The potential use of alkaline protease from Streptomyces albidoflavus as an eco-friendly wool modifier

The main task of this study is to search for the proper conditions of the enzymatic treatment using an alkaline bacterial protease, as an eco-friendly option, to improve some performance properties and dyeability of grey wool fabric with acid dyes. The efficiency of the enzymatic treatment has been improved by prewashing in the presence of a nonionic wetting agent alone and in combination with H₂O₂. The enhancement in wool performance properties as well as in the extent of post-acid dyeing is determined by pretreatment regime, enzyme dosage, as well as enzymatic treatment conditions. For modified wool fabric samples, as the weight loss increases, the nitrogen content decreases, the whiteness index as well as the dyeability with the acid dye improves compared with the prewashed fabric samples. Proper conditions for maximising the efficiency of enzymatic treatment along with attaining better performance properties and minimal wool damage are: prewashing in the presence of a nonionic surfactant along with H₂O₂ followed by enzymatic treatment using the enzyme dosage (3?ml/g fabric), pH (9), incubation time (45?min), temperature (40?°C), LR (1/20) and rotational speed (40?rpm). The enzyme inactivation was performed at 100?°C for 5?min, followed by thoroughly rinsing, neutralising and air-drying before testing. SEM images also provide evidence that pretreatment of the wool substrate enhanced the proteolysis of cuticle layers, their degradation and potential removal by the subsequent protease treatment.     

Bio-scouring process optimization of wool fiber and wastewater utilization

This paper is aimed at developing a method to optimize the wool‐scouring process with bio‐enzymes of Bacillus subtilis and Candida lipolytica. Good experimental conditions, first determined by single factor test, were the ratio of B. subtilis to C. lipolytica 1:4, temperature 40°C, pH 7.0, enzyme consumption 6%, bath ratio 1:35, and time 16 h. Based on these conditions, the Plackett–Burman design (P–B design) was used to determine the main influencing factors such as bath ratio, temperature, and time for enzymatic scouring. Then, a Response Surface Method (RSM) was used to optimize these factors, and the optimum parameters were solved with the quadratic regression equation: bath ratio 1:33.28, temperature 40.44°C, and time 18.11 h. Under these optimum conditions, the residual fat content in bio‐scoured wool was 0.75%. Furthermore, the wool surface was smoother and cleaner than the non‐optimized one. In addition, the lanolin was reclaimed as a valuable material in industry by centrifugation from wastewater, and it could reduce the content of organic substance to decrease the environmental pollution. Moreover, the residual lanolin, perspiration, dung, chaffy, short wool, and silt were utilized to make ecological organic fertilizer by compost treating. It could achieve the complex utilization of bio‐scouring wastewater.     

The utility of a fungal bibonuclease for reducing the nucleic acid content of permeabilized yeast cells

The main drawback of yeast biomass as a source of protein for human consumption is its high nucleic acid content. The present study deals with the development of a process for reducing the nucleic acid content of strains of Saccharomyces cerevisiae, Candida utilis, C.tropicalis and C.lipolytica by treating with an RNase of Aspergillus candidus strain Ml6a. The cells were permeabilised either by heat‐treatment at 95°C for 5 min. or by treatment with chloroform for 6h followed by a heat treatment at 65°C for 3 min. The former pretreatment was sufficient for C. utilis and C.tropicalis strains whereas S.cerevisiae required the latter treatment. The optimum conditions for the enzymatic treatment were a pH of 4.5–5.0, temperature of 45–55°C, incubation period of 60–90 min and an enzyme to cell ratio of 1:6,000 (w/v). Crude enzyme preparations showed a better activity than the pure enzyme. Under optimal conditions 80–85% of the total nucleic acid could be removed from yeast cells by the enzymatic treatment without any significant concomitant loss of protein.     

Comparison of enzymatic de-esterification of strawberry and apple pectin at elevated pressure by fungal pectinmethylesterase

