Rice Protein Hydrolysates Research Articles

Selenium-containing peptides as effective alleviators for low-level lead induced neural damage

The TSeMMM and SeMDPGQQ, two selenium-containing peptides derived from Se-enriched rice protein hydrolysates, have previously been demonstrated to show neuroprotective properties against high-dose lead exposure. However, the potential toxicological effects of these functional peptides on low-dose lead-induced neurotoxicity remain poorly understood. The present study aimed to investigate the protective mechanism of two selenium-containing peptides in mitigating low-dose Pb2+-induced damage in HT22 cells. Results showed that treatment with 40 μmol/L Pb2+ significantly reduced cell viability and increased apoptosis, both of which were alleviated by 40 μmol/L TSeMMM and SeMDPGQQ treatment. Furthermore, two peptides exhibited antioxidant potentials by reducing reactive oxygen species levels to 32.19% and 79.29% of the model group, respectively. They also enhanced antioxidant enzyme activities and mitigated oxidative stress through activation of the Keap1/Nrf2 pathway. Additionally, two peptides improved mitochondrial function by elevating mitochondrial membrane potential, ATP production while dramatically reducing reactive oxygen species levels. Interestingly, TSeMMM exhibited superior neurointerventional effects compared to SeMDPGQQ. The RNA sequencing analysis revealed that TSeMMM modulated gene expressions related to oxidative stress and neuroprotective function. The study provides insights into the protective mechanism underlying selenium-containing peptides for mitigating neuronal damage.

Yogurt fortified with various protein hydrolysates: Texture and functional properties

This work evaluated the impact of incorporating 1% of commercial protein hydrolysates [rice protein hydrolysate (RPH), pea protein hydrolysate (PPH), and casein hydrolysate (CH)] on the functional, microstructure, and texture properties of set yogurt. Yogurt prepared with RPH exhibited the highest viability number of Streptococcus thermophilus. The addition of three hydrolysate types to yogurt revealed significant increases in the antioxidant and ACE-inhibitory activities, where the highest values were noted for the yogurt prepared with RPH. RPH exhibited no differences in texture properties (firmness, consistency, and cohesiveness) to control yogurt. These results were confirmed by scanning electron microscope examination. RPH and control yogurts showed compacted and dense structures accompanied by small pores, whereas CH and PPH yogurt structures were characterized by coarse networks with large voids. Furthermore, there was no significant impact of adding protein hydrolysates on the overall acceptability of yogurt as indicated by a sensory panel.

Rice protein hydrolysates as natural emulsifiers for an effective microencapsulation of orange essential oil by spray drying

This study aimed to identify the influence of rice protein hydrolysates (RPH) (degree of hydrolysis DH of 2, 6, and 10%) and rice protein isolate (RPI) on the formation and stabilization of the volatile oil droplets and to verify how protein hydrolysate affects the distribution of components on the surface and physicochemical properties of the spray-dried microparticles. In general, RPHs could reduce the interfacial tension (3.78–4.04 mN/m) compared to non-hydrolyzed protein (4.74 mN/m). However, no significant difference was observed between RPH samples. A positive correlation was observed between the interfacial tension and the oil droplet size, in which RPH emulsions showed 8.29–8.66 µm while RPI was 9.06 µm. DH influenced the surface composition of the spray-dried RPH emulsions. RPH10 powder showed a greater presence of protein (3.3%) on the particle surface and consequently exhibited high oil retention (50.0%). In contrast, this sample presented high hygroscopicity attributed to the protein surface. This study provides insights into differences between RPH powders, which can potentially impact the powder functionality and protection of the active compound.

Antioxidant amyloid fibril derived from rice protein hydrolysate as stabilizer towards preparing high-stable emulsion

An antioxidant amyloid fibril was prepared as an emulsifier by fibrillating limited enzymatic hydrolysis-modified rice protein (HRP). The purpose of this study was to investigate the feasibility of using fibrillated HRP to stabilize oil-in-water emulsion. A free radical scavenging assay revealed that the antioxidant activity of fibrillated HRP was 2.09 times higher than that of native rice protein. Fibrillated HRP demonstrated a marked reduction in interfacial tension, increased surface hydrophobicity and contact angle (> 80°), and rapid adsorption to the interface, with 35.34 ± 2.43% interfacial adsorbed protein content. The fibrillated HRP barriers resisted environment stresses such as NaCl, pH variations, long-term storage, while reducing lipid oxidation degree. Additionally, fibrillated HRP-based emulsion was more effective in protecting β-carotene from degradation compared to other samples. These findings provide theoretical support for the development of rice protein-based antioxidant emulsifiers and modification of emulsifying properties of plant proteins.

