Slurry solutions - flow and consistency

You're cooking the stuff.
Vitamins will oxidize, you will lose some volatiles.
Flavor will change.
Is this a process for vitamin enriched beer??

I totally agree- especially about the beer. If that is not your goal, do a thermal balance calculation of all components - mass X specific heat X deltaT - then over-heat the water, add sugar, salt and honey and mix, add malt and remix, then add vitamins for a final remix and you are done. If the thermal balance calcs indicate too much "heat" needed at the water (>212F), preheat the water to about 200F and reheat the sweet saline solution as required before the malt and vitamins

We make breakfast cereal, mostly rice and multigrain flakes. We don't do thermal balance checks but I think we should. Can you tell me more about them?

Get a copy of ASHRAE fundamentals, or similar engrg manual. Look up the thermal characteristics of the various products that you use. For example, the specific heat (energy required to raise the temperature of one pound of material one degree F) of water is 1.000. Other products will usually be lower. The information will also give you the density of the product (pounds per Cu Ft) if you don't have that available. Then, calculate the weight of each material added, multiply the weight by the Spec Ht and by the temperature difference (say 150F - 70F). That will be the TOTAL BTU's required to heat the mix. Say the total BTU's is 750,000 for a batch, and the amount of water required is 50 gallons (8.33 X 50 = 4165 Lbs). 750,000 BTU will raise the temp of 50 gallons 180F. With a 45F starting point, that is too hot, so add heat to raise it to 200F (about 646,000 BTU) then add the "cold" dry goods and add the rest of the heat (104,000 BTU) to raise it up to say, 184F. Then, add the rest of the "cold" materials to get to the goal temp of 150F. I'd like to talk more about this, and your process so please cantact me at rewitte@emc2conserv.com.