Optimization of solar thermal dryer designs for the production of sun-dried apricots (Prunus armeniaca)(abstract)

Authors: Alleyne, Fatima; FERRY, MARIE-VICTOIRE - School Of Engineers Of Purpan; Milczarek, Rebecca

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/18/2016
Publication Date: 7/20/2016
Citation: Alleyne, F.S., Ferry, M., Milczarek, R.R. 2016. Optimization of solar thermal dryer designs for the production of sun-dried apricots (Prunus armeniaca) (abstract). American Society of Agricultural and Biological Engineers Annual International Meeting - Orlando, FL - July 17-20, 2016.

Interpretive Summary:

Technical Abstract: Solar thermal (ST) drying is a ubiquitous method that has had widespread use for fruit and vegetable crop preservation in developing countries. Conversely, in the United States solar thermal drying has found limited commercialization due to concerns about slow drying rates and poor product quality. If solar dryers can be designed such that the drying process can be accelerated at higher drying temperatures and thus, shorter drying times without compromising product integrity, the efficiency of drying can be improved. In this work, multi- and single layer solar thermal dryers were used to prepare dried apricots. The starting apricot materials consisted of an average initial moisture content of 87% and color values of L* 54.70, a* 18.78, and b* 30.75. Photo-selective cabinet dryers were constructed using materials with various optical properties. Both multi- and single layer drying cabinets were constructed using extruded (Ex), ultraviolet filtering (UV), and Heat Stop (HS) acrylics while Solar Sheet (SS) acrylic and piezoelectric polyvinylidene fluoride (PVDF) were only employed in the multi-layer drying cabinet designs. Multi-layer solar thermal dryers exhibited higher air temperature profiles (maximum temperature of 52oC) than that recorded for single-layer units, thus illustrating the potential to accelerate the drying process. Based on a target moisture content of 0.35, the first apricot samples to dry to completion in the multi-layer dryers were those dried in the extruded dryer, the only photo-selective material that allowed transmission of UV-A light and was not exposed to any post-treatment process e.g. film application. The ultraviolet filtering multi-layer cabinet produced dried apricots that were lighter, redder, and yellower compared to the extruded, Heat Stop, and Solar Sheet dryers. Statistical results reveal that no direct correlation could be made between drying time and drying temperature in the drying units. Thus, in this work we have demonstrated that a multi-layer solar thermal dryer, fabricated with the appropriate photo-selective material, can minimize quality degradation of dried apricots (Prunus armeniaca). Results of this work will inform the design of multi-layer solar thermal dryers in the agricultural industry.