Functional Properties and Bioactivities of Pine Nut (Pinus gerardiana) Protein Isolates and Its Enzymatic Hydrolysates

The functional properties and bioactivities of the pine nut protein isolates (PPI) and its enzymatic hydrolysates (PPH) prepared with Alcalase at 5 %, 10 %, 15 % and 25 % degree of hydrolysis (DH) were studied. The solubility of PPH significantly increased (p?<?0.05) with the increase of the DH, while the foaming capacity of PPH was only improved at a low DH. However, enzymatic hydrolysis reduced the emulsifying capacity of PPH. The DPPH radical scavenging and inhibition of linoleic acid oxidation activities of PPH were significantly improved by a low DH (5 %) compared with those of PPH with a higher DH and the original PPI (p?<?0.05). The reducing power of PPH at all DH decreased in comparison to that of the original PPI. Potent angiotensin-converting enzyme (ACE) inhibitory peptides could be generated by hydrolysis with Alcalase, and the ACE inhibitory activity of PPH increased (p?<?0.05) with the DH. These results revealed that a low degree of enzymatic hydrolysis was appropriate to obtain PPH with improved functional properties and good antioxidant activities, while a high degree of hydrolysis was essential to obtain highly potent ACE inhibitory peptides from PPI. These results suggest that the control of the DH may be an effective strategy to modify specific functional and bioactive properties of PPH, and PPH has potential as a functional food ingredient for related functional and health benefits.     

Influence of degree of hydrolysis on functional properties,antioxidant activity and ACE inhibitory activity of peanut protein hydrolysate

Functional properties, antioxidant and Angiotensin-converting enzyme (ACE) inhibitory activities of peanut protein isolate (PPI) and peanut protein hydrolysate (PPH) prepared using Alcalase, at different (10%, 20%, 30% and 40%) degrees of hydrolysis, (DH) were investigated. Hydrolysis (at DH > 10%) significantly (p < 0.05) improved the solubility (>80%) of PPI, especially in the pH range of 4–6. However, PPI showed better emulsifying and foaming properties than PPH (p < 0.05). As DH increased, ferrous ion chelating activity, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity and ACE inhibitory activity of PPH increased, while reducing power decreased (p < 0.05). Bleaching of beta-carotene by linoleic acid was suppressed better by PPI and PPH at 10% DH than of PPH at higher DH. Thus, the results reveal that DH affects functional properties, antioxidant and ACE inhibitory activities of peanut protein.     

Extraction and characterisation of Riceberry bran protein hydrolysate using enzymatic hydrolysis

Riceberry bran protein hydrolysate (RBPH) was prepared from bran of purple‐pigmented Riceberry rice using enzymatic hydrolysis. The effect of enzyme type (Alcalase, Flavourzyme and Neutrase) and hydrolysis time (2, 4 and 6 h) on protein content, protein yield, total phenolic content (TPC), antioxidant activities (ABTS and FRAP) and molecular weight patterns of RBPH was investigated. The enzyme type significantly (P < 0.05) affected the properties of RBPH whereas the hydrolysis time had no significant effect (P ≥ 0.05) on those properties. Flavourzyme was the most effective to increase protein yield, TPC and antioxidant activities compared to Alcalase and Neutrase. The optimal hydrolysis condition was 4 h using Flavourzyme which yielded 74.9% extracted protein. This hydrolysate contained peptides ranging from 16 to 64 kDa. The high antioxidant activity was related to negative charge peptides as shown by anion exchange chromatography. With high protein content and antioxidant properties, RBPH using Flavourzyme could be practically utilised in functional foods.     

Free radical scavenging activity of porcine plasma protein hydrolysates determined by electron spin resonance spectrometer

A study was conducted to investigate the antioxidant capacity of porcine plasma protein before and after enzymatic hydrolysis. Porcine plasma protein was hydrolyzed by using Alcalase with degree of hydrolysis (DH) ranged from 0 to 17.8%. The free radical scavenging effects of porcine plasma protein hydrolysates (PPH) were evaluated by electron spin resonance (ESR) spectrometer. The reducing power of PPH increased with increasing of DH (P < 0.05). The 5-h PPH exhibited the strongest inhibition of lipid oxidation, as indicated by lowest thiobarbituric acid-reactive substance values in a liposome-oxidizing system, and the strongest free radical scavenging ability on 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH), hydroxyl (OH) and superoxide (O₂-) radicals. The increase of protein concentration enhanced (P < 0.05) free radical scavenging effect of PPH. Although non-hydrolyzed plasma protein displayed an antioxidative effect, it was far less potent than PPH. The results indicated that the antioxidant capacity of porcine plasma protein could be enhanced by enzymatic hydrolysis of Alcalase.     

