I got an email from AtcNick, asking me to identify the yellow growth microorganism on his Allysandra. I`d like to share a little information at this point in the topic so that others may also possibly benefit from the material as well.
AtcNick wrote:
Hey chuck, I just posted some pictures of my salami with some questionable spots. Would you mind taking a look and giving me your expert advice. I would appreciate it dude, thanks.
Hi Nick,
Hey, I see in one of your photos that you little boy is really starting to grow up. What a good lookin' kid! What's his name? I saw a photo of him quite a while ago. Is he still helpin' ol' dad with the sausage?
I don`t know how expert my advice is, but I`ll try to explain a little. Yeasts in the sausage fermentation process, develop later during the longer "traditional" salami-making procedure whether we use a culture or not. If we make a fermented sausage using a "short" or "medium" fermentation-drying period, yeasts simply don`t have time to develop. However, in "long" fermentation periods yeasts develop normally and indeed metabolize some of the lactic acid that you worked so hard to create during the fermentation stage. This lowers the acidity by increasing the pH. When this happens in a slowly fermented sausage, it actually improves the flavor (because of the reduced acidity). Two yeasts that are deemed "desirable" for this process are
Debaromyces hansenii and
Candida formata. As long as there is high humidity in your chamber, yeasts will thrive and they are really not too particular at which temperature they choose to do so. And the pH drop doesn`t affect them at all.
Debaromyces hansenii and
Candida formata are less sensitive to salt than most other yeasts also. Also, they are anaerobic, needing little oxygen to survive. Of these two particular yeasts,
Debaromyces hansenii consumes both lactic and acetic acids (present in all fermented meat). This consumption of acid gives the sausage a much milder flavor. However,
Debaromyces hansenii also produces ammonia, which has a pH of about 11.5 which creates a new, higher pH of the meat, being less acidic. At this point it becomes both
proteolytic and
lipolydic, contributing to even more flavor by breaking down
proteins and
fat. Oh, and yes... they range from white to yellow.
As far as the "bare" spots go, that`s just where you`ve touched it initially. The colors you absolutely do not want are
grays and greens. Those are of the
Zygosaccharomyces genus - nasty little devils long associated with the food industry as spoilage yeasts. During their growth, yeasts metabolize some food components and produce metabolic end products. This causes the physical, chemical, and sensory properties of a food to change, as the food is spoiled. These species are hearty and able to grow in some of the more commonly used food preservation concentrations including ehanol, acetic acid, sorbic acid, high sucrose, benzoic acid, and sulfur dioxide.
Again, neither yeasts nor molds are affected by the pH drop during the fermentation stage of sausage-making, and as long as a high degree of humidity is sustained, they will grow within a wide temperature boundary. However, because the two microorganisms grow much slower than bacteria during the drying process, they develop much later. It is estimated that only 1% of all yeast species have been described. Yeasts are microscopic fungi that grow as single cells. They will grow on the surface or near the surface inside non-cooked, air-dried, fermented sausages, while molds grow only upon the surface. Unlike bacteria, there are no known species that grow only anaerobically (obligate anaerobes). Yeasts grow best in a neutral or slightly acidic pH environment but are able to grow in foods with a low pH, (5.0 or lower) and in the presence of sugars, organic acids, and other easily metabolized carbon sources.
The Chr. Hansen product Bactofermâ„¢ that you used initially, has a strong and precise culture placed into it. It has already done its job at this point. The color and flavor - forming have been fixed. All you`re waiting for is the precise drop of humidity to make it safe. Ol` pard, if you are at 71% yield, then you are now there! It`s time to clean `em up and cut one open. Be sure to send us a photo or two.
Best Wishes,
Chuckwagon