Modificaciones tecnológicas para mejorar la seguridad y calidad del jamón curado

Resumo

Some technological modifications were introduced into the common procedure for dry-cured Spanish ham manufacture (from white pigs) in order to improve the safety and quality of the product, as well as to investigate the relative importance of the various processes influencing the sensory quality. The modifications introduced in each of 3 experiments (a, b and c) were: a) the inoculation of a starter culture (SC) on ham surface, as well as the vacuum packaging of the hams prior to the resting phase (VP); b) the application of a modified atmosphere with a reduced content of oxygen (MARCO) (during the totality or the last part of the processing period) in two different processes that differed in the relative humidities (RH) applied; c) the use of high temperatures (35 ºC) during a 4-day period and the application of liquid lard fat (LLF) on ham surface. In every experiment, an experimental design of incomplete blocks was followed in order to block and evaluate the effect of the carcass factor on every parameter. The application of the SC prevented the growth of fungi on the ham surface, due to the competitive action of the growth of inoculated yeast, but it caused the development of off-odours or non-typical flavour traits and the reduction of the intensity of typical flavour attributes. These effects were consequence of both the SC direct action and the changes that the inoculation caused to the ham surface, such as the decrease in the quantity of exuded liquid fat. The VP brought about: a reduction of the growth of moulds on ham surface; a higher gradient of moisture between the interior and the exterior of the ham; a decrease in weight losses; an increase in the non-protein nitrogen; a decrease in the intensity of aged flavour and an increase in the intensity of white film and some off-odours. These effects were probably consequence of 3 factors: the increase in ham moisture content caused by VP; the fact that VP strengthened the effects of the use of the SC and that it caused some changes in ham surface. The use of a MARCO during the whole process caused an increase in the non protein nitrogen, a decrease in the concentration of cholesterol oxides and an increase in the intensity of the white film. Moreover, in combination with the use of low RH, the MARCO caused a decrease in the bacterial growth and prevented the growth of moulds, yeast and mites and the development of coquera. It also caused a drastic reduction in the intensity of ham flavour due to the decrease in the concentration of products derived from the lipid oxidation. When a MARCO was applied only during the last part of the process, the elimination of the mobile forms of the mites and the decrease in the intensity of coquera were achieved, the resultant product possessing a flavour slightly more intense than that of the product subjected to a MARCO during the whole processing period. The increase in the temperature from 25-27 ºC to 35 ºC for 4 days did not have any effects on the ham physical-chemical or sensory characteristics. The application of LLF onto ham surface prevented the excessive drying of the external part and the development of coquera and also caused an increase in the intensity of the aged flavour and a reduction of the incidence of negative flavour notes such as the roasted meat flavour. Therefore, the amount of liquid fat exuded during processing has a great influence on the sensory quality of Spanish dry-cured ham. The raw material was the factor that influenced the highest number of parameters.