共查询到20条相似文献,搜索用时 46 毫秒
1.
《Food chemistry》1999,66(2):173-180
Hydroperoxide lyase (HPL) was extracted from cucumber fruit (Cucumis sativus) and purified by centrifugation, solubilization with detergent, ion-exchange chromatography and hydroxyapatite chromatography. 9-Hydroperoxy-linoleic acid and 13-hydroperoxy-linoleic acid lysing activities were purified 88-fold and 82-fold, respectively. The purified HPL preparation consisted of a single major band following SDS-electrophoresis with a molecular weight of about 55 000 Da; pH 6 was optimum for the lysis of both 9-hydroperoxy-linoleic acid and 13-hydroperoxy-linoleic acid substrates. The enzyme was relatively stable and retained more than two thirds of original activity after 3 weeks at 4°C, but lost half of its activity after 2 min at 50°C. Apparent Km values for 9-hydroperoxy-linoleic acid, 9-hydroperoxy-linolenic acid, 13-hydroperoxy-linoleic acid and 13-hydroperoxy-linolenic acid were 6.76, 6.02, 5.46 and 12.4 μM respectively. Corresponding Vmax values were 19.3, 12.0, 7.58 and 11.4 μmol min. The Vmaxapp/Kmapp values for 9-hydroperoxy-linoleic acid, 9-hydroperoxy-linolenic acid, 13-hydroperoxy-linoleic acid and 13-hydroperoxy-linolenic acid were 2.86, 1.99, 1.39 and 0.92, respectively. It is suggested that cucumber mesocarp contains only one type of HPL which is able to more efficiently catalyse the lysis of the 9-acyl hydroperoxides and especially 9-hydroperoxy-linoleic acid.© 相似文献
2.
A cDNA encoding hydroperoxide lyase (HPL) was isolated from Solanum tuberosum, cloned into pQE-30 vector, and expressed in E. coli. The recombinant protein was purified by nickel affinity chromatography and showed an approximate molecular weight of 54 kDa
by SDS–PAGE analysis, which was similar to the predicted value based on the putative amino acid sequences (53.9 kDa). 13-Hydroperoxy-linolenic
acid (13-HPOT) was the preferred substrate for the enzyme compared with 13-hydroperoxy-linoleic acid (13-HPOD). The corresponding
volatile products were 2(E)-hexenal and n-hexanal tested by headspace-gas chromatography, respectively. The enzyme was optimally
active at 25 °C and pH 6.5. The K
m, V
max, and the catalytic efficiency (V
max/K
m) for 13-HPOT were 56.6 μM, 71.3 units/mg, and 1.26 units/mg · μM, respectively. Activity of the recombinant potato HPL increased
when Triton X-100, sodium chloride, or potassium chloride was added in the reaction mixture, while calcium chloride decreased
activity of the recombinant enzyme. 相似文献
3.
4.
Pseudomonas fluorescens Rm12 is a kind of Psychrotrophic bacteria growing in cold raw milk. It produced an extracellular heat resistant protease with an estimated molecular weight
of 45 kDa by size exclusion chromatography and SDS-PAGE under both reducing and non-reducing conditions. The enzyme, designated
Ht13, was purified to electrophoretic homogeneity from the culture supernatant by sequentially using ammonium sulfate precipitation,
ion-exchange chromatography, hydrophobic chromatography and size exclusion chromatography. The specific activity of the enzyme
increased 115.5-folds. The optimum pH value and temperature of Ht13 were 7.5 and 40 °C, respectively. Based on its biochemical
characteristics, Ht13 can be included in the group of metalloproteases, which was inhibited by 1, 10-phenanthroline and EDTA
but not by pepstatin A, chymostatin, STI, E-64, BBI, PMSF and pAPMSF. Mn2+ has positive effect on activity and can increased the heat resistance capability, while Ca2+ had a negligible effect. For the hydrolysis of azocasein, the Km was 0.012 mg mL−1. The enzyme showed typical heat-stable behavior. After treatment of 160 °C 20 s, the residual activity was 9%. The half-life
of the enzyme at 160 °C in buffer with Mn2+ was approximately 12 s. Among several main milk proteins, Ht13 can cleave αs-casein, β-casein and κ-casein. The sequence of 1st–16th amino acids of N-terminal was MSKVKDKAIVSAAQAS, which was same as
those proteases excreted from some other P. fluorescens. However, their molecular weights, the activation ion and amino acid composition were different, suggesting Ht13 from P. fluorescens Rm12 is a novel protease. 相似文献
5.
