The hygienic working practices of maintenance personnel and equipment hygiene in the Finnish food industry

Food Control 17 (2006) 1001–1011 www.elsevier.com/locate/foodcont

The hygienic working practices of maintenance personnel and equipment hygiene in the Finnish food industry Kaarina Aarnisalo

b

a,¤

, Kaija Tallavaara b, Gun Wirtanen a, Riitta Maijala b, Laura Raaska a

a VTT Biotechnology, P.O. Box 1500, VTT, FIN-02044 Helsinki, Finland Department of Risk Assessment, National Veterinary and Food Research Institute, P.O. Box 45, FIN-00581 Helsinki, Finland

Received 24 January 2005; received in revised form 21 July 2005; accepted 22 July 2005

Abstract The hygienic working practices of the maintenance personnel as well as the hygiene of the equipment in the food industry were investigated with questionnaires and microbial surveys. The protective clothing, washing of hands and tools as well as avoiding foreign bodies left on the production lines should be targeted when the hygienic working practices are developed for maintenance personnel. Based on the questionnaire to food processors, packaging machines, conveyers, dispensers, slicing and cooling machines were considered the most problematic pieces of equipment hygienically mainly because of poor hygienic design. In order to improve food safety, both the training of maintenance personnel in food hygiene and equipment design should be more emphasised. © 2005 Elsevier Ltd. All rights reserved. Keywords: Equipment hygiene; Hygienic working practices; Maintenance personnel

1. Introduction Food-processing equipment has been shown to be a source of contamination, e.g. Listeria monocytogenes, in many studies (Aguado, Vitas, & Garcia-Jalon, 2001; Autio et al., 1999; Fonnesbech-Vogel, Jørgensen, Ojeniyi, Huss, & Gram, 2001; Lawrence & Gilmour, 1994; Lundén, Autio, & Korkeala, 2002; Lundén, Autio, Sjöberg, & Korkeala, 2003; Miettinen, Björkroth, & Korkeala, 1999; Pritchard, Flanders, & Donnelly, 1995; Samelis & Metaxopoulos, 1999; Suihko et al., 2002; Tompkin, 2002). Legislation on the hygienic design of food-processing equipment or the hygienic maintenance of these equipment is rather vague. In Europe the most important legislation giving criteria for hygienic design of equipment is the Council Directive on the approxima*

Corresponding author. Tel.: +358 9 722 7126; fax: +358 9 722 7071. E-mail address: [email protected] (K. Aarnisalo).

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tion of the laws of Member States relating to machinery (89/392/EEC, revised 98/37/EC) (Anonymous, 1989), which contains safety requirements and the basic principles of hygienic design. National standards and/or directives applicable to the hygienic design of food machinery are available, but only a few international standards exist, directed mainly at the dairy industry (Holah & Timperley, 1999). A basic standard about hygiene requirements for the design of machinery is the ISO 14159:2002 (Anonymous, 2002a). The European committee for standardization (CEN) issues standards for equipment manufacturers to be able to fulWl the requirements of the directive. One important basic standard is the Standard EN 1672-2 “Food-processing machinery— Safety and hygiene requirements—Basic concepts—Part 2; Hygiene requirements” (Anonymous, 1997). However, there are also guidelines and methods published e.g. by the European Hygienic Engineering and Design Group (EHEDG, http://www.ehedg.org), 3-A Sanitary

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K. Aarnisalo et al. / Food Control 17 (2006) 1001–1011

