(SG Heat Treatment, 1994)  Thermal sterilisation is a process aimed at eliminating the risk of food poisoning and, when used in conjunction with aseptic filling, it aims to extend product storage life under ambient conditions.  This is achieved by the destruction of vegetative micro-organisms and relevant bacterial spores.  Earlier papers presented guidelines on continuous pasteurisation (Doc 1) and sterilisation (Doc 6) of liquid products without particles.  

This paper presents guidelines on the design of continuous and semi-continuous plants for the heat treatment of particulate foods.  Liquid foods containing particulates are inherently more difficult to process than homogenous liquids due to heat transfer limitations in particulate-liquid mixtures and the additional problems of transport and handling.

Although this document concentrates on sterilisation processes, the principles are consistent with other heat treatment processes.  Ohmic heating techniques are not covered.

SG Design Principles, 1996)  For food processing, it is important that the plant design takes into account factors affecting the hygienic operation and cleanability of the plant.  (See also previous guidelines on hygienic design criteria Doc 8, hygienic welding Doc 9, and the hygienic design of equipment for closed processing Doc 10.)

The risk of contamination of food products with relevant micro-organisms during open processing increases with the opportunity to grow in poorly designed equipment, as well as with the concentration of the micro-organisms in the environment.  This means that in open plants, environmental conditions, in addition to appropriate equipment design, have an important influence on hygienic operation.  Furthermore, the type of product and the stage of the manufacturing process must be taken into consideration.  Open processes incorporate many different types of equipment, including machines for the preparation of dairy products, alcoholic and non-alcoholic drinks, sweet oils, coffee products, cereals, vegetables, fruit, bakery products, meat and fish.

This paper deals with the principal hygienic requirements for equipment for open processing.  It describes methods of construction and fabrication, giving examples as to how the principal criteria can be met in open process equipment.

(SG Valves, 1996)  Valves are essential components of all food processing plants, and the quality of the valves used strongly influences the microbiological safety of the food production process.  Valves for food contact use must therefore comply with strict hygienic requirements

This paper discusses the basic requirements for hygienic and aseptic valves.  The guidelines apply to all valves used in contact with food or food constituents that are to be processed hygienically or aseptically.  Aside from general requirements with regard to materials, drainability, microbial impermeability and other aspects, additional requirements for specific valve types are also described. (See also Doc. 20 on double-seat mixproof valves.)

A method for the assessment of in-place cleanability of moderately-sized food processing equipment, 1997

(SG Test Methods, 1997)  A standard test procedure for assessing the in-place cleanability (i.e. suitability to be cleaned without dismantling) of relatively small equipment (such as pumps, valves and flowmeters) was earlier produced by this subgroup (ref Doc 2).

This document describes a test procedure for assessing the in-place cleanability of moderately sized equipment, such as homogenisers.  The degree of cleanliness is based on the removal of a fat spread soil, and is assessed by evaluating the amount of soil remaining after cleaning by visual inspection and swabbing of the surface.  This method is not as sensitive as the microbiological method described in Doc 2.

(SG Pipe Couplings, 1997)   This document identifies and defines critical design parameters for for pipe couplings which show the following characteristics : easily cleanable in-place; easily sterilisable  in place; impervious to micro-organisms, ease to install and reliable.  Its scope is limited to welded pipe couplings.

Gaskets of various types were tested for reliability and hygienic aspects using EHEDG cleanability test methods and repeated sterilisation. The objective was to provide a reliable dismountable joint which is bacteria-tight at the product side under the conditions of processing, cleaning and sanitation.

SG Pumps, edition 2, 2004) The objective of this guideline is to provide a set of minimum requirements for pumps, homogenisers and dampening devices for hygienic and aseptic applications, to ensure that food products are processed hygienically and safely.

Special demand is made on pumps, homogenisers and dampening devices used in the food processing and pharmaceutical industry with regard to CIP-capability, gentle product handling and ease of maintenance. In addition to this, pumps, homogenisers and dampening devices require good mechanical, hydraulic and thermal efficiency, a technically perfect construction and low-cost manufacture.

These requirements, their implementation and thereto related design principles are handled in detail in this guideline. The guideline applies to all pumps intended for use in food processing, including centrifugal pumps, piston pumps, lobe rotor pumps, peristaltic pumps, diaphragm pumps, water ring pumps, progressive cavity pumps, screw pumps, gear pumps and also to homogenisers, dampening devices and shall include any valves integral with the pump head and the complete homogeniser head.

