Interfacial and foaming properties of bovine β-lactoglobulin: Galactose Maillard conjugates

Changes in the structure and functional properties of soybean isolate protein: Effects of different modification methods

Soybean protein isolate (SPI) is an important plant protein in food processing; however, its spherical structure prevents the exposure of its hydrophobic residues and affects its functional properties. In this study, we elucidate the effects of deamidation, phosphorylation, and glycosylation on the structure (Fourier-transform infrared spectroscopy, circular dichroism, fluorescence, and scanning electron microscopy) and functional properties (solubility, emulsifying activity index (EAI), and emulsifying stability index (ESI)) of SPI. The zeta potentials of the deamidated, phosphorylated, and glycosylated (DSPI, PSPI, and MSPI, respectively) samples decreased significantly (p < 0.05) relative to those of SPI. The functional properties of the modified SPI samples were improved, with MSPI-2 showing the best solubility (86.73 ± 0.34%), EAI (118.89 ± 0.73 m2/g), and ESI (273.33 ± 0.59 min). Moreover, the effects of the three modifications on the SPI functional properties increase in the order MSPI > PSPI > DSPI. These results provide a theoretical understanding the relationship between the modifications and SPI structure.

Preliminary study of physicochemical, thermal, rheological, and interfacial properties of quinoa oil

Background: The growing popularity of nutrient-rich foods, among which is quinoa, is due to the increasing demand for healthier choices. Oils and hydrolyzed proteins from these foods may help prevent various health issues. The objective of this work was to perform extraction from the endosperm of the grain from high-protein quinoa flour by physical means via a differential abrasive milling process and extracting the oil using an automatic auger extractor at 160°C, as well as characterizing extracted oil. Methods: Quinoa oil extraction and physicochemical characterization were carried out. Chemical and physical quality indexes of quinoa oil were established, and both characterizations were conducted based on international and Columbian standards. Thermal properties were evaluated by differential scanning calorimetry, and rheological and interfacial properties of the oil were evaluated using hybrid rheometers and Drop Tensiometers, respectively, to determine its potential for obtaining functional foods. Results: The result was 10.5 g of oil/ 100 g of endosperm, with a moisture content of 0.12%, insoluble impurities of 0.017%, peroxide index of 18.5 meq O 2/kg of oil, saponification index of 189.6 mg potassium hydroxide/g of oil, refractive index of 1.401, and a density of 0.9179 g/cm 3 at 20°C. Regarding contaminating metals, it presented 7 mg of iron/kg of oil, a value higher than previously established limits of 5 mg of iron/kg of oil. The oil contained 24.9% oleic acid, 55.3% linoleic acid, and 4% linolenic acid, demonstrating antioxidant capacity. Quinoa oil showed thermal properties similar to other commercial oils. Conclusions: The interfacial and rheological properties were suitable for the stabilization of emulsions, gels, and foams, which are important in various industrial applications and could facilitate the development of new products. The extracted quinoa oil presented similar characteristics to other commercial oils, which could make it a potential product for commercialization and application in different industries.

Modified Structural and Functional Properties of Fish Gelatin by Glycosylation with Galacto-Oligosaccharides

This study aimed to investigate the effects of galacto-oligogalactose (GOS) glycosylation on the structural and functional properties of fish gelatin (FG). Results showed that with the increase of glycosylation time, grafting degree and browning increased, and new protein bands with increased molecular weight were observed by SDS-PAGE. Structural analysis showed that glycosylation reduced intrinsic fluorescence intensity and increased surface hydrophobicity of FG. FTIR analysis showed α-helix content decreased while random coil content increased in glycosylated FG. Emulsion activity index and emulsion stability index along with foam activity and foam stability were significantly elevated in GOS-4 and GOS-8, but FG glycosylated longer than 12 h exhibited less pronounced improvement. Glycosylated FG showed lower gel strength than control. The results indicate that moderate glycosylation could be applied to improve interfacial properties of FG.