Standards Inc. (3-A, http://www.3-a.org) and NSF International (http://www.nsf.org) available for helping in the design of new hygienic equipment. According to the EHEDG-guidelines, constructions that cause problems include dead ends, sharp corners, low-quality seals and joints etc. (Anonymous, 1993b, 1995b). In Finland the preventive risk management strategy in food-processing plants is called own-checking and, as in other Nordic countries, it is based on hygiene prerequisites or good hygiene practices (GHPs) and hazard analysis critical control point (HACCP) principles. A own-checking system became mandatory for Finnish food operators, caterers and retailers in 1995 (Anonymous, 1995a). The programmes can be certiWed according to standards, e.g. the technical standard of the British Retail Consortium (BRC) (http://www.brc.org.uk; Anonymous, 2002b). A draft version of the new ISO— series standard 22000 is also available (Anonymous, 2004a). In these standards, equipment hygiene and hygiene in maintenance are also mentioned, although only brieXy. Hygiene problems in equipment are caused when microorganisms become attached to the surfaces and survive on them (Wirtanen, 1995) and later become detached from them contaminating the product. This can be due to bad hygienic design in cases where the machines cannot be cleaned properly. A typical bacterium that causes hygiene and safety problems in foodprocessing equipment is L. monocytogenes. It can become attached to diVerent surfaces and tolerate low temperatures (Mafu, Denis, Goulet, & Magny, 1990; Walker, Ascher, & Banks, 1990), anaerobic (Buchanan, Stahl, & Whiring, 1989) and other process conditions, e.g. a wide pH range (Lou & Yousef, 1999), and also persist in food-processing equipment (Lundén et al., 2003). This bacterium can also be found on hands or gloves used in food-handling (Autio et al., 1999; Destro, Leitao, & Farber, 1996). The regulation on food hygiene (EU) No. 852/2004, Annex II (Anonymous, 2004b) states, that food-handlers must be supervised and instructed in food hygiene matters commensurate with their work activity. However, even if maintenance personnel do not actually touch the raw materials or food products, they presumably touch a multitude of surfaces in contact with unpacked products. For example, they dismantle machinery for cleaning procedures and reassemble it after cleaning in addition to maintaining the operation of machinery during production. Unfortunately very little is known about the eVect of maintenance on product hygiene and according to our knowledge, there are no scientiWc publications available on this question. The aim of this work was to study the level of hygiene knowledge and the hygienic practices of maintenance personnel in the food industry in order to identify aspects that could have a negative eVect on equipment

hygiene and that should be improved. Furthermore, this study was performed to evaluate the most problematic equipment in food-processing hygiene and also to Wnd out why it is problematic. The results are based on questionnaires and microbial surveys.

2. Materials and methods 2.1. Questionnaire on hygienic working practices of maintenance personnel A mail survey was sent in spring 2002 (and a pilot in autumn 2001, results are included) to maintenance personnel (330), food-handlers (118), quality managers (106) and cleaning personnel (224) in 106 Finnish food companies, i.e. a total of 778 questionnaires. In the questionnaires, opinions about the hygiene practices of maintenance personnel were sought from the maintenance personnel and from other employees in the food plant. Some questions were directed at quality managers only. These surveys contained questions categorised into nine topics: protective clothing, tools, hygienic working practices, control of practices, resources, guidelines and instructions, information Xow, training and background information. The respondents were able to answer anonymously. 2.2. Microbial sampling In addition to the questionnaires, the working practices of maintenance personnel during two normal work shifts was studied at four food companies (a meat company, a poultry company, a dairy and a bakery). Samples were taken both during production and during/after cleaning work shifts. Microbial samples of the tools, protective clothing, hands and working environment were analysed for total aerobic bacteria, Enterobacteriaceae and L. monocytogenes. The microbial sampling for total aerobic bacteria and Enterobacteriaceae was performed with commercial PetriWlm™ Count Plates (3M Health Care, St. Paul, MN, USA). PetriWlms were chosen as sampling method because they were easy to use and Xexible. The technique has been shown to have good repeatability and reproducibility (Senini & Cocconcelli, 1999). Furthermore, contact sampling methods and swabbing have been compared and the results have been similar (Salo, Alanko, Sjöberg, & Wirtanen, 2002; Salo, Laine, Alanko, Sjöberg, & Wirtanen, 2000). The PetriWlms were moisturised a day before sampling with 1 ml of a sterile physiological saline solution in accordance with the manufacturer’s instructions. The 3M PetriWlm™ Aerobic Count Plates contain standard method nutrients and a tetrazolium indicator that facilitates colony enumeration. Altogether, 95 samples were taken. PetriWlm™ Aerobic Count Plates were incubated at 30 °C for three days.

