Protein Content Of Extracts Research Articles

Characterization of Proteolytic Activity of Artichoke (Cynara scolymus L.) Flower Extracts on Bovine Casein to Obtain Bioactive Peptides.

Simple SummaryRecently, dairy proteins, in addition to their basic nutritional role in the diet, were recognized as a source of bioactive peptides. Such peptides are encoded within the primary structure of the protein and can be released by enzymatic hydrolysis. The growing interest in the development of functional foods for the benefit of consumer health led to a recent increase in research on the production of bioactive peptides from different matrices and production methods. The use of aspartic proteases from stigmas of mature artichoke (Cynara scolymus L.) flowers to obtain hydrolytic enzymes (cinarases) in the production of bioactive peptides would involve the utilization of an agricultural residue of a plant species of great socio-economic importance. In the present study, the characterization of the optimal hydrolysis conditions of artichoke flower extracts was carried out for the production of peptides from bovine casein. Furthermore, the angiotensin-converting enzyme-I inhibitory activity and the antioxidant capacity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS) free radicals in vitro were determined for the obtained hydrolysates. The results revealed that the water-soluble extract of artichoke flower could be suitable for the production of bioactive peptides from whole bovine casein.The aim of this work is to establish the most suitable proteolysis conditions to obtain bovine casein hydrolysates containing peptides with antioxidant and antihypertensive capacity. To this end, the proteolytic activity of Cynara scolymus L. flower extracts was characterized on whole bovine casein, evaluating the effect of several factors (pH, temperature, substrate concentration, enzyme concentration, and hydrolysis time). The optimal conditions to carry out the hydrolysis with the C. scolymus L. extract were as follows: pH 6.2, 50 °C, and 0.023 mg·mL−1 of extract-protein concentration. A Michaelis constant (Km) value of 5.66 mg·mL−1 and a maximum rate of reaction (Vmax) of 8.47 mUAbs∙min−1 were observed. The optimal hydrolysis time was 17 h. The casein hydrolysates obtained with these conditions contained peptides with antioxidant activity (1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity: 30.89%; Trolox equivalent antioxidant capacity (TEAC) against 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) free radical (ABTS●+): 4.43 mM Trolox equivalent·mg−1 peptide) and antihypertensive activity, showing 55.05% angiotensin-converting enzyme-I inhibition in vitro.

C-phycocyanin extraction from two freshwater cyanobacteria by freeze thaw and pulsed electric field techniques to improve extraction efficiency and purity

C-phycocyanin was extracted from Nostoc commune TUBT05 and Oscillatoria okeni TISTR8549 using freezing and thawing and pulsed electric field treatments. The results confirmed that freezing and thawing can be used to extract c-phycocyanin from both cyanobacterial strains, whereas pulsed electric field treatment can be used only with N. commune, whose cell structure allows extraction by this technology. The number of freeze/thaw cycles, the extraction solution used and the number of electric pulses had statistically significant influences on c-phycocyanin concentration, purity, yield and the total protein content in the crude extracts (p ≤ 0.005). Exposure of N. commune to three cycles of freeze/thaw in sodium-phosphate buffer yielded the highest c-phycocyanin content, purity, and yield. The results suggest that careful selection of both the number of freeze/thaw cycles and the extraction solution is required to ensure high productivity. Transmission electron microscopy micrographs confirmed that the cell wall structure and organization of the thylakoid were different in the two species, requiring a significantly different number of freeze/thaw cycles and pulse applications for optimal c-phycocyanin extraction. Both cyanobacterial strains were shown to be potential alternative strains for c-phycocyanin production. However, further work is needed to improve c-phycocyanin concentration and purity. We suggest that this will require refinement of the cultivation conditions and improved purification processes.

Enhancement of the sewage sludge dewaterability by using ethanol and Fe(III)-rice husk.

