Frozen foods are preserved by freezing and storing at temperatures cold enough to inhibit the growth of micro‐organisms and to retard chemical and physical reactions to a negligible rate. Quick‐frozen foodstuffs can be described as those foods that are subjected to the ‘quick‐freezing’ process, in which the temperature zone of maximum crystallisation is spanned as rapidly as possible and the product is then held (after thermal stabilisation) at a temperature of –18 °C or lower.1
45.1 Hazard analysis critical control point (HACCP) should be used as a management tool to develop a HACCP plan and associated food safety management system (FSMS) and quality management system (QMS). At critical control points (CCPs) and critical quality points (CQPs), critical limits and target levels and tolerances should be established so that a tendency towards a loss of control can be detected and rectified rather than waiting until a potentially unsafe product has been produced (see 45.12).
Personnel and Testing Facilities
45.2 Personnel engaged in management, production, quality control and maintenance should receive the necessary training and conform to the medical and hygiene requirements described in Chapter 17. Production should be supervised by appropriately qualified and skilled personnel. Facilities should be available for microbiological and quality testing.
45.3 Raw material specifications, acceptance and storage should be in accordance with the provisions stated in this Guide.
45.4 Raw materials should be selected for their ability to withstand freezing and thawing cycles, for example using specially modified starches to prevent syneresis.
45.5 Incoming high‐risk foods such as meat, poultry and fish should be subjected to microbiological testing. Such raw material should be temporarily quarantined until test results are available, that is, a positive release system must be in place.
45.6 Although microbial load may sometimes be reduced by freezing, this cannot justify the use of raw materials that have a high microbiological loading. Freezing does not destroy any microbial toxins that may have been formed, and does not eliminate the possibility of microbial problems at a later stage. Enzymes that have not been inactivated by treatment before freezing may continue to act after freezing with the associated reduction in product quality.
45.7 The freezing of food will not improve its quality. The flavours of some spices and other flavours can change quite drastically on freezing and subsequent storage. In products where enzyme systems are not fully inactivated, freeze concentration of enzymes and other substances can cause damage to texture and flavour. The sensory evaluation step of product development should be done after passing through one freeze/thaw cycle, with ultimate product life requirements being taken into account.
45.8 Preparation of raw material should be carried out in areas segregated from those concerned with cooked, blanched or finished product. Associated training programmes must underpin why such segregation is important for product safety and quality.
45.9 High‐risk raw material, for example poultry, meat or fish, should be prepared in rooms completely isolated from cooked or finished products by walls from floor to ceiling. There should be no interchange of staff or equipment between the areas. The preparation rooms should be maintained at a cool temperature and provided with air, filtered to remove micro‐organisms, at 8 °C under positive pressure.
45.10 For the production area and equipment, a ‘clean‐as‐you‐go’ regime should be instituted, debris and gross soiling being constantly removed, and each day a major strip‐down and cleaning and disinfection operation should be carried out according to a validated, documented cleaning schedule.
45.11 The only cryogenic media that should be used are air, nitrogen and carbon dioxide that meet purity criteria set by the European Commission.
45.12 CCPs should be established at points in the process where microbial proliferation could occur if suitable controls are not in place. All critical limits and target levels and tolerances at CCPs should be validated. Monitoring and verification programmes for these CCPs should be established and implemented by trained staff with the knowledge and skills required to ensure such actions are effective. Monitoring activities are those measurements and tests that are undertaken whereby if non‐conforming a process, material and/or product can be brought back under control within the production cycle, i.e. before it has left the manufacturing unit. All other forms of testing and measurement of a material, product or process are verification activities. Monitoring and verification of CCPs could involve:
- measurement of the temperature and residence time of a particular material at frequent intervals throughout the shift;
- assessment of the degree of build‐up of food debris or holding time of food material prior to or during processing, at frequent intervals throughout the shift;
- collection and microbiological testing of swabs or food samples at designated intervals during the production run. If the product is positively released on the basis of the sample results, this is monitoring; otherwise if a negative release system is in place, this is a verification activity.
- assessment to determine the presence of physical hazards in the product, for example metal detection, magnets, x‐ray or imaging equipment.
It is critical that as a result of an effective training programme production staff understand whether the assessment activities they are undertaking are monitoring or verification and the corrective action required in the instance of non‐conformance. Corrective and preventive action may involve holding and quarantining product on the manufacturing site as a result of a problem being identified via monitoring or the initiation of product withdrawal or recall in the event that a failure is identified as a result of verification activity. Timeliness of decision making is fundamental to effective good manufacturing practice (GMP) being demonstrated.
Results of monitoring and verification should be recorded, preferably as graphs or histograms, when considering process or product attributes, and then assessed for signs of trends. These results should form a basis for management review and internal audit programmes (see Chapter 11) so that preventive action, and if required corrective action, can be implemented to address potential weaknesses in the FSMS and QMS (see Chapter 28).