K. Aarnisalo et al. / Food Control 17 (2006) 1001–1011

The Enterobacteriaceae were sampled with 3M PetriWlm™ Enterobacteriaceae Count Plates containing modiWed violet red bile glucose (VRBG) nutrients and a tetrazolium indicator that facilitates colony enumeration. Altogether, 96 samples were taken. PetriWlm™ Enterobacteriaceae Count Plates were incubated at 37 °C for two days, after which the typical colonies were counted. For detecting the presence of L. monocytogenes, altogether 71 samples from three plants were taken from as large an area as possible with moisturised gauze pads kept in 10 ml of a peptone saline solution (Maximal Recovery Diluent, Lab M, Amersham, Bury, UK). The isolation and detection of L. monocytogenes were carried out according to the ISO 11290-2 method (Anonymous, 1996) with the following modiWcations: only Oxford agar (Oxoid, Hampshire, UK) was used as the selective agar and the preliminary identiWcation was carried out using API Listeria strips (bioMérieux, Marcy-l’Etoile, France) in accordance with the manufacturer’s instructions.

1003

the dairy industry, 1.6% in the Wsh industry and 18% in other types of food industry. All respondents from the maintenance personnel were males and 66.2% of the other respondents (n D 68) were females. The working experience of the respondents was as follows: 7.2% of the respondents (n D 126) had worked in the food company <1 year, 3.2% had worked 1–2 years, 23.7% > 2–5 years, 19.8% > 5–10 years and 46.1% > 10 years. The maintenance is outsourced in 36.4% of the plants (n D 22) and in 45.4% the plant’s own personnel took care of the maintenance. Both outsourced and a plant’s own personnel were involved in maintenance activities in 18.2% of the plants.

3.1. Questionnaire on hygienic working practices of maintenance personnel

3.1.2. Protective clothes, work practices and hygiene rules Most of the maintenance personnel work in the production area continuously (61%) or at least Wve times (23.7%) during a work shift (Fig. 1a). Of the maintenance personnel, 42.4% reported having touched surfaces with contact in food often or always (Fig. 1b) and while working in the production area 55.9% of them usually wore gloves (Fig. 1c). However, only 13.6% washed their hands after smoking and 23.7% before starting to work without gloves (Fig. 1d). Only 42.4% washed their hands before entering the production area. Almost all (91.5%) of the responding maintenance personnel (n D 59) knew which surfaces were in contact with food products. An open question asked the food and cleaning personnel, how the maintenance personnel should improve their working practices. The respondents (n D 32) named the following most often: use and cleanliness of protective clothing, cleaning after maintenance work, cleaning the tools and washing of hands (results not shown). According to the maintenance personnel and quality managers, most of the maintenance personnel had written hygiene rules given by the food company (64.2%) or by the maintenance company (32.3%) (n D 81). Most (63.6%) of the maintenance personnel knew where they could Wnd the hygiene rules (n D 55). Maintenance is part of the own-checking systems in most (73.9%) plants (n D 23), but a maintenance company is not normally (76.2%) audited by food companies. The quality managers were asked if they had ever received consumer complaints, which could be linked directly to the work of maintenance personnel. Such complaints were rarely or seldom reported by 62.5% of them (n D 16).

3.1.1. Characterisation of the respondents Answers were obtained from 23.6% of the plants (n D 106). Out of 778 employees 127 (16.3%) answered the mail survey. Of these, 59 were maintenance personnel and the rest belonged to other personnel groupings. One third (33.9%) of the respondents worked in the meat and poultry industry, 26% in the bakery industry, 20.5% in

3.1.3. Tools and foreign bodies One third (32.2%) of the respondents answered that they washed their tools once a day or always after work. The others answered that they washed their tools more seldom and 32.2% only once a year or never (Fig. 1e). Almost all (89.8%) of the maintenance personnel had personal tools which they themselves cleaned (n D 59).

2.3. Questionnaire on equipment hygiene A mail survey on equipment hygiene was performed in spring 2002. Questionnaires were sent to 184 Finnish food companies. The employee, who was the equipment hygiene expert in the company was asked to answer the survey. There were 34 questions categorised under the following seven topics: hygienically problematic equipment, acquisition of equipment, cleanability of equipment, cooperation between parties who aVect equipment hygiene, lubricants used with equipment, acquiring information on equipment hygiene as well as background information on the respondent and plant. The respondents were able to answer anonymously.

3. Results In the results of both mail surveys, individuals who did not give any response to a particular question were dropped from the analysis, thus causing varying respondent counts (n) for the diVerent questions.