Water soluble pectin was isolated from strawberries. Sugar composition, degree of esterification and molar mass were compared with commercial apple pectin. Both pectins were subjected to enzymatic de-esterification by recombinant Aspergillus aculeatus pectinmethylesterase (PME). Rate of enzymatic de-esterification at elevated pressures (0.1–500 MPa) and temperatures (20–60 °C) was assayed by measuring the release of methanol as a function of time. Optimal activity was observed at 200–300 MPa combined with 45–55 °C. At all conditions investigated, both pectins were de-esterified at similar initial rates. However, after prolonged enzymatic treatment at atmospheric pressure and 30 °C, apple pectin was de-esterified to a significantly lower degree of esterification (7%) than strawberry pectin (32%). The mode of action of A. aculeatus PME was investigated by enzymatic fingerprinting of de-esterified pectin chains. The enzyme de-esterified according to a “multiple chain, multiple attack” mechanism, irrespective of the substrate.Industrial relevanceThis article demonstrates that both strawberry and apple pectin de-esterification by recombinant Aspergillus aculeatus PME is accelerated by high hydrostatic pressure. Since de-esterification of pectin in fruits gives rise to a texture improvement, this enzyme can be used to minimize texture damage during high-pressure processing of fruits and fruit-based products. It was also shown that this enzyme de-esterifies strawberry and apple pectin according to a “multiple chain, multiple attack” mechanism. The resulting pattern of esterification might have an influence on textural properties of fruits.     

Biological Scouring of Flax Rove with Alkalophilic Strains

To achieve bio-scouring or biological degumming of the flax roving, a kind of eco-friendly techniques, an alkalophilic strain was screened from the rotten wrack around Zhoushan archipelago sea area. It was characterized as Cellulomonas sp and named Cellulomonas sp DA8 by measuring the strain morphology, physiology, biochemistry, and the 16s rDNA sequences. Determination of enzyme activity showed that the activities of petinase and xylanase were obtained, and enzyme activities are stable under 50°C and at pH values in the range of 6.5 to 9.0. It was utilized to scour the flax roving under alkaline conditions, and the result showed that the strain had a good characteristic of scouring, and less strength loss of flax fiber was 14.19%. Scanning electron microscopy (SEM) showed that the gum in the flax fiber was mostly degraded, and the most smooth fiber surface was displayed, compared with fiber untreated and scoured by caustic soda.     

Stability of β-Galactosidase from Aspergillus oryzae and Khyveromyces lactis in Dry Milk Powders

A milk-based beverage powder with 2% vegetable fat and reduced levels of lactose is needed by some segments of the consumer market as well as military units. To provide such, two commercial β-galactosidases were dry-blended into milk powders made with coconut, cottonseed, canola or sunflower oils and stored at ?20, 4, 25, and 45°C. Enzyme activity was measured monthly by reconstituting the powders and measuring freezing point depression after incubation at 32°C (optimum for P-galactosidase from Kluyveromyces luctis) and incubation at 50°C with pH adjusted to 5.0 (for activity of Aspergillus oryzae enzyme). Both enzymes retained >95% of original activity at ?20 and 4°C. Activity of K. Zuctis enzyme declined moderately at room temperature (～23°C) and rapidly at 45°C. The A. oryrae enzyme retained 93.4% of original activity after 6 mo at 45°C.     

Optimisation of hydrophilic antioxidant extraction from Hizikiafusiformis by integrating treatments of enzymes, heat and pH control

Effective extraction of algal bioactive compounds can be achieved by treatments such as pH control, heat and enzymatic hydrolysis. Hizikia fusiformis antioxidants were extracted with those treatments individually and extraction efficacies were compared by measuring yield, total phenolic content and antioxidant activities. Increased pH could successfully improve the extraction, and incubation at pH 12.0 for 12 h was the most effective pH treatment. Incubation at 100 °C for 45 min was significantly (P < 0.05) more effective than the other heat treatments. Optimum condition for enzymatic treatment was combination of 2% Alcalase (alkaline endopeptidase/protease) and 3% Ultraflo (β‐glucanase/carbohydrase) at pH 8.0 and 54–58 °C for 24 h. Integration of those optimised treatments in the extraction sequence of heat (H), enzymatic hydrolysis (E) and pH control (P) was the most effective sequence. Compared with other extraction sequences, HEP sequence indicated significantly higher phenolic content and antioxidative activities in 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) and hydrogen peroxide scavenging assays.     