Hygiene audits should also be analysed for trends, especially if this includes further verification by swab analysis. From such records, the key performance indicator (KPI) or critical success factor (CSF) for a particular line can be established, and any adverse departure from these indicators must be countered by implementing corrective action to improve hygiene. It should be borne in mind that if the product has to be thawed before cooking by the end user, high mould and yeast levels within the food can be a special problem.
45.13 Products or ingredients that are heated or cooked during manufacture should be cooled as quickly as possible to below 8 °C. Throughout the preparation stage, every effort should be made to keep the food cool and to keep it progressing along the production line.
45.14 A quality plan should also be implemented to monitor raw material and product quality attributes at quality points and CQPs in the process with the associated monitoring and verification activities as identified above.
45.15 Storage conditions and controls are addressed in Chapter 26. Frozen storage must be adequately controlled to prevent excessive build‐up of ice on walls, floors and ceilings. Consideration should be given to personnel health and safety when working in these areas, including the provision of alarms if personnel can be locked inside the store.
45.16 Primary long‐term (3 months or more) stores should be maintained at or colder than −26 °C. Temperature fluctuations of more than ±2 °C should be avoided and the frequency of the variation kept to a minimum. The monitoring and continuous recording of storage air temperature using calibrated probes is essential. The number and location of temperature probes should be such as to ensure effective monitoring. Air temperatures in cold stores should also be manually checked and logged at least once every 24 hours. If conditions warmer than specified warning and action limits are identified, then the prescribed corrective action must be followed. Records should be maintained that detail any incident and the corrective action taken. Raw material and product temperatures should also be monitored to ensure that they remain within acceptable levels. Records should be retained of such activities. The temperature of raw materials and products should not be higher than −18 °C. If the products have a temperature above −18 °C, they should be quarantined, inspected, records maintained and appropriate action taken.
45.17 Rapid and well‐controlled freezing without delay after preparation is essential, at a rate appropriate to the specific product. Mechanical damage to the texture of cellular products can result from slow growth of large ice crystals.
45.18 Freezing equipment should be designed to give the minimum amount of product dehydration in order to prevent dehydration damage on the outer surface of the product.
45.19 Freezing should not be regarded as complete until a temperature of −18 °C has been reached at the thermal centre of the food. The degree of homogeneity of the food needs to be considered, especially if it is of a particulate nature of varying sizes. Freezer exit temperature should be such that the temperature of the products should not rise above −18 °C during subsequent packing and palletisation. Some products can suffer surface cracking with too rapid freezing, for example pastry products, and in this case freezing will be a compromise of the process to give maximum safety control and quality to the centre phase while keeping the outer phase intact.
45.20 Food packaging should comply with the general requirements stated in Chapter 24, and also include a water vapour barrier to prevent dehydration and weight loss during storage.
45.21 Packaged frozen foods must carry the storage instructions necessary to validate the stated indication of minimum durability that has been determined by the manufacturer.
45.22 Precautions should be taken to ensure that packing integrity is maintained during processing, storage or distribution to avoid risk of product contamination, product rejection or freezer burn, which is caused by product dehydration.
45.23 When packing in bulk for later repacking, sacks or palletainers should be labelled with production date, process details, and variety and production batch to facilitate identification at a later date. End‐user packs should be labelled with repack dates (coded if necessary) and duration dates. A record should be kept of materials that have been sent to individual repacking points so that end‐user packs can be traced back to the actual production records if required (see Chapter 14).
45.24 Primary long‐term (3 months or more) stores should be maintained at or colder than −26 °C. Temperature fluctuations of more than 2 °C should be avoided and the frequency of variation kept to a minimum. The monitoring and recording of storage unit air temperature using calibrated temperature probes is essential. The number and location of temperature probes should be such as to ensure effective monitoring. Air temperatures in cold stores should be manually checked by quality control personnel and logged at least once every 24 hours. Temperature warning and action limits should be specified and responsibilities for taking corrective action defined. Records should be maintained that detail any incident and the corrective action taken.
45.25 During delivery to the primary cold stores, products should not be exposed to direct sunlight, wind or rain; transfers should be carried out with the minimum of exposure to outside temperature conditions. Products incoming to the stores should not be warmer than −15 °C and should remain in the stores until their temperature has reached −23 °C or colder. Products leaving the stores should be protected as before from adverse weather or temperature conditions; as much as possible of the pre‐removal operation should be carried out in the cold store. To afford maximum protection to the products during unloading and loading refrigerated transport, it is advisable to fit the stores with a loading bay with suitable protection positioned so that the temperature‐controlled vehicle can be brought into direct contact with the store. The same principles should apply to retailers and caterers where there is a cold receipt area.