Proteins of extracellular polymeric substances (EPS) in sewage sludge play a key role in the sludge dewatering. Ethanol can denature proteins and improve sludge dewaterability. In this study, ethanol was used to precondition and combined with Fe3+ and rice husk (RH) for dewatering enhancement. The experimental results of the capillary suction time (CST) reduction efficiency indicated that the sewage sludge pretreated with ethanol and Fe3+-RH revealed well cooperative formation mechanism with regard to dewatering performance. Using the response surface methodology (RSM) determined that CST reduction efficiency of sewage sludge reached 78.5% under optimal conditions of ethanol 25.21 g/g dry solid (DS), Fe3+ 185.70 mg/g DS, and RH 406.02 mg/g DS, respectively. Moreover, the results showed that the composite conditioner is effective for the specific resistance to filtration decreased from initial 1.66E + 13 m/kg to 2.44E + 11 m/kg. The analysis of EPS showed that extractable proteins in EPS increased to maximum when the sludge was pretreated by Fe3+-RH because EPS were destroyed and proteins in EPS were released. After the addition of ethanol, extractable protein content was reduced because of protein precipitation and released interstitial water and bound water. The sludge morphology analysis indicated that the RH as a skeleton builder provided the outflow passages, which enhanced the dewatering performance of sludge. From these results, the combination treatment of ethanol and Fe3+-RH is a promising synergetic strategy to enhance the dewaterability of sewage sludge.

Effects of Ocimum gratissimum and Citric Acid on the Nutritive and Sensory Qualities of Stored Pineapple Juice

Fruit juices values are reduced during the storage, its effect is of great concern to the consumer as well as to the economy of our great nation. Effects of leaf extract Ocimum gratissimum and citric acid on the proximate and sensory properties of stored at 30 ± 2°C pineapple juice was investigated using standard techniques. The extracted juice was divided into two-part, one part was treated with leaf extract O. gratissimum ranged from 5% - 40% while; the second part was treated with citric acid ranged from 0.2% - 0.5% and untreated one served as control. They were stored 10 days at ambient temperature. The results obtained revealed the concentration 40% leaf extract and 0.5% citric acid were able to stabilize the nutritional qualities during the storage. The moisture content for the best leaf extract at 40% concentration ranged from 77.95 ± 0.08% - 78.34 ± 0.05% while citric acid (0.5%) moisture effect ranged from 85.42 0.00% - 85.72 ± 0.06% and the untreated moisture content ranged from 85.42 ± 0.02% to 93.19 ± 0.00%. The ash content of leaf extract and citric acid-treated pineapple ranged from 1.10 ± 0.01% - 1.11 ± 0.01% and 0.30 ± 0.00% - 0.32 ± 0.00% while untreated juice ranged from 0.17 ± 0.00% to 0.32 ± 0.00%. The protein content of leaf extract and citric acid-treated pineapple ranged from 2.24 ± 0.01% - 2.29 ± 0.01% and 1.07 ± 0.01% - 1.08 ± 0.01% while untreated juice ranged from 0.95 ± 0.00% to 1.09 ± 0.00%. The carbohydrate content of leaf extract and citric acid-treated pineapple ranged 15.38 ± 0.00% - 15.46 ± 0.00% and 11.81 ± 0.00% - 11.95 ± 0.00% while untreated juice ranged from 5.10 ± 0.01% to 11.94 ± 0.00%. The fibre content of leaf extract and citric acid-treated pineapple ranged 2.41 ± 0.00% - 2.43 ± 0.01% and 0.95 ± 0.01% - 1.03 ± 0.01% while untreated juice ranged from 0.99 ± 0.01% to 1.03 ± 0.01%. The fat content of leaf extract and citric acid-treated pineapple ranged 0.51 ± 0.01% - 0.61 ± 0.00% and 0.11 ± 0.00% - 0.20 ± 0.01% while untreated juice ranged from 0.82 ± 0.00% to 0.20 ± 0.01%. Ocimum gratissimum (40% w/v) leaf extract was the best to increase and stabilize the nutrients in pineapple juice than 0.5% citric acid. The panelists rated pineapple juice treated with O. gratissimum leaf extract (40%) the best in colour and general acceptability and slightly affected the taste and flavour while 0.5% citric acid concentration best in flavour and taste evaluated.