Differences between the EHEDG Guidelines (Europe) and the 3A standards (USA) are indicated, where appropriate.

(EHEDG, 1998)  Passivation is an important surface treatment that helps assure the successful corrosion resistant performance of stainless steel used for product contact surfaces (eg tubing/piping, tanks and machined parts used in pumps, valves, homogenisers, de-aerators, process monitoring instruments, blenders, dryers, conveyors, etc).

The purpose of this document is to provide manufacturers, users and regulatory personnel with basic information and guidelines relative to equipment passivation.  The complete passivation process is described and environmental, as well as safety, concerns are discussed.

(SG Test Methods, 2000) Research over the last years has shown that the currently used hydrophobic membrane filters, with a pore size of 0.22祄, do not retain micro-organisms under all process conditions. Investigations have been conducted into risk assessment of sterilising hydrophobic membrane filters, evaluating the performance of the filters under a range of operating conditions.

To validate the  bacterial retention ability of sterilising grade hydrophobic membrane filters, a bacterial aerosol challenge test methodology was developed.

SG Valves, 2000) Today, food process plants incorporate various multifunctional flow paths. Often one piping system is cleaned while another still contains product. This simultaneous cleaning can potentially result in the dangerous situation where product and cleaning liquid are separated by just one single valve seat. Any cleaning liquid that leaks across such a seat will contaminate the product. Therefore, often two or three single seat valves in a "block-and-bleed" arrangement are applied.   Single-body double-seat butterfly valves are used as well, but these cannot be guaranteed to be mix-proof.  

This document describes the basic hygienic design and the safe use of single-body double-seat mixproof valves, that ensure that intermixing cannot take place.  Surge valves have been used in brewing, beverage,  food and milk plants in Europe for 20 years.

(SG Packing Machines, 2000)  This is the subgroup’s third guideline. The first two documents (Doc 3 and Doc 11) discuss how packing machines should be designed to comply with hygiene design criteria and thereby with the requirements specified in Annex 1 of the Machinery Directive1. Doc. 21 discusses how to determine whether those criteria are met. This requires validation of the design: measurement of essential parameters and testing to determine whether critical requirements are met.  This document gives proven methods for testing the performance of the various functions of packing machines.  The test methods may also be useful if the manufacturer wants to optimise or redesign a packing machine and if the food processor wants to compare various packing machines.

Upon delivery, a packing machine needs to be checked by a commissioning procedure to be agreed in advance between the food processor and the supplier of the machine. Commissionning may include physical tests as well as microbiological tests.   Additional tests are specified for commissioning of machines for aseptic packing,

1 Machinery Directive 98/37/EC – Annex 1, point 2.1, Agri-foodstuffs machinery

SG Dry Materials Handling, 2001)  In the food industry, many different types of dry materials are produced and handled.  Dry food processing and handling requires different types of equipment that are typically associated with wet and liquid products.

This is the first in a series of documents covering equipment design, installation and appropriate associated practices.  Such practices must take into account the possibility for material lump formation, creation of dust explosion conditions, high moisture deposit, formation in the presence of hot air, and material remaining in the equipment after shutdown.  Cleaning procedures are also specific to dry processes, dry cleaning being favoured to reduce risks of contamination. Such procedures are described.

SG Lubricants, 2002)  Lubricants, grease and oil are necessary components for the lubrication, heat transfer, power transmission and corrosion protection of machinery, machine parts, instruments and equipment.  Incidental contact between lubricants and food cannot always be fully excluded and may result in contamination of the food product.  This risk applies equally to food-grade lubricants and conventional lubricants. (The ISO Committee TC 199 recently recommended the use of the term "lubricants for incidental food contact" instead of “food-grade lubricants” to eliminate the notion that these lubricants are allowed in food.)

This guideline will assist lubricant manufacturers to understand better their responsibilities, based on the principles of GMP, by laying down the general requirements and recommendations for the hygienic manufacture and supply of food-grade lubricants.  The document also assists operators by explaining the hazards that may reasonably be expected to occur during the use of food-grade lubricants and the actions required to eliminate these hazards or to reduce their occurrence to acceptable levels.