SPI (soybean protein insolate) is usually extracted from soybean defatted meal which is from normal hexane solvent extraction workshop. The used soybean is high quality, cleaned and husked. This defatted meal is called “white flake” in industry. Isolating soybean protein removes various nonprotein ingredients, retain protein and make dry basis protein content up to more than 90% ( Nitrogen*6.25 ).
There are mainly nine steps to produce SPI.
The first step is alkaline water extraction. Water temperature, PH value and dwell time is very important in this step.
The second step is separating extracted white flakes from solvent with the help of machines.
The third is acid precipitation with hydrochloric acid.
The fourth is separating whey from stick.
The fifth is adjusting to get multiple different functional protein isolate.
The sixth is neutralization with NaOH.
The seventh is heat treatment and stick adjusting.
The eighth is dehydration with spray drying.
The ninth is weighing and packing.
We use intermittent extraction, acid precipitation and continuous isolating technology. PH value is under manually controlled system.
Besides guaranteeing extraction and acid precipitation effect, it can make technical process and parameters stable. So the SPI quality can be stable and consistent.
With double-dip extracting, it can extract good protein in white flakes fully and effectively.
Energy saving and consumption reducing are always important part in this process.
Sterilizing technics is going to use direct steam sterilization and flash dehydration cooling. On the one hand, it can kill bacteria in curd effectively. On the other hand, it can remove beany flavorand peculiar smell in soybean milk.
It is considered to use enzymolysis technology to produce injected protein isolate. It can increase product variety.