Main foodstuffs affected

4.5 Main foodstuffs affected

  The most frequently affected foodstuffs are confectionery and drinks. Con- fectionery is a sensitive food to taint. Wrappers are often laminates with high print coverage. Packaging surface area is relatively large compared to the bulk of the food. The flavour of chocolate is easily affected by chem- icals. Fats present in the chocolate are in direct contact with the wrapper and partitioning of the tainting compounds occurs onto the surface of the chocolate. The outer surface of the food can therefore act to concentrate the tainting compound in a small amount of food. Duek-Jun and Halek (1995) found that the extent to which solvents partition into the chocolate depends upon the temperature, the degree of crystallinity of the chocolate and the fat content. The order of partition was toluene > isopropanol > methyl ethyl ketone > ethyl acetate > hexane.

  Table 4.5 shows the relative proportions of foodstuffs affected by taint, which were investigated over a ten-year period at Pira International Analytical Laboratory.

  Table 4.5 Relative proportions of foodstuffs affected by taints

  Foodstuff

  of cases

  Flavoured milk drinks

  Alcoholic drinks

  Cakes and biscuits

  Cheese

  Crisps

  Water

  Beverages

  Packaging materials as a source of taints 79

  Table 4.6 Relative proportions of compounds causing taints

  Contaminant chemical type

  of cases

  Solvent or ink component

  Phenols or halogenated

  phenols anisoles Aliphatic aldehydes and ketones

  11 Others a 13

  a Others refers to compounds that do not re-occur as the source of taints.

  Table 4.6 shows the proportion of cases investigated over the same ten- year period at Pira International Analytical Laboratory associated with a particular chemical class of contaminant.

  Case study data from Nestlé ‘were reviewed by Huber et al. (2002). Huber reported styrene accounting for 15 of cases, halogenated phenols

  15 and solvent 28. In recent years the Pira International Analytical Laboratory has begun to identify bromoanisoles as the cause of musty odour and chemical taste in packaging where previously it was due to the presence of chloroan- sioles. In such cases the corresponding bromophenols, particularly 2,4,6- tribromophenol are also present. Until recently the source of these compounds has remained a mystery apart from studies reported in the literature. An excellent paper by Whitfield et al. (1997) traced the source to wood preservers used on wooden pallets. Whitfield et al. warned of the risk posed by the use of phenol-based wood preservers. At the time of going to press a large investigation carried out by Pira has established that 2,4,6- tribromoanisole derived from 2,4,6-tribromophenol was the cause of a musty odour reported simultaneously by at least two packaging manufac- turers. The problem was traced back to one particular supplier who had used wooden pallets treated with 2,4,6-tribromophenol (as the phenate, i.e. alkali salt form) to transport polyethylene raw material by sea. This case highlights a trend observed by the author of an increasing frequency of bro- moanisole contamination in packaging. Wooden pallets used to export product have to be treated to prevent spread of tree and plant diseases. Until phenol-based wood preservers are discontinued, they will continue to be one of the most common, costly and easily preventable packaging- related causes of taint, and wooden pallets will remain high risk contami- nating surfaces for packaging materials.

  80 Taints and off-flavours in food