Category: Fermentations

RESEARCH SPOTLIGHT: Characterization of Sensory Profiles of Yogurt Acid Whey Fermented with Five Different Yeasts

This week, we are highlighting the work of MPS student, Rossie Luo. If you have been following along with the research spotlights, you may have noticed that ARG does a lot of research investigating novel fermentations of dairy effluents to valorize waste products and create a more sustainable process. But how do these fermented beverages actually taste?? Rossie’s research sets out to answer that question!

Rossie’s work is centered around evaluating the sensory profile of fermented beverages made from yogurt acid whey. Unlike sweet whey that can be used to make whey protein powder, yogurt acid whey typically has limited value-added applications and is mainly used as animal feed or as a fertilizer. Yet, acid whey still has residual lactose, making it a suitable substrate for yeast fermentation. The goal of her research is to ferment yogurt acid whey with five different yeasts to evaluate the sensory profiles that each yeast creates during fermentation.

To do this, Rossie set up fermentations with five different yeast strains and monitored the density, pH, and cell concentration throughout the duration of the fermentation to characterize the fermentation profiles of each yeast. She also compared the sugar, ethanol, and organic acid concentration at the beginning and end of fermentation for each yeast. What she saw is that each yeast creates a unique fermentation profile for the yogurt acid whey!

Once the fermentations were complete, she set out to characterize the sensory profiles of each beverage prototype. Through the Sensory Evaluation Center at Cornell, a focus group was conducted and was followed by an individual questionnaire. During the focus group, participants were guided to discuss various aspects of their sensory perception of the beverage prototypes such as aroma, flavor, mouthfeel, and aftertaste. A list of sensory descriptors was then generated and used as metrics for the individual questionnaire to evaluate the prototypes. It turns out that these yeasts were able to impart different and unique flavors to the fermented yogurt acid whey!

This study provides important insights that can guide further product development of a fermented acid whey beverage. It is exciting to think that we can be part of a more sustainable future with delicious and nutritious fermented yogurt acid whey beverages!

---

[1] Siyi (Rossie) L, Timothy A. D, Dana D, Samuel D. A. (2021) Characterization of the Fermentation and Sensory Profiles of Novel Yeast-Fermented Acid Whey Beverages. (manuscript in preparation).

RESEARCH SPOTLIGHT: Optimizing alcoholic fermentations to develop new products from whey permeate

This week, we are highlighting the work of PhD student, Viviana Rivera Flores. Viviana is working on optimizing the fermentation process of whey permeate under anaerobic conditions to develop low-alcohol beverages with potential functionality. Whey permeate is the dairy effluent that results after obtaining protein concentrates from cheese whey. For every pound of cheese produced, about seven and a half pounds of permeate are created.

While whey permeate has gained attention in the food industry as an additive, novel biomanufacturing technologies can open avenues for greater valorization of this product. In oxygen-deprived atmospheres, yeast can convert lactose from this substrate into ethanol and galactose, offering a sustainable and flexible alternative. Galactose acts as a prebiotic precursor and provides energy without altering our sugar balance, hence a beverage with this sugar would have functional properties. On the whole, anaerobic fermentation of whey permeate is a versatile process from which we can generate bioethanol, recover galactose, or develop novel beverages. Three possible products from only one raw material!

General steps of her methodology include substrate preparation, yeast propagation, fermentation experiments, product analysis, optimization model development, and further process optimization.

Currently, Viviana is working on the optimization model of the fermentation process. She is evaluating the impact of different parameters (like temperature and time) on ethanol and galactose concentration. To make this possible, she works with a software that builds statistical models that take multiple factors to optimize the desired products. For better optimization, this software uses a design called response surface methodology, which is an efficient way to assess the individual impact of each fermentation parameter and understand their interactions. If ethanol and galactose are maximized, more efficient valorization and better functionality of this waste stream can be achieved.

RESEARCH SPOTLIGHT: Fermenting surplus skim milk into a value-added product

This week, we are highlighting the work of master’s student Lucas Wise. Lucas is focusing on repurposing surplus skim milk into a value-added product. High prevalence of lactose intolerance in the world and increased demand for plant-based milk alternatives has caused a decline in skim milk consumption. For producers, this is resulting in financial loss and environmental damage from increasing skim milk waste. The goal of his project is to develop technologies to derive added value compounds, ingredients, and products from skim milk via the fermentation of lactose.

The anaerobic fermentation of lactose also produces ethanol, the ingredient in all of our favorite drinks!

The fermentation process can leverage the lactose in discarded skim milk and provide an alternative method of upcycling this dairy waste, easing the burden of waste on dairy producers. Companies could avoid major financial losses and reduce their environmental impact because the skim milk surplus gets repurposed.

Currently, Lucas is in the screening stage, using a variety of yeast species to determine the best process performance parameters and improve the fermentation stability and sensory properties of the product. This will be followed by an optimization seeking to maximize ethanol and galactose yields from the fermentation. This work could potentially be used to create a stand-alone fermented beverage!

RESEARCH SPOTLIGHT: Fermentation of Dairy Waste Stream into Value-Added Product