Microbial-based products can be produced either in solid or liquid form, depending on their target and mode of application. One of the common microbial-based products that have been marketed around the world is a product containing Trichoderma sp. This fungus has been proven to function as a biocontrol agent and biostimulant for plants [1] [2] . The use of Trichoderma-based products in oil palm plantations has emerged as a promising strategy to mitigate the severity of Ganoderma infection [3] [4] . The consequential yield losses in oil palm due to Ganoderma disease have led to substantial economic setbacks in the industry [5] . Most of the Trichoderma-based products are typically formulated in dry powder form, employing various production methods. The preference for dry formulation was due to its simple manufacturing process, cost-effectiveness, easy handling, reduced susceptibility to contamination, and easy of store at room temperature [6] .

In a way to produce dried powder Trichoderma-based products, proper drying process is essential. The dried powder formulation serves to prevent microbial contamination and ensure an extended product shelf-life [7] . Even though drying process is a crucial step in the production of microbial-based products, the reduction of water content might cause a negative effect such as cell damaged and loss of cell viability [8] . The cell viability might be affected at elevated temperature during the drying process [9] [10] . Therefore, the selection of suitable drying methods for microbial-based products is important. Commonly, freeze-drying, spray-drying and fluidized bed drying are selected as the dehydration method in the production of microbial based products [7] [11] . However, the use of these three drying methods may require some new machinery with the high investment cost [9] [12] .

In this study, considering the limitations in production costs, it is crucial to adopt an economical and practical approach to improve the drying process without incurring higher additional costs. The use of dehumidifier is a common practice in various industries for managing moisture and providing a straightforward solution to excess humidity [13] [14] . The dehumidifier works by absorbing the excess moisture and changing the moisture from its vapors state to liquid state. The water vapor in the airstream condenses and is gathered in a reservoir. The dehumidified air then passes through the condenser, where it is warmed and recirculated back into the room as dry air [15] [16] . The application of dehumidifier-based drying technology was subsequently incorporated to enhance the drying process of microbial-based products.

The microbial product containing Trichoderma asperellum M103 was mass cultivated and formulated in powder form through a simple and straightforward production process involving submerged fermentation and clay-mixing procedure. Mass-scale production took place in an open-area plant, posing the potential risk of bacterial contamination. The product was air-dried at a room temperature by spreading the product on a polyethylene (PE) tarpaulin. However, this drying method was time-consuming and susceptible to weather conditions. To address these challenges, the study aimed to assess the use of a dehumidifier to enhance the drying process of the microbial-based product in powder formulation without affecting cell viability or increasing the risk of product contamination.

The drying process of a microbial-based product cannot involve high temperatures as the microbial cell or spores might lose viability, except for thermophile bacteria or fungi. In this study, the microbial-based product (M103) was left to dry without using any heating elements. The moisture inside the product will evaporate to become water vapors, and the fan used helps to circulate the moisture inside the drying room.

In normal conditions without a dehumidifier, the drying process takes a long time to achieve the targeted moisture content of the final product. In addition, the drying process is also affected by the current weather. Sometimes, if the drying process was delayed for too long to achieve the targeted moisture content, bacterial contamination might take place. Table 1 shows the RH and temperature readings in the drying room with and without the dehumidifier. The RH value decreased upon using a dehumidifier, reducing the product’s moisture content.

According to Figure 3, without a dehumidifier, the drying process takes around 8 days to achieve targeted moisture content, while with a dehumidifier, it requires only 3 days. The excess moisture from the microbial-based product and surrounding area of the room were removed efficiently. In general, humidity refers to the amount of moisture or water vapor in the air [20] . Without a dehumidifier, the relative humidity was around 82 to 88% in the drying room. Compared to the addition of a dehumidifier, the relative humidity of the drying room can be reduced to 50 to 60% (Table 1). The dehumidifier works by removing excess moisture from the air through the condensation process.

As a conclusion, the dehumidifier proves to be a useful, straightforward, and cost-effective tool for the drying process of microbial-based products, ensuring no adverse effects on their viability. Utilizing a dehumidifier enhances manufacturing efficiency by reducing the required drying time, thereby increasing the overall productivity of microbial-based products.

This research was funded by FGV R&D Sdn. Bhd. The authors would like to thank FGV Agriculture Services Sdn. Bhd. for lending some machinery and to Applied Air Quality Specialists Sdn. Bhd. forallowing us to rent the dehumidifier for this study.

The authors declare no conflicts of interest regarding the publication of this paper.

Bohari, N.H., Fishal, E.M.M., Razak, I.B.A., Nasir, M.A.A.M. and Abidin, C.M.R.Z. (2024) Short Communication: Enhancing the Drying Process of Microbial-Based Products with a Dehumidifier. Advances in Microbiology, 14, 333-339. https://doi.org/10.4236/aim.2024.146024