Effect of pH on Freeze-thaw Stability of Glycated Soy Protein Isolate

Abstract

Introduction Many proteins are used as high-efficiency emulsifiers because they contain both hydrophobic and charged hydrophilic regions, which reduce the surface tension and interact at the emulsions interface 1 , they are widely used in food, nutrition, and pharmaceutical industries. In order to maintain microbiological and chemical stability and extending the shelf life of food products, freezing becomes one of the most important preservation methods. When the emulsions are stored at 20 , a variety of phenomenon can occur including creaming, sedimentation, oiling off and phase separation of the emulsions 2 , which limit its application in the food industry. And protein emulsions stability is sensitive to environmental stress, such as pH, ionic strength, and temperature 3. Degner et al. 4 reported that the freeze-thaw instability of emulsions was mainly related to the crystallization of oil-water phase and the change in droplet microenvironment conditions pH, viscosity, osmotic pressure and ionic strength. Both proteins and polysaccharides play an important role in terms of structure and stability 5. Polysaccharides and proteins can be used in the preparation of edible film applications in the food field 6. Polysaccharides can also act as catalysts to promote the amination of 1,2-epoxycyclohexane 7. In addition, polysaccharides can be used in the medical field due to their biological activity 8. The enhanced emulsifying properties of protein-polysaccharide

Effect of Ionic Strength on Freeze–Thaw Stability of Glycosylated Soy Protein Emulsion

“…Later, the enzyme was incubated for 10 min (heat inactivation). Soy Protein Isolate Hydrolysate (SPH) having a degree of hydrolysis of 3% was obtained, followed by lyophilization to obtain a SPH solid, which was stored at −20 °C (Wang et al, 2019).…”

Glycation of Plant Proteins Via Maillard Reaction: Reaction Chemistry, Technofunctional Properties, and Potential Food Application

“…The optimal degree of glycation again depends on the molecular weight of the carbohydrate [120]. After the adjustment of these parameters, glycated soy proteins are able to form emulsions with smaller droplets that are better able to withstand heat treatment [121,122], ionic stress [123,124], changes in pH [124,125], and freeze-thaw cycling [126,127] compared to emulsions stabilized by non-glycated soy proteins. Changes in the secondary and tertiary structure of the protein, as well as their increased molecular weight, suggest that the conjugated carbohydrates on the emulsion-droplet surface provide steric stabilization against these environmental influences [120].…”

“…Numerous studies have evaluated the emulsifying activity index and the emulsion stability index of the glycated proteins compared to the proteins before glycation [130,192,197]. In addition, the resistance of these emulsions against extrinsic factors such as heat treatments, salt addition, pH changes, or freezingthawing has been evaluated [121,127,179].…”

Glycation of Plant Proteins via Maillard Reaction: Reaction Chemistry, Technofunctional Properties, and Potential Food Application

“…The optimal degree of glycation again depends on the molecular weight of the carbohydrate [119]. After the adjustment of these parameters, glycated soy proteins are able to form emulsions with smaller droplets that are able to withstand heat treatment [120,121], ionic stress [122,123], changes in pH [123,124] and freeze-thaw cycling [125,126] better compared to emulsions stabilized by non-glycated soy proteins. Changes in the secondary and tertiary structure of the protein as well as their increased molecular weight suggest that the conjugated carbohydrates on the emulsion droplet surface provide steric stabilization against these environmental influences [119].…”

“…Numerous studies evaluate the emulsifying activity index and the emulsion stability index of the glycated proteins compared the proteins before glycation [129,191,196]. In addition, the resistance of these emulsions against extrinsic factors such as heat treatments, salt addition, pH changes or freeze-thawing has been evaluated [120,126,178].…”