Extraction of Proteins and Pasting and Antioxidant Properties of Soybean Hulls

Soybean hulls are a by-product from soybean processing for oil and meal production which comprise approximately 8% of the whole seed. This study investigated water holding capacities and pasting properties, and first reported the phenolic contents and antioxidant activities from soybean hulls which are important to our long-term health. In addition, the conditions for extracting proteins from soybean hulls including optimum pH, as well as homogenizing and separation methods for extraction, were also studied. Higher protein content in extracts and recoveries was obtained with extraction at pH 9. Using sieve separation may be an effective way to extract proteins from hulls for industrial applications. The precipitated protein content increased from 51.52% to 59.29% after purification by washing with water once; however, after two washes, no further improvement was shown. The extracted proteins can be used for food applications. The ground hull powders (10% protein), dried supernatant (14% protein) and sediments (7-8% proteins) along with valuable fibers should be good food ingredients for several food categories. This research explored the great potential of converting the low value by-products into value-added functional food uses along with the benefit of reducing food and agricultural wastes.

Evaluation of leaf extracts from Algerian Argania spinosa. L. Skeels. (Sapotaceae) trees: Total phenol content, protein content, and Antibacterial activities against six against clinical phytopathogenic bacteria

Argania spinosa (L.) Skeels. (Argan) is tropical species, this plant is known bythese therapeutic and medecinal uses. For this purpose, we test antibacterial potential of leaf extracts of three Algerian population of Argan trees andwe evaluate the geographical distribution and solvent extraction effect onthe antibacterial activities. In first, Levels of total phenol content, total protein content of leaf extracts were determined by UV-spectrophotometer,secondary, The agar well diffusion method were used to determine enzymeactivities of proteins, antibacterial effect and the minimal inhibitory concentration (MIC) of extracts. The amounts of the phenol and protein concentrations in tested extracts were in ranged respectively between (118.83-147.17mg/mL) of Gallic acid equivalents (mg/mL) ) and (31.33-40.55mg/mL)of BSA (mg/mL), the crude fresh extract and crude protein extract showperoxidase activities, while protease activities were not found in ours extracts. Microbiological tests showed a high antibacterial potential of methanol extracts against tested bacteria ,Enterococcus faecalis (ATCC 29212) wasmost sensitive to methanol extracts (IZD: 17mm to 23.5),in opposite, aqueous extracts show weak antibacterial activities. Crude protein extracts hadnot antibacterial effects while crude fresh extracts were efficiency againstbacterial growth, biochemical enzyme tests revealed that crude extracts ofthe leaves show peroxidase activity wish may to increase antibacterial activities of crude extracts. The high activities of leaf Argan extracts were detected in Oran samples (littoral area) followed by Tindouf samples (arid area),this result confirmed positive relationships between geographical distribution of samples and their antibacterial activities.

Differential Tick Salivary Protein Profiles and Human Immune Responses to Lone Star Ticks (Amblyomma americanum) From the Wild vs. a Laboratory Colony.

Ticks are a growing concern to human and animal health worldwide and they are leading vectors of arthropod-borne pathogens in the United States. Ticks are pool blood feeders that can attach to the host skin for days to weeks using their saliva to counteract the host defenses. Tick saliva, as in other hematophagous arthropods, contains pharmacological and immunological active compounds, which modulate local and systemic immune responses and induce antibody production. In the present study, we explore differences in the salivary gland extract (SGE) protein content of Amblyomma americanum ticks raised in a laboratory colony (CT) vs. those collected in the field (FT). First, we measured the IgG antibody levels against SGE in healthy volunteers residing in Kansas. ELISA test showed higher IgG antibody levels when using the SGE from CT as antigen. Interestingly, antibody levels against both, CT-SGE and FT-SGE, were high in the warm months (May–June) and decreased in the cold months (September–November). Immunoblot testing revealed a set of different immunogenic bands for each group of ticks and mass spectrometry data revealed differences in at 19 proteins specifically identified in the CT-SGE group and 20 from the FT-SGE group. Our results suggest that differences in the salivary proteins between CT-SGE and FT-SGE may explain the differential immune responses observed in this study.

BIO-CACO3 FROM RAW EGGSHELL AS ADDITIVE IN NATURAL RUBBER LATEX GLOVE FILMS

ABSTRACT Raw hen eggshell powder, a calcium carbonate source, was used as a biofiller in the natural rubber latex compound and latex glove film formation via dipping process. The powder was anticipated to improve the physical (smoothness and thickness of film) and mechanical properties (tensile strength and elongation at break) of latex film and to reduce the extractable protein content on film surface. Eggshell powder ground by a rapid mill was fine particles of approximately 37.48 μm in diameter, suitable for homogeneous and compatible addition into the natural rubber latex compound. Dipping hand mold into the natural rubber latex compound with 50 wt% eggshell added was the best formula to obtain a smooth, clear, thin film surface, with the tensile strength of 23.24 ± 0.745 MPa and the highest elongation at break of 723.99 ± 14.60%, along with a low protein content, a dense film without water leakage, and with a good contact angle. The natural rubber latex glove film possessed good physical-mechanical properties and a low protein content as the results of the raw eggshell powder added as a biofiller.

