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. 
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                  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 
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                   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