Aolong Chemical Product Knowledge
Choose a calcium propionate grade by starting with how it will be used. For a dry mix, check how evenly it spreads and whether the blend stays even during transfer. For an automatic feeder, measure how much material comes out over time. For a solution tank, measure how long it takes to reach the required dissolved concentration.
Ask for the grade name, batch test results and particle size data before comparing samples. These details help explain why two bags with the same chemical assay can behave differently on a production line.
What do powder, granules and crystalline powder mean?
Calcium propionate is the calcium salt of propionic acid. Its CAS number is 4075-81-4 and its anhydrous formula is C₆H₁₀CaO₄. The FAO and WHO JECFA specification describes white crystals, powder or granules. China's GB 1886.356-2022 lists these appearances and gives the formula as C₆H₁₀CaO₄·nH₂O, with n equal to 0 or 1. [1] [2]
| Form name | What the name describes | What to ask for |
|---|---|---|
| Powder | Fine particles as supplied. | Particle size results and how the powder feeds or spreads in the mix. |
| Granules | Separate particles that are usually larger than a powder grade. | The mass in the agreed size range, the fine fraction and results after handling. |
| Crystalline powder | A powder described by its crystalline appearance or structure. | The exact grade and measured size distribution. If the solid form matters, ask for the relevant test results. |
For a powder sample, look at how easily it breaks up during mixing and how much material stays in the bag or hopper. For granules, check the size range and what happens after the normal unloading and transfer steps. A sample in a jar gives you a first look. A sample taken at the mixer inlet shows what actually reaches the process.
Aolong lists powder, granular and crystalline powder products. Its public Powder TDS describes the appearance as white crystalline powder. If a supplier offers both Powder and Crystalline Powder, ask for the two grade codes, their particle size results and the agreed limits for each. That makes the comparison specific enough to use in an order. [3]
How do you compare the assay on two certificates?
A technical data sheet, or TDS, describes the grade. A certificate of analysis, or COA, records test results for a batch. Aolong's public Powder and Granular TDS both give a minimum assay of 99.0% on a dried basis. For a trial, use the batch values and check how the assay is reported. [3]
Dried-basis assay is the share of the dried sample reported as calcium propionate. The amount in a bag as received also depends on how much mass the sample loses on drying. Loss on drying measures mass driven off by the test. If the process depends on water content or hydrate identity, agree on a suitable test for that specific property. [1] [2] [6]
Here is a calculation example. A 100 g sample with a measured loss on drying of 2.0% leaves 98.0 g on that drying basis. If its dried-basis assay is 99.0%, it contains 98.0 × 0.99 = 97.02 g of calcium propionate, expressed on the same chemical basis as the assay. Use matching batch results and the same drying basis when making this conversion. These numbers are for illustration.
How do you make a particle size requirement measurable?
For a sieved grade, ask for the sieve opening sizes in millimetres or micrometres. Record the mass that stays on each sieve and the mass that passes the smallest opening. Include the sampling method and the test settings so another lab can repeat the comparison. Fine powders may need a different size method when particles stick together or block the sieve. [4]
In an example test, 4 g of a 100 g sample stays on a 1.00 mm sieve. Another 92 g passes that sieve and stays on a 500 µm sieve. The last 4 g passes 500 µm. The result is 92% by mass in the stated sieve band and 4% below it. Use your trial to set the acceptable limits for your equipment.
When you compare incoming and transferred material, sample the same lot using the same size test. For a long transfer run, take samples at several points in the run. A rise in fines at the outlet tells you that the material reaching the next step has changed. Check the sampling locations and handling conditions before attributing the change to particle breakage.
How should each grade be tested on the line?
Dry mixing and transfer
Start with the real recipe or a premix with similar ingredients. Keep batch size, the order of addition, mixing time and mixer settings the same across grades. Take several samples at set points during discharge and test each separately for the ingredient level. A single combined sample can show an average while leaving large differences between portions hidden.
If the mix then travels through a chute, conveyor or holding bin, sample again near the point where it is used. Lab chute tests on other powders show that the size mix can change by sampling position during transfer. A good blend at the mixer should therefore be checked at the next step too, especially if it goes through several transfers. [8]
Automatic feeding
Bulk density is the mass per volume of the material in a container, including the spaces between particles. A change in bulk density can change the mass delivered by a feeder set to move a fixed volume. Record how the density was measured and compare samples prepared the same way. Confirm the result on the feeder you plan to use. [5]
Set the feeder to its normal speed and collect material for several equal time periods. Weigh each portion. Record the average output, the range and any breaks in flow. Test at a normal hopper fill level and again near the level where the plant usually refills it. Note any material that forms an arch and stops flowing above the outlet.
For example, collecting 250 g in 30 seconds gives a feed rate of 30 kg per hour. Use the separate collection weights to see whether the rate holds steady. A feeder that falls below the target for part of the run and goes above it later can still give the right average. Agree on the variation your process can accept as well as the average rate.
Making a solution
JECFA describes calcium propionate as freely soluble in water. Solubility describes how much can dissolve under stated conditions. Dissolution time describes how long the chosen sample takes to reach the required level in solution. For a plant that prepares a liquid premix, the time needed to reach that level can affect the batch schedule. [1]
Use the same vessel, water source, temperature, mixing speed and target concentration for each sample. Weigh each grade using its batch assay if you need to compare equal amounts of calcium propionate. Use the same order and speed of addition. Start timing at the same point in the process and record whether material floats, forms lumps or settles during mixing.
Set the test endpoint in advance. A visual check for visible particles can help compare trial runs. If dissolved concentration determines acceptance, take a sample at the planned mixing time and check it with a suitable test. Record any residue and repeat the comparison under the same conditions so you can judge how much the result varies.
How does form selection relate to shelf life?
The feeding, blending and solution tests show how well the grade can be added to the recipe. For shelf life, test the finished product with the intended process, packaging and storage conditions. Keep the target amount of calcium propionate the same across the samples if the purpose is to compare forms.
Suhr and Nielsen studied bakery spoilage fungi in lab media under different conditions. They observed shorter times before spoilage at higher pH and water activity in their screening tests. Water activity describes how available water is in the food. The study helps identify conditions to track in a product trial, together with the recipe, storage temperature and test duration. [7]
What belongs in the purchase specification?
- Grade and batch. State the commercial grade, the chemical standard agreed for the order and the assay basis. Keep the COA for the trial lot.
- Particle size. State the sampling and test method, the required mass in the sieve band and the limit for fines where it affects the line.
- Trial conditions. Record where the samples were taken and the settings used for feeding, mixing or dissolving.
- Acceptance results. Set limits that the plant can check, such as the acceptable feeder output range, the spread of results across blend samples or the time to the solution endpoint.
- Approval sample. Keep a labelled sample and the test record so later deliveries can be checked against the same requirements.
Sources and further reading
[1] FAO and WHO JECFA calcium propionate specification
[2] GB 1886.356-2022, Food Additive Calcium Propionate
Official copy of the Chinese standard
[3] Aolong Chemical product listings and technical data sheets
Product catalogue
Powder TDS
Granular TDS
Crystalline powder catalogue entry
[4] USP General Chapter 786, Analytical Sieving
[5] USP general chapters on bulk density and powder flow
Chapter 616, Bulk Density of Powders
Chapter 1174, Powder Flow
[6] USP General Chapter 731, Loss on Drying
[7] Suhr and Nielsen (2004), weak acid preservatives and bakery spoilage fungi
International Journal of Food Microbiology 95, 67–78
Study abstract in the DTU Research Database