Drying is a process aimed at reducing the water content in plant materials below a limitwhere the activity of microbes and decomposing enzymes deteriorate the quality of medicinal andaromatic plants. Today, the interest of consumers towards medicinal and aromatic herbs has registereda growing trend. This study aims at designing a low-cost real-time monitoring and control system forthe drying process of aromatic herbs and evaluating drying ecacy on the microbial communityassociated with the studied herbs. Hot-air drying tests of sage and laurel leaves were carried outin a dryer desiccator cabinet at 40C and 25% relative humidity using three biomass densities(3, 4 and 5 kg/m2). The prototype of the smart system is based on an Arduino Mega 2560 board,to which nine Siemens 7MH5102-1PD00 load cells and a DHT22 temperature and humidity sensorwere added. The data acquired by the sensors were transmitted through Wi-Fi to a ThingSpeakaccount in order to monitor the drying process in real time. The variation in the moisture content ofthe product and the drying rate were obtained. The system provided a valid support decision duringthe drying process, allowing for the precise monitoring of the evolution of the biomass moistureloss and drying rate for laurel and sage. The three dierent biomass densities employed did notprovide significant dierences in the drying process for sage. Statistically significant dierencesamong the three tests were found for laurel in the final part of the process. The microbial loads of thearomatic herbs after drying were influenced by the dierent leaf structures of the species; in particular,with laurel leaves, microbial survival increased with increasing biomass density. Finally, with thedrying method adopted, the two species under consideration showed a dierent microbial stabilityand, consequently, had a dierent shelf life, longer for sage than laurel, as also confirmed by wateractivity (aw) values.
|Numero di pagine||19|
|Stato di pubblicazione||Published - 2020|
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