ICSA: 3rd International Conference on Sustainable Agriculture

Utilising oil palm empty fruit bunches (EFB) provides a sustainable mushroom production and waste management solutions. However, the high contamination risk associated with untreated EFB necessitates effective disinfection methods for successful cultivation of mushrooms. Conventional steaming requires considerable heating energy and is inaccessible to small mushroom producers. Therefore, the potential of cold disinfection using calcium hydroxide (Ca(OH)₂) on EFB for mushroom cultivation was assessed. The concentration for microbial suppression was determined by soaking EFB in Ca(OH)₂ in concentrations ranging from 0.02 g L^-1 to 4.00 g L^-1, for 24 hours. Three replications of each concentration were arranged in completely randomised design. Significant difference was determined using one-way analysis of variance, and mean comparison by Tukey. Concentrations ≤2.0 g L^-1 resulted in gradual decrease in pH, while the concentrations 3.0 g L^-1 and 4.0 g L^-1 were able to maintain pH at 12.36 to 12.99. Plating the soaked EFB on potato dextrose and nutrient agar showed no fungal or bacterial colonies at 3.0 and 4.0 g L^-1, indicating efficient microbial suppression, whereas lower concentrations showed considerable microbial growth. Consequently, the concentration 3.0 g L^-1 and 4.0 g L^-1 were selected for further testing alongside steam sterilization as a control. The initial fungal and bacterial loads before any form of disinfection was 1.31 × 10⁸ CFU g^-1 and 1.66 × 10⁸ CFU g^-1, respectively. Both Ca(OH)₂ and steam sterilization eliminated 99.99% microbes in EFB. It was found that soaking EFB in 4.0 g L^-1 Ca(OH)₂ exhibited significantly better microbial suppression compared to 3.0 g L^-1 Ca(OH)₂ and steam sterilization, and able to sustain lower microbial formation for an extended period of time. Calcium hydroxide at 4.00 g L^-1 suggested as an alternative to the conventional steam sterilization. This approach supports efficient mushroom cultivation from agricultural waste while reducing reliance on energy-intensive methods.