Most of our frozen foods contain a thickener, sometimes also (but incorrectly!) called a binder. Why do we use thickeners? The answer is simple: to be able to pump the food through the hopper lines or dispensing nozzles of the used processing equipment.
Should we package bloodworms only (for example) and not add any water or any thickener solution, the pumps and dispensing nozzles of the filling machines would not be able to pick up, or suck up, the bloodworms. Even only adding water will not help as the bloodworms will not stay in suspension and sink to the bottom of the filling tray or hopper. Most of the time the nozzles would only be sucking up water! We therefore add a thickener to the water, before mixing the solution with the organisms being processed.
What is a thickener? It is any agent or substance able to increase the viscosity (the thickness) of a liquid (water in our case). It’s like adding starch to soup to make it thicker. We make a thickener solution by dissolving a fixed amount of thickening agent in a fixed amount of water, with this thickener solution then being added to the food, e.g. bloodworms. Because the thickness of the solution has increased, the bloodworms and the thickener solution do not separate anymore (the bloodworms stay in suspension) and our filling equipment is able to pick up and transport the food into the cube blisters or flat-packs.
We only use one thickener: guar gum. Other thickeners used years ago were carrageenan, sodium alginate and xanthan gum. All of these are carbohydrates which have the following properties:
- They are rather easy to dissolve in cold water.
- They do not gel under our processing conditions.
- Dissolving these substances results in a clear solution.
Should we use corn, bean or potato starch for example, the resulting solution would have a milky color which would not be acceptable for most people keeping an aquarium.
Something frequently stated in certain discussion forums years ago was ‘Binders contain a high phosphate (PO43-) level and as such will cause havoc in reef aquaria’. That is an incorrect statement however, as phosphorus cannot even be detected in guar gum, which is logical as guar gum is a carbohydrate (or polysaccharide) composed of the sugars galactose and mannose, and these sugars do not contain any phosphate groups.
Maybe the binders used in the food industry were being confused with the binders, consisting of phosphates, added to laundry detergents? When using a detergent with hard water, so water having a high mineral content, it’s hard to get a soapy solution as the detergent reacts with the minerals (mostly calcium and magnesium) to form soap scum. Therefore phosphates are added as water softeners, so to bind to the minerals and turn the hard water into soft water. But those phosphates, named ‘binders’ because the added phosphates will bind to the minerals, are a completely different set of substances compared to the thickeners we use in our foods. Those binders and our thickeners have absolutely nothing to do with each other.