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K. Aarnisalo et al. / Food Control 17 (2006) 1001–1011

50

50

40

40

30

30

%

23.7

22.0

1.7

83.1

never

seldom

81.4

80 71.2 55.9

60

60

40

%

39.0

44.0

42.4

40

13.6

20

23.7

other

coat

gloves

overall

cap

20 footwear

(c)

3.4

0

(b)

80 %

once

91.5

2-3 times

> 5 times

93.2

approx. 5 times

continuously

0

10

0.0

sometimes

3.4

always

6.8

5.1

none

10

0

33.9

20

20

(a)

39.0

often

%

61.0

13.6 1.7

1.0

other occasions

no answer

0

(d)

after visiting after work before lunch before restroom when hands and coffee entering became breaks production dirty area

before starting work without gloves

after smoking

25

%

20 15

20.3

18.6 13.6

11.9

10 5

5.1

5.1

5.1

13.6

6.8

0

(e)

always once a once a 2-4 twice a once a once a never no answer after day week times a month month year or less month work

Fig. 1. Answers of maintenance personnel to the question on their working practices and their use of protective working clothes: (a) How many times do you have to visit the production area during a work shift? (b) How often do you have to touch food contact surfaces in your work? (c) What type of protective working clothes do you usually wear when working in a food plant? (d) When do you wash your hands during a work shift? (e) How often do you clean and/or disinfect the tools you use daily? (n D 59).

For tools that are in common use, no persons were in charge of the cleaning in 71.9% of all the cases reported (n D 57). According to the majority of maintenance personnel, foreign bodies are never or seldom left on surfaces after the maintenance work but, according to the majority of food and cleaning personnel, they are sometimes or even often left (Fig. 2). Clear diVerence between opinions could be found. 3.1.4. Resources, information Xow and training There were enough maintenance personnel in the plant according to 47% of the answers obtained from maintenance personnel and quality managers (n D 83). A majority (69%, n D 87) of them considered that there were

enough washing points available for cleaning tools, and adequate cleaning agents and disinfectants were also available (74.7%, n D 83). The opinion of 61.4% (n D 83) was that there were enough sets of protective clothing available. There was not much diVerence between the answers given by maintenance personnel and quality managers. Meetings between maintenance, food-processing and cleaning personnel in which hygiene issues were also discussed, were not arranged in 52.9% of the plants (n D 119). 33.9% of maintenance personnel found they had not received enough information about hygiene commensurate with their work. Studies about food hygiene were not included in their basic education (89.9%, n D 59).

K. Aarnisalo et al. / Food Control 17 (2006) 1001–1011

47.0

50

respectively). However, the deviation between samples was high and e.g. some tools had 25–40 cfu/cm2 aerobic bacteria. Listeria spp. was found in six samples (5%) of which L. monocytogenes was found in only one sample (1.4%) taken from a screwdriver. Enterobacteriaceae were not found in samples except on one of the gloves (100 cfu/cm2).

45.8 42.4

40 % 30

24.2

21.2 20 10.1 10

1005

6.1 1.7 1.5

0 often

sometimes

maintenance (n=59)

seldom

never

3.3. Questionnaire on equipment hygiene

cannot answer

3.3.1. Characterisation of the respondents The response rate in the questionnaire on equipment hygiene was 23.9% (44/184): 14 plants from the meat, poultry and ready-to-eat food industry, 11 bakeries, eight Wsh companies, six dairies and Wve plants representing other branches of the food industry. There were mainly 10–90 employees in the plants (69.2%), but there were also companies with fewer than 10 employees (5.1%) and 150–650 employees (25.7%) among the respondents (n D 39). The respondents (n D 43) were very often working as quality managers/hygiene responsible operatives (44.2%) or production managers (25.6%).

food and cleaning (n=66)

Fig. 2. Opinions of respondents whether foreign bodies were left on production surfaces after the maintenance work (n D number of respondents).

3.2. Microbial sampling The total number of aerobic bacteria in samples taken from the hands and clothing of maintenance personnel was 14 cfu/cm2. However, the deviation between samples was very high (23 cfu/cm2) (Table 1). In particular, the gloves and sleeves of overalls were highly contaminated with aerobic bacteria (22 and 25 cfu/cm2, respectively). Tools and environmental samples clearly carried fewer aerobic bacteria (average 5 and 8 cfu/cm2,

3.3.2. Acquisition of equipment New equipment investment in the plants (n D 33) is on average 2.1% of the annual turnover with a standard

Table 1 Microbial results of samples taken from maintenance personnel and their clothes, tools and work environment Samples

Aerobic total bacteria

Listeria spp.

