Have you ever heard of Yeast Derivative Products (YDPs)? If you are exposed to the wine industry, you have probably come across them as they are becoming more widely used in that industry. Rarely do I hear about there use in cider. I should clarify that point. I do hear about there use but not as YDPs. I’ll explain more in a minute but let’s first define YDPs before we discuss how they can be used. Peggy Rigou and associates define YDPs as inactivated yeast preparations obtained from Saccharomyces and/or non-Saccharomyces yeasts through
different industrial processes(1). To break down that further, inactivated yeast are yeast cells that have died. They are no longer capable of reproducing and fermentation. However, that doesn’t mean inactivated yeast won’t influence the various compounds in your hard cider or wine. In fact, that is exactly what they do and why they are added.
YDPs have three main functions. They can be added as a source for Yeast Assimilable Nitrogen (YAN), improving colloidal stability, and increasing sensory characteristics. This last is a more recent use YDPs. In my articles on cultivating yeast and making a yeast starter for cider, I talk about using yeast nutrient to aid in growing yeast biomass (bulk up your yeast cell count). The yeast nutrient I recommend is organic nitrogen, like Ferm-O. This is YPD. The YDP releases organic YAN into the juice to aid yeast reproduction. This type of nutrients produces less off flavors and can be more readily utilized by active yeast. The other main use for YDP is to stabilize colloids. Colloids are compounds that form and create cloudiness. YDP release macromolecules that reduce turbidity, improve color, remove excessive tannins, and aid filtering. The final use of YDPs is to improve aroma. The various compounds that can feed yeast or decrease turbidity by binding with various proteins and phenolic compounds can can also bind with volatile aromatics. This can preserve and enhance the aromatic complexity of a cider.
All of this makes sense when you think about what YDPs really are and how they have been used for ages. YDPs are dead yeast cells that breakdown and release the compounds that are stored in the cell walls as well as the other cell elements like the cytoplasm. These include amino acids, proteins, mannoproteins, lipids, fatty acids, and other compounds that help the fermentation process turn apple juice into great cider. This is autolysis and it occurs when cider is aged on lees. Aging on lees is a process that has been done since antiquity. YDPs are simply a commercialization of this process that offers more consistent results by preparing the yeast so that it forms the compounds most desired. This is done by many different processes including heat, enzymes, and physical processes like filtering. YDPs offer the home cider maker an opportunity to use natural products to evolve their cider. If you are like me in that you try to control your process, YDPs might be of interest. You can think of them like commercial yeasts strains, which started out as wild strains that were isolated and cultured to ensure consistent performance. YDPs originate naturally as well and are simply isolated to create specific results.
Many commercial yeast suppliers now offer various YDPs. As I noted, Ferm-O nutrient is really a YDP. Check out what’s available from your local yeast supplier and experiment. You can also do the less expensive and natural method by allowing some cider to age on its lees. I would still recommend doing this on fine lees versus gross lees but try both. Your results will most likely be a little more random but I suspect both will result in good and interesting ciders.
(1) P. Rigou and associates, Impact of industrial yeast derivative products on the modification of wine aroma compounds and sensorial profile, Food Chemistry 358, 2021
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