Lessons learnt from on-farm mechanical drying of almonds in 2017

Abstract

In order to collect almonds earlier from the field to minimise weather damage, and manage rain affected almonds, several almond growers in Australia used three different types of dehydration facilities for drying bulk almonds. These systems were fitted with temperature and relative humidity sensors placed in with the almonds at fixed locations. From knowing the moisture status of the air in the bulk almonds and that of ambient conditions, aeration fans were selectively run to condition the almonds to a desired kernel moisture content. Firstly, early season over dried almonds were re-humidified in a shed with a vented floor. The shed was also used to finish dry later season higher moisture almonds. Secondly, stockpiles of almonds with a central aeration vent running along the length of the stockpile and aeration fans at each end were used to finish dry almonds. Tests showed using fans at both ends dried the almonds quicker than using only one fan at one end. Aeration of an uncovered 50 m long stockpile (no tarp) was measured to be uniform and effective along its length. Thirdly, the performance of four modified 12 m open top shipping containers with a false perforated floor was monitored for the drying of end of season rain affected second shake almonds using heated air. It was found that by aerating the very wet almonds for 24 h with heated air and then letting them sit for several days a 6% kernel moisture content could be achieved. The monitoring provided the operators with an insight into the progressive drying of the almonds and provided data for dehydration management decisions. The placing of sensors in the container dehydrators highlighted the need to improve the uniformity of air flow into the almonds. The work showed that the dehydration facilities can be used to reduce the time almonds need to remain in the orchard and thus reduce losses from weather and other sources of damage.