L. monocytogenes

Std. dev. (cfu/cm2)

No. of positive samples/ no. of samples

No. of positive samples/ no. of samples

7 7 2 5

7 11 1 6

0/13 1/8 0/5 0/13

0/13 1/8 0/5 0/13

1–10 –

6

6

– 1/1

– 0/1

50

1–40

5

8

2/40

1/40

9 6 6 13 2

2–19 3–100 3–100 1–40 3–30

7 25 22 11 17

5 38 38 11 19

0/4 1/4 0/4 1/8 2/4

0/4 0/4 0/4 0/8 0/4

No. of samples

Range (cfu/cm2)

12 13 5 18

2–25 1–40 1–4 1–25

2 0

Total Personnel Hands Gloves Sleeves of overalls Knees of overalls Soles Total

Tools Tongs Screwdrivers Hexagon spanners Adjustable and open ended spanners Hammer Pneumatic machine

Average (cfu/cm2)

36

1–100

14

23

4/24

0/24

Environment Tables Grindstone Dish washer for tools Tap Tool bag

6 1 0 1 1

3–10 20 – 7 4

6 20 – 7 4

2 – – – –

0/4 0/1 0/1 0/1 –

0/4 0/1 0/1 0/1 –

Total

9

3–20

8

5

0/7

0/7

The samples were taken with PetriWlm™ plates for aerobic bacteria and with gauze pads for Listeria sampling.

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K. Aarnisalo et al. / Food Control 17 (2006) 1001–1011 reliability of manufacturer/ importer 7%

other 2%

availability of spare parts 8%

operational reliability 34%

availability of maintenance 8%

economical efficiency of use 10%

cleanability 11%

cost 20%

Fig. 3. Factors aVecting equipment investment (n D 38).

deviation of 2.4%. The respondents were asked what factors aVect the acquisition decision (Fig. 3). Operational reliability (34%) was clearly the most important factor aVecting this decision, followed by costs (20%) and cleanability (11%). The respondents were asked to identify the 10 countries from which they buy most of the equipment. As some (15.9%) of the respondents (n D 44) did not put them in order, the results were calculated according to how many times the countries were mentioned. According to the results, the equipment in the Finnish plants is mainly from Germany (84.1%), Finland (77.3%), Denmark (29.5%), Holland (27.3%) and Sweden (22.7%). Of the respondents, 2.3% had bought none of the equipment from outside Finland, 11.4% had bought 1–20%, 6.8% had bought 21–40%, 25% had bought 41– 60%, 34.1% had bought 61–80%, 18.2% had bought 81– 99% and none had bought all of the equipment from outside Finland. There was self-made equipment in use in 45.2% of the plants (n D 42). It can be concluded that self-made and domestic equipment were also considered more hygienic than equipment bought from outside Finland (Fig. 4a). 3.3.3. Most problematic equipment The respondents were asked to name the Wve most problematic pieces of equipment hygienically in their plants and also to put them in order. As some (18.2%) respondents did not put them in order, the results were calculated according to how many times the equipment was mentioned. The respondents were given 39 equipment names with the possibility of naming some other equipment seen as non-hygienic in their own process. Altogether 61 types of equipment were listed at least once. Packaging machines, conveyers, dispensers, slicing machines and cooling machines were considered the most problematic equipment. Table 2 shows diVerences between the food areas studied. Of those respondents, who put the equipment in order, the packaging machines were listed by 16.7% as the most problematic and conveyers by 13.9% (n D 36). The main reason for these pieces

