THE SCIENCE
Hitting the Marc Science transforming winery waste SOPHIE PREECE There’s a nice dose of serendipity behind an Auckland scientist’s work to ‘upcycle’ grape marc into high-value stock feed using bioprocessing. Environmental biotechnologist Dr Shan Yi saw a news article on grape marc in 2021, highlighting the lack of large-scale solutions to deal with increasing volumes of the pips and skins left in winery presses after juice has been extracted from grapes. “I found this challenge very intriguing and started mulling over the possible microbial biotechnology to help solve the problems mentioned in the article,” she says.
“This bioprocess represents a promising grape marc valorisation technology with economic, environmental, and social benefits.” Dr Shan Yi Now Shan is running a two-year grape marc project with the University of Auckland, thanks to funding through the New Zealand Wine Futures Fund (NZWFF), looking to transform marc into high-value, functional medium-chain organic acids, such as caproic acid, for goods such as stock feed. “My research focuses on applying the fundamental understanding of microbial metabolism and interactions to improve the performance of engineering bioprocesses,” says Shan, who joined the chemical and materials engineering department at the University of Auckland in December 2019, to research the synergy between chemical and environmental engineering. “To align my research with New Zealand’s needs, I am specifically interested in developing low carbon-emission engineering bioprocesses
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Giesen grape marc
to valorise biomass feedstock from New Zealand’s primary industries.” At the time of reading the online article, Shan’s lab had just started a research project with a couple of chemical engineering undergraduate students in the university’s Part IV Project, which tasks participants with tackling a real-world problem “We were enriching the microbiomes for anaerobic chain elongation, a bioprocess that converts small organics, such as acetate and ethanol, into medium-chain organic acids with higher values,” says Shan. “The anaerobic chain elongation represents a sustainable low carbon-emission platform biotechnology that can be applied to different types of renewable feedstock. My instinct told me that this biotechnology could be an essential part of the picture to tackle the grape marc challenges.” In a moment of “serendipity,” she received an invitation from Analeise Murahidy, the Director of Strategic Growth at UniServices, to join a workshop with Bragato Research Institute (BRI) at around the same time. Grape marc challenges came up in discussions, and Shan’s interest was further piqued. Grape marc is packed with organic carbons that the grapevine has “worked really hard to fix from atmospheric carbon dioxide through photosynthesis”, says Shan. “These grape marc organic carbons represent a carbon-neutral and renewable feedstock if we can use them to produce chemicals and energy. However, grape marc organics are complex biomolecules that can be costly and energy-intensive to process.”
I NEW ZEALAND WINEGROWER I AUGUST/SEPTEMBER 2022
The research focuses on developing a novel anaerobic bioprocess to convert the bulk organics in grape marc to mediumchain organic acids by the catalytic abilities of microorganisms. “Compared with previous proposed alternative treatments, this new bioprocess produces higher-value products but does not require intense operation parameters such as heat or high-power consumption,” says Shan. “In addition, the products from our bioprocess can be used directly by wine (or another crop) growers to promote plant growth and fight against plant disease, creating a circular route for wine offerings and enhancing sustainability of the New Zealand wine industry,” she continues, noting “economic, environmental, and social benefits”. Previous research on the alternative anaerobic bioprocess, such as biogas production from anaerobic digestion, revealed that biodegradation of grape seeds and other marc components is challenging. “Also, the price of biogas cannot offset the high cost of removal or processing the grape seeds, rendering the biogas production process economically unsound for commercialisation.” However, the project’s production of higher-value products will likely justify the treatment cost, she says. “We will test the efficiency of a range of treatment methods in breaking down the recalcitrant organics. We will also identify the optimal treatment methods for future implementation and commercialisation by rigorously examining our bioprocess’s environmental and