When choosing ingredients for phycocyanin, the key question is often not extraction itself but what happens after extraction: drying, encapsulation, storage, and incorporation into a food. Trehalose and maltodextrin can both help formulate stable powders, but they play different roles, and the best choice depends on the process and product.
1. Trehalose: a protein protectant for demanding processing
Trehalose is a non-reducing disaccharide. In dry formulations, sugars such as trehalose are often used to protect proteins through hydrogen-bonding and glass-formation models sometimes described as water replacement and vitrification. These mechanisms are formulation principles; the measured protection still depends on concentration, moisture, pH, drying method, and the phycocyanin source.
There is direct evidence for trehalose-containing phycocyanin systems under specific conditions. A high-hydrostatic-pressure study tested sugars including trehalose and found concentration-dependent protection of Spirulina phycobiliproteins during pressure treatment. Another study formulated phycocyanin in gelatin candies with trehalose and citric acid and observed improved pigment retention during simulated gastric digestion with pepsin. That in-vitro result does not establish increased absorption or bioavailability in people. Read the pressure study and the digestion study.
Trehalose is not automatically the best choice for heat stability. In an aqueous Spirulina-extract comparison at similar concentrations, sucrose provided greater thermal stabilization than trehalose. The study also found that sugar concentration and water activity mattered, so this result should not be generalized to every dry powder or food matrix. Read the thermal-stability study.
2. Maltodextrin: an economical wall material and carrier
Maltodextrin is commonly used as a wall material in spray-dried and freeze-dried powders. It can help form a dry matrix around phycocyanin and is often selected for its low cost, mild flavor, and formulation flexibility. In one study using trehalose and trehalose–maltodextrin carriers, increasing the maltodextrin share raised the measured glass-transition temperature. During high-temperature storage, the maltodextrin-containing delivery systems better preserved Spirulina-extract color than the trehalose system under the tested conditions. Freeze-dried samples retained more than 89% of their phycocyanin after encapsulation, regardless of matrix composition. Read the carrier-comparison study.
Maltodextrin can also be combined with other wall materials. In a freeze-drying study, a maltodextrin–gum-arabic blend helped retain C-phycocyanin color; the reported best blend for that specific formulation was 25:75 maltodextrin to gum arabic. It is a useful starting point for further testing, not a universal optimum. Read the freeze-drying study.
What about Maillard browning? Maltodextrin has reducing end groups, so reaction with protein amino groups is chemically possible. However, calling the risk “high” in every phycocyanin formula is too broad. Reaction rate depends on factors such as dextrose equivalent (DE), moisture, temperature, pH, time, and the protein-to-carrier ratio. General protein–maltodextrin studies show that controlled glycation can be used intentionally, while more extensive reaction can change color and protein properties. For a phycocyanin product, monitor color, fluorescence, and storage stability in the actual formula rather than assuming browning will occur. See a study of Maillard reaction conditions in a protein–maltodextrin system.
3. How should formulators choose—or combine them?
| Formulation goal | Possible starting point | What to verify |
|---|---|---|
| Protect pigment through freeze-drying or pressure processing | Screen trehalose and mixed-sugar systems | Residual color and protein structure at the actual pH, pressure, and concentration |
| Build an economical powder wall and improve warm-storage performance | Screen maltodextrin, including blends with another wall material | Glass transition, water activity, solubility, caking, and color retention |
| Balance protection and carrier cost | Compare trehalose–maltodextrin ratios side by side | Drying yield, storage stability, flavor, reconstitution, and batch-to-batch consistency |
A practical comparison should use the same phycocyanin source, solids level, drying process, package, and storage conditions. Maltodextrin is often a strong carrier choice; trehalose may be useful when the formulation needs a non-reducing sugar and targeted protein protection. A blend can balance those functions, but its performance must be measured rather than assumed.
One market claim also needs care: saying trehalose is generally poorly accepted in Europe is not supported by regulatory status alone. Trehalose has been authorized as a novel food ingredient in the European Union; authorization does not prove consumer preference, which should be assessed separately for each market and product. See the EU Union list of novel foods.
Takeaway: Trehalose is most often discussed for protein protection, while maltodextrin is valued as a carrier and powder-forming wall material. The evidence does not support a universal winner: choose based on the processing step, storage target, color requirements, cost, and results from the finished formulation.