Efficacy of Agricultural and Food Wastes as the Growing Media for Sunflower and Water Spinach Microgreens Production

The growing media is one of the significant elements affecting microgreens’ yield and quality. This experiment investigated the possibility of waste utilization instead of employing peat moss to produce sunflower and water-spinach microgreens. The treatments consisted of peat moss (Control), coconut coir dust (CD), leaf compost (LC), food waste compost (FC), CD:LC = 1:1 <i>v</i>/<i>v</i>, CD:FC = 1:1 <i>v</i>/<i>v</i>, LC:FC = 1:1 <i>v</i>/<i>v</i>, and CD:LC:FC = 1:1:1 <i>v</i>/<i>v</i>. The results proved that the highest yield of sunflower microgreens was observed when cultivated in 1:1 <i>v</i>/<i>v</i> of CD:LC media (10,114.81 g m⁻²), whereas the highest yield of water spinach microgreens was recorded under the treatments of CD, Control, 1:1 <i>v</i>/<i>v</i> of CD:LC, and 1:1:1 <i>v</i>/<i>v</i> of CD:LC:FC media (10,966.67–9800.00 g m⁻²). The biochemical composition of the microgreens varied within the types. Our findings demonstrated that a tendency of an increase in chlorophyll and carotenoid contents depended on the growth of both microgreens under different growing media. All growing media did not cause excess nitrate residue or pathogenic contamination in both microgreens, namely <i>Clostridium perfringens</i>, <i>Salmonella</i> spp., and <i>Staphylococcus aureus</i>. In contrast, almost all the growing media resulted in a higher population of <i>Bacillus cereus</i> contamination in both microgreens than the standard set limit, except for sunflower microgreens grown in the control and CD growing media. These findings could suggest that the 1:1 <i>v</i>/<i>v</i> of CD:LC and CD media were the most effective growing media for sunflower and water spinach microgreens, respectively, but further cleaning before consumption is recommended to avoid or reduce the foodborne incidences caused by <i>B. cereus</i> in microgreens.