Bioactivity of Soy Protein Hydrolysates Conjugated with Mannose and Allulose

The practical question

If you formulate with soy protein or rare sugars, you want to know what conjugation actually buys you. This paper from Foods (DOI: 10.3390/foods13193041) answers that with data. The researchers linked soy protein hydrolysates to mannose and allulose through the Maillard reaction. Then they tested what those conjugates could do.

Why this matters

Non-enzymatic conjugation of peptides through the Maillard reaction is not just a flavor chemistry story. It is becoming a way to boost biological function. Soy protein hydrolysates already contain bioactive peptides. Add a sugar like allulose, and those peptides may gain new antioxidant or enzyme-inhibiting properties. This matters for product developers who want functional claims without adding exotic enzymes or costly processing steps.

What the study did

The team created conjugates of soy protein hydrolysates with mannose and allulose. They measured DPPH radical scavenging, ferric reducing antioxidant power (FRAP), pancreatic lipase inhibition, and ACE inhibition. Each assay points to a different product benefit. DPPH and FRAP tell you about antioxidant capacity. Lipase inhibition relates to fat digestion. ACE inhibition connects to blood pressure regulation.

Key findings

The allulose conjugate, referred to as SPHA, stood out. It showed strong DPPH radical scavenging activity at 280.87 ± 16.39 µg Trolox/mL. FRAP reached 38.91 ± 0.02 mg Trolox/mL. That is a solid electron-donating capacity. The same conjugate inhibited pancreatic lipase by 29.43 ± 1.94%. That is not a massive number, but it is meaningful for a peptide-sugar conjugate.

The ACE data looks different. Both the conjugated mixtures and the rare sugars themselves showed ACE inhibitory properties. That means the sugar component may be doing some of the work, not just the peptide.

Assay	SPHA result
DPPH radical scavenging	280.87 ± 16.39 µg Trolox/mL
FRAP	38.91 ± 0.02 mg Trolox/mL
Pancreatic lipase inhibition	29.43 ± 1.94%
ACE inhibition	Present in conjugated mixture and in rare sugars alone

What this means for manufacturers

This gives ingredient buyers a concrete reason to look at allulose beyond sweetness. Allulose can act as a functional conjugation partner. The antioxidant evidence is measurable, not just theoretical. That opens the door for prototypes aimed at oxidative stress or weight management. The lipase inhibition data supports products positioned around fat handling.

Formulators should ask suppliers for the exact reaction conditions. Sugar-to-protein ratio, time, and temperature will change the outcome. The abstract does not give dosage data. You will need your own stability and matrix testing before making claims. But the starting point is promising.

FAQ

Does this mean allulose alone is an antioxidant?

No. The activity comes from the conjugate, not from allulose by itself. The rare sugar may contribute, but the peptide-sugar structure drives the measured effects.

What does SPHA stand for?

SPHA appears to be the soy protein hydrolysate–allulose conjugate. The paper uses that abbreviation for the allulose version. Check the full text for exact preparation details.

Can I use this for a label claim?

Not yet. This is one dataset. You need verification in your food matrix and, depending on your market, regulatory review before making health-related claims.

Where this leaves you

Soy protein hydrolysates already earn their place in food formulas. Conjugate them with allulose, and you get measurable radical scavenging, FRAP activity, lipase inhibition, and ACE inhibition. That combination is rare in a single ingredient. Buyers should ask for SPHA prototypes. Formulators should test them in real recipes. The data is early, but it gives you a clear next step.