Improvement effect of different polysaccharides on the functional properties of curcumin-loaded rice protein hydrolysate nanoparticles

The impact of different polysaccharides (chitosan, pectin, and chondroitin sulfate) on the functional properties of curcumin-loaded rice protein hydrolysates (RPH) was explored. Polysaccharides provided more surface charges for RPH nanoparticles, and enhanced the hydrogen bonds and electrostatic interactions between nanoparticles, thus contributing to the stability of RPH nanoparticles against environmental changes. Notably, RPH nanoparticles coated with chitosan have the largest surface charge (+33.04 mV) and best pH, ionic strength, and thermal stability. Furthermore, RPH nanoparticles coated with chondroitin sulfate had a more compact spherical structure with smaller particle size (111.23 nm), and possessed desirable sustained release properties. This study demonstrated the potential of polysaccharides to enhance the functional properties of rice protein-derived delivery systems for hydrophobic biomolecules, and suggested the necessity of polysaccharide type for creating ideal protein-polysaccharide composite nanoparticles.

Compositional aspect and mechanism of surface formation of spray-dried microparticles with surface-active rice protein hydrolysates

Flavourzyme enzymatically hydrolyzed rice protein isolate to different degrees of hydrolysis (DH, 2, 6, and 10%) to stabilize formulated linseed oil emulsions with different protein concentrations (0.5, 1.0, and 1.5%). The emulsions were spray dried, and the microstructure, surface composition by X-ray photoelectron spectroscopy (XPS), and oxidative stability of the resultant microparticles were investigated. The physicochemical properties of powders were also evaluated. DH and protein concentration did not affect solubility, hygroscopicity, wetting time, and particle size. However, a strong and positive correlation was found between DH and oxidative stability. The lowest peroxide value (2.48–1.99 meq/kg oil) was found from the powder formulated with protein hydrolysate (DH 10%) and 1.5% of protein concentration during the entire storage study. Fluorescence optical microscopy and atomic force microscopies also allowed identifying the effects of these variables on oxidative stability. Through XPS analysis, it was possible to observe that higher DH favored the surface accumulation of proteins at the powder surface. The protein content on the particle surface (9.8%) was overrepresented compared with the bulk composition (1.5%). These results showed that the degree of hydrolysis exerted an influence on the distribution of components and the percentage of protein on the powder surface.

Preparation, structural characterization and properties of feruloyl oligosaccharide–rice protein hydrolysate conjugates

Rice protein hydrolysate (RPH) and feruloyl oligosaccharides (FOs) were conjugated under the catalysis of laccase and free radical, and the structure and properties of the resultant conjugates were studied. Electrophoresis analysis demonstrated that conjugation with FOs increased the molecular weight of some fractions in RPH, which confirmed the formation of both conjugates. The conjugation degree of laccase-induced conjugate and radical-induced conjugate was 60.45% and 22.70%, respectively. Laccase-catalyzed conjugation decreased the tyrosine residue content of RPH but had no significant effect on the free amino group content, which suggested that tyrosine residues were the conjugation site in the laccase-induced conjugate. However, radical-catalyzed conjugation decreased both the free amino group content and the tyrosine residue content, which indicated that both free amino groups and tyrosine residues were the conjugation site in the radical-induced conjugate. The ultraviolet, fluorescence and circular dichroism spectroscopy analysis revealed that conjugation with FOs significantly altered the secondary and tertiary structure of RPH. In addition, conjugation with FOs increased the solubility and antioxidant activity of RPH but decreased the emulsifying activity and stability. Particularly, the radical-induced conjugate had greater anti-aggregation capacity and antioxidant activity but lower emulsifying activity and stability than the laccase-induced conjugate, which might be due to that their conjugation site and degree were different.

