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Bokashi Microbial Carrier from Locally Recovered Resources

Microbial carrier produced by the local farmer allows hospitality professionals to safely ferment and store food waste right in the industry kitchen.

Bokashi is pretty similar to kimchi. At any scale, you want fresh, source-separated food waste, airtight containers (possibly with a spigot to drain out excess liquid), and you want a carrier material for the beneficial microbes that actually do the work. In kimchi, a brine or marinade serves this purpose. For our SoilFeeders’ bokashi carrier, Soil Trust has developed its own microbial formula to stay independent from imported products, utilize local waste, reinvigor indigenous farm knowledge, and save costs. We use locally sourced sawdust, rice bran, or even coffee chaff as carrier medium that we innoculate with microbes from self-generated fruit peel eco-enzyme.

Initially, Soil Trust (泥玩) used organic rice bran (米糠) from a Japanese rice mill that we microbially super-charged with DIY eco-enzyme from fermented fruit peels (see next blog entry). Also, organic wheat bran is commonly used as a base material for our bokashi’s microbial carrier (also known as ‘bedding’). Bran is actually the powdery residue of the cereal’s germ and thus contains substantial amounts of valuable oils, minerals, vitamins, and proteins. Due to their high nutrient contents, rice and wheat bran quickly perish and cannot be stored for more than a week in Hong Kong’s subtropical climate. Moreover, in combination with food scraps, the bran’s nutrition load was too intense for direct soil application and required an extra maturation step where we had to add wood shavings for counter-balancing. In our first year of operation, we noticed how our bran-based bokashi buried in the soil attracted ants and their unwelcome companion species aphids, which infested our crops with fungal and viral diseases. For these reasons and to diversify our input sources, we started experimenting with alternative carrier materials. One option is sawdust that we source from the municipal mulch plant (Y-Park yard waste recovery) and from local sawmills. While most wood types in Hong Kong are suitable as microbial carriers, Poplar, Maple, and Walnut are difficult to ferment due to their antiseptic qualities. Other non-bran materials that Soil Trust is experimenting with or considering for bokashi bedding are coffee chaff (dried skin of coffee beans released during the roasting process), biodegradable paper packaging, powdered dry leaves or charred rice hulls (biochar).

Research into localized bokashi carrier inputs: Using sawdust mixed with ground egg shells and microbially super-charged with eco-enzyme for layering, thus fermenting food trimmings.

We inoculate the sawdust in food-safe, airtight buckets with mature eco-enzyme and add finely ground eggshells as a calcium-based soil supplement. The ratio for Eggshell:Eco-enzyme:Sawdust we are using is approximately 1:10:40. We make sure to compress this sandy-moist mixture to remove all air pockets. Typically, preparing this bokashi carrier is a very social, enjoyable event for the Soil Trust communities involved, including members of a veggie co-purchasing platform, ethnic minority gardeners, and university students. Once the microbes from the eco-enzyme colonize the bran – after two weeks of maturation time – we can use it as a carrier to fermentatively transform our hospitality food scraps in larger collection containers.

Keywords: Fermentation starter, microbial inoculant, enzymic catalyst, DIY-bokashi bedding, bokashi sprinkle, bioregional integrity.


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