鳙鱼鱼肉蛋白的酶解及其对功能性质的影响

为了改善鳙鱼鱼肉蛋白(BCMP)的功能性质以扩大其在食品工业中的应用,以鳙鱼为原料制备了鳙鱼鱼肉蛋白,并利用碱性蛋白酶Alcalase2.4L对其进行水解,得到了3种不同水解度(DH4.5%、DH9.0%、DH13.5%)的酶解物。研究了BCMP及其酶解物的功能性质,包括溶解性、持水性、持油性、乳化性、起泡性。结果表明,与原鳙鱼鱼肉蛋白相比,酶解物的功能性质除持油性以外均有不同程度的提高。此外,DH4.5%的酶解物乳化性和起泡性最高,过度水解(DH9.0%、DH13.5%)反而造成乳化性和起泡性下降。     

Production and characterisation of duck albumen hydrolysate using enzymatic process

Influences of different ultrasound treatments combined with heat pretreatment on enzymatic hydrolysis, emulsifying properties and antioxidant activities of hydrolysates from duck egg albumen were studied. Heat pretreatment at 95 °C for 30 min inhibited both serine and cysteine protease inhibitors effectively. Ultrasonication of heated duck albumen at 60% amplitude for 10 min yielded the highest surface hydrophobicity. Coincidentally, aforementioned pretreatment rendered the hydrolysate with highest degree of hydrolysis (DH) than other pretreatments when Alcalase was used. The resulting hydrolysate showed the highest antioxidant activities including DPPH radical and ABTS radical cation scavenging activities and ferric reducing antioxidant power as well as emulsifying properties when hydrolysis time of 90 min was used. The hydrolysate possessed the peptides with molecular weight of 219–255 Da with the highest ABTS radical scavenging activity. Thus, heat pretreatment, followed by ultrasonication of duck albumen under appropriate condition could increase DH, antioxidant activities and emulsifying properties of duck albumen hydrolysate.     

ENZYMATIC HYDROLYSIS OF WHEY PROTEINS BY TWO DIFFERENT PROTEASES AND THEIR EFFECT ON THE FUNCTIONAL PROPERTIES OF RESULTING PROTEIN HYDROLYSATES

Whey protein concentrate (WPC 80) was hydrolyzed by Alcalase 2.4 L and Protamex to 5, 10, 15 and 20% degree of hydrolysis (DH). WPC 80 and its hydrolysates were analyzed, compared and used for measuring some functional properties. All hydrolysates were different from WPC 80 in protein, moisture and ash content. Free amino groups and protein solubility increased with increasing DH. The peptides produced by hydrolysis had smaller molecular sizes, and their average molecular weight decreased as the DH increased. Except hydrolysates generated by Alcalase 2.4 L at 5% DH, all others showed poor emulsifying and foaming properties compared with unhydrolyzed WPC 80. Gelation properties of WPC 80 and its hydrolysates were different. The global amino acid compositions did not differ significantly between the different hydrolysates, and they were very close among WPC 80 and its hydrolysates except for Methionine, Glycine, Histidine and Valine.     

Preparation and Functional Properties of Enzymatically Deamidated Soy Proteins

Heat-denatured soy protein was hydrolyzed by Alcalase to 2.0% or 4.0% degree of hydrolysis (DH), heated again at 100°C and deamidated with B. circulans peptidoglutaminase. The extent of deamidation was 6.0% and 8.2% for 2.0 DH hydrolysates and 12.8% and 16.0% for 4.0 DH hydrolysates heated for 15 and 30 min, respectively. Deamidation increased protein solubility and substantially enhanced emulsifying activity under mildly acidic (pH 4–6) as well as alkaline conditions. Deamidation improved emulsion stability and foaming power of heat-denatured hydrolysed soy proteins. Enzymatically deamidated soy protein hydrolysates had improved functional properties compared to nondeamidated hydrolysates and the native soy protein.     