Ultrafiltration fractionation of rice protein hydrolysates: Physicochemical properties and potential biological activities of different rice protein hydrolysate fractions

In this study, rice protein hydrolysate (RPH) was separated by membrane ultrafiltration, and three ultrafiltration fractions (UFs) with distinct molecular weights (RPP-1, RPP-2 and RPP-3) were yielded. The physicochemical properties and in vitro bioactivities of these fractions were characterized. Among RPH and its UFs, RPP-1 exhibited highest DPPH radical scavenging activity (IC50 = 4.42 ± 0.08 mg/mL) and ferric reducing antioxidant power (84.21 mg GSH/g). RPP-3 exhibited the highest ABTS radical scavenging activity (IC50 = 0.97 ± 0.01 mg/mL). All the samples exhibited angiotensin converting enzyme inhibitory activity (5.38% ± 0.76%–54.14% ± 3.04%) and α-glucosidase inhibitory activity (−38.90% ± 3.20%–99.99% ± 0.01%). In addition, the activation of alcohol dehydrogenase by RPH and its UFs was observed in this study, with an activation percentage of 46.20% ± 4.96%–199.77% ± 7.71%. However, no inhibitory activity towards acetylcholinesterase was detected. In present study, the potential antialcohol and hepatoprotective activity of RPH was observed. Overall, this study would provide a new idea for the high-value utilization of RPH and a theoretical foundation for the development of bioactivity peptides derived from rice protein.

Investigation of the effect of ultrasonic exposure on polymer solutions in the production of biodegradable packaging materials

One of the options for improving the structure and properties of films obtained from polymer solutions is ultrasonic exposure to solutions of various chemical nature. The use of this effect on polymer solutions with various additives and agents showed not only an improvement in physical and mechanical properties, but also antibacterial properties, which contributed to an increase in the shelf life of food products. The main components of the compositions whose studies are presented in scientific articles were: polyvinyl alcohol, proteins and pullulan, they were mixed with various additives and agents, with different duration of exposure to ultrasonic treatment of solutions. The studied compositions had the following compositions: polyvinyl alcohol and hemicellulose with an antioxidant agent of tea; polyvinyl alcohol, sodium-carboxymethyl cellulose, zinc oxide nanoparticles, as well as multilayer graphene nanoplates; polyvinyl alcohol and chitosan; fish scale collagen, polyvinyl alcohol and potassium sorbate; egg white; quinoa protein and chitosan; pea protein; rice protein hydrolysate and chitosan; whey protein hydrolysate; aqueous soy extract with bee wax and essential oil of cloves; oat protein with pullulan and nizin; pullulan with the addition of nanoemulsion with cinnamon essential oil; pullulan and trehalose with tea polyphenols saturation. Some of the films made from these formulations were tested on food products such as strawberries, apples, pears and cupcakes. Based on the considered scientific data, it can be concluded that in order to improve the properties of films from polymer solutions, it is necessary to have an optimal time of ultrasound exposure to solutions, since longer ultrasonic exposure can worsen the physical and mechanical properties, namely, to reduce the tensile strength and elongation at break, in contrast to moderate exposure.

Proteolysis improves the foaming properties of rice protein fibrils: Structure, physicochemical properties changes, and application in angel food cake

Proteolysis prior to fibrillation can change the functional properties of protein fibrils. This study aimed to investigate the effects of proteolysis pretreatment by alkaline protease on formation, structure, and foaming properties of rice protein fibrils. Thioflavin T fluorescence and conversion assays showed that proteolysis reduced the fibril formation capacity of rice protein. After 12 h of heating, the percent conversion of rice protein and rice protein hydrolysates to fibrils reached 60.32 ± 1.07% and 30.43 ± 2.01%, respectively. Transmission electron microscopy images showed that fibrils derived from rice protein hydrolysates had a longer contour length than rice protein fibrils. The foaming capacity and stability of rice protein hydrolysate fibrils increased by 16.70% and 11.27%, respectively, compared with those of rice protein fibrils. The addition of rice protein hydrolysate fibrils improved the texture of cakes. These results suggested that rice protein hydrolysate fibrils could be a promising plant-based foaming agent.