The sea cucumber Stichopus japonicus protein was hydrolyzed by pepsin, trypsin, papain, acid protease and neutral protease, respectively, to get five kinds of
peptide fractions: pepsin peptides (PP), trypsin peptides (TP), acid protease peptides (AP), neutral protease peptides (NP)
and papain peptide (PAP). Antioxidative activities of all peptide fractions were evaluated by hydroxyl radical– (·OH) and
Superoxide anion (O2
· −
)–scavenging activity. Trypsin peptide (TP) exhibited the highest antioxidative activity compared to other peptide fractions.
In considering scavenging effects on hydroxyl radicals (·OH) and Superoxide anions (O2
· −
), TP was employed for isolation, purification and identification of antioxidant peptide. To purify and characterize antioxidative
peptide, two steps gel filtration, one-step ion-exchange column chromatography and reversed-phase high-performance liquid
chromatography (RP-HPLC) were used. The purified antioxidative peptide TP2b-1 was a novel peptide and was sequenced as GPEPTGPTGAPQWLR,
in which the low molecular weight and some amino acid constituents played important role in the radical-scavenging effects
according reports. The IC50 values of TP2b-1 were 138.9 μM on ·OH and 353.9 μM on O2
· −
. 相似文献
6.
Sitthipong Nalinanon Soottawat Benjakul Hideki Kishimura 《European Food Research and Technology》2010,231(2):259-269
Pepsins 1 and 2 from the stomach of skipjack tuna (Katsuwonus pelamis) were purified to homogeneity by using a series of chromatographic purification involving DEAE-cellulose, Sephadex G-50 and
Sephadex G-75 with increase in purity of 246-fold and 213-fold, respectively. Molecular weights of pepsins 1 and 2 were estimated
by SDS–PAGE to be 33.9 and 33.7 kDa, respectively. The N-terminal amino acid sequences of the first 20 amino acids of both
isoenzymes were YQDGTEPMTNDADLSYYGVI. The optimal pH and temperature for pepsin 1 were 2.5 and 50 °C, respectively, while
pepsin 2 showed optimal activity at pH 2.0 and 45 °C. The activity of two pepsins was stable in the pH range of 2–5 and at
temperatures up to 50 °C. The activity of purified pepsins was strongly inhibited by pepstatin A in a dose-dependent manner.
SDS and cysteine showed inhibitory effects toward both pepsins. Activity of pepsin 2 was slightly activated by NaCl, but NaCl
had no effect on pepsin 1. Pepsins 1 and 2 had high affinity and hydrolytic activity toward hemoglobin with K
m of 54 and 71 μM, respectively. k
cat of pepsins 1 and 2 were 38.1 and 44.3 s−1, respectively. Both pepsins effectively hydrolyzed bovine serum albumin, egg white, natural actomyosin from brownstripe red
snapper muscle and acid-solubilized collagen from arabesque greenling skin. Nevertheless, the hydrolytic activity was slightly
less than that of pepsin from porcine stomach. 相似文献
7.
The present work was devoted to investigations concerning the fructooligosaccharide producing activity of Cryptococcus sp. LEB-V2 (Laboratory of Bioprocess Engineering, Unicamp, Brazil) and its extracellular fructofuranosidase. After cell separation,
the enzyme was purified by ethanol precipitation and anion exchange chromatography. The enzyme showed both fructofuranosidase
(FA) and fructosyl transferase (FTA) activity. With sucrose as substrate, the data failed to fit the Michaelis–Menten behaviour,
showing a substrate inhibitory model. The K
m, K
i and v
max values were shown to be 64 mM, 3 M and 159.6 μmol mL−1 min−1 for FA and 131 mM, 1.6 M and 377.8 μmol mL−1 min−1 for FTA, respectively. The optimum pH and temperature were found to be around 4.0 and 65 °C, while the best stability was
achieved at pH 4.5 and temperatures below 60 °C, for both the FA and FTA. Despite the strong FA activity, the high transfructosylating
activity allowed for good FOS production from sucrose (35% yield). 相似文献
8.
Purification and enzymatic characteristics of a novel polyphenol oxidase from lotus seed (Nelumbo nucifera Gaertn.)