Preliminary Assessment of the Antihypertensive and Antioxidative Activities of the Peptides from “Saba” Banana (Musa balbisiana Colla) Flesh

The crude proteins were isolated using 0.125 M Tris-HCl with 50 mM NaCl at pH 7.4. The protein content of the crude extract was determined using the Lowry assay and was found to be 4.28 mg/mL. The major band which corresponds to the major protein has an approximate molecular weight of 20 KDa. The isolated crude proteins were subjected to enzymatic digestion using pepsin, trypsin, chymotrypsin, and thermolysin for 3, 4, 12, and 24 hours. The 24-hour digest was found to have the highest percent anti-Angiotensin Converting Enzyme (ACE) activity (36.02%) while the 12-hour digest was found to have the highest anti-oxidative activity (33.14%) using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The 24-hour digest was subjected to Ultra-Performance Liquid Chromatography (UPLC) to determine the peptide fraction responsible for the ACE inhibitory activity. Three peptide fractions (PF1, PF2 and PF3) were chosen and PF2 exhibited the highest percent inhibitory activity (32.21) against ACE. PF2 was subjected to thin layer chromatography (TLC) and the possible identity is EK based on the Rf value traveled by glutamic acid (E) (0.43) and Lysine (K) (0.13). In silico analysis was done to correlate the results with the presence of putative peptides with antioxidative and antihypertensive activities. Results showed that antihypertensive peptides EK, GS, TY, FNE, FP, LKA, PT, PP, FAL and antioxidative peptides IR and VPW were found based on the sequence of the protein in “Saba” banana. The presence of the antihypertensive peptide EK was verified using thin layer chromatography (TLC).

Urea as a single denaturing agent in deproteinisation of natural rubber latex

This paper describes the utilisation of urea as a single chemical agent to obtain deproteinised high ammoniated natural rubber latex (HA-NRL). The role of urea in HA-NRL deproteinisation was further investigated by employing two different concentrations of urea solution which are low (0.01–0.05%) and high (1.0–5.0%) concentrations. The study assessed the potential usage of urea as a single denaturing agent in the presence of neither stabilising agent nor additives during the deproteinisation process. The effect of different urea concentrations on properties of deproteinised NRL was further scrutinised by using sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS-PAGE), nitrogen content analysis, extractable protein (EP) content, Zeta potential, attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy and physical strength. The presence of residual urea is pertinent as the concentration of urea increases while contributing to the increase of total nitrogen content in the resultant film. Leaching the film with hot water is sufficient to remove the residual urea as supported by an ATR-FTIR analysis. Initial exploratory data analysis of low and high urea concentrations on the effect of nitrogen content, EP, surface charge properties of latex and green strength of the deproteinised NRL were evaluated and their relation to each factor was further discussed. Based on the initial findings, urea was observed to be less effective as a single denaturant. Nonetheless, the properties of the deproteinised HA-NRL treated with urea were revealed to be markedly influenced by the urea concentration.

Sequential bioprocessing of Ulva rigida to produce lignocellulolytic enzymes and to improve its nutritional value as aquaculture feed

The macroalgae aquaculture industry has grown up in the last years, and new applications for macroalgae should be considered. In this work, sequential biological treatments as solid-state fermentation (SSF) by Aspergillus ibericus and enzymatic hydrolysis (EH) were applied to washed and unwashed Ulva rigida. SSF of unwashed macroalgae showed higher xylanase (359.8 U/g), cellulase (73.07 U/g) and β-glucosidase (14.9 U/g) activities per dry mass of macroalgae. After SSF, two strategies to carry out EH were assayed. The best process was SSF followed by EH by simply adding a buffer. The non-starch polysaccharides content was reduced by 93.2%, achieving a glucan conversion of 98%. In addition, the antioxidant activity was improved 2.8-fold and the protein concentration of macroalgae extracts increased from 16.9% to 29.8% (w/w). These biological treatments allowed to increase macroalgae value as feedstuff with potential for use in aquafeeds.

