Preventing taints

4.10 Preventing taints

4.10.1 The legislation

  The first European Council Directive laying down the basic rules for food contact materials and articles was adopted in 1976. This became known as the Framework Directive, 76893EEC, with the title ‘On the approxima- tion of the laws of the member states relating to materials and articles intended to come into contact with foodstuffs’. Article 2 Directive 76893EEC specifies requirements for food contact materials as:

  Materials and articles shall be manufactured in accordance with good manufacturing practice, so that, under their normal and foreseeable

  102 Taints and off-flavours in food

  conditions of use, they do not transfer their constituents to foods in quantities, which could: – endanger human health – bring about a deterioration in the organoleptic characteristics of

  such food or an unacceptable change in its nature, substance or quality.

  In the UK, these basic requirements for food contact materials and articles from Directive 76893EEC were incorporated into UK law by Statutory Instrument (SI) No 1523 (1987); The Materials and Articles in Contact with Food Regulations. A new EC Framework Directive 89109EEC was intro- duced in 1988 but the above health and organoleptic requirements were retained.

  In the United States, similar regulations to those in Europe exist to pro- hibit packaging affecting the organoleptic qualities of packaged food. The Federal Food, Drug and Cosmetics Act, Section 402(a)(3) specifies that any ‘indirect food additive’ originating from packaging should not transfer to food ‘odour or off-taste rendering it unfit for consumption’.

4.10.2 Test methods

  A number of sensory-type tests are described by Tice (1996). A brief summary is given here of the most useful tests for taint prevention. The purpose of the following tests is to ensure that a taint does not occur in the packaged food as a result of chemicals migrating in sufficient quantities from the packaging.

  Panel tests can be odour and taste tests. Ideally they are best done in a neutral odour test room (DIN 10962). The odour tests include the German DIN Standard 10955, 1993, BSI Standard BS EN 1230-1:2001 and the American ASTM standards E462-84 (reapproved 1989) and E619-84 (re- approved 1989).

  The EN standard 1230-1:2001 for odour assessment is carried out in the following manner. Test portions of area 6 dm 2 are placed in a wide neck, flat

  bottom glass container. The containers are sealed and maintained at 23°C for 20 to 24 hours. At the end of the exposure time the container is opened and the odour intensity assessed using the following scale:

  0 = no perceptible odour

  1 = odour just perceptible (but still difficult to define)

  2 = moderate odour

  3 = moderately strong odour

  4 = strong off-odour. Half-number scores may be recorded if considered necessary by a

  panellist. The median is calculated from all the individual scores. One indi- vidual result may be discarded if it differs from the median by 1.5 or more.

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  If there are fewer than six consistent results the test is repeated with fresh samples.

  DIN standards have been used for odour testing. These are either a ranking in order of odour intensity (DIN 10963), or a paired comparison test against a reference (DIN 10954).

  For taste testing on packaging, there is the standard EN 1230-2:2001 part

  2. Companies often use their own test procedures, which are usually based on the Robinson test. The Robinson test involves exposure of chocolate to the packaging followed by a sensory panel test. In the EN 1230-2:2001 part

  2 test the packaging material (6 dm 2 ) is placed in a sealed container sepa- rated from the test food. The humidity of the air inside the container is

  maintained at between 53 and 75 using selected saturated salt solutions. After 44 to 48 hours at 20°C the test food is removed. A sensory test is then used to determine whether a taint has transferred to the chocolate.

  Three types of panel tests may be used in EN 1230-2:2001 part 2 proce- dure. These are the triangle test, the extended triangle test and the multi comparison test. In the extended triangle test, one portion of the test choco- late that has been exposed to the packaging under test, is placed next to two portions of control food exposed to similar conditions without the pres- ence of the packaging material. A panel of 10 assessors is used. The asses- sors are asked to pick out the test food and rate it on the following scoring system:

  0 no perceptible off-flavour

  1 off-flavour just perceptible (still difficult to define)

  2 moderate off-flavour

  3 moderately strong off-flavour

  4 strong off-flavour. The median score is calculated from all the individual scores discarding any

  scores given for the control test chocolate. If more than five assessors iden- tify the test food it is concluded that at the 95 confidence level a taint has been transferred. Results are not easily compared on a numerical or statis- tical basis with results from other laboratories especially if they operate dif- ferent scoring systems. As a quality control tool the test can be very useful. It is important to maintain a reliable set of panellists. The triangle test is carried out in the same way as the extended triangular test except that no intensity ratings are required. In the multi comparison test the panellist is required to score the intensity against a known test portion used as a control which is assigned a taint intensity of 0.

  The triangle test is used when a taint intensity rating is not required. The extended triangular test is useful for the comparison of a number of pack- aging samples. The multi comparison test is useful for large numbers of samples.

  Residual solvent analysis is widely carried out. The best technique is static headspace gas chromatography as described in Section 4.7.2. The

  104 Taints and off-flavours in food procedure to be followed is set out in a current European Committee for

  Standardisation (CEN) draft standard Draft prEN 13628-1 (July 1999) and Draft prEN 13628-2 (July 1999). Part 1 is the quality control monitoring procedure. Part 2 is the more accurate definitive test procedure. There are no limits set for retained solvents in packaging. However, there is an indus-

  try guide limit of individual solvents not exceeding 5 mg m -2 and total solvent residues not exceeding 20 mg m -2 . The packaging should be selected

  in the knowledge of any promotional items required. It is useful to have a specification for the packaging. Items to include in this specification are listed in Section 4.10.3 below. Simple taint panel tests can be carried out to ensure that the packaging cannot transfer taint to the food. Accelerated storage tests are also useful to assess the likelihood of a taint problem occurring.

4.10.3 Practical steps to avoid the occurrence of taints

  Many taint problems could be avoided by setting and ensuring compliance with suitable packaging specifications. Specifications could include the following: • -2 Residual solvent: <20 mg m • -2 Individual solvents (esters): <5 mg m

  • Promotional items in food packaging: flow wrapped with PVDC coated

  OPP (oriented polypropylene) unless the absence of a taint transfer has been proved

  • Gauge of promotional flow wrap: resistant to puncture by promotional

  item • Packaging and promotional items: passes panel taint tests • Inks: low odour from a reputable supplier • Solvents: high purity from a reputable supplier • Paper: preferably not recycled for direct food contact • Plastic packaging: certified for food use, tested to ensure compliance

  with US or European law for the conditions of use. Any new packaging or change in packaging format should be checked with

  a trial production run and a panel test.