f o o d-inf o .net http://www.food-info .net/uk/eng/docs/doc8.htm

Food-Info.net : Hygienic Equipment Design Criteria

An

init iat ive of :

WageningenUniversity

Van Hall-Larenstein

Food-Inf o.net> Topics > Food Engineering > HygienicEngineering >

Hygienic Equipment Design Criteria(Published as EHEDG Document 8, April 2004)Table of Contents

1. IntroductionThis document describes the criteria f or the hygienic design ofequipment intended f or the processing of f oods. Itsf undamental objective is the prevention of the microbialcontamination of f ood products. Such contamination may, ofcourse, originate f rom the raw materials, but the product mayalso be contaminated with micro-organisms during processingand packaging. If equipment is of poor hygienic design, it will bedif f icult to clean. Residues (soil) may be retained in crevices anddead areas, allowing the micro-organisms which they harbour tosurvive and multiply. These may then cross-contaminatesubsequent batches of product.Although a primary objective of design remains that theequipment is able to f ulf il its engineering f unction, sometimesthe requirements of hygiene will conf lict with this. In seeking anacceptable compromise it is imperative that f ood saf ety is neverput at risk.Upgrading an existing design to meet hygiene requirements canbe prohibit ively expensive and may be unsuccessf ul and sothese are most ef f ectively incorporated into the init ial designstage. The long-term benef its of doing so are not only productsaf ety but also the potential to increase the lif e expectancy ofequipment, reduce maintenance and consequently loweroperating costs.This document was f irst published in 1993 with the intention todescribe in more detail the hygienic requirements of theMachinery Directive (89/392/EEC superseded by 98/37/EC; ref. 1). Af terwards parts of it have been included in the standards EN1672-2 and EN ISO 14159.

2. Objective and ScopeThis document details the principal hygienic design criteria to bemet by equipment f or the processing of f oods. It givesguidelines on how to design, construct and install suchequipment so that it does not adversely af f ect f ood quality;especially saf ety. The guidelines apply to durable equipmentused f or batch and continuous, open and closed manuf acturingoperations.The susceptibility of the product to microbial activity willdetermine the balance between normal engineering demandsand those of hygiene. For example, dry products do not supportthe growth of micro-organisms and requirements will be morerelaxed than f or moist products. However, if the equipment is tobe used f or products destined f or 'at-risk' consumer groups,the hygiene demands on design will be more stringent. Here thedesigner may need to consult appropriate authorit ies such thatthe right balance is achieved.

European MastersDegree in FoodStudies - anEducationalJourney

3. Normative referencesThe f ollowing documents contain provisions that, throughref erence, constitute provisions of this EHEDG Guideline. Atthe time this Guideline was prepared, the edit ions listed belowwere valid. All documents are subject to revision, and parties areencouraged to investigate the possibility of applying the mostrecent edit ions of the documents indicated below.

EN 1672-2:1997 Food processing machinery Basicconcepts Part 2: Hygienic RequirementsEN ISO 14159:2002 (E) Saf ety of machinery Hygienerequirements f or the design of machinery

4. Def initionsThe def init ions in the Hygienic Design Glossary apply to thisguideline. The most relevant def init ions specif ic to hygienicequipment design are:

Product contact surface All equipment surf aces that intentionally orunintentionally (e.g. due to splashing) come in contactwith the product, or f rom which product or condensatemay drain, drop or be drawn back into the main product orproduct container, including surf aces (e.g. unsterilisedpackaging) that may indirectly cross-contaminate productcontact surf aces or containers. A risk analysis can helpto def ine areas of cross contamination.Non-product contact surfaceAll other exposed surf aces.Non-toxic construction materials Materials which, under the conditions of intended use, donot release toxic substances.Non-absorbent materials Materials which, under the conditions of intended use, donot internally retain substances with which they come intocontact.Conditions of intended use (for the equipment) All normal or reasonably anticipated operating conditions,including those of cleaning. These should set limits f orvariables such as time, temperature and concentration.

