Interesting… I take about 7 grams of CrM, which I purposely add to my coffee after I’ve cooled it down with a good dose of cold milk, inulin, cocao… so I think its likely around 120 to 140 degrees F at that point.
The point about “Stability” below seems to suggest at temps below 60C its still very stable, so us coffee drinkers should be ok (assuming only moderately hot coffee, not really hot), shouldn’t we?
6. Solubility
One of the limitations in terms of developing consumer products containing CrM is that CrM powder is not highly soluble. For example, when mixing CrM in solution, some CrM residue remains at the bottom of the glass requiring consumers to add more fluid, swirl, and quickly ingest to ensure they consumed all the creatine. While this has no effect on creatine bioavailability as CrM is nearly 100% bioavailable [12,25,58,59], there has been interest in finding ways to improve the solubility of creatine. The solubility of creatine in water increases linearly with increasing temperature. In this regard, about 6 g of creatine dissolves in one liter of water at 4 °C (39.2 °F) while 14 g/L are dissolved at 20 °C (68 °F), 34 g/L are dissolved at 50 °C (122 °F); and, 45 g/L are dissolved at 60 °C (140 °F) [25]. This is the reason that some researchers initially administered CrM to participants in warm to hot water [12] or hot tea [60]. Creatine solubility can also be improved by administering CrM in lower pH solutions like juices and sport drinks that generally have pH levels ranging from 2.5–3.5 [61] and/or blending CrM with carbohydrate and/or protein powders or in juice which helps suspend CrM in solution, reduce sedimentation, and enhance creatine uptake into muscle [20,21,22,23,62].
Stability
Creatine monohydrate is very stable in powder form, showing no signs of degradation to creatinine over years, even at elevated temperatures [25]. For example, Jäger [51] reported that CrM powder showed no signs of degrading to creatinine even with temperatures up to 40 °C (104 °F) for more than three years. Additionally, even when CrM was stored at 60 °C (140 °F), creatinine could only be detected in trace amounts after 44 months of storage [51]. However, creatine is not as stable in solution due to intramolecular cyclization that converts creatine to creatinine (see Figure 4A). Generally, creatine degrades to creatinine in solution at a faster rate as pH decreases and temperature increases [25,52,53,54]. For example, as seen in Figure 4B, Harris and coworkers [55] reported that creatine is relatively stable for 3 days in solution at neutral pH (6.5 to 7.5) However, the rate of degradation to creatinine increased when stored at 25 °C when pH decreased (e.g., 4% at 5.5 pH; 12% at 4.5 pH; and 21% at 3.5 pH) [55]. However, as described below, the conversion of creatine to creatinine is halted at pH levels < 2.5. For this reason, it is recommended that CrM should be consumed immediately after it is mixed in an acidic beverage or refrigerated to slow the degradation to creatinine and consumed within a couple of days. However, recent reports presented shelf-life stability data of CrM suspended in a solution of 70% for 13-months at neutral pH and 100% for 12 months at a pH of 2.8 [56,57].
Creatine Monohydrate
As noted above, CrM is the gold standard to compare other purported forms of creatine due to its known bioavailability, pharmacokinetics, efficacy, and safety