45.26 Secondary or distribution cold stores should be maintained at −23 °C or colder. Temperature probes that monitor storage temperatures should be so positioned as to ensure effective monitoring. To this end, it is important that the relationships between core and surface temperatures are understood and their implications within the distribution and storage system taken into account. An alarm system should be operational to warn of any breakdowns. All autographic recorders and temperature probes should be accurate to within 1 °C and ideally 0.5 °C, and be calibrated at predefined intervals in such a way as to give traceability back to a national standard. If an autographic system is not available, manual logs should be maintained.
45.27 Cyclic variation of temperature, whether above or below the recommended temperature, is undesirable as it accelerates dehydration even in hermetically sealed packs when it causes migration of moisture from product to form ‘snow’ inside the packaging.
45.28 Clearly defined procedures should be laid down to deal with wide temperature fluctuations or refrigeration breakdown. Should the air temperature rise to −12 °C, the cold store should be closed until the fault has been cleared and the correct store temperature restored. Products in the store during the period of breakdown should be checked by the quality control manager or designate and records maintained of the decision for product disposition and associated actions, including the removal of product to an alternative store.
45.29 Primary distribution vehicles should be designed so as to maintain the same temperature as the primary cold stores, and operated in such a way that the delivery temperature of the product is not higher than −18 °C. If the products have a delivery temperature above −15 °C, their quality should be checked, records maintained and appropriate action taken. Documented transport breakdown procedures should be in place that define the actions to be taken in the event of vehicle or refrigeration unit breakdown, and the records to be maintained that detail the incident and the corrective action taken.
45.30 Secondary distribution vehicles are those used for transporting products between secondary cold stores and point of sale. They should be designed and operated in such a way that the food can be delivered at −15 °C. If the product temperature is above −12 °C, the overall quality should be checked, records maintained and appropriate action taken. Documented transport breakdown procedures should be in place that define the actions to be taken in the event of vehicle or refrigeration unit breakdown, and the records to be maintained that detail the incident and the corrective action taken (see 32.17).
45.31 Temperature monitoring and recording in all distribution vehicles and holding centres should be such that relevant personnel are able to verify the temperatures of vehicles and cold stores. Further recommendations are therein given for the transport, handling, storage and display by the wholesaler and retailer, and it is to the producer’s ultimate advantage to encourage the observation of such recommendations (see Chapter 32).
45.32 Reference may also be made to the British Frozen Food Federation website for further guidance (http://www.bfff.co.uk) and to the Ice Cream (Heat Treatment, etc.) Regulations 1959, SI 1959 No. 734 as amended by SI 1962 No. 1287 and SI 1963 No. 1083, to the Quick‐frozen Foodstuffs Regulations 1990, SI 1990 No. 8136, as amended by SI 1994 No. 298 and the Quick Frozen Foodstuffs Regulations 2007, that are implemented in the UK, and the EU Directives on the approximation of the laws of the Member States relating to quick‐frozen foodstuffs for human consumption (89/108/EEC, 92/1EEC and 92/2/EEC as subsequently amended). Associated EC legislation includes (EC) No. 37/2005 of 12 January 2005 on the monitoring of temperatures in the means of transport, warehousing and storage of quick‐frozen foodstuffs intended for human consumption.
45.33 The Quick Frozen Foodstuffs Regulations 2007 (implementing EC 37/2005) and replacing the Quick Frozen Foodstuffs Regulations 1990 prohibit the placing on the market of a quick‐frozen foodstuff unless certain conditions are satisfied. Specific legislation for quick frozen foodstuffs (QFFs) does not apply to ice‐cream and edible ices. The regulations require that all temperature monitoring instruments used in the transport, warehousing and storage of QFFs must comply with European standards (EN12830, EN13485 and EN13486). All relevant organisations must keep documentation demonstrating that instruments meet relevant European standard(s). QFF produced by a manufacturer that is to be marketed in its packaging to the ultimate consumer or to a caterer must include on the label, in addition to normal labelling requirements:
- ‘quick frozen’;
- the date of minimum durability – a ‘best before’ date;
- the maximum advisable storage time;
- the temperature or the equipment that should be used to store it;
- a batch or lot mark; and
- wording such as ‘do not refreeze after defrosting’.
QFF packed by manufacturers for further processing must include on the label:
- ‘quick frozen’;
- a batch or lot mark; and
- the name (or business name) and address of the manufacturer or packer, or a seller in the EU.
45.34 QFFs must be prepacked in a way that prevents contamination, deterioration and dehydration of the food material. Temperature records must be traceable to a given date, and by inference the batches of food stored and these records must be retained and be retrievable for at least one year or longer, depending on the nature and shelf life of the QFFs they relate to.