Structural and Functional Characteristics of Hemp Protein Isolate–Pullulan Polysaccharide Glycosylation Conjugate in an Aqueous Model System

Hemp protein, with its important nutritional and industrial value, has trickled into the aisles of protein demand; however, its poor functional properties have largely limited its implementation in food. Herein, we aimed to modify hemp protein isolate (HPI) via glycosylation coupling with pullulan polysaccharide, and we subsequently characterized its structural and functional properties. The conjugation variables were HPI to pullulan ratio (i.e., 3:1, 2:1, 1:1, 1:2, and 1:3 w/w), incubation temperature (i.e., 50, 60, 70, 80, and 90 °C), and incubation time (i.e., 3, 6, 12, 24, and 48 h). Native HPI was used as a control for comparison purposes. We found that DG tended to decrease when the pullulan to HPI ratio was greater than 1:1 and when the temperature exceeded 80 °C. SDS-PAGE analysis shows that when the DG is increased, wider and heavier molecular weight bands emerge near the top of the running gel, while such observations were absent in the control. Further, glycosylation could loosen the HPI’s secondary and tertiary structures, as well as increase surface hydrophobicity. The solubility of HPI after glycosylation significantly increased (p < 0.05) at pH 7.0 compared to HPI without glycosylation. Emulsifying activity improved significantly (p < 0.05), with glycosylation with HPI–pullulan at a ratio of 1:3 showing maximum emulsifying activity of 118.78 ± 4.48 m2/g (HPI alone: 32.38 ± 3.65 m2/g). Moreover, the HPI–pullulan glycosylation time of 24 h showed maximum foaming activity (23.04 ± 0.95%) compared to HPI alone (14.20 ± 1.23%). The foaming stability of HPI (79.61 ± 3.33%) increased to 97.78 ± 3.85% when HPI–pullulan was conjugated using a glycosylation temperature of 80 °C. Compared with the un-glycated HPI, HPI–pullulan also increased WHC (4.41 ± 0.73 versus 9.59 ± 0.36 g/g) and OHC (8.48 ± 0.51 versus 13.73 ± 0.59 g/g). Intriguingly, correlation analysis showed that protein functional characteristics were significantly and positively correlated with DG. Overall, our findings support the notion that pullulan conjugation provides further functional attributes to the HPI, thereby broadening its potential implementation in complicated food systems.

Characterization and functional properties of Maillard reaction products of β-lactoglobulin and polydextrose

The Maillard reaction products (MRPs) between polydextrose (PDX), a popular polysaccharide in formula powder, and β-lactoglobulin (β-LG), a major whey protein, were studied in aggregation degree, structure, hydrophobic, antigenic and antioxidant activity changes of β-LG. Incubation of PDX and β-LG (60 ℃, 79% relative humidity) for up to 72 h yielded MRPs with increases in furosine, UV absorbance, fluorescence intensity and loss of free amino groups. High molecular weight β-LG-PDX MRPs were observed by SDS-PAGE. Circular dichroism spectroscopy revealed negligible change in β-LG secondary structure. Changes in the tertiary structure of β-LG were detected by tryptophan fluorescence spectroscopy consistent with an increase in surface hydrophobicity of heated β-LG-PDX. Antigenicity reduction of β-LG in β-LG-PDX reached its peak when heated for 24 h. After heating for 72 h, DPPH radical-scavenging activity of β-LG-PDX increased by 7.4-fold, and the ferric reducing antioxidant power reached 61.1 µmol ascorbic acid/g protein.

Impact of Phenolic Acid Derivatives on β-Lactoglobulin Stabilized Oil-Water-Interfaces

The physical stability of protein-based emulsions depends on intra- and intermolecular interactions of the interfacial protein-film. As studied in aqueous systems before, phenolic acid derivatives (PADs) non-covalently or covalently crosslink proteins depending on pH-value and thus, may impact interfacial protein-films. Whether these interactions occur in the same manner at the interface as in water and how they vary the properties of the interfacial protein-film has not been clarified. The present study aimed to investigate the interfacial protein-film viscoelasticity and physical emulsion-stability after non-covalently (pH 6.0) and covalently (pH 9.0) crosslinking depending on PAD-structure. For this purpose, we studied an interfacial β-lactoglobulin film with dilatational rheology after crosslinking with PADs, varying in number of π-electrons and polar substituents. Then, we analyzed the physical emulsion-stability by visual evaluation and particle size distribution. The results indicate that PADs with a high number of π-electrons (rosmarinic acid and chicoric acid) weaken the protein-film due to competing of phenol-protein interactions with protein-protein interactions. This is reflected in a decrease in interfacial elasticity. PADs with an additional polar substituent (verbascoside and cynarine) seem to further weaken the protein film, since the affinity of the PADs to the interface increases, PADs preferentially adsorb and sterically hinder protein-protein interactions. In emulsions at pH 6.0 and thus low electrostatic repulsion, PADs promote bridging-flocculation. Due to higher electrostatic repulsion at pH 9.0, the PADs are sterically hindered to form bridges, even though they are polymeric. Hence, our research enables the control of protein-film viscoelasticity and emulsion-stability depending on the PAD-structure.

