Mushrooms growing on carrot scraps can serve as a sustainable and tasty protein source. This is shown in a study by researchers from Justus Liebig University Giessen (JLU) and the Technische Hochschule Mittelhessen (THM): Vegan patties and sausages made with mushroom protein tasted better to the taste testers than products made from plant-based proteins.
The study was published in the journal "Journal of Agricultural and Food Chemistry" in the special issue "Upcycling Food Waste into Value-Added Natural Foods and Ingredients" of the American Chemical Society (ACS). Researchers from the working groups of Dr. Martin Gand at the Institute of Food Chemistry and Biotechnology at JLU and Prof. Dr.-Ing. habil. Denise Salzig, Professor of Process Analytics in Bioprocess Engineering and Pharmaceutical Processes at THM, participated in the study.
As the world's population continues to grow and many people still suffer from hunger, the need for nutrient-rich foods and sustainable, efficient production methods is increasing. One possibility is edible mushrooms, which can grow on a variety of organic waste generated in considerable quantities during food production—for example, apple pomace from apple juice production and whey from cheese making. Even residues from carrot processing, such as those generated during the extraction of natural dyes, can serve as a substrate for mushroom growth, as the study shows. "These contain valuable nutrients that we wanted to utilize for human nutrition," explains Dr. Gand. Instead of harvesting the mushroom fruiting bodies, the researchers focused on the root-like mycelia, which require less time and space to grow yet still produce essential nutrients.
Initially, they cultivated over 100 mushroom strains on the remains of orange and black carrots, a byproduct of natural dye production at GNT Europa GmbH. This allowed them to identify which mushroom grew best and had the highest protein content. Pleurotus djamor, also known as the pink oyster mushroom or rose oyster mushroom, emerged victorious. The researchers further optimized the growth conditions to improve yields. They were thus able to produce proteins similar to those of animal and plant proteins, meaning they were nutritionally valuable. Furthermore, the mycelia of the rose oyster mushroom proved to be low in fat.
Another important aspect: the mycelia are palatable. The researchers used them to produce vegan patties, replacing the typical soy protein with varying proportions of mycelia. Volunteers who tasted these patties evaluated them based on characteristics such as texture, taste, and smell. The patties in which all the soy protein was replaced with mycelia tasted best. The volunteers then tasted vegan sausages made either with soaked chickpeas or with fresh mycelia. Here, too, the sausages made with mycelia scored higher in terms of smell and taste.
“The results suggest that fungal mycelia are a sustainable and palatable protein source that can also offer similar nutritional benefits to plant-based proteins,” said Dr. Gand. “Since food-grade byproducts are used to produce high-quality proteins, no additional agriculture is required to promote food security. This reduces the environmental impact.”
Publication
Pleurotus djamor mycelium: sustainable production of a promising protein source from carrot side streams, Journal of Agricultural and Food Chemistry, https://doi.org/10.1021/acs.jafc.5c11223