The other preparation stages require different thermohygrometric conditions and hence differing conditioning plant characteristics.
In the initial part of the resting phase, accentuated drying is needed (low relative humidity and high air speed) and thus ventilated plants with a high degree of refrigeration power are suitable. The plants utilized for the subsequent resting stages may be the same as those of the initial stage, although the control parameters must be modified—for example there should be an increase in mean relative humidity. These parameters must be chosen on the basis of objective data (temperature, relative humidity, weight loss of the product) and sensory evaluations (hydration conditions of the surface of the product, surface microbial growth, etc.).
During the drying and ripening stages, the temperature of all the heat exchangers can be higher than 0°C; it is thus possible to eliminate the breaking time and to envisage long periods at constant relative humidity equal to a value close to the Aw of the product.
Figure 1 (a) Behavior of RH in salting of Italian hams. (b) Behavior of T in salting of Italian hams.
Most plants involve the setting of the minimum and maximum temperature and relative humidity values; in some cases (poor precision and/or uncertainty of measure in operating conditions, cycles characterized by slight relative humidity fluctuations with time) it is advisable to program different control parameters—for example minimum and maximum drying, or cooling, and breaking times. The conditioning plants for products other than ham, including minced meat-based ones, do not differ substantially from those described above.
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