Executive Summary: Adding value to Marlborough waste streams

Summary of Project and Key Findings:
The wine and seafood industries are important primary industries in Marlborough and produce large volumes of organic by-products (grape marc, juice and wine lees and mussel shells respectively) each year. Disposal remains a significant and costly challenge for industry and local authorities. Insect bioconversion is a new technology that presents an opportunity to create much higher value end-products from Marlborough’s organic by-products while supporting a circular economy.

The aim of this research was to determine if insect protein ingredients (for aquafeeds) and soil conditioners / biofertilisers derived from insect frass can be successfully produced by feeding insects organic by-products generated from Marlborough-based primary industries. This research has also supported the development of nationally unique scientific capability that can help extend insect bioconversion across other New Zealand regions with different organic by-products.

Investigations included:

• Production of mealworm diets from Marlborough organic by-products
• Characterisation of larvae fed on formulated diets:
• Characterisation of insect meal for use in aquafeed
• Characterisation of palatability trial small batch aquafeeds:
• Characterisation of frass from mealworm diets
• Multiresidue testing of by-products, mealworm larvae and frass

Of the small number of agricultural compounds detected in the mealworm larvae and frass, all were below allowable MRLs for agricultural compounds in food as specified by Ministry for Primary Industries. These results support the safe inclusion of mealworm meal in aquafeed and frass for use as a soil conditioner and biofertiliser.