Profile PhotoMark Floerke
Keymaster
@independant-consultant
Post count: 223

Hello @affammm,

Dr. Lin also suggested you review the Ask Dr. Lin video on shelf life:  https://youtu.be/Uyh7ele-7og

Water activity is not about how much water you add.  This is expressed as Aw and is the moisture in a product that is available to move freely, and be available for bacterial growth.  Sugar and other humectants trap water and provide softness in texture.

A household recipe may state that the bars keep for 2 weeks.  The average home kitchen is not as sanitary as a food processing facility, and the home processing methods are not as stringent.  Keeping for 2 weeks could simply mean that the crust gets stale, and or the filling dries up and gets hard.

Before you choose to send samples to a lab for shelf life testing, you need to know what the criteria for your shelf is.  If micro bacteria is present and can be cultured on a fresh sample, that will simply get worse, not better, over time, whether accelerated or not.  Therefore one first step might be to get samples tested for yeast, mold, coliform, salmonella, staphylococcus, etc.  If they are completely clean, there is unlikely any contamination after baking.  If anything shows up, there is some sort of contamination.  The level and type of results determine your actions.

Accelerated shelf can be done, and as mentioned, shelf life for what?  How much firmness is too firm?  What about flavour? If you have something like a traditional cookie crust, what about staling?  Are there any bioactives you are adding post bake that need to be tested for viability?  Any nutritional components that could degrade?  And fats, like omega-3, with low oxidative stability?

Shelf life is used as a catch-all phrase for many things.  At a minimum you want the food to be safe to consume.  That is the purpose of microbiological testing.  You also want the consumer to purchase the product repeatedly, even if they were to consume it close to or at the end of shelf life.  What is you minimum acceptability for this?  In general, yes, if all conditions are handled properly, a preservative may not be necessary.

I hope this information is useful to you.