Survivability of yeasts in high heat environments
I recovered 2 different species of yeasts from post CIP swabs at our filler nozzles. Our product is hot filled no colder than 180 F (82.2 C), but usually around 187 F (86.1 C). From there they travel to a cooling tunnel ~ 40 seconds away. I am having trouble finding a study that exposes yeasts to this temp range. I have seen some people saying 160 for 10-15 minutes to ensure no recovery, but nothing to verify that claim. I want to ensure that the product is hot enough for long enough to avoid any spoilage risk. Product pH is usually around 3.6. Has anyone seen a study that has this information?
Can't find any data for those temperature ranges in the literature for thriving yeast. Some helpful kill curves can be found here: http://www.agraria.c...erias_-_ing.pdf
What is the material of your filler nozzles? Connected to the filler any sort of silicone material might stay cooler than the product or the steel and allow biofilms to form which would have even more heat resistance.I would swab the nozzles before your CIP and make sure they weren't introduced via your rinse water or CIP lines.
You isolated yeast, the 10-15 minutes is probably to help with outgrowth of mold spores that would survive your hot fill.
I apologize for the delay in responding. Our nozzles are stainless, and connected to those are about 2 feet of silicone hose. Temperatures going into the filler are ~187 F and temperature checks of bottles just filled and capped are ~180 F. I isolated yeast both right after a CIP was performed and right before the next CIP was performed a week later.
I am having similar problem with 3 different bread came out very high with yeast. even though our oven baking temperature is higher then 300 to 400c. really struggling to understand how could yeast survived on such high temperature..?
@Nadim, your oven temperature is not indicative of the time/temperature curve of the inside of your bread. If you want to know what sort of lethality you get when baking you need to hide a datalogger of some kind inside the loaf and bake it. Remember, turkeys are cooked at 350º for hours, but the internal temperature just barely makes it to 165º in that time.
@DS1, sounds like a potential biofilm issue since your CIP was ineffective at removing the yeast. I would actually hand-scrub your equipment parts followed by a prolonged or double CIP to see if you can get it out of there and see if that makes a difference.
All of our CIP chemicals are their most effective ~150 F, so that is what our CIP is ran at. I am going to recommend a hot rinse of 220 F for as long as we are able to so hopefully nothing in the lines survive. I am hoping to find something that has a high temperature yeast can survive in so I can reference it in why this process needs to be included in our weekly CIP process and not be removed in the future if I am no longer here.
All of our CIP chemicals are their most effective ~150 F, so that is what our CIP is ran at. I am going to recommend a hot rinse of 220 F for as long as we are able to so hopefully nothing in the lines survive. I am hoping to find something that has a high temperature yeast can survive in so I can reference it in why this process needs to be included in our weekly CIP process and not be removed in the future if I am no longer here.
Correction, our hot rinse process is at 205 F, not 220
Get with your chemical supplier. They can recommend something.
I'm willing to bet you have a hard to clean crevice on the hoses, such as cracked / damaged hoses, or the fittings on the ends of the hoses that meet the stainless. Yeast is typically very easy to kill / remove during sanitation.
The hot rinse you describe will help, but it won't solve your root problem. The yeast is coming / harboring from somewhere and your CIP is not removing it.