-18/2000, the level of water hardness should be at requirements, and controlling with monitoring the co- the range between 60 to 500 mg/L, the level of iron in operation between all system components, and times water cannot exceed the value of 0.2 mg/L, the level of when the normal food production is not continue. magnesium in water have not to be higher than 0.05 Particular values of the above indicated specific pa- mg/L, and the alkalinity value similar to potable water, rameters depend on the types of final food products, i.e., pH about 7.0 [3]. on the workplace healthy, safety and prevention of the The fourth factor is related to the air flows in the food discomfort conditions, on the air flow rate sufficient production area and air data needed for its delivery for fresh air required by people and for amount of air and movement parameters. Air flows can increase con- exchange regarding the high or low risk zone opera- tamination risk inside and around food factories, and tions to prevents any increase of the airborne contam- it is the potential source of microbial hazard. Usually, ination. The main components of the air delivery are the risk from airborne contamination can be identified as follows: panel type filter, dehumidifier cooling coil, using HACCP standard procedures, during the assess- humidifier, droplet eliminator, heating coil, fan section, ment of the entire unit food production operations air distributor, bag type filter, and HEPA filter that can when identifying Critical Control Points in all places be present as a whole in the system or some of them where equipment is located and in the space around it. in a different configuration. At the high risk production If the airborne contamination places are pointed out, zone special attention should be paid to chosen the their location should be taken into account as a prior to HEPA filter that is build up with the highest filter grade changes to the air delivery and handling equipment, and design for removal particles bigger than one over especially for air parameters description and food pro- one thousand micrometres [1]. cess conditions to be achieved. From this point of view The fifth factor embody of the designing food engi- the air conditions in the air handling system should neering equipment parameters and its attributes. This be maintained at all times, including production and factor can be divided into the sub-factors with expect- whole cleaning procedure. In another words it means ed specific requirements as for: that adequate air temperature and pressure during manufacturing time together with air flows around - The tools types used in the cutting out into pieces the the food products have to be continuously controlled. raw fresh or frozen materials, with their basic made of Also as equally importance is the unit operation staffs material, surface roughness, with shape and suitable understanding the air enter places into factory and value sharpness or blunt of knife-edge. In Figure 1 for their own footpath movement closely to the servicing example there is the tool as a disc knife presented. Usu- equipment by them. The assessment of the air flows ally, this tool is made of from the stainless tool steel, movement is particularly importance in the high-care at least the knife-edge. The shape of knives-edges dif- food production area, when air flows can disperse ferentiate from the smooth line on the circumference droplets from cleaning operations existing in the air to the many teeth on the circuit with different subdi- as aerosols. These kind of droplets in the air may have vision and knife-edge angle, that both influencing on micro-organisms on their surfaces or inside, and can the cutting process effectiveness. For instance the effi- deliver contaminant to the food product. There is a lot ciency of cutting process in commercial filleting of fish of washing and cleaning operation in the food plant is affected by the type of deformation of the fish tissue area that can be a sources of contamination namely: under and around the shape of the cutting edge. This boot and hand washing when entering to the factory, deformation depends on the the shape of the cutting tray and equipment washing, floor and product wash- edges, conditions of the blade, cutting speed, and cut- ing. Additionally, the airborne contamination can be ting resistance of scales, skin, fish meat and bones. The found in the moving or rotating parts of equipment cutting resistance may vary and is influenced by many such as like: mixers, fillers, conveyors, motors, slicers, factors that determines the rate of the cutting edge blenders, as well as in the packaging materials, per- blunting. In the cutting process it is necessary to apply sonnel clothing, and in the inappropriately designed a sufficiently large force to overcome the resistance of and maintained air delivering and handling systems. the raw material due to its elastic and plastic deforma- To achieve the minimal airborne contamination risk tion, as well as frictional and cohesive forces. In case the hazard analysis should be continuously carried out for fish product the cutting forces on the disc knife are at the raw materials delivery area, on the unit opera- composed of: force initiating the cutting process (i.e., tions equipment located along technological line area, causing contact stress at the knife/fish interface), forc- on the whole factory structure with all layouts and the es of frontal resistance on knife edges, frictional forc- personnel movement, and including principally the air es on the surface of knife wedge, and frictional forces handling equipment. In the air handling system the on side surfaces of the knife (including cohesion and 40 Journal of Hygienic Engineering and Design adhesion). The maximum resistance