Enzymatic preparation and functional properties of wheat gluten hydrolysates

The water-insolublity of wheat gluten is one of the major limitations for its more extensive use in food processing. Wheat gluten was enzymatically hydrolyzed by several commercially available proteases (Pancreatin Trypsin 6.0S, Porcine pepsin, Pancreatin and Alcalase 2.4L) with protein recovery varying from 42.5 ± 0.7% to 81.3 ± 0.1%. The hydrolytic efficiency of these proteases on wheat gluten was also compared. Alcalase served best for the preparation of wheat gluten hydrolysates (WGHs). Thus, Alcalase-assisted hydrolysates of wheat gluten (AWGHs) with different degrees of hydrolysis (DH 5.0, 10.0 and 15.0%) were further assessed for their functionalities. All the AWGHs had excellent solubility (>60%) over a pH range of 2–12. The emulsifying and foaming properties of AWGH with relatively low DH (5.0%) were remarkably higher compared to the original gluten. However, extensive hydrolysis of gluten resulted in remarkable reduction in emulsifying and foaming properties.     

Solubility,functional properties,ACE‐I inhibitory and DPPH scavenging activities of Alcalase hydrolysed soy protein hydrolysates

Soy proteins are less soluble at acidic pH value, which impedes their utilisation in acidic beverages. Soy protein isolate (SPI) was hydrolysed using varying Alcalase concentrations (0.0001–2.0 U g^?1 protein) at different pHs (3.0–4.0). Degree of hydrolysis (DH) of soy protein hydrolysates (SPH) at pH 3.0, 3.5 and 4.0 were 5.0–10.7%, 2.3–6.1% and 0–5.4%, respectively, while solubilities ranged from 70.7 to 74.9%, 18.8 to 51.2% and 7.1 to 40.4%, respectively. The highest solubility (74.9%) was observed at pH 3.0 with 1.5 U Alcalase per g protein (DH = 9.2%). Emulsifying activities of SPHs at pH 3.0 and 4.0 ranged from 0.49 to 0.63 AU and 0.19 to 0.24 AU, respectively, while the emulsifying stabilities were 12.2–14.7 min and 18.7–56.0 min, respectively. The foaming capacity at pH 3.0 and 4.0 was 44.9–46.3 mL and 31.2–41.3 mL, respectively, whereas the foaming stability was 25.5–35.2 min and 12.8–15.1 min, respectively. However, hydrolysates had an insignificant effect on ACE‐I inhibitory and DPPH scavenging activities in comparison with SPI.     

Reducing and radical-scavenging activities of whey protein hydrolysates prepared with Alcalase

Antioxidant activities of whey protein isolate (WPI) hydrolysates prepared by Alcalase treatment at different concentrations and times were investigated. The antioxidant activity of WPI hydrolysates, indicated by peroxide value and thiobarbituric acid-reactive substance values in a liposome-oxidizing system, increased with increasing hydrolysis time up to 5 h (P < 0.05). The WPI hydrolysates also showed greater radical-scavenging ability, greater Cu²⁺-chelating ability and improved reducing power when compared with non-hydrolysed WPI (P < 0.05). An increase in protein concentration was shown to significantly enhance antioxidant activities (P < 0.05). Although non-hydrolysed WPI displayed an antioxidative effect, it was far less potent than the hydrolysed WPI. This study shows that enzyme-hydrolysed WPI can act as a hydrogen donor, a metal ion chelator, and a radical stabiliser to inhibit lipid oxidation. The WPI hydrolysates produced by Alcalase could be employed in the food industry as an antioxidant to replace synthetic antioxidants.     

Amino acid composition,antioxidant and functional properties of protein hydrolysates from the roe of rainbow trout (Oncorhynchus mykiss)

A fish roe protein hydrolysate from rainbow trout (Oncorhynchus mykiss) trout roe protein hydrolysates (TRH) was produced by pepsin and Alcalase. Proximate, amino acid compositions, protein digestibility and molecular mass distribution of the hydrolysates were determined. The degree of hydrolysis was found to be 44.08% and 27.62% (pepsin and Alcalase, respectively). The two hydrolysates contained a high amount of essential amino acids (33.53% Alcalase–29.39% pepsin). The results showed that TRH by different enzymes is a good source of the leucine and lysine amino acids. The pepsin produced a white powder with higher brightness (L* = 89.50). Alcalase hydrolysate was brownish yellow in colour (L* = 52.85, a* = 10.30, b* = 26.25). The hydrolysates represented excellent antioxidant activities in various concentrations. TRHs showed a good foaming and emulsification properties. The results thus revealed that protein hydrolysates from rainbow trout roe could be used as food additives possessing essential amino acids and antioxidant activity.     

