Bitterness Of Hydrolysates Research Articles

Protein hydrolysate from salmon frame debittered by plastein reaction: amino acid composition, characteristics and antioxidant activities

SummaryImpacts of plastein reaction on bitterness, physicochemical and antioxidant properties of salmon frame hydrolysate with the aid of various proteases (alcalase and papain) at different concentrations and varying reaction temperatures were investigated. Plastein was produced from hydrolysate by papain at 40°C, which had 30% degree of hydrolysis (30DHP). Rearrangement of peptides in hydrolysate was performed by 1% papain at 40°C for 10 h, yielding plastein namely ‘30DHP‐P1’. It showed the lowest bitterness (P < 0.05) than other plasteins and hydrolysates. Surface hydrophobicity was not related well with bitterness. Therefore, the size of peptides also determines the bitterness. 30DHP‐P1 had augmented solubility; however, its antioxidant activities (DPPH and ABTS radical scavenging activities and ferric reducing antioxidant power) were slightly lower (P < 0.05) than those of hydrolysates. Bitterness of hydrolysate was markedly debittered via plastein reaction under optimal condition. Plastein generally had lighter colour and still possessed antioxidant activity.

Ферментные препараты бактериальных протеаз для получения белковых гидролизатов без горечи

Casein hydrolysates were obtained using enzyme preparations (EPs) of bacterial proteases, Alcalase, Protamex, Neutrase, and Protosubtilin. The dependence of the hydrolysate bitterness on the decrease of the EP proteolytic activity in the presence of PMSF, an inhibitor of serine proteases, was observed. It was found that the use of Neutrase provided non-bitter hydrolysates, while the proteolytic activity of Neutrase decreased by 44% in the presence of PMSF. A domestic EP of Protosubtilin lost 59% activity in the presence of PMSF and formed bitter hydrolysates. Casein hydrolysates obtained using Alcalase were characterized by the most severe bitterness, probably due to the fact that almost all proteolytic activity in this preparation is represented by a serine protease. The Bacillus subtilis 359 strain with a ratio of neutral and serine protease activities of 52 to 48% was selected from the VNIIPBT Collection of Bacterial Producers of Proteases. The concentrated preparation was obtained from the culture liquid of B. subtilis 359 strain by spray-drying. The preparation obtained hydrolyzed casein similarly to Neutrase and ensured the absence of bitterness in hydrolysates. neutral protease, serine protease, bitterness of hydrolysates, Bacillus subtilis This work was financially supported by a Grant of the Basic Research Program of the Russian Academy of Sciences for 2019-2021 (Project no. 0529-2019-0066).

INFLUENCE OF FACTORS ON THE BITTERNESS AND SENSORY TASTE IN PROTEIN HYDROLYSATE FROM SPENT

Spent brewer’s yeast, obtained after the main fermentation stage, is a rich- in-protein source (protein content accounts for 48 - 50 % dry matter). In order to use efficiently this protein source for using in food industry, it was hydrolysed by different methods into mixtures of peptides and amino acids. So that it has a wide range of applications in food. It can be used as emulsifying agents in a number of applications such as salad dressings, spreads, ice cream, coffee whitener, cracker, and meat products like sausages. However, bitterness in hydrolysates is one of the major undesirable aspects for various applications in food processing. In this study, influences of factors (E/S ratio, pH and temperature) on bitterness of hydrolysate were studied to choose the best hydrolysis conditions by using flavourzyme, alcalase and neutrase. The bitterness of hydrolysate was determined by intensity sensory method (using quinine standard) and amino acid content was analysed by HPLC method. The result showed that bitterness of brewer’s yeast hydrolysate by flavourzyme is the lowest and that by neutrase is the highest. In particular, the bitterness of hydrolysates have reached values of 15.2–40.42 µmol quinine/l (FH - flavourzyme hydrolysate), 21–64.99 µmol quinine/l (AH - alcalase hydrolysate) and 34.62–64.26 µmol quinine/l (NH - neutrase hydrolysate), respectively. The hydrolysis conditions in using flavourzyme were chosen at 50 oC, pH 7, E/S ratio 7.1U/g and in using alcalase - at 55 oC, pH 8, ratio E/S 7.2 U/g, respectively. At this conditions, bitterness reached values 15.44 µmol quinine/l (in FH) and 21.16 µmol quinine/l (in AH).

