We received an inquiry today from one of our plants about using pea starch as an alternative to corn starch. The question I have is what are the critical properties of unmodified Pea Starch used in corrugating adhesives? Also, is there a Caustic Sensitivity Test Procedure for pea starch.
What a coincidence, just last week we had a presentation by Roman Skuratowskicz from Ingredion regarding this subject. He has again been so gracious to share his knowledge.
Most of the critical properties are the same that apply to corn starch used in corrugating.
Primarily, the alkali sensitivity must be controlled to prevent the adhesive from having an unstable viscosity and prevent possibility of gelling in storage.
The base starch needs to have consistent viscosity as well. Because of the high variability of base pea material, and the lack of expertise with manufacturing product for corrugating applications, it is difficult to find a consistent source of pea starch for corrugating.
Also, many providers will actually have lower purity (closer to pea flour) since their primary product is the pea protein for food use. This will impact both formulation and stability in storage.
Pea starch is also significantly different than corn starch in formulation. It will require less caustic and borax, is hydrophobic, and has a larger particle size than corn starch which impacts conveyance and cookout. As a result, significant formulation changes will be necessary if you find a consistent source of pea starch. If the starch properties are inconsistent, then each batch will need custom formulation.
We have two internal test methods we use on incoming starch. I’ll provide these as reference only.
SMA-A51 – Brookfield UL method – fast test, requires specific instrument.
SMA-A52 – settling test method – basic equipment required, takes 24 hours to run and prone to errors, otherwise useful as field test.
Thank you Roman for sharing your knowledge and this useful information.
I’ll research this a bit more as interest in the topic seems to be growing. Some information I have discovered. If, as Roman points out, you can find a supplier with a consistent product, and achieve the proper formulation, tests have shown that pea starch can be stable and have similar performance characteristics to corn starch. The addition of waterproof resins can result in a water resistance exceeding 24 hours.
Tests have shown pea starch has a gel temperature approx. 5 degrees F lower than corn. Therefore, it could lead to lower energy consumption/cost, and faster tack/setup could lead to higher running speeds on the corrugator. However, more research is needed before it’s decided if this is a viable option for NA corrugated operations.
We’ll keep digging, and as usual, if others have knowledge or experience to share, please do.