下载免费PDF全文
![点击此处可从《International Journal of Food Science & Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Xi‐Xi Cai Yong‐Xiang Hong Shao‐Yun Wang Li‐Na Zhao Ping‐Fan Rao 《International Journal of Food Science & Technology》2015,50(4):1026-1032
A polyphenol oxidase (PPO) from lotus seed was purified by the procedures including ammonium sulphate precipitation and affinity chromatography. The apparent molecular mass was 38.6 kDa by SDS‐PAGE. Kinetic studies showed that the Km and Vmax values for catechol were 6.04 mm and 416.67 U, respectively. The PPO performed optimal activity in 20 °C and pH 7.0. The enzymatic activity could be mainly maintained up to 50 °C and pH 4.0–7.0. The activity could be inhibited by various inhibitors including thiourea, urea, sodium hydrogen sulphite, EDTA·2Na, SDS, citric acid, guanidine hydrochloride, ascorbic acid, sodium sulphite and sodium thiosulphate. The metal ions Ba2+, Mg2+, Ca2+, Mn2+, Co2+ and Zn2+ could inhibit the activity of PPO, while Cu2+ performed obvious enhancement. The enzymatic properties of PPO could probably provide practical application in inhibiting the PPO activity and preventing enzymatic browning in the process of picking, transportation, processing and storage of fresh lotus seeds. 相似文献
9.
The present work was carried out with the aim to investigate some properties of an extracellular fructofuranosidase enzyme,
with high transfructosylating activity, from Candida sp. LEB-I3 (Laboratory of Bioprocess Engineering, Unicamp, Brazil). The enzyme was produced through fermentation, and after cell separation from the fermented medium, the enzyme was
concentrated by ethanol precipitation and than purified by anion exchange chromatography. The enzyme exhibited both fructofuranosidase
(FA) and fructosyltransferase (FTA) activities on a low and high sucrose concentration. With sucrose as the substrate, the
data fitted the Michaellis–Menten model for FA, showing rather a substrate inhibitory shape for fructosyltransferase activity.
The K
m and v
max values were shown to be 13.4 g L−1 and 21.0 μmol mL−1 min−1 and 25.5 g L−1 and 52.5 μmol mL−1 min−1 for FA and FTA activities, respectively. FTA presented an inhibitory factor K
i of 729.8 g L−1. The optimum conditions for FA activity were found to be pH 3.25–3.5 and temperatures around 69 °C, while for FTA, the optimum
condition were 65 °C (±2 °C) and pH 4.00 (±0.25). Both activities were very stable at temperatures below 60 °C, while for
FA, the best stability occurred at pH 5.0 and for FTA at pH 4.5–5.0. Despite the strong fructofuranosidase activity, causing
hydrolysis of the fructooligosaccharides (FOS), the high transfructosilating activity allows a high FOS production from sucrose
(44%). 相似文献
10.
Prashani Mudika Ekanayake Chamilani Nikapitiya Mahanama De Zoysa Ilson Whang Se Jae Kim Jehee Lee 《European Food Research and Technology》2008,227(3):897-903
Natural fermentation was tested as a method of releasing active compounds during screening for potential anticoagulant activity
in three types of algae (Pachymeniopsis elliptica, Sargassum horneri, and Ulva pertusa). Freeze dried algae samples (2.5 g) were fermented by adding 75 g of sugar and 500 mL of water and thereafter kept at room
temperature (25 °C) for 3 months. Activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT)
were measured every 2 weeks for 3 months to determine the optimum time for the highest activity. Fermented P. elliptica, (which had the highest activity) was subjected to anion exchange chromatography (DEAE-cellulose) and sepharose 4B gel permeation
chromatography. The purified sample was analyzed by agarose-gel electrophoresis and polyacrylamide gel electrophoresis (PAGE)
to confirm the purification and to determine the molecular mass, respectively. The 360 μg/mL of purified compound (Mwt > 500,000 Da)
had both APTT and PT activities (>1,000 s). However, at the concentrations of 180 μg/mL, purified compound and heparin showed
540 and >1,000 s APTT activity, respectively. Though, the purified compound of P. elliptica considered as a weaker anticoagulant than heparin, this purified anticoagulant polysaccharide could be considered as a good
alternative source as an anticoagulant. Moreover, the technique of fermentation is an inexpensive and feasible, this purified
anticoagulant polysaccharide compound could be used in pharmaceutical and biomedical industry. Further investigations need
to be performed to determine the mechanism of this novel anticoagulant compound.
