Polymerase chain reaction (PCR) of puroindoline b and ribosomal/puroindoline b multiplex PCR for the detection of common wheat [Triticum aestivum] in Italian pasta

Italian traditional pasta is manufactured using Triticum durum semolina. Italian national legislation excludes the use of Triticum aestivum to prepare this traditional food and permits a contamination of durum wheat by T. aestivum in a maximum content of 3%. However, the use of soft wheat is frequent in other European countries. The protection of traditional pasta requires a sensible technique, possibly by passing the use of protein as molecular marker. In fact, proteins are easily denatured by thermal technologies (high-temperature dried pasta). The PCR of some sequences of T. aestivum has been optimized using two sets of primers designed on puroindoline b gene. The specificity of this method has been studied towards T. durum varieties and towards some cereals. Universal ribosomal primers written on internal transcribed spacers region (ITS) have been employed to set up a multiplex PCR protocol. This approach allows obtaining a useful tool to distinguish the presence of soft wheat in pasta. The detection limit of this method is 0.2% T. aestivum in T. durum. The analyses of commercial samples showed that this method works well also on high-temperature dried pasta.