New Coproduct Technology Produces Food-Grade Yeast

Process expands potential ethanol capacity by shortening fermentation.
By Don McLellan | April 06, 2016

Typically, in ethanol production the nonfermentable leftovers from the feedstocks and yeast are combined and sold either as wetcake or dried distillers grains for feed. But the yeast included in that sale of animal feed includes protein, sometimes vitamins and minerals, cell walls and nucleotides, which have a value in their own right on world markets.

So the questions are: 1. How can those components be collected separately without losing them in the mix?  2. Isn’t there some way that ethanol producers can earn some additional revenue from these components?

Traditional yeast companies sought to find new strains of their yeasts to improve productivity, and some were successful, but none could enable the yeast cells to remain intact through the process. Australian researcher David MacLennan developed a continuous fermentation process to produce single-cell protein while at Sydney University. He formed Biotechnology Australia Pty. Ltd. and continued his work on protein and ethanol. That company was acquired by Rio Tinto. He has since formed his own R&D company, Agritechnology Pty. Ltd., and partnered with me to form Alternative Fuels Corp., which contracted the research to Agritech, is the owner of the patents and is aiming at commercializing the AFC Yeast technology.

MacLennan’s concept is to keep these important components intact within the yeast cell and not to leave them in the ethanol fermentation for as long. By substantially increasing the volume of the active yeast into the ethanol fermenters, the fermentation time has been reduced to seven to 10 hours, much shorter than standard practices. When the ethanol fermentation process is finished, the yeast cells, still intact and maintaining their full integrity, can be centrifuged off from the beer prior to distillation. Note that none of the agricultural feedstocks are used to produce ethanol. All are completely applied to producing the human food-grade yeast product.

The separated, washed and dried yeast has a protein content between 45 and 55 percent, is rich in B vitamins and minerals and contains 7 percent ash. It also contains beta glucans and mannans that have medical applications along with the potent antioxidant glutathione and traces of other elements. As a vegetable yeast, it is suitable for vegans and vegetarians and has GRAS status (generally regarded as safe under the U.S. Food and Drug Administration.)

To present some idea of the enormity of this opportunity, it could be possible to achieve a ratio of one metric ton of yeast for every 5,000 liters of ethanol produced annually. If even half of the global ethanol plants were converted to enable this system to be implemented, the volume of this high quality yeast protein would satisfy the world’s demand for protein well into the future.

Other challenges involved in product development include discerning the best form and whether it can compete in existing markets or a new one. Some possible uses for the yeast protein include:

• A highly nutritious protein ball supplement.

• An egg substitute in baked goods such as cakes, biscuits, muffins or donuts that retains the protein content previously provided by eggs.

• A milk extender that can increase milk volume by 30 percent, without settling due to the yeast’s functional property of solubility. This would have particular relevance for feeding young animals because of the presence of nucleotides.

• A protein concentrate for use in sports and health drinks or in a range of textured vegetable protein dishes intended as meat substitutes.

The research findings have potential to be attractive to the ethanol producer economically. Because the ethanol fermentation period is so short, it may be possible to have a second fermentation in the same original time, increasing capacity by 67 to 100 percent. More distillation equipment probably would be required. Additionally, the potential revenue from the sale of the yeast is many times greater than for distillers grains. Depending on costs of feedstocks, labor and power, it is possible that existing profitability could be increased by a factor of four to five times.

Of course, there has to be a market for the yeast protein. There is much talk of a looming global lack of protein, and different new ideas get suggested as the next opportunity. Yeast protein has not had significant attention simply because, until now, it has been too expensive to compete as a protein. Yeast itself is common, because it is the major one used in baker’s and brewer’s yeasts and in yeast extracts used as flavor enhancers in many foods.

It is only now, because of the patented process that this yeast protein can compete against the likes of soy. Besides being a vegetable yeast, not an allergen, generally regarded as safe and the fact that it can be produced almost anywhere in the world, the yeast also is cheap to produce.
It now offers food developers, manufacturers and sellers a great opportunity to help create a new emerging wave of high protein, low cost and medically beneficial applications. And they are backed by the knowledge that supplies of the raw material yeast protein can be produced virtually globally in large quantities.

Yeast protein can become part of a new food revolution.

Author: Don McLellan
Chairman, Managing Director, AFC Yeast
+61 4 0384 5520