Mechanisms of rice protein hydrolysate regulating the in vitro digestibility of rice starch under extrusion treatment in terms of structure, physicochemical properties and interactions

The effect of protein hydrolysates on starch digestibility has been observed in other heat treatments but has yet to be extensively researched under extrusion. This study aimed to analyze the physicochemical properties, structure, and starch digestibility of extruded rice starch–protein hydrolysate (ERS–RPH) complexes prepared by extrusion treatment. The resistant starch contents of ERS–RPH (12.30 %–19.36 %) were higher than those of extruded starch alone (6.33 %). The interaction forces, physical barrier effects, and enzyme inhibition indicated that RPHs at varying hydrolysis degrees hindered starch digestibility by reducing its contact with enzyme and via adhesion and hydrogen bonding with starch. RPHs with higher hydrolysis exhibited greater inhibition of starch digestibility, limiting the swelling power of starch and the leaching of amylose, thereby improving the thermal stability of starch. Fourier transform infrared spectroscopy results revealed the presence of hydrogen bonding interactions between RPHs and starch in complexes, intensifying the ordered structure of starch. Extrusion caused an increase of 6.8 %–10.8 % in the relative crystallinity of ERS-RPH compared to extruded starch alone. Moreover, the strength of V-type structure was reinforced after extrusion. These results enhanced comprehension of how PRHs regulate starch digestibility under extrusion, and offer direction for producing slow-digesting foods.

Potential antidiabetic effect of muffins formulated with different protein hydrolysates: Role of bioactive peptides formed during digestion

This study aimed to evaluate whether the reformulation of a conventional muffin (CM) by incorporating hydrolysates of casein, soybean protein, pea protein, and rice protein at two concentrations as wheat flour replacement, affected the glycemic index (GI) and the release of bioactive peptides (BAPs) during the digestion in vitro.Compared to CM, muffins with hydrolyzed pea and rice proteins lowered GI by 15% and 5%, respectively, without a significant dose-dependent effect; moreover, during digestion they delivered BAPs, including some amylase-inhibitors. Conversely, the muffins incorporating casein hydrolysate at high concentration showed the highest GI and delivered highest amount of opioid and DPPIV-inhibitor BAPs. Soy protein hydrolysates did not significantly affect the GI or BAPs released.Findings suggested that reformulating a muffin with protein hydrolysates, besides a reduced GI, as in the case of pea and rice protein hydrolysates, may provide further biological effects through the release of BAPs during the digestion.

Improving functional properties of rice protein isolates by hydrolysis using alcalase enzyme and assessing bioactivities of hydrolysates

AbstractBackgroundDeveloping value‐added products from rice grains is becoming increasingly significant to enhance productivity from excess rice grains. Therefore, the objective of this study was to improve the functional properties of rice protein from four rice varieties, namely, RRF‐127, RRF‐105, Swarna, and Protezin by enzymatic hydrolysis, and also to evaluate bioactivities like antioxidant, ACE, and DPP‐IV inhibitory activities of the hydrolysates.ResultsThe alcalase hydrolysis increased protein solubility to >80% in the pH range of 4–10. The foaming capacity and stability of rice protein hydrolysates (RPHs) improved with the increase in pH. The hydrolysis significantly improved the emulsification activity index (EAI) in the pH range of 5–9. The hydrolysates showed antioxidant activity, namely, ABTS•+radical scavenging, reducing power, and metal ion chelation. RRF‐105 was found to possess the most potent antioxidant capacity among the hydrolysates. RPH could alleviate oxidative damage in erythrocytes, and their protective effects were concentration‐dependent. The hydrolysates had stronger inhibition of ACE and DPP‐IV enzymes. Protezin exhibited the highest ACE inhibition (63%), while Swarna demonstrated the most effective DPP‐IV inhibition (66%).ConclusionHydrolysis with alcalase improved the functional and bioactive properties of rice proteins, indicating that RPH could serve as a source of bioactive peptides or as a functional ingredient with potential properties.

Performance of rice protein hydrolysates as a stabilizing agent on oil-in-water emulsions

