Biological Activities of Soy Protein Hydrolysate Conjugated with Mannose and Allulose

A new functional angle for allulose

Allulose keeps looking less like a simple sugar swap. In this study, researchers took soy protein hydrolysate, conjugated it with mannose and allulose through the Maillard reaction, and screened the resulting molecules for bioactivity. The allulose conjugate, abbreviated SPHA, carried most of the weight in the reported results. The paper appears in Foods (DOI: 10.3390/foods13193041).

Background

The Maillard reaction does more than brown bread. When peptides react with reducing sugars, the non-enzymatic conjugation creates new glycated compounds. Those compounds often carry biological functions that the starting peptide or sugar lack. That’s why food chemists use this reaction to upgrade protein hydrolysates. Soy protein hydrolysate is already a versatile ingredient. Attaching rare sugars like allulose to it could make it even more useful.

What the Study Did

The researchers made conjugates from soy protein hydrolysate and two sugars: mannose and allulose. They then ran a set of bioassays. DPPH and FRAP measured antioxidant activity. A pancreatic lipase test measured potential to slow fat digestion. An ACE inhibition screen checked for blood pressure modulation potential.

Key Findings

SPHA stood out in the antioxidant tests. DPPH radical scavenging activity reached 280.87 ± 16.39 µg Trolox/mL. FRAP reducing power hit 38.91 ± 0.02 mg Trolox/mL. Those numbers tell formulators that the conjugate can neutralize free radicals and donate electrons.

The lipase result is smaller but still relevant. SPHA inhibited pancreatic lipase by 29.43 ± 1.94%. That suggests a possible role in formulations aimed at reducing fat digestion.

ACE inhibition showed up in the conjugated mixture and in the rare sugar itself. The sugar is not just a passive carrier. It contributes directly to that activity.

Assay	What it tells formulators	SPHA (allulose conjugate) result
DPPH	Free radical scavenging capacity	280.87 ± 16.39 µg Trolox/mL
FRAP	Antioxidant reducing power	38.91 ± 0.02 mg Trolox/mL
Pancreatic lipase inhibition	Potential to slow fat digestion	29.43 ± 1.94% inhibition
ACE inhibition	Potential blood pressure modulation	Detected in conjugate mixture and rare sugar alone

What It Means for Manufacturers

This is a practical signal for ingredient buyers. A single conjugated peptide-sugar system can deliver antioxidant and lipase-inhibiting activity together. That combination fits weight management and cardiovascular product concepts. But read the data at ingredient level, not clinical level. These are bioassays, not human outcomes.

Formulators will still need to confirm that the conjugate survives processing, holds its activity in a food matrix, and tastes acceptable. The study stops at bioactivity. The next step is figuring out how to deliver it in a real product.

FAQ

What does SPHA stand for?

SPHA refers to the soy protein hydrolysate–allulose conjugate used in the study. The Maillard reaction forms the link between the hydrolysate peptides and allulose.

Did the sugars themselves show activity?

Yes. The rare sugar alone displayed ACE inhibitory activity in the experiments. That matters because it means the bioactive effect is not entirely dependent on the peptide carrier.

Is this ingredient ready for commercial use?

Not based on this paper alone. The study provides bioactivity data, not finished-product validation. Treat it as a starting point for development work and supplier conversations.

Closing

The science is early, but the direction is clear. Rare sugars can do more than replace sucrose. When paired with soy protein hydrolysate, allulose becomes part of a molecule with antioxidant, lipase-inhibiting, and ACE-inhibiting potential. That’s a combination worth testing in your own lab.