of equipment being considered the most problematic was poor construction (Table 3). In an open question the respondents were asked to list the functions that would improve the cleanability of equipment according to their own wishes concerning process hygiene (results not shown). Thirty respondents answered this question. The main conclusion is that the equipment should be easy to dismantle and clean, and simpler constructions should be used. The materials should also tolerate strong cleaning and disinfecting agents as well as heat. Furthermore, it should also be possible to use water in cleaning the equipment. Coverings should be easy to open for cleaning. According to 41.9% and 27.9% of respondents (n D 43), their opinions have had a positive eVect on the equipment design of Finnish and foreign manufacturers, respectively. 3.3.4. Cleaning of equipment The cleaning of equipment was performed by the plants’ own personnel (56.8%), by outsourcing (29.6%) and by both groups (13.6%) (n D 44). According to 43.2% of respondents, the manufacturers have given instructions on how to clean the equipment and according to 40.9% part of the manufacturers have. When instructions were available, most (76.7%) followed them (n D 43). However, 58.1% of respondents found the instructions inadequate. Most (70.5%) of the respondents (n D 44) were given enough information about cleaning agents and disinfectants from the cleaning agent manufacturers. 3.3.5. Information Xow Food personnel cooperate closely with cleaning agent and disinfectant manufacturers and also with cleaning personnel. However, only 15% of the respondents found that the cooperation between food-processing personnel and cleaning personnel works well (Fig. 4b). Cooperation between food-processing personnel and equipment manufacturers was considered inadequate. It was also asked why the cooperation and information Xow did not work. Many (38.1%) of respondents (n D 21) answered e.g. that equipment manufacturers are not interested in or do not understand hygienic aspects or, especially after concluding the contract, do not bother about the cleaning aspects of equipment (results not shown). According to the answers, the best information to questions about equipment hygiene were obtained from cleaning agent manufacturers (78.0%), equipment manufacturers (53.7%) and cleaning companies (48.8%). Information channels such as importers, seminars, other representatives of food companies, literature, the internet and equipment hygiene organisations were of minor importance. In the case of the last-mentioned, most (68.3%) of the respondents (n D 41) did not know what equipment hygiene organisations do (EHEDG, 3-A, NSF International). Only 29.3% had heard about one or

K. Aarnisalo et al. / Food Control 17 (2006) 1001–1011

1007

a Equipment from outside Finland

5

Finnish equipment

42

15

Self-made equipment (n=23)

32

22

37

22

7

17

10

22

30

15

26

0

0

b Food personnel Cleaning personnel

Food personnelEquipment manufacturers

15

2

Food personnel Maintenance personnel

7

49

22

0

29

40

5

12

27

39

20

20

27

39

27

Food personnelCleaningand disinfectant manufacturers

5

12

49

60

5

10 0

80

100

%

good or excellent

satisfactory

passable

poor

cannot say/ no answer

Fig. 4. (a) Respondents’ attitudes towards the hygiene of Finnish and foreign equipment as well as self-made equipment (n D 41). (b) Respondent attitudes towards cooperation and Xow of information on equipment hygiene between food-processors, cleaning personnel, maintenance personnel and cleaning agent and disinfectant manufacturers (n D 44).

more of these organisations, and only one (2.4%) participated in the activities of one or more of these organisations. 3.3.6. Hygiene of lubricants Of the respondents, 95.5% (42/44) gave some information on the use of lubricants in their equipment. On the question about hygiene problems with lubricants, 21.4% of the respondents (n D 42) had noticed some problems and 61.9% had not. A multiple choice question showed that the respondents (n D 11) recognised the cause of hygiene problems in lubricants to be: lubricants collecting a lot of soil (72.7%); traces of lubricants are left on production surfaces during maintenance work (63.6%); inability to clean surfaces of lubricant residues (54.5%);

and a lot of microorganisms being found in the samples taken from sites containing lubricants (36.4%). The respondents were allowed to list more than one reason in replying to the above-mentioned issue.

4. Discussion Many papers have been published concerning unsatisfactory hygienic practices of food-handlers (Haupt, Köfer, & Fuchs, 1999; Henroid & Sneed, 2004; Uppman & Reuter, 1998) and outbreaks caused by them (Duncanson, Wareing, & Jones, 2003; Kishimoto et al., 2004; LaPorte et al., 2003). According to our knowledge, this is the Wrst reported study dealing with hygienic working

1008

K. Aarnisalo et al. / Food Control 17 (2006) 1001–1011

Table 2 The most problematic equipment hygienically in diVerent food industry sectors (n D number of respondents) Most problematic equipmenta

All (n D 44)

Meat and poultry (n D 14)

Bakery (n D 11)

Fish (n D 8)

Dairy (n D 6)

Other (n D 5)

Packaging machines Conveyors Dispensing equipment Slicing machines Cooling equipment Proving drawers Brining equipment Pasteurising equipment Macerating equipment Mixers and blenders Cutters Cold stores Heat exchangers Pulping machine Ovens Bagging machines Pumps Filleting machines Dicing machines Filling machines Shredders Grinders

20 17 15 15 9 6 5 5 5 5 4 4 4 4 4 4 4 3 3 3 3 3

7 7 4 9 6 – 3 – 5 1 3 1 1 2 1 1 1 – 2 1 2 3

4 6 8 3 2 6 – 1 – 1 – – – 1 3 3 – – – 1 1 –

5 1 2 3 – – 2 – – 1 1 1 – – – – – 3 1 – – –

3 3 1 – 1 – – 4 – – – 2 3 1 – – 2 – – – – –

1 –b – – – – – – – 2 – – – – – – – – – 1 – –

a b

The equipment listed was mentioned at least three times by the respondents. No answers.

