5 Curing

5.1.1 The Charter participant shall have standard operating procedures and records in place to ensure the effective thawing of frozen raw material before curing. This shall include the monitoring of product temperature during the thawing process.

5.1.2 The outer surface of the product shall not exceed +7°C during the defrosting period.

Evidence

Documented procedures for the thawing of frozen raw material. Examples of defrost temperatures records since the last audit.

All prepared pork raw materials for curing shall be clean, free of blood, bruising, bone splinters, dust and loose pieces of meat or glands.

Evidence

Visual examination of product.

5.3.1 The composition of curing brines shall comply with standard operating procedures, specifications and brine make-up recipes supported by chemical analysis and batch processing records.

5.3.2 Curing brines, whether intended for injection or cover, shall be positively released for use based on the salt content (as documented within the process specification) and temperature (Injection brines shall not exceed +7c and cover brines shall not exceed +5c). 

5.3.3 Where non-conformance occurs, the site shall investigate root cause and implement corrective action.

Guidance

The type of brine and cure shall be subject to the scope of the site’s processes and requirements of customer specification. 

Evidence

Documented production procedures, specifications, brine make-up recipes, chemical analysis and batch processing records. Examples of positive release records (salt & temperature) for curing brines and where applicable corrective action reports since the last audit. 

5.4.1 There shall be standard operating procedures, recipes and work instructions in place for the operation and management of the injection process.

5.4.2 The product temperature during the injection process shall be 0°C to +5°C.

5.4.3 Injection gains shall be monitored, recorded and checked against specified ‘pick-up’ targets for each batch of pork being processed by weight checks measured pre and post-injection on a specified number of products. 

5.4.4 Checks shall be carried out on the injection needles before injection commences to verify that needles are intact and there is no blockage of the needles that could result in ‘mis-cure’. 

5.4.5 Where non-conformance occurs, the site shall investigate root cause and implement corrective action

Guidance

‘Pick up’ is the amount of cure retained by the pork during curing. Recipes and work instructions shall detail the required criteria for the range of products produced on site. It is acknowledged that customers own brand label products may determine the recipe formulation.

Whilst the legal maximum temperature limit for meat in process is <8°C EHO`s tend to give some flexibility which maybe reflected by the approach taken by the auditor i.e. if temperatures of >8°C are seen but there is clear evidence that product temperatures are returning to <8°C within 4hours of final packing then it would be appropriate to raise this as an observation, however if the product was still at >4°C 4hours after final packing then this shall be viewed as a minor non-conformance.

Irrespective of the recipe formulation, in-process checks shall be undertaken to monitor the product temperature up to the point of filling. Records of temperatures shall be held.

Evidence

Documented procedures, recipes and work instructions for the operation and management of the injection process. Examples of product temperature records, injection gains and checks on needle integrity and evidence of records where corrective action was undertaken. 

5.5.1 There shall be standard operating procedures and work instructions in place for the operation and management of the dry curing process.

5.5.2 Curing shall, by definition, be carried out using only dry ingredients – the use of brines or other wet ingredients is not permitted.

5.5.3 Curing gains shall be monitored, recorded and checked against specified “pick-up” targets for each batch of pork being processed by weight checks measured pre and post cure on a specified number of products.

5.5.4 Where bacon is also air dried, there shall be evidence of net weight loss in compliance to specified tolerances.

Evidence

Documented procedure, work instructions, recipes, specifications and process records for the operation and management of the dry curing process. 

Review curing gain records and ‘pick up’ target records.

Where bacon has been air dried review records of net weight loss aligned to specified tolerances.

Visual inspection of product to verify adherence to specification.

5.6.1 Pork raw material intended for Wiltshire curing shall be either cured on the side, as primal cut, or as individually butchered muscles. The use of ham hock incorporating primary and/or secondary hock muscle) may be used.

5.6.2 The injection and cover brine shall only contain salt, (NaCI) sodium or potassium nitrite and/or sodium or potassium nitrate. 

5.6.3 Injection may be carried out manually or by multi-needle injection.

5.6.4 It is a characteristic feature of Wiltshire curing that the live cover brine shall be re-used continually. Therefore, standard operating procedures work instructions, and records shall be in place that state the compositional targets and tolerances (salt, nitrate, nitrite, pH and temperature), and the actions to be taken when these fall outside of stated limits, so that the condition of the live cover brine can be maintained and where necessary corrected. All actions and brine amendments shall be recorded.

5.6.5 Due to yield loss, the quantity of live cover brine will deplete over time. Therefore, a standard operating procedure shall be in place for the process to “top-up” an existing live cover brine or, in extreme circumstances, the creation of a new batch of live cover brine.Where a “top-up” brine is used this shall not exceed 25% of the mother batch of live cover brine.

5.6.6 use of a starter culture in the production of Wiltshire bacon shall be restricted to the creation of a fresh batch of cover brine after the original has been lost or has soured.

5.6.7 In order for the live cover brine to mature and stabilise the fresh batch shall be used to cure products for at least two months before it can be used to manufacture product that can be certified as BMPA Quality Assured Bacon and Gammon (Wiltshire).

5.6.8 Live cover brines not in regular use shall be regularly aerated and monitored (d) to maintain their condition

5.6.9 Records shall be maintained for live cover brine composition. A recorded log of cover brine history, adjustment and “top-up” shall be maintained to demonstrate composition and provenance.

5.6.10 Pork shall be fully immersed in the live cover brine for a minimum period of 3 days (72hours).

5.6.11 After immersion, and prior to further processing, the cured sides/pork cuts shall be allowed to drain and then matured in air at +2°C to +5°C for a minimum of 4 days and to a clearly specified maximum time that shall be validated using shelf life and food safety analysis.