Graphical abstract

Effects of ultrasound-assisted glycosylation on the interface and foaming characteristics of ovotransferrin

Ovotransferrin (OVT) is one of the major functional proteins in egg white protein. Most of the industry only paid attention the biological activity of OVT in iron supplement, antibacterial and other aspects, few reports were carried out on its processing characteristics such as foaming, interfacial behavior such as emulsification and foaming, which was an important processing functional attribute affecting its application scenario. In this study, the effects of ultrasound-assisted glycosylation on the interface and foaming characteristics of OVT were investigated. The results showed that proper ultrasonic treatment had a significant effect on the structure and physicochemical properties of OVT glycosylation products. When ultrasonic treatment lasted for 20 min, the grafting degree of OVT was 20.98%, the particle size decreased and the absolute value of potential increased. The foaming ability of OVT increased first and then decreased after ultrasonic-assisted glycosylation treatment. The foaming ability of OVT increased from 43.54% to 96.73% and the foaming stability increased from 68.92% to 89.19% after ultrasonic-assisted glycosylation treatment for 20 min. The experimental study effectively discovered the effect of ultrasound-assisted glycosylation on the foaming property of OVT, and would provide important technical references for expanding its application in food, biology, medicine and other fields.

Mechanism of differences in characteristics of thick/thin egg whites during storage: Physicochemical, functional and molecular structure characteristics analysis

This study systematically analyzed and compared thechanges of physicochemical, functional and molecular structural characteristics between thick egg white (KEW) and thin egg white (NEW) during storage. Analysis of physicochemical properties showed that moisture content decreased significantly with the increase of pH during storage. KEW was gradually thinning, while NEW was closer to Newtonian fluid. Functional properties indicated that KEW thermal gel was gradually hard and brittle with the properties of NEW. KEW had better emulsifying property than NEW, and NEW had superior foaming ability. The α-helix and β-sheet in the FT-IR spectrum showed a downward trend, revealing secondary structure changed from order to disorder. Enhancement of fluorescence intensity indicated the structural unfolding and exposure of tryptophan residues. SDS-PAGE proved that OVO might be related to the difference between KEW and NEW characteristics. This study provided new idea and reference value for egg storage and diversified utilization of egg white.

Study of biological activities and physicochemical properties of Yamú (Brycon siebenthalae) viscera hydrolysates in sodium alginate-based edible coating solutions

The fishing industry produces waste such as viscera, which is an environmental problem for many countries. Obtaining protein from these wastes are useful for the food industry. In this study, the chemical composition, amino acid profile, solubility, digestibility and thermal properties of Yamú protein isolate (PI) and its hydrolysates obtained by enzymatic hydrolysis were characterized. The hydrolysates (0.05, 0.1, 0.5, 1 and 2% w/v) were mixed with a sodium alginate-based solution to form an edible coating solution (ECS). Antioxidant capacity antimicrobial activity, Zeta potential (ζ) and adsorption kinetics properties were determined. PI contains 88% (w/w) protein showing better solubility, digestibility and thermal stability properties. The hydrolysate concentrations with DPPH inhibitory ECS were 0.1 and 0.5% (w/v). The kinetic properties of ECS showed good stability and excellent adsorption. These results suggest that this Yamú protein has high nutritional potential as an ingredient for the production of functional foods.

Adverse Effects of Thermal Food Processing on the Structural, Nutritional, and Biological Properties of Proteins

Thermal processing is one of the most important processing methods in the food industry. However, many studies have revealed that thermal processing can have detrimental effects on the nutritional and functional properties of foods because of the complex interactions among food components. Proteins are essential nutrients for humans, and changes in the structure and nutritional properties of proteins can substantially impact the biological effects of foods. This review focuses on the interactions among proteins, sugars, and lipids during thermal food processing and the effects of these interactions on the structure, nutritional value, and biological effects of proteins. In particular, the negative effects of modified proteins on human health and strategies for mitigating these detrimental effects from two perspectives, namely, reducing the formation of modified proteins during thermal processing and dietary intervention in vivo, are discussed.

