1. Materials of the machine parts in contact with food
The materials of the parts in contact with food should be guaranteed not to release toxic substances or toxins due to machine’s operation or contact with food, or due to external corrosion. Generally stainless steel is suggested.
Stainless steel: AISI-304, 18% Cr / 10% Ni,
Stainless steel: AISI-304L (DIN 1.4307; EN X2CrNi18-9)
2. Machine surface treatment
Machine surface treatment mustn’t use toxic substance: asbestos, dyes or paints with lead content.
3. Macromolecule or polymer substances should possess the following properties:
Able to withstand the food’s own properties and the acid-base substances released by the food itself;
Able to withstand the corrosion of the detergents;
Able to withstand the high and low temperatures during food processing;
Able to withstand steam (CIP/SIP);
Water resisting;
The surface should be smooth so that the cleaning is convenient. It’s suggested that the surface shouldn’t have many grooves which may be dead corners for cleaning;
Residual material absorption and cleaning;
Leaching treatment
Good elasticity and roughness;
Low temperature resisting;
Wear resisting.
4. Suggested polymer substances:
Acetals
Fluorine-containing substances
Ethylene-tetra-fluoro-ethylene (ETFE)
Polyfluoroalkoxy (PFA)
Polytetrafluoroethene (PTFE)
Polyvinylidene fluoride (PVDF)
Fluorinated ethylene propylene (FEP)
Polycarbonate (PC)
Polyetheretherketone (PEEK)
Polyethersulfone (PESU)
High Density Polyethylene (HDPE)
Polyphenylsulphone (PPSU)
Polypropylene (PP)
Polysulfone (PSU)
Polyvinyl chloride polymer (PVC)
Only PTFE is not proper due to its poriferous feature; however, after fluorine-containing treatment, it can conform to laws and regulations after inspections.
Other substances, like glass, steel, magnet, enamel, coating glaze, etc, should be checked and confirmed for their compatibility with relevant food materials.
1. Rubber substance
Washer:
Ethylene propylene diene monomer (EPDM) *
Fluorinated Hydrocarbon rubber (FKM)**, high temperature resisting: 180℃
Hydrogenated butadiene-acrylonitrile rubber (HNBR)
Natural rubber (NR)
Hydrorubber (NBR)
Silicone rubber (VMQ) **, high temperature resisting: 180℃
Full fluorine ether rubber (FFKM)***, high temperature resisting: 300℃.
2. Tags: in line with general norms; the tags should adhere to packages strongly.
3. Lubricants: lubricants shouldn’t be in direct contact with foodstuff.
4. Heat insulation device:
Heat insulation devices shoudn’t have chlorides.
5. Liquids with signal transmisson function:
Some liquids possess signal transmision function; these liquids must be edible foodstuff.
6. Machine surface treatment and contact surface in contact with food
Machine surfaces shouldn’t cotain or release toxic substances, or absorb toxic substances due to friction and being soaked in liquids.
Machine surfaces shouldn’t have seams; especially for germ-free processing, metals of different materials are not recommended for welding.
Height differences on the surface are not suggested.. The whole surface should be flat, avoiding dead corners and resulting bacteria reproduction.
Grooves should be avoided.
90°verticality should be avoided. 6°chamfer is suggested for corners. In any cases, the chamfer shouldn’t be lower than 3°.
All the surfaces in contact with food must be open type, so that the clean degree can be easily inspected.
7. Surface smoothness:
Generally speaking, the surface smoothness of cold forged steel sheet is Ra = 0,2 a 0,5 μm; further polishing is not required.
It’s suggested that the smoothness shouldn’t be higher than Ra >0,8 μm.
8. CE norms
All electric fittings should have CE certificate;
Wire colors in the power distribution cabinets should be arranged according to the color schemes stipulated in CE standard;
Wire numbers should be marked apparently;
Safety concern: Emergency power off system should be provided.
Safety rails for operations and emergency power off system.