Pasteurization substrate in weight

The new method of thermal treatment of the substrate, called "bulk pasteurization" or "bulk pasteurization", over the last decade has become widely used in the practice of mushroom . The essence of this method consists in that the uniform layer of loose packed height 1.8 - 2 m substrate purified air is blown predetermined temperature . The metabolic products are removed from the substrate by forced convection, allowing more flexibly adjust the temperature of the substrate to provide it with oxygen and air .

To conduct the bulk substrate pasteurization tunnel is closed after filling the substrate include a few hours with a ventilation system in order to equalize the temperature in the mass of the substrate . During this period, increasing microbial activity and substrateIt rises in temperature from 45 to 50 ° C . steam supply is then turned on for heating the substrate to a temperature pasteurization . When the temperature reached 56 - 57 ° C pasteurisation process begins, the duration of which, as in pasteurization on racks, is 6 - 8 h . In this period, care must be taken not to allow the temperature andits increase to more than 58 - 60 ° C. the peak temperature is allowed to 62 - 63 ° C for 1 - 2 hours, which does not adversely affect the quality of the substrate .

After completion of the pasteurization process the substrate by enhancing the cold fresh ventilation air is cooled to 52 - 54 ° C for 8 - 12 h . Csince this conditioning period begins during which the supply of fresh air to be mixed to the recirculation is controlled so as to maintain the temperature between 50 - 54 ° C and at the same time to have a carbon dioxide concentration of not more than 2% . approximate need Outdoor ranges from 20 to 50 m3 / h per 1 msubstrate (Fig. 32).

The temperature during heat treatmentsubstrate temperature control of air flow under the slatted floor tunnel and the air temperature above the substrate layer in the upper region of the tunnel . The temperature of the substrate layers has at its minimum, and the variation is always between the temperature of air in the upper and lower zones of the tunnel, a difference which generally does not exceed 3 - 3,5 ° C .

Leaving process is determined by conditioning a substrate concentration of ammonia in the air tunnel, which must not exceed 10 - 15 mg / m3 .