Biochemical properties and antioxidant activity of myofibrillar protein hydrolysates obtained from patin (Pangasius sutchi)

Antioxidant activities of myofibrillar protein hydrolysates (MPH) prepared from patin (Pangasius sutchi) using papain and Alcalase^® 2.4 L with different degrees of hydrolysis (DH) were investigated. With a DH of 65.83%, the hydrolysate prepared with papain exhibited the maximum of 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical‐scavenging activity (71.14%) with a reducing power of 0.310. At a concentration of 1 mg mL^?1, the papain‐MPH exhibited a Trolox equivalent antioxidant capacity (TEAC) of 70.50 ± 1.22 μmol g^?1 protein. With a DH of 83.6%, the Alcalase‐MPH had the highest metal‐chelating activity. Low molecular weight peptides showed higher antioxidant activities than high molecular weight peptides. Both papain‐MPH and Alcalase‐MPH contained high amounts of the essential amino acids (48.71% and 48.10%, respectively) with glutamic acid, aspartic acid and lysine as the dominant amino acids. These results suggest that the protein hydrolysates derived from patin may be used as an antioxidative ingredient in both functional food and nutraceutical applications.     

鸡蛋清蛋白水解物的物化及功能性质的研究

蛋清蛋白质溶解性欠佳且容易起泡,使其应用受限。本文利用Alcalase酶解鸡蛋蛋清蛋白制取水解度为5~15%的酶解物并对酶解物的理化性质和功能性质进行了表征。测定性质包括乳化性、起泡性及稳定性以及溶解性、表面疏水性。所有酶解产物具有较低的表面疏水性,水解大大提高了溶解度,当水解度15%时最大值为89%,但乳化性有所降低,起泡性及稳定性也大约下降了40%。     

Germination‐Assisted Enzymatic Hydrolysis Can Improve the Quality of Soybean Protein

This study aimed to investigate the effects of combined germination and Alcalase hydrolysis on the quality of soybean protein. Protein profiles, water solubility, foaming and emulsifying properties, thixotropic properties, and in vitro protein digestibility (IVPD) were tested, the chemical score (CS), essential amino acid index (EAAI), and protein efficiency ratio (PER) of soybean protein were also defined. The combined treatment of germination and Alcalase hydrolysis remarkably improved the solubility, emulsification activity index, emulsion stability index, and foaming capacity of soybean protein. Notably, a decrease in foaming stability was detected. The electrophoretic profile showed a weak breakdown of soybean protein during germination. However, a strong breakdown of protein was observed after the hydrolysis with Alcalase. The combined treatment also decreased the CS and EAAI of soybean protein, but only by 18%. Meanwhile, the IVPD and PER of soybean protein were significantly improved. Moreover, the protein of the germinated and hydrolyzed soybean flour demonstrated better swallowing properties. These findings indicated that the combined treatment of germination and enzymatic hydrolysis can improve the quality of soybean protein.     

Enzymatic hydrolysis of hard‐to‐cook bean (Phaseolus vulgaris L.) protein concentrates and its effects on biological and functional properties

Inadequate postharvest handling and storage under high temperature and relative humidity conditions produce the hard‐to‐cook (HTC) defect in beans. However, these can be raw material to produce hydrolysates with functional activities. Angiotensin I‐converting enzyme (ACE) inhibitory and antioxidant capacities were determined for extensively hydrolysed proteins of HTC bean produced with sequential systems Alcalase‐Flavourzyme (AF) and pepsin–pancreatin (Pep‐Pan) at 90 min ACE inhibition expressed as IC₅₀ values were 4.5 and 6.5 mg protein per mL with AF and Pep‐Pan, respectively. Antioxidant activity as Trolox equivalent antioxidant capacity (TEAC) was 8.1 mm  mg^?1 sample with AF and 6.4 mm  mg^?1 sample with Pep‐Pan. The peptides released from the protein during hydrolysis were responsible for the observed ACE inhibition and antioxidant activities. Nitrogen solubility, emulsifying capacity, emulsion stability, foaming capacity and foam stability were measured for limited hydrolysis produced with Flavourzyme and pancreatin at 15 min. The hydrolysates exhibited better functional properties than the protein concentrate.     

鲤鱼鱼肉蛋白酶水解物抗氧化性及功能特性

采用碱性蛋白酶对鲤鱼鱼肉蛋白进行酶解,制备不同水解度的水解物。测定水解物的抗氧化活性以及不同pH值条件下水解物的功能特性。结果表明:随着水解度的逐渐升高,水解物的抑制脂质氧化能力、D PP H自由基清除能力、还原能力以及金属离子(Cu2+和Fe2+)螯合能力逐渐增加(P<0.05);同时,水解物的溶解性、乳化性和起泡性都在pH值为4.0(等电点)时达到最低,而后溶解性和乳化性随着pH值升高而增大(P<0.05),而起泡性随着pH值的升高先上升后又下降。因此,鲤鱼鱼肉蛋白碱性蛋白酶水解物可以提高蛋白质的抗氧化活性和溶解性,但是较高的水解度会在一定程度上降低其乳化性和起泡性。     