Partitioning Behavior and Interfacial Activity of Phenolic Acid Derivatives and their Impact on β-Lactoglobulin at the Oil-Water Interface

Proteins are able to stabilize dispersed food systems due to their amphiphilic nature, acting as emulsifiers. Their interfacial properties can be influenced by different methods, including the formation of protein-phenol nanocomplexes. In this study, the interfacial behavior of phenolic compounds and protein-phenol nanocomplexes was first characterized according to the oil-water partitioning behavior of phenolic acid derivatives according to their molecular structure and its impact on interfacial tension. The influence of the phenolic compounds on protein film formation and its properties by dilatational rheology was then evaluated. The most phenolic acid derivatives are predominantly present in the aqueous phase. Despite their hydrophobic benzene body, weak interfacial activity was observed depending on their chemical structure. This result supports possible protein-phenol nanocomplex formation in the aqueous phase and possible interactions at the oil-water interface. Protein-phenol nanocomplexes showed decreased interfacial adsorption properties and decreased viscoelastic interfacial behavior, depending on the expansion of the delocalized π-electrons in the phenol.

Glycation of soy proteins leads to a range of fractions with various supramolecular assemblies and surface activities

Dry and subsequent wet heating were used to glycate soy proteins with dextran or glucose, followed by fractionation based on size and solubility. Dry heating led to protein glycation (formation of furosine, Nε-(carboxymethyl)-l-lysine, Nε-(carboxyethyl)-l-lysine, and protein-bound carbonyls) and aggregation (increased particle size); while subsequent wet heating induced partial unfolding and de-aggregation. The measurable free amino group content of soy proteins changed from 0.77 to 0.14, then to 0.62 mmol/g upon dry and subsequent wet heating; this non-monotonic evolution is probably due to protein structural changes, and shows that this content should be interpreted with caution as a glycation marker. After both heating steps, the smaller-sized water-soluble fractions showed higher surface activity than the larger insoluble ones, and dextran conjugates exhibited a higher surface activity than their glucose counterparts. We thereby achieved a comprehensive understanding of the properties of various fractions in plant protein fractions, which is essential when targeting applications.

Protein-Polysaccharide Composite Materials: Fabrication and Applications

Protein-polysaccharide composites have been known to show a wide range of applications in biomedical and green chemical fields. These composites have been fabricated into a variety of forms, such as films, fibers, particles, and gels, dependent upon their specific applications. Post treatments of these composites, such as enhancing chemical and physical changes, have been shown to favorably alter their structure and properties, allowing for specificity of medical treatments. Protein-polysaccharide composite materials introduce many opportunities to improve biological functions and contemporary technological functions. Current applications involving the replication of artificial tissues in tissue regeneration, wound therapy, effective drug delivery systems, and food colloids have benefited from protein-polysaccharide composite materials. Although there is limited research on the development of protein-polysaccharide composites, studies have proven their effectiveness and advantages amongst multiple fields. This review aims to provide insight on the elements of protein-polysaccharide complexes, how they are formed, and how they can be applied in modern material science and engineering.

Glycation of whey proteins: Technological and nutritional implications

Whey proteins are globular proteins that have received much attention due to their high nutritional value and characteristic functional properties. In addition to being part of the protein system in milk, they constitute the main proteins in whey and whey protein products. Interaction of whey proteins with reducing sugars and carbohydrates via Maillard reaction have been extensively studied in milk and in model systems. Glycation of individual whey proteins results in variable increases in their solubility, thermal stability, antioxidant activity, and emulsion and foam stabilization. Limited glycation of whey protein products particularly whey protein isolates (WPI) using polysaccharides has been studied with the aim to produce conjugates with modified functional properties and acceptable sensory properties. An overview is presented here on the effect of glycation on individual whey proteins and whey protein products and the potential uses of the glycated whey proteins.