Changes in quality attributes of pulsed light and thermally treated mixed fruit beverages during refrigerated storage (4 °C) condition

The effect of batch pulsed light (PL) irradiation (3000 J cm⁻²) on the shelf-life of the beverage blend comprising apple ber (Indian jujube), carambola (star fruit), and black table grapes was investigated. The equivalent thermally treated beverage (90 °C|5 min) exhibited greater stability from microbial and enzymatic spoilage but retained 27% less antioxidants and 14% less vitamin C than PL-treated juice. Thermally and PL-treated blends possessed sensory scores of 5.8 and 7.2, respectively. The beverage's microbial shelf-life (population ≤ 6-log₁₀ cfu/mL) was extended to 45 days at 4 °C after the PL treatment. The PL exposure did not alter the pH and soluble solids during storage. The PL-treated juice, after 45 days, was placed on par with the freshly prepared juice by the sensory panel. The PL-treated juice preserved 61% more antioxidants, 38.8% more phenolics, and 68.2% more vitamin C than the thermally pasteurized beverage after 45 days of refrigerated storage.Industrial relevanceWhile the fruit processing industry demands microbial safety and enzymatic stability, today's consumer demands juices of high nutritional quality. This study utilizes under-explored fruits like apple ber (Indian jujube) and carambola (star fruit) to make a shelf-stable mixed fruit beverage. This study will help the industry understand the potential of PL treatment in accomplishing microbial safety, enzymatic stability, and nutritional quality, along with the utilization of under-explored fruits.     

Characterization and Cheese-Making Properties of Rennet-Like Enzyme Produced by a Local Algerian Isolate of Aspergillus niger

An ochratoxin free extracellular acid protease was produced by solid state cultivation of Aspergillus niger FFB1. The purified enzyme (48.7 kDa) showed an optimal milk clotting activity at pH 5.5 and 45°C in the presence of 0.01 M CaCl₂. The enzyme was stable at least 24 h at 35°C in the pH range of 5.5–7.0. Thermal denaturation started above 45°C. Fresh cheese manufactured with reconstituted cow milk and the purified enzyme showed similar basic characteristics (pH 4.5, acid taste, white color) as marketed cheeses obtained with calf rennet. This emphasizes the value of exploiting local biological resources for value added food processing in developing countries.     

Enzyme—Pretreatment of Pinto Bean High Protein Fraction and Time of Blending Corn Meal Affects Extrudate Properties

High protein fraction of pinto bean, treated with papain and cellulose enzymes (Solvay Enzymes Inc.), was blended with corn meal (30%) and extruded at 120°C. Changes in expansion, texture, color, pH, in vitro protein digestibility, reducing sugars and functional properties of extmdates were recorded. Changes depended on type of enzymes and time of corn incorporation (before or after enzymatic pretreatment). The best texture of the extrudates was obtained using a cellulase enzyme. Papain affected some functional properties such as NSI and WSI. The best improvement in in vitro protein digestibility and reducing sugars was found with a cellulase treatment. Protein and fiber could be modified to improve physicochemical and functional properties of extrudates.     

First extraction of polyphenol oxidase from edible desert truffle (Terfezia leonis Tul.) and its thermal behavior

Polyphenol oxidase (PPO) is a common enzyme with large applications in food processing and analysis, especially based on their monophenolase activity. In this context, extraction and surfactant-mediated activation of PPO from desert truffle Terfezia leonis Tul. were successfully achieved. In the presence of l-tyrosine, the cresolase activity was optimal in the pH 5–6 domain and in the 35–45 °C temperature range. In the presence of pyrocatechol, the catecholase activity was optimal at neutral pH and 30 °C. Kinetics studies revealed higher affinity of PPO for l-tyrosine than for pyrocatechol. Both enzyme–substrate complexes were structurally robust, and their thermosensitivity was mainly related to entropy changes. These properties may reflect the adaptation to desert conditions where T. leonis grows and should be useful for the development of enzymatic catalysts and sensors.     

微泡菌昆布多糖酶Lam128A的酶学性质及酶解产物抗氧化活性

该研究探讨微泡菌ALW1来源的昆布多糖酶Lam128A的酶学性质及其酶解产物的抗氧化活性。利用毕赤酵母异源表达重组蛋白rLam128A,该昆布多糖酶的分子量为70 ku,最适反应温度和最适反应pH值分别为45 ℃和pH值5.5;温度低于45 ℃时稳定,分别在pH值3.0、5.0和11.0条件下处理96 h后,残余酶活力不低于60%。还原试剂二硫苏糖醇（DTT）对昆布多糖酶活力有促进作用,rLam128A对螯合剂乙二胺四乙酸（EDTA）表现出良好的稳定性,对去垢剂Tween 20和Tween 80、变性剂尿素表现出一定的稳定性。昆布多糖经rLam128A水解后,酶解产物对DPPH、ABTS和OH·自由基的半数抑制剂量IC50分别为7.12、1.01和 2.40 mg/mL,相比未经酶解处理的昆布多糖表现出更显著的抗氧化活性。微泡菌昆布多糖酶Lam128A的酶学性质为该酶开发利用昆布多糖生物资源提供了理论基础。     