Pilose Antler Extracts (PAEs) Protect against Neurodegeneration in 6-OHDA-Induced Parkinson's Disease Rat Models.

Parkinson's disease (PD) is one of the most common neurodegenerative diseases worldwide. Although dopamine replacement therapy mitigates motor dysfunction in PD patients, there are no therapeutics that are currently available to reverse neuronal cell death in the substantia nigra pars compacta (SNc), which is the main region for dopamine loss in PD patients. The protein concentration of the Pilose antler extracts (PAEs) was estimated using the Bradford Protein Assay Kit. Hematoxylin and eosin (HE) staining was used to evaluate the protective effect of PAEs on 6-OHDA induced cell death in PD model rats. Immunohistochemistry (IHC) was used to detect the tyrosine hydroxylase (TH) positive neuronal cell in SNc. HPLC-MS was used to detect dopamine (DA), 3,4-Dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), and glutamate (Glu) levels in the striatum and cerebrospinal fluid (CSF). The amino acid level in the striatum and CSF was measured by HPLC-FLD. Protein expression of growth associated protein-43 (GAP-43) and neurofilament heavy polypeptide (NF-H) was measured using western blotting. The components of PAEs through blood vessels were detected by HPLC/MS/MS. In this study, PAEs with proteins ranging from 10 kDa to 250 kDa molecular weight was administered to 6-OHDA-induced PD rats. We found that PAEs inhibited 6-OHDA-induced neuronal cell death and TH-positive neuronal loss in SNc. PAEs administration also increased the levels of DA, DOPAC, and 5-HT, in addition to DOPAC/DA and HVA/DA indexes in the CSF and Striatum of 6-OHDA induced rats. Conversely, PAEs decreased the levels of Glu and GABA. Treatment with PAEs and Madopar increased GAP-43 and NF-H expression in the SNc and striatum. Proteomic analysis using LC/MS/MS indicated that 11 components of PAEs may have neuropharmacological effects. These results demonstrate that PAEs protects against 6-OHDA induced toxic effects in the PD rat models. Intragastric administration of PAEs may be a novel therapeutic strategy for neurodegenerative disorders like PD.

Extractable Protein Levels in Latex Products and their Associated Risks, Emphasizing American Dentistry

Background: Over 8% of the US population have detectable Type I hevea latex IgE antibodies and, upon exposure to natural latex and rubber products, are at risk for potentially dangerous reactions, especially in dental settings where these products meet mucosal membranes. Methods: Extractable antigenic protein levels were quantified in dental dams, examination gloves, and various other dental and rubber products. ASTM standards D6499 (antigenic protein) and D5712 (total protein) were used to quantify protein content. Results: In dental dams, extractable protein content ranged from low/non-sensitizing levels (<3 μg/dm2) to high/ sensitizing levels (130 200 μg/dm2). Also, while examination gloves from Malaysian glove manufacturers consistently exhibited a lower extractable protein content (<9 μg/dm2), than gloves from Thai manufacturers (16-23 μg/dm2) these levels should both still be non-sensitizing. There was no correlation between extractable protein content and the price or thickness of dental dams or examination gloves. Most of the other assorted dental products tested displayed low extractable protein content (<2.5 μg/dm2). Nearly all dental products made from natural rubber contained detectable antigenic Hevea proteins, subjecting previously sensitized patients and providers to risk of severe allergic reaction. A case study describes a female patient, with no previous history of Type I latex allergy, who reacted severely to a dental dam mouth exposure, necessitating her admission to the intensive care unit (ICU) of a local hospital for management of respiratory failure, with discharge after 4 days. Conclusions: Some dental products may pose a significant risk of Type I latex protein allergy sensitization, due to repeated contact, and that a single exposure can induce a severe reaction in a previously sensitized person, even when no prior latex allergy history is known.