Comparative Studies on Physicochemical Properties of Bovine Serum Albumin–Glucose and Galactose Conjugates Formed by Glycation Combined with Ultrasonic Pretreatment

The effects of ultrasonication on the physicochemical properties of bovine serum albumin (BSA)–glucose and the galactose conjugates formed by glycation was investigated. Fourier transform ion cyclotron resonance mass spectra analysis showed that the conjugates had a higher molecular weight than the native and ultrasonicated BSA. Ultrasonicated BSA had significantly higher emulsifying and foaming properties than native BSA. The browning intensity, surface hydrophobicity, emulsifying property and foaming capacity of the conjugates were substantially improved while the free amino groups, intrinsic fluorescence emission and foaming stability were decreased compared to native and ultrasonicated BSA. The results of this study indicate that ultrasonication is an efficient technique to improve the physicochemical properties of proteins. The glycation between ultrasonicated BSA and monosaccharide can effectively improve the physicochemical properties of BSA, and the glycation rate order is galactose \gt glucose. It also shows the critical role of monosaccharide conformational changes in improving the glycation and physicochemical properties of proteins.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2011-2012

This review is the seventh update of the original article published in 1999 on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2012. General aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, and fragmentation are covered in the first part of the review and applications to various structural types constitute the remainder. The main groups of compound are oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. Also discussed are medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 36:255-422, 2017.

Antioxidative, Antibacterial, and Food Functional Properties of the Half-Fin Anchovy Hydrolysates-Glucose Conjugates Formed via Maillard Reaction

The antioxidative, antibacterial, and food functional properties of the half-fin anchovy hydrolysates (HAHp)-glucose conjugates formed by Maillard reaction (MR) were investigated, respectively. Results of sugar and amino acid contents loss rates, browning index, and molecular weight distribution indicated that the initial pH of HAHp played an important role in the process of MR between HAHp and glucose. HAHp-glucose Maillard reaction products (HAHp-G MRPs) demonstrated enhanced antioxidative activities of reducing power and scavenging DPPH radicals compared to control groups. HAHp-G MRPs produced from the condition of pH 9.6 displayed the strongest reducing power. The excellent scavenging activity on DPPH radicals was found for HAHp(5.6)-G MRPs which was produced at pH 5.6. Additionally, HAHp(5.6)-G MRPs showed variable antibacterial activities against Escherichia coli, Pseudomonas fluorescens, Proteus vulgaris, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, Bacillus megaterium, and Sarcina lutea, with the MIC values ranging from 8.3 to 16.7 μg/mL. Result of scanning electron microscopy (SEM) on E. coli suggested that HAHp(5.6)-G MRPs exhibited antibacterial activity by destroying the cell integrity through membrane permeabilization. Moreover, HAHp(5.6)-G MRPs had excellent foaming ability and stability at alkaline conditions of pH 8.0, and showed emulsion properties at acidic pH 4.0. These results suggested that specific HAHp-G MRPs should be promising functional ingredients used in foods.

Effect of processing on polyamine content and bioactive peptides released after in vitro gastrointestinal digestion of infant formulas

This study examined the influence of processing on polyamines and peptide release after the digestion of a commercial infant formula designed for children during the first months of life. Polyamine oxidase activity was not suppressed during the manufacturing process, which implicates that polyamine concentrations were reduced over time and during infant formula self-life. In gel electrophoresis, in vitro gastrointestinal digestion of samples with reduced amount of enzymes and time of digestion shows an increase in protein digestibility, reflected in the increase in nonprotein nitrogen after digestion and the disappearance of β-lactoglobulin and α-lactalbumin bands in gel electrophoresis. Depending on the sample, between 22 and 87 peptides were identified after gastrointestinal digestion. A peptide from β-casein f(98-105) with the sequence VKEAMAPK and antioxidant activity appeared in all of the samples. Other peptides with antioxidant, immunomodulatory, and antimicrobial activities were frequently found, which could have an effect on infant health. The present study confirms that the infant formula manufacturing process determines the polyamine content and peptidic profile after digestion of the infant formula. Because compositional dissimilarity between human milk and infant formula in polyamines and proteins could be responsible for some of the differences in health reported between breast-fed and formula-fed children, these changes must be taken into consideration because they may have a great effect on infant nutrition and development.

Caseinate-gelatin and caseinate-hydrolyzed gelatin composites formed via transglutaminase: chemical and functional properties

BACKGROUND

Treatment of food proteins by enzymatic crosslinking and other reactions can confer modified properties on the treated proteins. Bovine gelatin and hydrolyzed bovine gelatin were used to generate two caseinate-based composites via transglutaminase, and potential useful properties to food processing were investigated for both composites.

