Efforts to control mites on Iberian ham by physical methods

This study is aimed at the development of a method for integrated mite control in the industrial production of Iberian and Alentejan ham. The investigations were carried out on the premises of five factories in the southwest of the Iberian Peninsula. Tyrophagus longior was predominant on hams in the drying rooms, Tyrophagus putrescentiae in cellars, while Tyrolichus casei was observed only in one factory, together with Melichares dendriticus (Acari: Ascidae), a predator of tyroglyphids. Relative humidity levels below 60% reduced the growth of mites on the ham surface, but these conditions forced the mites to seek refuge: T. putrescentiae and T. casei were found in cavities inside the ham. At the end of the experimental curing period, 11% of the hams were totally disintegrated by mite damage inside. Mites survived high-temperature treatments which are detrimental to the hams: 71 degrees C, 11 min; 57 degrees C, 30 min and 40 degrees C, 96 h. They also survived a long low-humidity period: 1 month at 18 degrees C and 32% R.H.