I'm making some hazelnut spread at home and trying to preserve it as long as possible. Basically, I blended a mixture of ground roasted hazelnuts, skimmed milk powder, sugar, cocoa powder and very little amount of hot water in food processor. I then added melted vegetable shortening and lecithin in the mixture and blended until it has a nice texture and spreadability. It was kept in a sterilised glass jar.
I was hoping the finished product might last a few months before it turns bad, however, there were some bacteria/mold/fungus on the surface only after about three-four weeks.
My questions are 1.) what causes the bacteria growth (is it caused by the water/moisture level) ? 2.) what other substitutes for hot water (to dissolve the powder mixture)?
Thanks in advance guys :)