5. Materials of constructionMaterials used in the construction of f ood machinery must f ulf ilcertain specif ic requirements. Product-contact materials mustbe inert both to the product and to detergents anddisinf ectants under the conditions of intended use. They mustalso be corrosion resistant, non-toxic, mechanically stable, andtheir surf ace f inish must not be adversely af f ected under theconditions of intended use. Non-product-contact materials shallbe mechanically stable, smoothly f inished and easily cleanable.It is worthwhile maintaining an awareness of new developmentsin materials and products f or the f ood industry and seeking theadvice of materials suppliers where appropriate.

5.1 Non-toxicity5.2 Stainless steel5.3 Polymeric materials5.4 Elastomers5.5 Adhesives5.6 Lubricants5.7 Thermal insulation materials5.8 Signal transfer liquids

5.1 Non-toxicityAs the presence of toxic elements in the f ood is unacceptable,the designer has to take care that only non-toxic materials ofconstruction are used in direct contact with the product. It isimperative to check legislative aspects many countries havecodes of practice and directives covering the composition ofmaterials in contact with f oodstuf f s and it should be ensured

that the use of a specif ic material is permitted under existing orpending legislation (ref. 2) .Stainless steels are the logical choice f or materials ofconstruction f or process plant in the f ood industry but,depending on the application, some polymeric materials mayhave advantages over stainless steel such as lower cost andweight or better chemical resistance. However, their non-toxicity, and those of materials such as elastomers, lubricants,adhesives and signal transf er liquids, must be assured.

5.2 Stainless steelGenerally stainless steels of f er excellent corrosion protection,and they are theref ore widely used in the f ood industry. Therange of stainless steels available is extensive and theselection of the most appropriate grade will depend on thecorrosive properties (in terms not only of the chemical ionsinvolved but also the pH and the temperature) of the processand of the cleaning and antimicrobial chemicals. However, thechoice will also be inf luenced by the stresses to which the steelwill be subjected and its machinability, f ormability, weldability,hardness and cost.Where good resistance to general atmospheric corrosion isrequired, but the conditions of intended use will involve onlysolutions with a pH of between about 65 and 8, low levels ofchlorides (say, up to 50mg/l [ppm]) and low temperatures (say,up to 25C), the most common choice would be AISI-304, anaustenitic 18%Cr/10%Ni stainless steel, or its low-carbonversion AISI-304L (DIN 1.4307; EN X2CrNi18-9), which is moreeasily welded.If both the level of chlorides and the temperature exceedapproximately double these values, the material will requiregreater resistance to the crevice- and pitt ing-corrosion whichmay result f rom chlorides concentrating locally. The addition ofmolybdenum to AISI-304 (creating AISI-316) improves itscorrosion-resistance and this grade of stainless steel isrecommended f or components such as valves, pump casings,rotors and shaf ts, while its low-carbon equivalent AISI-316L(DIN 1.4435; EN X2CrNiMo18-14-3) is recommended f orpipework and vessels due to its enhanced weldability.Alternatively, t itanium may be appropriate.As temperatures approach 150C, even AISI-316 stainlesssteels may suf f er f rom stress-corrosion cracking whereregions of high stress are exposed to high levels of chloride.Here AISI-410, AISI-409, AISI-329, or even Incoloy 825 (ref. 3)may be required f or their high strength and/or high corrosionresistance, although they may be more costly.AISI, DIN and EN designations of stainless steels commonlyused in the f ood industry are given in Table 1.

Table 1. AISI, DIN and EN designations of stainlesssteels commonly used in the food industry

AISI DIN/EN Typical analyses

C% Cr% Ni% Mo% Ti% N%

304L eg: DIN 1.4307(EN X2CrNi18-9)

Home

Topics

Questions and Answers

Food Products

E-numbers

About Food-Inf o

Contact

Links

Food Components

Food Allergies

Food Saf ety

Food Hygiene

Functional f oods

Food Engineering

Food Ingredientlist/Glossary

Food Colours

Carbohydrates

Minerals

Proteins

Vitamins

Natural colours

Anthocyanins

Beetroot colour

Carotenoids

Chlorophyll

Cochineal

Curcumin

Synthetic colours

Azo dyes

Browning

Caramelization

Maillard reactions

Enzymatic browning

Starch

Fructans

Amino Acids

Structure

Biological Value

Milk Proteins

Introduction

Lactose intolerance

Fructose intolerance

Gluten and wheat

Tree nut allergies

Shellf ish allergies

Soy allergy

Egg allergy

Mustard allergy

MSG (E 621)