OPTIMIZATION FOR BATCH PROTEOLYTIC HYDROLYSIS OF SPENT BREWER’S YEAST BY USING PROTEASES

The yield of proteolylic hydrolysis for spent brewer’s yeast by protease and aminoacid contents of hydrolysates (the main factors influencing in taste of hydrolysed product) depends on factors influencing in catalytic activities of enzymes as temperature, pH value, type of used enzymes and ratio enzyme/substrate. With the purpose to hydrolyse the spent brewer’s yeast for food application, bitterness of hydrolysate takes the firth consideration, and than the yield of hydrolysing process plays economic role. In this paper, it is dealt with determination of optimal conditions to obtain the highest yield of hydrolysis process and the lowest bitterness of hydrolysate (the bitterness is determined by sensory evaluation, expressed equivalently with concentration of quinine). Response surface methodology (RSM) was used to determine optimum condition for batch proteolytic hydrolysis of spent brewer’s yeast. The influencing factors were investigated as temperature (X1): 40 oC–60 oC; pH (X2): 6.0–9.0, ratio E (flavourzyme)/S (X3): 5–10 U/g and hydrolysis time (X4): 6–9 hours. The experimental responses including degree of hydrolysis (Y1) (%) and bitterness of hydrolysate (Y2) (μmol quinine/ml) are performed in second-degree model. The optimal conditions for obtaining high degree of hydrolysis and low bitterness are determined: Ratio of enzyme mixture (alcalase 7.5 U/g and flavourzyme 8.5 U/g), pH 7.5, hydrolysis temperature at 52oC and hydrolysis time 9 hours. Under the optimal conditions, the actual values obtained for the yield of hydrolysis was 40.81 ± 0.044 % and the bitterness equivalently with concentration of quinine was 16.37 ± 0.03 μmol quinine/ml.

Original article: Thermal pretreatment and chemical modifications as a means to alter hydrolytic characteristics and prevent bitterness in hydrolysates of fishery by‐catch (Decapterus maruadsi) protein

SummaryIn this study, fishery by‐catch protein (Decapterus maruadsi) was first thermal treated (60–100 °C), phosphorylated (0.5–4.0 g g−1 protein) or succinylated (0.05–0.3 g g−1 protein) before hydrolysis to prevent the bitterness of the resulting hydrolysate. Hydrolysis was performed at 50 °C, 10 h, pH 8.0 by Alcalase. Results showed that thermal treatment upon 80 °C, succinylation and phosphorylation resulted in significant decrease in amino acid content and increase in larger peptide content (>1450 Da). Succinylation did not reduce the bitterness as a result of higher content of small peptides (<550 Da), which was found to be correlated positively with the bitterness of hydrolysates. However, thermal treatment, especially phosphorylation, could reduce the bitterness to discernible level, indicating that phosphorylation before hydrolysis could be a potential means to prevent the evolution of bitter flavour which restricts the practical uses of the hydrolysates.

Angiotensin-I-converting enzyme inhibitory activity and bitterness of enzymatically-produced hydrolysates of shrimp ( Pandalopsis dispar) processing byproducts investigated by Taguchi design

The importance of water-to-substrate ratio, protease type, percent enzyme and incubation time on hydrolysates produced from shrimp processing byproducts was investigated using Taguchi’s L 16 (4 5) experimental design. Protease type significantly ( p < 0.05) influenced soluble yield, degree of hydrolysis (DH), angiotensin-I-converting enzyme (ACE) inhibitory activity and bitterness of hydrolysates, while percent enzyme only affected the DH. Hydrolysates produced by Alcalase and Protamex possessed strong ACE inhibitory activity ( IC 50 = 100–200 μg/ml and 70 μg/ml, respectively), accompanied by high yield, high DH and strong bitterness. Furthermore, ACE inhibition was positively correlated ( r 2 = 0.87) with bitterness of the hydrolysates. Fractionation by size-exclusion chromatography revealed that the bitter substances, which also showed strong ACE inhibition, were <3 kDa in size and contained many hydrophobic residues, including Tyr, Phe, Leu, Ile, Val and Lys. Despite the bitterness, these hydrolysates may have potential health benefits, arising from their potent ACE inhibitory activity.