Rice protein isolate (RPI) has been receiving increasing attention from the food industry due to its performance as an emulsifier. However, it is possible to enlarge its field of applications through enzymatic hydrolysis. Therefore, this work aimed to investigate the effects of the controlled enzymatic hydrolysis (degree of hydrolysis DH as 2, 6, and 10%) using Flavourzyme on the physicochemical properties of rice protein and to identify the minimum concentration of these hydrolysates (0.5, 1.0, and 1.5%) to form and stabilize oil/water emulsion. The physicochemical, interfacial tension (IT), and surface characteristics of RPI and their hydrolysates (RPH) were determined. Even at a lower protein concentration (1.0%), protein hydrolysate presented lower IT when compared with RPI at a higher protein concentration (1.5%). The interfacial tension decreased from 17.6 mN/m to 9.9 mN/m when RPI was hydrolyzed. Moreover, enzymatic hydrolysis (DH 6 and 10%) enhanced the protein solubility by almost 20% over a pH range of 3–11. The improved amphiphilic property of RPH, supported by the results of IT and solubility, was confirmed by the higher emulsion stability indicated by the Turbiscan and emulsion stability indexes. Emulsions stabilized by RPH (DH 6% and 10%) at lower protein concentrations (1%) exhibited better physical stability than RPI at higher protein concentrations (1.5%). In this work, we verified the minimum concentration of rice protein hydrolysate required to form and stabilize oil-in-water (O/W) emulsions.

低タンパク質米製造過程で生じる抽出米タンパク質分解物が脂質代謝に及ぼす影響

低タンパク質米製造過程で生じる抽出米タンパク質分解物が脂質代謝に及ぼす影響

Antifungal activity of protein hydrolysates from Thai Phatthalung Sangyod rice (Oryza sativa L.) seeds.

Fungal zoonoses are an economic and public health concern because they can cause various degrees of morbidity and mortality in animals and humans. To combat this issue, alternative natural antifungals, such as products derived from rice protein hydrolysates or rice antifungal protein/peptide are being considered because they are highly bioactive and exhibit various functional properties. Thailand is a leading rice producer and exporter. Among the various cultivated rice varieties, Sangyod rice (Oryza sativa L.) is exclusively indigenous to Thailand's Phatthalung province; it has a Thai geographical indication tag. Here, we investigated whether the Phatthalung Sangyod rice seeds have bioactive antifungal peptides. Antifungal activity in four Sangyod rice seed extracts (SYPs) - namely, (1) the crude lysate, SYP1; (2) the heat-treated lysate, SYP2; (3) the heat- and pepsin digested lysate, SYP3; and (4) the heat- and proteinase K-digested lysate, SYP4 - was analyzed. Protein concentrations in these SYPs were determined using the Bradford assay. The total phenolic compound content was determined using the modified Folin-Ciocalteu method in a 96-well microplate. Then, the SYP protein pattern was determined using the sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Subsequently, using the agar well diffusion method, the antifungal properties of these SYPs were tested against ten medically important pathogenic fungi. The minimal inhibitory concentration (MIC) and minimal fungicidal concentration values were determined for the active SYPs - SYP2-4. Finally, the clinical safety of SYP4 was determined using a hemolytic assay (using canine red blood cells [RBCs]). The crude lysate SYP1 did not show antifungal activity against any of the ten tested pathogenic fungi. Surprisingly, hydrolysates SYP2, SYP3, and SYP4 displayed antifungal properties against the ten tested pathogenic fungi. Thus, heat and enzymatic hydrolysis seem to transform the bioactivity of the crude protein extract - SYP1. Further, SYP4 shows the most effective antifungal activity. It completely inhibited Cryptococcus neoformans, Talaromyces marneffei yeast phase, Trichophyton mentagrophytes, and Trichophyton rubrum. A partial inhibitory action on Candida albicans and Microsporum gypseum was possessed while showing the least activity to C. neoformans. SYP4 was nontoxic to canine RBCs. Hemolysis of canine RBCs was undetectable at 1 × MIC and 2 × MIC concentrations; therefore, it can be safely used in further applications. These results indicate that heat and proteinase K hydrolyzed SYP is a very potent antifungal preparation against animal and human fungal pathogens and it can be used in future pharmaceuticals and functional foods.

Formation and Characterization of Self-Assembled Rice Protein Hydrolysate Nanoparticles as Soy Isoflavone Delivery Systems