Allergy dictionaries

Bacteria

Food-borne toxins

Viruses

Heavy metals

Golden rules of WHO

Hygienic Design Glossary

EHEDG Guidelines

Hygienic Equipment Design Criteria

Introduction

Examples

Probiotics

Prebiotics

Food Hygiene

Hygienic Design Glossary

EHEDG Guidelines

Hygienic Equipment Design Criteria

Allergies and intolerances

Biotechnology

Food ingredients

Food products

Food saf ety

Nutrit ion

Food Packaging

Miscellaneous

Additives (general)

Acidity regulators

Anti-oxidants

Aroma

Colours

Emulsif iers

Enzymes

Fats and oils

Flavour enhancers

Minerals

Preservatives

Proteins

Sugar and Sweeteners

Thickening agents

Vitamins

Beer

Bread and bakery products

Chocolate

Cof f ee

Conf ectionery

Dairy products

Drinks

Eggs

Fish and Shellf ish

Fruits and Vegetables

Herbs and Spices

Legumes and beans

Meat

Nuts and peanuts

Pasta and pizza products

Potato products

Salt

Tea

Water

Wine

Other products

Food Saf ety (general)

GMOs

Bacteria (general)

Salmonella

Listeria

E.coli

Ent.sakazakii

Viruses

Avian inf luenza

Fungi and moulds

Mycotoxins

Toxins (other)

Nitrates

BSE

Cof f ee

Dairy products

Fish

Olive oil

Pasta

Roots and tubers

Spices and herbs

Sugar

Sweets and conf ectionary

Tea

Wine

Edible Insects

Introduction

History

The cof f ee plant

Cof f ee production

Cof f ee producing regions

Decaf eination

Cof f ee chemistry

Cof f ee aroma descriptors

Cof f ee drinks

Caf f eine

Aroma

Kahweol and caf estol

Acid compounds

Production of cheese

Overview of cheeses

Introduction

History of pasta

Pasta shapes

Pasta production

Cassava

Cocoyam

Sweet Potato

Yam

Introduction

History

Sources

Production

Chemistry

Types of sugar

Beet sugar

Cane sugar

Barf i

Liquorice

Marshmallows

Marzipan

Introduction

History

Cultivation

Production

Varieties

Grading

Introduction

History

Grapes

Production of wine

Ageing of wine

Sparkling wines

Fortif ied wines

Fruit wines

Flavoured wines

Introduction

Classes of edible insects

E-numbers f rom animal origin

Which E-numbers are halal ?

E100-E200

E200-E300

E300-E400

E400-E500

E500-E600

E600-E700

E700-E800

E900-E1000

E1000-E1300

E1400-E1500

E1500-E1525

Alphabetical list

Question about E-numbers ?

Organisation

Team

New

Poster

Awards

Activit ies

Sitemap

Ask your question

Contact

Links United Kingdom

Links Ireland

Links United States

Links Canada

Links Australia

Links New Zealand

Links Other Countries

International Organisations

Food Companies

Alcoholic drinks

Beer

Chocolate

Cof f ee

Dairy Products

Flavours

Multinationals

Nuts

Wine

Food-Info.net : Hygienic Equipment Design CriteriaEuropean Masters Degree in Food Studies - an Educational Journey

Hygienic Equipment Design CriteriaAn initiative of :1. IntroductionWageningen UniversityVan Hall-Larenstein

2. Objective and Scope3. Normative references4. Definitions5. Materials of construction5.1 Non-toxicity5.2 Stainless steel5.3 Polymeric materials5.4 Elastomers5.5 Adhesives5.6 Lubricants5.7 Thermal insulation materials5.8 Signal transfer liquids

6. Functional requirements6.1 Cleanability and decontamination6.2 Prevention of ingress of micro-organisms6.3 Prevention of growth of micro-organisms6.4 Compatibility with other requirements6.5 Validation of the hygienic design of equipment

7 Hygienic design and construction7.1 Surfaces and geometry7.2 Surface finish / surface roughness7.3 Drainability and lay-out7.4 Installation7.5 Welding7.6 Supports7.7 Insulation7.8 Testing the hygienic characteristics of equipment

8. References9. AuthorsLast Update: Monday 13 May, 2013