Table 3 Number of responses to reasons why equipment is diYcult to clean Reason

Packaging machines

Conveyers

Dispensing equipment

Slicing machines

Poor construction (all sites cannot be cleaned or are diYcult to clean) Poor surface materials or surfaces (e.g. roughness) Poor placement in production area Other a,b,c,d,e

15

13

11

11

7

4 – 2d

1 3 2e

5 – 5a

6 6 4b

3 2 2c

Cooling equipment

Respondents were allowed to list more than one reason. a A lot of components which do not tolerate water (n D 3), open equipment, old equipment with special problems. b Open equipment, Xat-top conveyors with special problems, inner parts of belts and gaps diYcult to clean, belts hard to loosen, lots of constructions diYcult to clean. c DiYcult to dismantle for cleaning. d A lot of narrow belts. e Joints and piping which are badly cleaned in CIP cleaning.

practices of maintenance personnel in the food industry. The maintenance personnel in food plants have to move between the production and non-production areas and touch food contact surfaces frequently. While they were conscious of this and they knew which surfaces come in contact with food, only about half of them reported to use gloves when working in food production area and even less washed their hands in situations where they should in order to work hygienically. One reason for not wearing the gloves was probably that they may hinder the performance of some work tasks. In situations like this the washing of hands should be highlighted. This study also showed that some of the maintenance personnel did not know where they could Wnd the hygiene rules. It is most important that the rules are available for all.

They must also be clear and planned especially paying attention to the maintenance personnel and their work. About 40% of the maintenance personnel and food managers found that there were too few persons working on maintenance in the plant. However, the majority of both maintenance personnel and food managers considered both the resources for cleaning the tools and also the number of sets of protective clothing suYcient. The amount of bacteria on maintenance personnel and their clothes and tools, was, on average high. According to the manufacturer of the Hygicult-TPC® contact agar method (Orion Diagnostica, Espoo, Finland), less than 5 cfu/cm2 of aerobic bacteria is considered an acceptable amount for cleaned surfaces in contact with food, which was also concluded by

K. Aarnisalo et al. / Food Control 17 (2006) 1001–1011

Rahkio and Korkeala (1997). The surfaces investigated in this study were, however, not directly in contact with food. The microbial samples showed that the maintenance personnel carried larger amounts of total aerobic bacteria compared to the work environment or tools. This result may reXect the true situation although it can also partly be caused due to the problems of using PetriWlm™ Count Plates for varying forms of tools. The result points out the need for regular and suYcient change period of the protective clothing and the need to change the clothes whenever they get dirty. In this study, tools were not shown to be of special importance in contamination but it is possible that they transfer contaminants within the process area; L. monocytogenes was sampled from one screwdriver and another Listeria spp. from a pneumatic machine in common use. Tools should also be cleaned and disinfected regularly with eVective agents. The questionnaire showed that the person in charge of cleaning the tools in common use was often missing. Also during the study it was noticed, that the responsibilities, who should clean the equipment after work of maintenance personnel, was not always deWned. All responsibilities in hygiene rules in a company must be clear. In general, the observations made during the follow-up studies largely supported the results of the questionnaire. During the study, many of the maintenance personnel reported that according to their opinion they had not received enough information about hygiene commensurate to performing their work. The situation has likely improved after the beginning of 2002, when for Finnish food personnel handling easily spoiling food products, it became mandatory to pass a test about food hygiene, the so called ‘hygiene passport’ (Anonymous, 2001). A number of maintenance personnel have also accomplished this test to strengthen their knowledge and fulWl the demands of food-processing companies. The requirement for suYcient hygiene knowledge of especially this personnel group should also be stated in legislation and studies about food hygiene should be obligatory in their basic education. The respondents to the equipment hygiene questionnaire rated equipment hygiene the third-most important factor after operational reliability and costs aVecting their investment decisions. In the Finnish food industry, equipment is mainly bought from outside Finland, especially from Germany; However, a large number also came from Finland. One of the advantages of buying the equipment in Finland is that the respondents found they could have a bigger inXuence on the hygienic design of domestic equipment manufacturers than when buying from foreign countries. This is probably due to easier communication. In almost half the plants self-made tailored equipment is also used and that leaves a lot of responsibility for hygienic design with the companies themselves.