The authors Prashani Mudika Ekanayake and Chamilani Nikapitiya contributed equally to this work. 相似文献
11.
Evaggelia D. Tzika Theodore G. Sotiroudis Vassiliki Papadimitriou Aristotelis Xenakis 《European Food Research and Technology》2009,228(3):487-495
The enzyme peroxidase (POD) activity was extracted from olives (Olea europaea cv. Koroneiki) and was partially purified by ammonium sulfate fractionation and gel permeation chromatography (Sephacryl
S 300). Further characterization of the POD was performed using the ammonium sulfate purified fraction. POD showed a molecular
mass of 44 ± 2 kDa and it expressed catalytic activity with 2,2′-azino-bis(3-ethylbenz-thiazoline-6-sulfonic acid) (ABTS),
N,N-dimethyl-p-phenylenediamine (DMPD) and some olive fruit phenols. However, the enzyme was found ineffective as regards the oxidation
of oleuropein, the major polyphenol of olives, as well as with coumaric, ferulic, ascorbic and p-hydroxy benzoic acids. pH optimum of the peroxidase-catalyzed oxidation depended on the substrate used and it varied from
4.0 to 6.0. Olive peroxidase shows high thermal stability. Oleuropein, the major polyphenol of olives, drastically inhibited
ABTS peroxidation by the POD preparation with an IC50 value of 47 μM. The presence of POD enzyme activity in virgin olive oil samples was also confirmed. 相似文献
12.
Sarita Yadav Rama S. S. Yadav Kapil D. S. Yadav 《International Journal of Food Science & Technology》2013,48(5):927-933
The extracellular α‐l ‐rhamnosidase has been purified by growing a new fungal strain Aspergillus awamori MTCC‐2879 in the liquid culture growth medium containing orange peel. The purification procedure involved ultrafiltration using PM‐10 membrane and anion‐exchange chromatography on diethyl amino ethyl cellulose. The purified enzyme gave single protein band in SDS‐PAGE analysis corresponding to molecular mass 75.0 kDa. The native PAGE analysis of the purified enzyme also gave a single protein band, confirming the purity of the enzyme. The Km and Vmax values of the enzyme for p‐nitrophenyl‐α‐l ‐rhamnopyranoside were 0.62 mm and 27.06 μmole min?1 mg?1, respectively, yielding kcat and kcat/km values 39.90 s?1 and 54.70 mm ?1 s?1, respectively. The enzyme had an optimum pH of 7.0 and optimum temperature of 60 °C. The activation energy for the thermal denaturation of the enzyme was 35.65 kJ?1 mol?1 K?1. The purified enzyme can be used for specifically cleaving terminal α‐l ‐rhamnose from the natural glycosides, thereby contributing to the preparation of pharmaceutically important compounds like prunin and l ‐rhamnose. 相似文献
13.
Seok-Chun Ko Min Cheol Kang Jung-Kwon Lee Hee-Guk Byun Se-Kwon Kim Seung-Cheol Lee Byong-Tae Jeon Pyo-Jam Park Won-Kyo Jung You-Jin Jeon 《European Food Research and Technology》2011,233(6):915-922
Angiotensin I-converting enzyme (ACE) inhibitory peptide was isolated from Styela plicata. The S. plicata was hydrolyzed with various proteases including Protamex, Kojizyme, Neutrase, Flavourzyme, Alcalase, trypsin, α-chymotrypsin,
pepsin, and papain. The hydrolysate prepared with Protamex had the highest ACE inhibitory activity compared to the other hydrolysates.
We attempted to isolate ACE inhibitory peptides from hydrolysate prepared with Protamex using ultra-filtration, gel filtration
on a Sephadex G-25 column and reversed-phase high-performance liquid chromatography (RP-HPLC) on an ODS column. IC50 value of the purified ACE inhibitory peptide was 24.7 μM, and Lineweaver–Burk plots suggest that the purified peptide from
S. plicata acts as mixed-type inhibitor against ACE. Amino acid sequence of the purified peptide was identified as Met-Leu-Leu-Cys-Ser,
with a molecular weight 566.4 Da. The results of this study suggest that peptides derived from S. plicata may be beneficial as anti-hypertension compounds in functional foods resource. 相似文献
14.