Functional properties of gelation-like protein hydrolysates from scallop (<Emphasis Type="Italic">Patinopecten yessoensis</Emphasis>) male gonad

Gelation-like protein hydrolysates from scallop (Patinopecten yessoensis) male gonad (SMG) were obtained by enzymatic hydrolysis using neutrase. Functional properties of SMG hydrolysates (SMGHs) with different degree of hydrolysis (DH: 4.94, 6.84, 7.53 and 11.86%, respectively) were evaluated with the objective to investigate the relations between hydrolysis characteristics and functionalities. The results showed that hydrolysis with neutrase improved the gelation property, solubility, water-holding capacity (WHC), oil-holding capacity (OHC), and surface hydrophobicity (SH), but not foaming capacity (FC) of SMG. The SMGHs at high DH (11.86%) showed better gelation property and solubility than that at low DH (4.94–7.53%). However, the maximum values of WHC, OHC, and SH of SMGHs were found at DH of 4.94%, significantly higher than (p < 0.05) or equivalent to (p > 0.05) that of soy protein isolate (SPI) for WHC and OHC. Emulsifying capacity of SMGHs is independent of DH, but restricted by pH environment. The emulsifying activity index of all SMGHs was significantly higher than that of SPI in pH 5 (p < 0.05) and slightly higher than or equivalent to that of SPI in pH 7. Meanwhile, SMG and SMGHs were abundant in glycine, lysine, alanine, glutamic acid, and aspartic acid, containing all the essential amino acids (41.63–42.90% of the total amino acids). These results imply that SMGHs might be utilized as multifunctional and nutritive ingredients in food industry.     

Identification and characterization of antioxidant peptides from sweet potato protein hydrolysates by Alcalase under high hydrostatic pressure

Sweet potato protein hydrolysates (SPPH) were generated by Alcalase under high hydrostatic pressure (HHP, 100, 200 and 300 MPa). HHP significantly improved the degree of hydrolysis (DH) and antioxidant activity, and increased the < 3 kDa fraction content of SPPH (P < 0.05). SPPH by Alcalase at 300 MPa for 60 min exhibited the highest DH and antioxidant activity and was separated into three fractions by ultrafiltration. The most active fraction FIII (< 3 kDa) was further separated into fifty four fractions by semi-preparative RP-HPLC and measured using the ORAC assay. In addition, more active fractions were examined by LC–MS/MS, and diverse peptides were identified, matching sequences of Sporamins A and B. To evaluate the structure–activity dependences, twenty sequences were synthesized, of which the antioxidant activity was assessed. Five peptides showed good activity: HDSASGQY ≥ YYMVSA ≥ HDSESGQY ~ YYIVS ~ RYYDPL, with the contribution of His and Tyr.Industrial relevanceThis study will give a novel technique for using industrial waste slurry, a byproduct in the process of sweet potato starch manufacturing, which contains various bioactive components (such as protein, minerals, etc.) since most of them are normally discarded. The present study is focused on assessing the effects of enzymatic hydrolysis by Alcalase under high hydrostatic pressure (HHP) on the release of antioxidant peptides from sweet potato protein (SPP). The results of this work provide a potential application of enzymatic hydrolysis assisted by HHP on the development of ingredients from SPP in functional foods.     

Production and characterisation of antioxidant peptides from sweet potato protein by enzymatic hydrolysis with radio frequency pretreatment

Effect of radio frequency (RF at 70, 80 and 90 °C) pretreatment on production and characterisation of sweet potato protein hydrolysates (SPPH) prepared using Alcalase (ALC), Protease (PRO) and the combination of ALC + PRO was investigated. RF highly improved degree of hydrolysis (DH) and enhanced antioxidant activity of all SPPH produced by ALC, PRO and the combination as compared to traditional water bath (WB) heating pretreatment (P < 0.05). RF significantly increased molecular weight (MW) <3 kDa peptide fraction from SPPH produced by ALC, and MW <3 kDa peptide fraction from RF80- and RF90-pretreated samples has higher antioxidant activity. Diverse peptides in MW <3 kDa fractions with RF80 and RF90 pretreatments were identified using LC–QTOF–MS/MS, which matched the sequences of sporamins and contained antioxidant amino acids Trp, Tyr, Met, Phe and/or His. There is a great potential application of using SPPH in functional foods as a novel ingredient.