쌀의 품종에 따른 미강 추출물의 이화학적 품질특성 및 항산화 활성모니터링

Rice bran is widely used in various types of food supplement as oil, functional materials. In this study, we compared the physicochemical characteristics and antioxidant activities of rice bran extracts according to extraction solvent (water, 80% ethanol, and 80% methanol) and cultivar (Bukkyeong 2012-2, Han-ahreum, and Jasmin 85) to develop a useful food processing materials. The moisture content of rice bran powder was 8.19-9.00% depend on cultivars. Its color variables ranged as follows: L value, 50.06-55.18; a value, 2.35-2.97; and b value 11.65-13.88. The total polyphenol and total flavonoid content of 80% ethanol extract of Bukkyeong rice bran (E-BRB) extract were 6.75 and 5.18 g/100 g, respectively, which were higher than those of other extracts. Whereas, the total protein content of hot-water extract of Bukkyeong rice bran (H-BRB) was the highest, with 18.46 g/100 g. The DPPH and ABTS radical scavenging activities of E-BRB extract at 10 mg/mL concentration were 95.94% and 96.47%, respectively. The ferric-reducing antioxidant power and reducing power of E-BRB extract at 10 mg/mL concentration were 1.39 mM and 1.97, respectively. These results suggest that 80% ethanol extract of Bukkyeong rice bran can be used as a physiologically active substance for functional materials and functional food in food industry.

Human IgE mAbs define variability in commercial Aspergillus extract allergen composition.

Sensitization to Aspergillus species is associated with allergic respiratory diseases. Allergen immunotherapy with nonstandardized Aspergillus extracts is commonly used as therapy in these patients. Unfortunately, no method exists to measure the relevant allergen protein content in diagnostic and therapeutic extracts. Thus, there is a critical need for Aspergillus extract standardization. We hypothesized that development of Aspergillus-specific human IgE mAbs would allow for the characterization of the relevant human allergenic epitopes among currently available commercial Aspergillus fumigatus extracts. Patients with allergic bronchopulmonary mycosis were recruited from Vanderbilt University Medical Center. IgE antibody-secreting B cells were grown and immortalized using human hybridoma techniques first described here. Twenty-six human Aspergillus-reactive IgE mAbs were used as capture and detection reagents to characterize the Aspergillus allergen content of commercial extracts. We found extreme variability in the specificity and quantity of their protein targets. Just 4 mAbs reacted with all available extracts, and only 1 of 4 extracts contained the major allergen Asp f 1. This degree of variability will almost certainly affect the efficacy of these reagents when used in diagnosis and treatment. Human IgE mAbs represent an innovative tool for the evaluation of relevant human allergenic epitopes, which may assist in future development and long-term standardization of mold extracts.

Aktivitas Enzim Amilase Isolat Bakteri Amilolitik dari Tepung Sagu Basah dan Lingkungan Tempat Penyediaannya Secara Tradisional di Jayapura

The study about the activity of the enzyme amylase from amylolytic bacterial isolates from wet sagoo starch and  its traditional provision environment had been done in Jayapura. The purposes of this study were to determine the activity of amylase enzyme and to identify the bacteria isolated from wet sagoo starch and its processing environment in Jayapura district. The method used was an experimental laboratorium in which isolation of amylolytic bacteria was performed by using nutrient agar medium with 1% soluble starch on spreed pour plate method. The enzyme activity was detected with 0.2% iodine in 2% potassium iodide which were able to form a clear zone. The protein content of the crude enzyme extract was determined by the Bradford method using bovine serum albumin (BSA). Amylase enzyme activity was determined by the formula: DUN/ml = [(R0-R1)/R0] [dilution factor] DUN/ml (dextrinizing units per ml). The results showed that there were 15 isolates amylolytic bacteria. Four (4) bacterial isolates have amylolytic power of more than 30 mm. The amilase activity of amylolytic bacterial of all  isolates were quite high: which were 35 577, 18 903,  32 106 and 46 600 U/mg for SU4, SU13, SU23 and SU40 respectively. The identification of isolates indicated that the three isolates are members of the Bacillus cereus ATCC 14 579 types with a similarity value of 71.70% to 81.10%, and one isolate is Bacillus subtilis ATCC 6501 members with a similarity value of 94.30%. Keywords: Amylolytic bacteria, amylase activity, characterization, sago flour.

