Buyers comparing ascorbic acid 90% granules with 99% fine powder usually start from price per kilogram, and that is the one comparison that misleads. The two products differ in vitamin C content, in how they behave on a blending line, and in what they cost per unit of vitamin C delivered into the finished product. This page sets out the comparison the way a purchasing and production team actually needs it.
What the two products are
Both are L-ascorbic acid, CAS 50-81-7. The difference is what else is in the bag.
|
Ascorbic acid 90% granules |
Ascorbic acid 99%+ fine powder |
| Composition |
About 90% L-ascorbic acid granulated with starch as the inactive ingredient |
L-ascorbic acid with only trace impurities |
| Assay |
89.0 – 92.0% on dry basis |
99.0 – 100.5% on dry basis |
| Physical form |
Coarse granule: 90% min through 20 mesh, 25% max through 100 mesh |
Fine crystalline powder |
| Vitamin C per kg |
About 900 g |
About 990 g |
| Standard |
Food / feed grade with a supplier specification |
FCC, E300, USP/EP depending on grade |
Where they behave differently
| Consideration |
90% granules |
99%+ powder |
Practical consequence |
| Flow through a feeder |
Free-flowing and predictable |
Bridges, rat-holes and floods |
Granules suit volumetric and loss-in-weight feeders without an agitator |
| Dust |
Low |
High |
Powder needs extraction, PPE and more housekeeping |
| Segregation in a dry blend |
Low – granule size is close to typical carriers |
High – fines sift downward through flour or premix |
Granules hold their place in the blend through conveying and packing |
| Dissolution |
Slower, leaves a light haze from the starch |
Fast and clear |
Powder for liquids and clear beverages; granules for dry systems |
| Compaction in storage |
Resists caking better |
Cakes in humid conditions |
Granules are more forgiving in tropical stores |
| Cost per kg |
Lower |
Higher |
Not the comparison that matters – see below |
| Cost per unit of vitamin C |
Higher (about 10% of the weight is starch) |
Lower |
The granules carry 10% more mass in the blend, the bag and the freight |
The comparison that actually decides the bid
Convert every quote to cost per kilogram of vitamin C before comparing, and add the freight and handling difference on the extra 10% of mass.
| Step |
How to do it |
What goes wrong if skipped |
| 1. Normalise the assay |
Divide the price per kg by the assay as a fraction (0.90 or 0.99) |
A cheaper granule can be more expensive per unit of vitamin C |
| 2. Check the assay basis |
Confirm both quotes are on a dry basis |
Comparing an as-is figure with a dry-basis figure |
| 3. Add freight per unit of vitamin C |
Granules ship 10% more mass for the same vitamin C |
Delivered cost comparison comes out wrong for distant destinations |
| 4. Cost the handling difference |
Dust extraction, PPE, feeder performance, blend rework |
The cheapest powder can be the most expensive line to run |
| 5. Check the label consequence |
Starch has to be declared; the 90% figure is not vitamin C per weight |
Nutrition declaration errors and relabelling |
Choosing, by situation
| If your use is… |
Choose |
Why |
| Flour, cereal or grain fortification |
90% granules |
Needs to survive dry blending and conveying without segregating |
| Feed premix or compound feed |
90% granules |
Dust and segregation are the dominant problems, not dissolution |
| Tablet or capsule blend |
90% granules |
Better flow to the press, less dust in the room |
| Beverage, syrup or clear liquid |
99%+ powder |
The starch hazes the product and the dissolution is slower |
| Solution made up in the plant |
99%+ powder |
Fast dissolution and no carrier residue |
| Pharmaceutical formulation |
99%+ monograph grade |
The 90% granule is a food/feed grade, not a compendial grade |
Buying checklist for the granulated grade
| Item |
What to confirm |
| Assay and basis |
89.0-92.0% on dry basis, stated as such |
| Particle size |
20 mesh / 100 mesh limits – this is the parameter that delivers the flow |
| Loss on drying |
Max 0.7%; moisture drives oxidation and caking |
| Microbiology |
TPC, yeast and mould, E. coli – starch is a microbial substrate |
| Starch declaration |
Which starch, and the allergen statement that goes with it |
| Packaging |
25 kg sack with PE liner; liner integrity matters more than for powder |
| Documentation |
Batch COA plus SDS and a food-grade statement |
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