In this study, soy isoflavones-loaded nanoparticles were prepared using rice proteins (RPs) hydrolyzed by four types of enzyme (alcalase, neutrase, trypsin, and flavorzyme). After optimizing the preparation conditions, the encapsulation efficiency (EE) of the nanoparticles ranged from 61.16% ± 0.92% to 90.65% ± 0.19%. The RPs that were hydrolyzed by flavorzyme with a molecular weight of <5 KDa showed better characters on the formation of nanoparticles, and the formed nanoparticles had the highest EE and loading capacity (9.06%), the smallest particle size (64.77 nm), the lowest polymer dispersity index (0.19), and the lowest zeta potential (-25.64 mV).The results of Fourier transform ion cyclotron resonance, X-ray diffraction, and fluorescence spectroscopy showed that the nanoparticles were successfully encapsulated. The study of interaction showed that the formation of nanoparticles may depend mainly on hydrogen bonds, but other interactions, such as hydrophobic interactions and electrostatic interactions, cannot be ignored. After encapsulation, the pH stability, temperature stability, ionic stability, and oxidation resistance of the nanoparticles were enhanced. Moreover, the in vitro release experiment showed that the encapsulated nanoparticles had a certain protective effect on soybean isoflavones. In summary, rice protein hydrolysates are promising carriers for soybean isoflavones.

Development of chitosan/rice protein hydrolysates/ZnO nanoparticles films reinforced with cellulose nanocrystals

In the present work, the composite films were obtained by the solution casting method from chitosan and rice protein hydrolysates, reinforced with cellulose nanocrystals (CNC) of different contents (0 %, 3 %, 6 % and 9 %). The influence of different CNC loadings on the mechanical, barrier and thermal properties was discussed. SEM showed the formation of intramolecular interactions between the CNC and film matrices, leading to more compact and homogeneous films. These interactions had a positive influence on the mechanical strength properties, which was reflected in higher breaking force of 4.27 MPa. The elongation dwindled from 132.42 % to 79.37 % with increasing CNC levels. The linkages formed between the CNC and film matrices reduced the water affinity, leading to a reduction in their moisture content, water solubility and water vapor transmission. Thermal stability of the composite films was also improved in the presence of CNC, by increasing maximum degradation temperature from 311.21 to 325.67 °C with increasing CNC contents. The strongest DPPH inhibition of the film was 45.42 %. The composite films exhibited the highest inhibition zone diameter against E. coli (12.05 mm) and S. aureus (12.48 mm), and the hybrid of CNC and ZnO nanoparticles exhibited stronger antibacterial activity than their single existent forms. The present work shows the possibility of obtaining CNC-reinforced films with improved mechanical, thermal and barrier properties.

Effects of molecular weight fraction on antioxidation capacity of rice protein hydrolysates

Rice protein was used as a starting material to provide rice protein hydrolysates (RPH) through enzyme-assisted extraction. RPH was further fractionated using ultrafiltration membrane (UF) and classified by molecular weight (MW; MW < 1 kDa, MW 1–10 kDa, and MW > 10 kDa). Peptides with MW < 1 kDa possessed superior antioxidant properties (p < 0.05). Therefore, UF demonstrated great efficacy in selectively separating antioxidant peptides. A Pearson correlation analysis revealed that the total phenolic concentration was correlated with oxygen radical absorbance capacity (ORAC; r = 0.999, p < 0.05). Amino acid contents had negative correlations with the scavenging activity (specifically, IC50) of 1,1-diphenyl-2-picrylhydrazyl and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radicals (r = − 0.986 to − 1.000). Reducing power was related to aromatic amino acid contents (r = 0.997, p < 0.05). In this study, enzymatic hydrolysis was discovered to be an effective method of extracting and isolating natural antioxidant proteins from broken rice, thus preserving the nutritional quality of rice and making those proteins more accessible in future applications.

Combined effects of drying methods and limited enzymatic hydrolysis on the physicochemical and antioxidant properties of rice protein hydrolysates

The combined effects of drying methods and limited enzymatic hydrolysis on the techno-functional characteristics of rice protein hydrolysates (RH) were investigated. With the increasing hydrolysis degree, the average size, exposed and total SH content, iron chelating capacity, hydroxyl and DPPH radical scavenging activity increased. Drying methods and enzyme type can alter the conformation of protein. Trypsin-derived spray dried RH exhibited higher α-helix contents while neutrase-derived ones had lower α-helix contents. The freeze-dried RH owed higher hydroxyl and DPPH scavenging activity than their spray-dried counterparts, which was related to higher sulfhydryl group and hydrophobic amino acids contents. RH derived from trypsin had higher metal chelating capacity than that from neutrase, which was in an agreement with higher amount of peptide <1000 Da. The shifting to lower relaxation time in spray-dried RH reflects lower water absorption capacity and slower water mobility, which are less susceptible to spoilage bacteria. Freeze drying would be a more prevalent technique for fully utilization of RH as bioactive components in the food system.