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Although packaging machines and conveyers were found to be the most problematic equipment in this study, it also showed that hygiene problems in each company are individual; altogether 61 diVerent pieces of equipment were mentioned. However, a common cause of the hygiene problems in the most problematic pieces of equipment was poor hygienic design. If the design is poor, more frequent and longer cleaning and aggressive chemicals are needed (Lelieveld, Mostert, & Curiel, 2003), and even this may not guarantee hygienic and safe food production. Especially in the case of conveyers, bad placement in the production area was found to be one of the important factors for poor equipment hygiene. This is understandable while the conveyers move products in the plant and usually occupy a large area and, therefore, can transmit contamination (Cotton & White, 1992). Packaging machines have also been found to be a source of contamination (Miettinen et al., 1999; Tompkin, 2002). Packaging is the last step before the product is transported to retailers and to consumers, and the shelflife of a product depends to a great extent on proper packaging. A common problem with packaging machines is that they often do not tolerate water because of electronic circuits, which makes the cleaning and disinfection procedures very diYcult. An important factor mentioned in the questionnaire, was that the equipment should be easy to open and dismantle. Equipment is often complex and, therefore, diYcult to clean, as it requires laborious dismantling. Once cleaned, it should also be easy to reassemble. The construction should be as simple as possible, but take into account technical and occupational safety aspects. If, due to these factors, cleaning the equipment is diYcult, this should be noticed and the best possible solution for improving cleanability should be established immediately (Lelieveld et al., 2003). Hygiene should be included in the equipment design at the beginning of the design process (Holah & Timperley, 1999). Methods for assessing the cleanability of constructions that are in the equipment development phase should be further developed and also be used more. The EHEDG has published guidelines and methods for assessing the cleanability of closed processing equipment (Anonymous, 1992, 1993a). Lubricants were used in equipment at all the respondent plants and some of the respondents had noticed hygiene problems in using them. Some earlier studies also showed the ability of lubricants to support the growth of microorganisms (Hamilton, 1991; Ortiz, Guiamet, & Videla, 1990; Rossmoore, 1988; Van der Waa, 1995). Information on questions about equipment hygiene should Xow easily between the diVerent parties concerned and, according to the results, this should be improved, especially with equipment manufacturers. A majority of respondents found the cleaning instructions given by equipment manufacturers inadequate, but

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when the instructions were available, many food processors rely on them. The manufacturers are obliged to give instructions for cleaning the equipment in the EU Machine Directive (Anonymous, 1989). This Directive does not specify, what kind of instructions they should give and it may be that many of the manufacturers do not have enough knowledge of cleaning to give suYcient information to the client. They should be made in cooperation with cleaning specialists. The response rates obtained from the both questionnaires are comparable with the rates of other questionnaires regarding food safety/hygiene matters sent to food industry. The response rates of recent postal surveys sent to food industry employees have not exceeded 35% (Hielm, Tuominen, Aarnisalo, Raaska, & Maijala, in press). In case of questionnaire about maintenance hygiene, the results from non-respondent plants could have aVected the results more negatively due to the fact that hygiene issues may not be taken care of actively in these factories. In conclusion, maintenance personnel are a potential source of contamination of food products due to the nature of their work. They should have enough training concerning hygiene matters to be able to act and work commensurate with this. Their impact on product safety should be studied further. The results also showed that hygiene problems with food-processing equipment are mainly caused by poor hygienic design and equipment designers should perform better in this area. Acknowledgements The authors are grateful to the participating companies and employees. Dr. Tiina Autio is acknowledged for commenting on the questions in the equipment hygiene questionnaire and colleagues assisting in collecting the results and in the implementation of the hygiene surveys are also acknowledged. The research was Wnanced by the National Technology Agency of Finland (Tekes) and research and industrial partners participating in the two projects on Equipment Hygiene in Food Industry and on Food Industry, Safety and Hygiene Management coordinated by VTT Biotechnology.

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