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In order to support effective recycling of resources in a bioregenerative life support system (BLSS), the processing of inedible agricultural wastes into edible food products must be included. The process of converting agricultural waste into usable food resources is called secondary food production. Secondary food production offers a way to reclaim part of the energy and nutrients already sunk in inedible biomass, thus increasing the efficiency of the BLSS and crop harvest index. However, multi-step processes and lower yields and acceptability have made some secondary food production processes in the past problematic and costly. This paper presents preliminary process descriptions for secondary food products which are likely to be cost effective and well accepted: sugar syrup prepared from biomass hydrolysate, single cell oil produced from biomass hydrolysate, and Pleurotus mushroom fruit bodies grown on recalcitrant biomass and unused substrate.

Current projections for the crop mix in the Bio-Plex and the future Lunar bioregenerative life support system indicate that without supplemental oil production, the crew's diet will be extremely low in fat, with little refined oil available for food processing or preparation. Although soybeans, peanuts and dwarf brassica (similar to canola) have been suggested as oil crops, each one poses significant problems either in horticulture, harvesting, productivity or byproduct utilization. An alternative to plant oils is “single-cell oil” or SCO. Lipid-accumulating “oleaginous” micro-organisms may accumulate up to 60% of their dry weight as triglycerides. Their high growth rates enable them to synthesize lipids with far greater productivity than higher plant systems. The current top candidate species for use in a bioregenerative system is a yeast, Cryptococcus curvatus.