The efficiency of renewable bioresources is becoming increasingly important. Along with the European Union's Green Deal and plans to decouple economic growth and prosperity from resource consumption, a new way of thinking must be adopted. Resource efficiency is no longer limited to electricity, heat or non-renewable resources. Previous studies have described the classification of the value of bioresources, which is usually formed as a pyramid depicting the values of the obtained products and the demand for their volume. The approach of the circular economy in the bioeconomy with its principles - reuse, recycle and regenerate - is also widely described in the scientific literature. Combining these two approaches, we created a bioresource utilization index, which would show the efficiency of bioresource use in an enterprise, along with the enterprise's contribution to the bioeconomy. In open interviews with representatives from multiple companies, we identified bioresource flows and mapped the factors that influence these flows in an enterprise. The proposed bioresource utilization index gives an insight into resource efficiency in a specific enterprise by quantifying the incoming raw material, the outgoing product, by-products, and waste. The elucidated factor nexus could be used as a map for easier detection of place for improvement.