Guidance

In a Wiltshire-curing system, the objective is to maintain the live cover brine in a stable condition with a predictable and controlled rate of conversion of nitrate to nitrite. 

Brines used in different plants vary in their behaviour due to differences in their micro flora and this behaviour should be recognised. Because of their singular nature, a unique characteristic is that the live brine is continually re-used. The practice of freshly and routinely preparing the live cover brine by the addition of a starter culture is a modern short cut intended to circumvent the traditional time aged process and is not compliant with the requirements of clause 5.6 that is specific to the traditional process. To be certified by the Charter such products, for the purpose of labelling and differentiation from authentic and traditionally Cured Wiltshire Bacon, should be clearly described as “Wiltshire-Style” (or similar) within the legal name of the product.

The function of the starter culture is to ensure that the right microbiological flora is present for the live brine to mature to a point where it can be self-maintaining with occasional additions of salt, nitrite and nitrate to maintain its condition. Typical levels of microflora are a count greater than 10⁶ and are predominantly made up of large concentrations of micrococci and lactobacilli. Once the mature live cover brine has been created the brine can then be re-used without further addition of the starter culture

There will be occasions when existing cover brines will need to be replenished by the addition of a top-up cover brine – this should be an occasional practice rather than routine. weekly. It is expected that the manufacturer should know the quantity (in litres) of live cover brine they have on stock, so it should be a simple calculation to work out the 25%. Details of the opening stock, closing stock, and top up additions would need to be documented. “this should be an occasional practice rather than routine e.g. weekly, not daily.” 

Immersion forms an essential part of the Wiltshire process. In Wiltshire curing, the relative concentrations of the injection and live cover brines result in a net withdrawal of water from the pork during curing because the concentration of salt in the injection brine is considerably less than that of the live cover brine.

The pH of a live cover brine is usually stable and typically falls within a range of 5.0 to 6.9. The pH value may be checked whenever brine is being re-strengthened and live cover brine with pH outside this range may be used if the Charter participant can demonstrate that the brine remains stable (different starter cultures can create different pH levels). Occasional peaks outside of the set limits would not be an issue if the Charter participant is monitoring the pH trends and takes corrective action when non-typical pH profiles emerge. A gradual and persistent rise in the pH value indicates that the brine is becoming unstable, and a critical situation will arise if this goes above 6.9, when off-odours will develop.

The rise in pH is usually accompanied by an increase in the nitrite level, as a more rapid reduction of nitrate occurs.

Wiltshire-cured sides and cuts are frequently stored in an unprotected form Excess surface brine drains off (the use of hooks, racks, or slatted tray are acceptable as long as free drainage can be demonstrated) and the lean and fat become firmer in texture and noticeably drier. These changes are due to the gelling of the water/salt/protein complex formed within the meat during curing and a gradual hardening of the fat as the crystallizing process continues after slaughter.

Evidence

Examples of records to be reviewed since the last audit shall comprise:

• Live cover brine composition
• Log of cover brine history, adjustments and “top-up” to demonstrate provenance.
• Temperature monitoring
• Shelf life and food safety analysis
• Appropriate work instructions

5.7.1 Post cure boning, cutting, slicing and similar operations shall be carried out with minimal damage to soft tissues.

5.7.2 During further processing, the temperature of the bacon shall not exceed +7°C (except for smoked and further heat-treated product) and shall subsequently be reduced to +5°C or lower.

Guidance

Any potential increase in the product temperature shall be minimised by controlling the volume of product being processed which shall be aligned to pre-production plans. 

Evidence

• Visual inspection of butchery standards.
• Examples of temperature monitoring records since the last audit.

5.8.1 There shall be standard operating procedures, work instructions and records in place for the bacon smoking process that details the operation of the smoking chamber and the time, temperature, and wood types specific to each product specification. 

5.8.2 For smoked bacon, only natural wood smoke shall be used in the smoking process. Synthetic smoke mixtures and extracts of wood smoke shall not be used.

5.8.3 Care shall be taken to ensure that the bacon is uniformly smoked in compliance to the process specification (time and temperature of smoking) and quality attribute specification (colour and taste) and it is not contaminated with tar in the smoke chamber

Guidance

Traditionally, smoke is produced from hard woods, normally beech, oak, applewood – scented or resinous woods like conifers are not used due to excess tarring or flavour migration.

Product may be hung on racks or hooks but shall not touch walls or other product that may impede the circulation of smoke around the chamber. Any covering used e.g. bags, netting etc. shall be suitable for intended use. The smoke chamber and racks shall be kept clean.

Evidence

Review standard operating procedures. 

Copy of current wood specifications and review examples of completed processing records since the last audit. 

Visual inspection of smoke chamber. Review process specification, QAS and examples of quality control records since the last audit

5.9.1 There shall be standard operating procedures, work instructions and process records in place for the handling of bacon/gammon prior to heating/cooking.

5.9.2 Bacon/gammon shall be held in chill storage at −4°C to +5°C for up to 7 days unless it has been massaged or tumbled, in which case it shall be cooked within 24 hours. 

5.9.3 The period of storage prior to cooking can exceed 7 days if bacon/gammon is either deep chilled to a validated process or if it frozen and held at -12°C or below. The site shall undertake shelf-life verification under worst case conditions that includes sensory evaluation and microbiological quality of the finished product. 

Evidence

Examples of temperature monitoring records where deep chilled cured or frozen bacon has been stored for longer than 7 days shelf life data for the product shall be available. Validation data for the deep chill or freezing facility.