Purification and characterisation of β‐mannanase from Lactobacillus plantarum (M24) and its applications in some fruit juices
下载免费PDF全文
![点击此处可从《International Journal of Food Science & Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Hayrunnisa Nadaroglu Ahmet Adiguzel Gulsah Adiguzel 《International Journal of Food Science & Technology》2015,50(5):1158-1165
β‐Mannanase was purified 2619.05‐fold from the Lactobacillus plantarum (M24) bacterium by ammonium sulphate precipitation and ion exchange chromatography (DEAE‐Sephadex). The purified enzyme gave two protein bands at a level of approximately 36.4 and 55.3 kDa in the SDS‐PAGE. The purified mannanase enzyme has shown its maximum activity at 50 °C and pH 8, and it has been also determined that the enzyme was stable at 5–11 pH range and over 50 °C. The Vmax and Km values have been identified as 82 mg mannan mL?1 and 0.178 mm , respectively. The effects of some metal ions such as Fe2+, Ca2+, Co2+, Ni2+, Mn2+, Cu2+ and Zn2+ on the mannanase enzyme have been also investigated, and it has been determined that all metal ions had significant effects on the activation of the mannanase enzyme. In addition, the effectiveness of the purified mannanase enzyme on the clarification of some fruit juices such as orange, apricot, grape and apple has been investigated. During the clarification processes, the enzyme was more effective than crude extracts on the clarification of the peach juice with a ratio of 223.1% at most. 相似文献
15.
Response surface methodology was used to predict optimum conditions for hot air roasting of barley grains (temperature, time,
and amount). Antioxidant capacity in the grains was highest under optimum conditions of 250 °C, 63.5 min and 42 g (one and
a half layers). A correlation of R
2 = 0.74 (p < 0.05) was found between 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and total phenolic contents. Ethanol
and aqueous extracts were prepared from grains roasted under optimum conditions and assessed for antioxidant capacity. Antioxidative
compounds in the extracts were then identified using GC–MS. The IC50 value of ethanol extract was significantly lower (11.45 μg mL–1) than that of aqueous extract (33.54 μg mL–1) and α-tocopherol (12.6 μg mL–1) but higher than BHT (9.59 μg mL–1). The same trend was observed in linoleic acid assay. In reducing power, the ethanol extract and α-tocopherol were not significantly
different. Phenolic acids p-hydroxybenzaldehyde, vallinic and gallic acids were identified as the major compounds in the extracts. The results obtained
from this study show that it is possible to optimize antioxidant capacity in barley grains during roasting. 相似文献
16.
Collagen extracted from jellyfish (Rhopilema esculentum) was hydrolyzed with alcalase to prepare the ACE-inhibitory peptide. The optimal hydrolyzing conditions were determined using
response surface methodology. The results showed that the optimal conditions were temperature of 52.7 °C, pH of 8.63 and enzyme-to-substrate
ratio (E/S) of 3.46%, and the ACE-inhibitory activity of the obtained hydrolysates could reach 81.7%. Jellyfish collagen peptide, UF3-B2,
was purified from the hydrolysates using ultrafiltration, ion-exchange chromatography and gel filtration. The IC50 value of UF3-B2 was 43 μg/ml, and the yield accounted for 6.25% of the hydrolysates. The molecular weight distribution of
UF3-B2 was from 200 to 600 Da. Amino acid analyses showed that UF3-B2 was rich in Gly, Pro, Glu, Ala, and Asp. 相似文献
17.
Ali Bougatef Rafik Balti Naïma Nedjar-Arroume Rozenn Ravallec Estelle Yaba Adjé Nabil Souissi Imen Lassoued Didier Guillochon Moncef Nasri 《European Food Research and Technology》2010,231(1):127-135
In this study, smooth hound protein hydrolysates (SHPHs), obtained by treatment with various gastrointestinal proteases, were
analyzed for their angiotensin I-converting enzyme (ACE) inhibitory activities. Protein hydrolysates were obtained by treatment
with crude alkaline enzyme extract, low molecular weight (LMW) alkaline protease, trypsin-like protease and pepsin from Mustelus mustelus, and bovine trypsin. All hydrolysates exhibited inhibitory activity toward ACE. Hydrolysate generated with alkaline protease
extract displayed the highest ACE inhibitory activity, and the higher inhibition activity (82.6% at 2 mg/mL) was obtained
with a hydrolysis degree of 18.8%. This hydrolysate was then fractionated by size exclusion chromatography on a Sephadex G-25
into five major fractions (P1–P5). ACE inhibitory activities of all fractions were assayed, and P3 was found to display a high ACE inhibitory activity (62.24% at 1 mg/mL). P3 was then fractionated by reversed-phase high-performance liquid chromatography (RP-HPLC) and ten fractions of ACE inhibitors
were found (F1–F10). Sub-fraction F3 showed the strongest ACE inhibitory activity, being able to suppress more than 60% of initial enzyme activity at a concentration
of 100 μg/mL. The amino acid sequence of peptide F3 was determined by ESI/MS and ESI–MS/MS as Ala-Gly-Ser, and the IC50 value for ACE inhibitory activity was 0.13 ± 0.03 mg/mL. Further, purified peptide F3 maintained inhibitory activity even after in vitro digestion with gastrointestinal proteases in order to demonstrate gastrointestinal
stability digestion to enable oral application. These results indicate that smooth hound protein hydrolysate possesses potent
antihypertensive activity. 相似文献
18.