Synergistic effects of ultrasound and soluble soybean polysaccharide on frozen surimi from grass carp

Ultrasound and water soluble soybean polysaccharide (SSPS) were applied during the freezing of grass carp surimi. Ultrasound-assisted immersion freezing (UF) process was observed from 0 °C to −15 °C. Based on characteristic freezing time, tempering-stage freezing rate and the quality change of surimi after a 14-day storage period, the optimal sonication was performed 5 times at 300 W, for 10 s, with 40 s intervals. The cryoprotective effects of SSPS content on surimi myofibillar protein were subsequently investigated during 28-day frozen storage at −18 °C. The Ca2+-ATPase activity, total sulphydryl content, active sulphydryl content, salt extractable protein content, whiteness and water-holding capacity of frozen surimi were determined after adding SSPS (0%, 1%, 3% and 5%). The results showed that synergism of SSPS and UF occurred. Consequently 3% SSPS was best for mitigating the protein denaturation during processing.

Permeation of salicylic acid through skim natural rubber films

The skim natural rubber latex (SNRL) with about 4 wt% dry rubber content was incubated with 0.012 wt% urea and 0.025 wt% ethanol both without and with stirring for various times to yield deproteinized rubber films (DSNR). The extractable protein (EP) content was determined by modified Lowry method. The salicylic acid permeation through rubber films was checked by measuring the concentration on the sink side at various times by using spectrophotometer at the wavelength of 344 nm. The studies show that after SNRL were incubated both without and with stirring, the up-and-down patterns of EP contents were seen along the incubation time. Incubation with stirring significantly reduced the EP content and the minimum was seen when SNRL was incubated for 1 h with 52% reduction. The findings also suggest that the SNRL film with a higher EP content yielded the higher the flux. The permeation kinetics through SNR films followed Fickian diffusion. Apart from being more easily peeled of glass plates, SNR films containing higher EP contents were superior to HANR films for their higher permeation fluxes. In addition, the flux of the SNR/HANR blend increased with increasing SNR fraction so the permeation rate could be controlled by adjusting the blend ratio.

Analysis of volatile compounds and nutritional properties of enzymatic hydrolysate of protein from cod bone

Hydrolysis of the proteins from cod bone was performed using flavourzyme and trypsin. The nutritional properties of hydrolysates by flavourzyme (HF) and trypsin (HT) were investigated. By comparison, HF exhibits a better degree of hydrolysates (DH) and nitrogen recovery (NR) than HT. The protein content of extract is 97.39% and had a good nutritional value due to the high protein digestibility-corrected amino acid score (PDCAAS) of 0.95 for adults. The content of total amino acids is 942.55 mg/g. The free amino acids content of hydrolysates derived from flavourzyme is 136.82 mg/g after hydrolyzing 3 h, while 17.12 mg/g of such hydrolysates was obtained by using trypsin. The main flavor compounds are alcohols, aldehydes, ketones, acids and alkanes. The molecular weight of predominant peptides ranged from 1000 to 3000 Da in both enzymatic hydrolysates. This study provided a theoretical basis to the preparation of nutritional components with attracting flavor in functional food industry.

Effect of cryogenic immersion freezing on quality changes of vacuum-packed bighead carp (Aristichthys nobilis ) during frozen storage

The effect of cryogenic immersion freezing (CIF) on the quality characteristics of bighead carp fillet was investigated during frozen storage and compared with air‐blast freezing (AF). Freezing rate of CIF treated filets was approximately 4.5 times higher than that of AF treated samples. Cryogenically frozen carp fillets showed higher retention (60%) of texture and better integrity of the muscle microstructure than the AF treated samples during the frozen storage. Additionally, a significant inhibition effect (p < .05) on the decrease of salt extractable protein and total SH content, Ca²⁺‐ATPase activity were observed in CIF than AF. Compared with the AF treatment, the CIF technique improved the quality of frozen carp fillets overall and the shelf‐life could be extended to at least 6 months. The findings indicated that cryogenic immersion freezing could be an effective rapid freezing technology for long‐term storage of freshwater fish with better scale‐up feasibility. PRACTICAL APPLICATIONS: Bighead carp fillets were frozen approximately 4.5 times faster by cryogenic cabinet quick freezer than by air‐blast freezer. Cryogenic immersion frozen carp fillets had better overall quality as compared with the samples frozen by air‐blast freezer. Cryogenic immersion freezing could be considered as an effective rapid freezing technology for long‐term storage of freshwater fish with better scale‐up feasibility.