Feeding wine waste to abalone

Seafood and wine have long been considered a culinary match. Now, researchers at the South Australian Research and Development Institute (SARDI) have discovered that recycled wine waste is excellent abalone feed.

According to the Journal of Shellfish Research, there was a global production of 129,000 tonnes of farmed abalone in 2015 compared with just 6500 tonnes of wild-caught abalone. But as noted by SARDI Nutrition and Feed Technology Associate Professor David Stone, one of the major challenges facing aquaculture is finding sustainable food sources that minimise the use of marine ingredients. The use of a waste product such as steam distilled grape marc — the heat-treated skins, pulp, seeds and stems of grapes left over after wine is made — goes part of the way to achieving this.

Barossa Valley wine waste company Tarac Technologies produces about 130,000 tonnes of steam distilled grape marc per year. Registered as Acti-Meal, the product was originally developed for agriculture as a feed source for cattle, sheep and pigs but is now turned into everything from grape spirit to stock feed, grape seed extract, grape seed oil and soil improvers. It was only after discussions with SARDI, however, that the company identified aquaculture as a potential opportunity.

A three-month lab trial conducted by SARDI in partnership with Tarac showed that an experimental formulated diet containing 5–20% Acti-Meal improved the growth performance and feed utilisation of juvenile greenlip abalone compared to a commercial diet. The abalone on the grape marc diet showed a 6% improvement in biomass gain and a 2.9% increase in shell growth rate compared with abalone fed on a commercial diet.

The grape marc-fed abalone also outperformed the other abalone in a food conversion ratio, which is the amount of food given compared with the amount of weight gained. The commercial feed returned a ratio of 0.81 grams of feed per gram of growth while just 0.67 grams of the feed containing 20% grape marc was required per gram of growth.

“As we added the grape marc in we got a significant improvement in growth and feed utilisation,” said Associate Professor Stone.

“We are removing something that costs $500–$800 a tonne and replacing it with what is effectively a waste product that costs $250–$400 a tonne — it’s a price reduction with a growth benefit.”

A six-month trial of a test feed produced by Aquafeeds Australia containing 20% Acti-Meal is set to begin at an abalone farm in November 2017. If all goes well, Associate Professor Stone said the feed containing Tarac’s steam distilled grape marc product could be commercially available in the second half of 2018.

This news item is modified version of two stories published by The Lead South Australia under CC BY 4.0