Development and Performance Investigation of an Inflatable Solar Drying Technology for Oyster Mushroom

We developed an inflatable solar dryer for mushroom drying, which was adapted from the Solar Bubble DryerTM originally designed for paddy drying. The improved dryer with an added perforated elevated floor ensured the quality without any requirement of mixing or turning of the mushrooms during drying. Its drying performance and economic feasibility were evaluated through determination of the drying parameters including moisture content (MC) reduction, mushroom quality, energy efficiency, greenhouse gas emissions, and cost-benefits ratio. Mushroom MC was reduced from 90% down to 40–60% within 2–4 h, corresponding to the drying rate at this stage of 10–20% h−1. At the next stage, it took about 4–6 h corresponding to a drying rate of 2–10% h−1 to reach the required product MC of 8–10%. The color of the dried mushrooms still remained white-cream. The drying process required 4.57 MJ, emitted 0.33 kg CO2e, and required an input cost of 1.86 $US kg of dry product. For the specific case in the Philippines, this can generate a net profit of 468–1468 $US−1 year−1 and the investment will break even in 1.3–4.0 years corresponding to the selling price of dry mushroom of 10–12 $US kg−1. The study developed a solution to improve the solar bubble dryer and verified its drying process for mushroom drying at farm scale. It would add a significant value to farmers’ income as well as a diversified source of nutrient-rich food.

Drying Performance and Aflatoxin Content of Paddy Rice Applying an Inflatable Solar Dryer in Burkina Faso

The drying performance of paddy rice using an inflatable solar dryer (ISD), or also known as GrainPro® Solar Bubble Dryer™, was evaluated and compared to conventional sun drying in Burkina Faso. Drying time was around eight hours. Thermal imaging was conducted to observe temperature distribution in the ISD during drying and mixing. Shadow casting was observed in the ISD due to the round shape of the black plastic film, which reduced the temperature of the paddy rice to about 10 °C. The temperature inside the ISD was up to 13 °C higher than the ambient temperature, whereas the temperature of paddy rice on the top layer was about 5 °C higher than on the bottom. The final moisture content of paddy rice dried in the ISD and under the sun was not considerably different. Under certain circumstances, impurities in paddy rice dried in the ISD could be substantially lower than for sun drying. The aflatoxin level of paddy rice was under the maximum limit of the EU regulation. Drying paddy rice seemed to be effective to remove aflatoxin type AFG2 content. Further adaptation of the ISD design for drying operations on rough surfaces and sandy soils is suggested.

Low-temperature manufacturing of fine pharmaceutical powders with supercritical fluid aerosolization in a Bubble Dryer®

Aerosols play an important role in thin film deposition, fine powder generation, and drug delivery. Green processes to form aerosols are needed to eliminate the use of toxic organic solvents and minimize the production of liquid wastes and the emission of halogenated and oxidant-forming organic compounds. We have developed a new patented process, Carbon Dioxide-Assisted Nebulization with a Bubble Dryer® (CAN-BD), that can generate a dense aerosol with small droplet and microbubble sizes that are dried to form particles less than 3 µm in diameter [1­9]. The process uses carbon dioxide as an aerosolization aid, and this permits drying at lower temperature than usually needed in conventional spray-drying. Intimate mixing of supercritical carbon dioxide with aqueous protein solutions causes the formation of microbubbles, which are rapidly dried in less than 5 s. The process is more environmentally benign than traditionally used methods, and is superior when thermally unstable materials are being processed. Fine-particle pharmaceutical powders can be rapidly and easily made by this new CAN-BD process, requiring less energy and eliminating residues of toxicologically or environmentally objectionable solvents. Manufacturing dry powders of pharmaceuticals for pulmonary drug delivery and increasing bioavailability are the purposes of developing and marketing the new Temco Bubble Dryer.