Thulasy Gayathri Ashalatha S. Nair 《International Journal of Food Science & Technology》2014,49(2):429-434
Bananas are the most important fruit crop in the world. Short shelf life of the fruit is the major limiting factor in international trade, and this is due to the softening of the pulp during ripening. Fruit softening is an important aspect of ripening process in fleshy fruits and is caused by the cumulative action of a group of cell wall‐modifying enzymes. Polygalacturonase (PG) is the key enzyme involved in the fruit softening process in banana, and this study reports the isolation, purification and characterisation of polygalacturonase enzyme from ripened fruits of a delayed ripened banana cultivar found specifically in Kerala (Musa acuminata cv. Kadali). PG was purified by ammonium sulphate fractionation followed by DEAE cellulose ion exchange chromatography and gel filtration using Sephadex G 100. The purified protein showed two subunits on SDS‐PAGE and a single band on native PAGE. Enzyme showed maximum activity at pH 3.5 and 40 °C. Fe3+ enhanced the activity more, while Mg2+ and Ca2+ slightly stimulated the activity of purified enzyme. Km value for substrate polygalacturonic acid was 0.06%. 相似文献
19.
Aspergillus subolivaceus dextranase is immobilized on several carriers by entrapment and covalent binding with cross-linking. Dextranase immobilized
on BSA with a cross-linking agent shows the highest activity and considerable immobilization yield (66.7%). The optimum pH
of the immobilized enzyme is shifted to pH 6.0 as compared with the free enzyme (pH 5.5). The optimum temperature of the reaction
is resulted at 60 °C for both free and immobilized enzyme. Thermal and pH stability are significantly improved by the immobilization
process. The calculated K
m
of the immobilized dextranase (14.24 mg mL−1) is higher than that of the free dextranase (11.47 mg mL−1), while V
max of the immobilized enzyme (2.80 U μg protein−1) is lower than that of the free dextranase (11.75 U μg protein−1). The immobilized enzyme was able to retain 76% of the initial catalytic activity after 5.0 cycles. 相似文献
20.
An approach to improve ACE-inhibitory activity of casein hydrolysates with plastein reaction catalyzed by Alcalase 总被引:2,自引:0,他引:2
The preparation method of casein hydrolysates with high ACE-inhibitory activity was studied by Alcalase-catalyzed hydrolysis
coupled with plastein reaction. Casein hydrolysates with an IC50 value of about 47 μg mL−1 were first prepared by hydrolysis of casein with Alcalase and then modified with plastein reaction catalyzed by the same
enzyme. The impacts of four reaction conditions on plastein reaction of casein hydrolysates were studied, and then optimal
conditions were determined using response surface methodology with the decrease of free amino groups in the reaction mixture
as response. When the concentration of casein hydrolysates was fixed at 35% by weight, the maximum decrease of free amino
groups in the reaction mixture of 181.8 μmol g−1 proteins was obtained. The optimum conditions for the above decrease were found to be an E/S ratio of 7.7 kU g−1 proteins, reaction temperature of 42.7 °C and reaction time of 6 h. Analysis results showed that ACE-inhibitory activity
of casein hydrolysates prepared could be improved significantly by plastein reaction. When casein hydrolysates were modified
by plastein reaction, with a decrease of free amino groups in the mixture of about 154.7 μmol g−1 proteins and 181.8 μmol g−1 proteins, their IC50 values could be decreased to 0.6 and 0.5 μg mL−1. 相似文献