RESULTS

Caseinate-gelatin and caseinate-hydrolyzed gelatin composites contained 33.4 and 10.3 g kg(-1) protein of 4-hydroxyproline, respectively. Caseinate conjugation with gelatin and hydrolyzed gelatin resulted in two composites with stronger absorption at five wavenumbers during Fourier transform-infrared analysis, demonstrating that they were rich in hydroxyl and carboxyl groups. Both composites exhibited higher viscosity values in aqueous dispersions, lower thermal stability (i.e. higher mass loss) during thermogravimetric analysis and worse emulsifying properties than original caseinate, owing to conjugation and crosslinking via transglutaminase. However, confocal laser scanning microscopy (CLSM) analysis revealed that both composites actually had better emulsion stability after 2 weeks of storage.

CONCLUSION

The composites generated were different in chemical characteristics and better in viscosity and emulsion stability than original caseinate. They might have potential as protein thickeners and emulsifiers. CLSM is a better technique to assess emulsion stability of food proteins than the classic turbidity method.

Comparative study on the effects of nystose and fructofuranosyl nystose in the glycation reaction on the antigenicity and conformation of β-lactoglobulin

Our previous work indicated that the antigenicity of bovine β-lactoglobulin (β-LG) decreased after conjugation with fructo-oligosaccharides (FOS) which was related to its conformational changes. In attempt to unravel further changes of β-LG antigenicity, nystose (GF3) and 1(F)-β-fructofuranosyl nystose (GF4) of FOS were used to investigate the relationship between conformation and antigenicity. The antigenicity of β-LG after conjugated with GF3 and GF4 decreased from 143.4 to 29.5 and 31.6 μg/mL, respectively. The results of mass spectrometry revealed that the molecular weight of β-LG increased from 18.4 to 19.8 and 19.1 kDa after conjugation with GF3 and GF4, respectively. It was shown that the conformational changes of β-LG after conjugation with GF3 were bigger than that with GF4, including quenching of fluorescence intensity, the red-shift of fluorescence spectra, and the increase in sulfhydryl content. However, there was no significant difference in the antigenicity between β-LG-GF3 and β-LG-GF4 conjugates (P>0.05).

Antioxidant Activity and Functional Properties of Polymerized Whey Products by Glycation Process

The antioxidant properties of sweet and acid whey products were incremented by polymerization of their proteins by glycation of whey protein concentrates (WPC) and their hydrolyzates (WPCH) with ribose and glucose in individual experiments under similar concentration. Heating at 50°C during 20 h maximum and pH 7 and pH 9 were used in all tests. The higher activity was found in WPC glycosylates products with ribose at pH 7 and heating during 10–15 h. In comparable form, antioxidant activity in WPCH was incremented by prior hydrolysis to glycation with 25–45% of hydrolysis degree. Further functional properties of whey proteins (solubility, emulsion, and foam) were also improved by the polymerization with ribose. The color of polymerized products due to Maillard reactions was associated with antioxidant activity of each compound; however comparative color in glycosylates products with glucose and ribose did not show this effect.

The effect of soy protein structural modification on emulsion properties and oxidative stability of fish oil microcapsules

Hydrolysates of soy protein isolate-maltodextrin (SPI-Md) conjugate were used as wall material to prepare fish oil microcapsules by freeze-drying method. Effects of the protein structural modifications on the physicochemical properties of the emulsion and the oxidative stability of the microcapsules were characterized. Compared with emulsions of SPI-Md conjugates or soy protein isolate/maltodextrin (SPI/Md) mixture, lower droplet size (212.5-329.3nm) and polydispersity index (PDI) (0.091-0.193) were obtained in the fish oil emulsions prepared by SPI-Md conjugate hydrolysates. The improved amphiphilic property of SPI-Md conjugate hydrolysates was supported by the results of surface and interfacial tension, and further confirmed by the improved emulsion stability during the storage period. Although the microencapsulation efficiency (MEE) of SPI-Md conjugate hydrolysates slightly decreased from 97.84% to 91.47% with the increasing degree of hydrolysis (DH), their oxidative stabilities (peroxide value and headspace propanal) were apparently improved compared with native SPI/Md mixture or SPI-Md conjugates system. Moreover, favorable thermal stability as well as a porous and uniform surface structure of the microcapsules coated by SPI-Md conjugate hydrolysates (DH 2.9%) was observed via the thermal analysis and scanning electron microscope (SEM) micrographs, respectively.