during cutting The way of inside body connection between the unit process occurs on the cutting edge, on so-called in- operations section through the internal transport sys- termediary surface created by the external rounding tem. Based on the concept of unit operations section with the arc radius ρ in the knife angle. The main effect distribution, the internal connection inside the body of change in the knife sharpness is noticeable on this depends on the method relevant to the expected en- surface. Blunting is a process of continuous change in gineering processes. The design of the internal trans- the knife micro-geometry. These changes are strongly port system can be considered as a raw material or influencing on the quality of cutting process, and also semi-product or final product handling conveyor with on the fouling knives surfaces with accumulation or different types of tape like flat that may vary with sur- deposition of raw materials components (among oth- face shape and made of materials. There are also wire er things fat, protein, biofilms) that subsequently are net tape, and with frictional elements matched with later on deposited to stagnant equipment areas. The the surface shape of transported raw materials. The quantity and variety of fouling should define the pa- other types like hook, clamp or clasp conveyors are rameters for cleaning process and the proper strategy very often used in the meat industry, among other for accumulated soil removal from any of unhygienic things in continuous animal transportation for killing part of equipment. It have been recognised that the before further processes. All of them regarding shape hardness of the knife surfaces is good enough with and fixing elements, required different cleaning and 0 the range value 55to 60 HRC, with roughness value disinfection procedure to keep their contact elements of those surfaces from 1.2 to 1.4 μm. The sharp knife with food in a very good hygienic conditions. should have a radius ρ = 5μm, and for the fish filleting The food-grade lubricants used for the equipment knives blunting limit are about 40 μm as still accept- parts in motion. It is necessary to stress that the food- able for high quality fish products. grade lubricants need to be dispelled and overcome, The way of tool(s) fixing in the body together with the i.e., not only to assist in improving production perfor- motor, gearbox and coupling localisation, bearings, mance of the equipment elements in motion, but also and power transmission needed for the tool revolution to reduce contamination risk. The food contamination speed and its control movement in the horizontal and can occur from drips off chains, oil leaks from seals and vertical direction. In general, tools with other compo- gearboxes and from hydraulic hose failure, as well as nents needed to perform their expected processing realise from compressed air containing an oily mist. function should have as much as possible free access Moreover, it is the common knowledge that processing for daily inspection, routine service and to allow easy equipment incorporates many moving parts requiring maintenance and efficiency of the cleaning process. lubricants to obtain reliable and effective operations. Some of the above mentioned components, of the Additionally, lubrication quality play a major impact on power transmission mainly, are working as an open life of equipment and the cost of maintenance. In the equipment. Therefore they have to be equipped with food industry recently more popular became the food special covers and mounted with screw and bolt with grade synthetic lubricants that are odourless, tasteless, cap nut for not accumulating soil. The type and size of and remaining effective in the sub-zero cold of freezers bearings depends on the range and direction of forc- and the heat of ovens. In general opinion application es acting on the element supported by them. In case of the synthetic lubricants, improving lubricants prop- of rotational shafts with attached there for example erties and performance together with good water re- disc knives, in contact with raw material during cutting sistance, in compare with food-grade mineral oil-based process, and under continuously clean water flow, for lubricants. Apart from, the food-grade lubricants are necessary lubrication the best are so-called self-lubri- harmless if accidentally consumed in quantities below cating bearings. the described maximum level. For example, the U.S. The distribution and arrangement of single or mul- Food and Drug Administration (FDA) prescribed that ti-unit operational sections in the equipment body. level of 10 ppm. It should be done in the way with respect to the se- The arrangement of the cleaning and disinfection quences of cutting process step by step in agreement installation as required for system used to keep the with the idea described by technologist receipt for re- equipment in hygiene conditions to eliminate the risk ceiving certain part of the pieces of meat (fish, chicken, of cross contamination at the tools and others equip- pork or beef meat, and poultry). For instance, the fish ment surfaces open for soil like residual parts of raw fillets can be received when de-heading fish, cutting of materials left after unit operations and airborne con- a belly and to take away intestines, the bones removal tamination as well. The modern food processing plant after cutting skin in several places of the fish surface, is being designed to permit the cleaning operation in and finally to remove the skin with scales (or without one of two different ways either by: dismantling and removal it). cleaning or through the system known as C.I.P. Factors influencing the degree and effectiveness of cleaning, 41
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