Characteristic Property of Low Bitterness in Protein Hydrolysates by a Novel Soybean Protease D3

ABSTRACT: Enzymatic hydrolysis is 1 means of improving the functional properties of food protein; however, in most cases, bitter peptides are generated by such treatment, and the resulting product is therefore not acceptable as a food ingredient. We have already reported a novel cysteine protease, D3, purified from germinating soybean cotyledons. Because of its substrate specificities, most hydrophobic amino acid residues in the hydrolysate are presumed not to be located at the peptide termini. It was therefore expected that protein hydrolysate by protease D3 would taste less bitter than other enzymatic hydrolysates. The objective of this study was to demonstrate the low bitterness of protein hydrolysates by protease D3. For that purpose, soy protein and casein hydrolysates were prepared with treatment of protease D3, subtilisin, pepsin, trypsin, and thermolysin, respectively. The bitterness of these hydrolysates was evaluated by measuring points of subjective equality (PSE). The PSE value demonstrated that the protein hydrolysates by protease D3 were significantly less bitter than the other enzymatic hydrolysates, indicating that the products had a taste mild enough to be acceptable as a less‐bitter peptide food ingredient. These results suggested that a prominent feature of protease D3 was its capacity to produce less‐bitter peptides. Therefore, it is thought that protease D3 could be applied to produce protein hydrolysates for use as ingredients in a variety of food products.

Preparation of hydrolysates from bovine red blood cells and their debittering following plastein reaction

Protein hydrolysates from bovine red blood cells were prepared using commercially available Alcalase. The best nitrogen recovery (69.2%) was achieved at a degree of hydrolysis (DH) of 25%. However, the product so obtained had a strong bitter taste (4.3 on a 5-point scale). At DH 16%, the nitrogen recovery was 65.9% and the bitter taste of product decreased (to 3.5). The hydrolysate contained 81.8% crude protein (N × 6.25), 2.4% moisture and 15.8% sodium chloride and had excellent solubility characteristics in water in the pH range 2.6–9.5. The Hunter colour parameters of the hydrolysate showed that good release of haem compounds during the process had occurred. Incorporation of hydrolysates (up to 3%) in meat model systems enhanced their cooking yield by about 5%. The protein efficiency ratio value of the hydrolysate was 3.7 as compared with that of beef (2.8), pork (2.5) and cod (2.5) proteins. However, low contents of isoleucine and sulphur-containing amino acids gave an essential amino acid index of 67.3 for the product. The bitterness of hydrolysate was reduced considerably by plastein reaction with diethyl ester of glutamic acid. The resultant product had a crude protein (N × 6.25) content of 96.3% and contained 30.6% of glutamic acid. The total free amino acid content in the product decreased from 18.6 mg g −1 hydrolysate to 1.85 mg g −1 plastein.

Production of Peptic Hemoglobin Hydrolyzates: Bitterness Demonstration and Characterization

Hemoglobin could be valorized in enzymatic hydrolysate form aimed at human and animal feeding. Thus, the hydrolysis of hemoglobin by pepsin was studied. A bitter taste in the hydrolysates was encountered, so different separation processes were developed to isolate the bitter fractions according to several characteristics. Therefore, ultrafiltration, reversed phase chromatography, and organic solvent extraction were used. Bitter peptides were concentrated in YM5 membrane (cutoff : 5000) permeate. They were eluted with 30-40% CH 3 CN from a C 18 bonded silica column and selectively extracted by 2-butanol. They were also adsorbed on a Superose 12 gel filtration column, and so they were represented by a chromatographic peak appearing after total column volume. Chromatography on Superose 12 could thus constitute an interesting analytical method for detecting bitterness in hydrolysates.

COMPARATIVE STUDY OF THE BITTER TASTE OF ENZYMIC HYDROLYSATES FROM COW, EWE AND GOAT CASEINS

ABSTRACTThis study was initiated to explain the rare occurrence of bitter defects in goat and ewe cheeses, compared to cow cheeses. The main difference between whole caseins from these three species is their relative content of αS1 ‐ and β‐caseins. The tastes of enzymic hydrolysates (obtained with rennet, porcine pepsin, α‐chymotrypsin, trypsin and thermolysin) of whole caseins from these species were compared as well as those of cow αS1 ‐ and β‐caseins. In each case (except with chymotrypsin) the bitterness of hydrolysates from cow whole casein was much stronger than those of goat and ewe whole casein hydrolysates. Cow αS1 ‐casein hydrolysates were more bitter than cow β‐casein hydrolysates, except with thermolysin.