Optimized Preparation, Functional Evaluation and Performance in Spray Drying of Soybean Peptide-Saccharide Conjugates Prepared by Wet Heating Maillard Reaction.

To improve the functional properties and drying aid role in spray drying of soybean peptide (SP), SP was respectively conjugated with eight saccharides (maltose, lactose, maltodextrin, inulin, α-cyclodextrin (α-CD), β-CD, dextran-20000, and dextran-40000) via wet-heated Maillard reaction, and the efficacy of conjugates in spray-drying of Lycium barbarum extracts rich in low-molecular-weight sugars and organic acids was systematically evaluated. Among the conjugates, SP-α-CD exhibited the highest graft-browning equilibrium index (143.52%) and emulsifying activity index (4.63 m2/g). Through Box-Behnken experimental optimization, the ideal conjugation conditions were identified as: 30 mg/mL SP concentration, 70 °C reaction temperature, and 2.5 h reaction time. When SP-α-CD (10% w/w) co-spray dried with the extract (90%), it could effectively prevent the wall sticking, and the powder yield reached 73.94% (~ 20.74% higher than that achieved by the native SP). The hygroscopicity and softening point (being increased to 69.77 °C) of the powder was improved. X-Ray photoelectron spectroscopy analysis revealed that during spray drying, SP-α-CD tends to distribute on the powder surface, encapsulating the extract components and achieving stronger drying aid and encapsulation effects. Collectively, it is expected to be developed as a spray drying aid for sugar-containing extracts and as a wall material for food and pharmaceutical microencapsulation.