Launderometer based test method for determining shrinkage of wool

A test method based on use of launderometer has been proposed for determining shrinkage of small wool samples in the lab. Effect of laundering parameters such as liquor ratio, detergent concentration, pH, temperature and time of treatment on shrinkage of wool was studied. Parameters that best simulate the extent of shrinkage obtained by the ISO 6330 test method were identified. The proposed method is conducted on 12?×?12 cm² samples which are subjected to one wash for relaxation shrinkage – 1 g/l detergent, pH 6, 40 °C, 60 min, followed by three washes for felting shrinkage – 0.3 g/l detergent, pH 6, 40 °C, 60 min at liquor ratio of 1:20. Treated samples showed ~47% shrinkage, comparable to that obtained by the ISO method. Results obtained by the optimised process are consistent and reproducible when validated on a range of high shrinking wool fabrics. It can be concluded that launderometer-based test method can be used to test small wool samples for shrinkage with consistent and reproducible results.     

Effects of transglutaminase and cooking method on the physicochemical characteristics of 3D-printable meat analogs

Mimicking the textural properties of beef remains challenging for 3D-printable meat analogs, owing to the limited extrusive force of 3D printers. We aimed to develop 3D-printable meat analogs that imitate the physicochemical properties of beef using transglutaminase (TG, 0–8 U/g protein) and cooking (steaming, microwaving, baking, or frying). Increased TG incorporation enhanced the rheological properties of the raw meat analogs. When TG was added at 4 U/g protein, the printed meat analogs had smooth surfaces after being incubated at 25 °C for 30 min and relatively high hardnesses after 2 h of incubation. Moreover, meat analogs baked at 170 °C for 25 min had a similar hardness and springiness as beef (P > 0.05). The hardnesses of cooked beef and meat analogs were related to microstructural compactness, cooking loss, and transverse shrinkage. This study provides a method for modifying the texture of meat analogs using enzyme catalysis and cooking.Industrial relevanceCurrently, the application of 3D printing in the production of meat analogs yields an elastic strength comparable to beef by implementing a fiber structure. However, modifying the textural properties of 3D-printable meat analogs to mimic the firm mouthfeel of meat is still one of the challenges that restrict the large-scale industrialization and commercialization of 3D food printing. In this study, we proposed a method for developing meat analogs, which combines enzyme treatment and suitable cooking methods, and investigated the effects of these two technologies on the physicochemical properties of 3D-printable meat analogs. This study provides essential guidance to the industry for developing meat analogs using novel protein sources and combining different technologies.     

7–THE LIQUID RETENTION OF REDUCED WOOLS IN AQUEOUS SOLUTIONS

An investigation is reported in which samples of wool fabric were converted to the thiol, S-carboxymethyl, and S-aminoethyl forms by reduction with tributylphosphine and alkylation with either iodoacetate or bromoethylamine. The liquid retention of the samples was measured after immersion in aqueous solutions at 20°C under various conditions of pH and ionic strength.

Plots of liquid retention against pH for the different samples are explained on the basis of the net charge on the sample at a given pH. Untreated wool has a liquid retention of 38–45% (w/w) throughout the pH range examined, whereas the treated wool samples all have maximum liquid retentions of more than 150% at pH values distant from their iso-electric points. Liquid retentions of less than 50% are observed at the iso-electric points of the various samples. The extent of liquid retention of reduced wools is shown, in most instances, to diminish with increasing ionic strength of solution.

Wool fabrics in which a small fraction of the disulphide cross-links has been broken also show slightly increased liquid retention. The importance of cross-link breakdown and electrostatic-charge balance on swelling during wool processing is discussed.     

The effect of thermal treatment on β‐glucosidase inactivation in vanilla bean (Vanilla planifolia Andrews)

The conditions for enzyme activity (pH and temperature) and kinetic parameters for the thermal inactivation of β‐glucosidase enzyme in vanilla beans have been investigated. The maximum enzyme activity was detected at pH 6.5 and 38 °C. The values obtained for V_max and K_m were 62.05 units and 2.07 mm, respectively. When hot water treatment (the most practical method of vanilla bean killing) was applied, β‐glucosidase treated at pH 6.0 and 60 °C for 3 min lost 51% of activity, while at 70 °C for 90 s the enzyme lost 60% of activity and at 80 °C for 30 s the enzyme lost 48% of its activity. When vanilla beans were cured in an oven at 60 °C for 36 to 48 h all β‐glucosidase activity was lost.     

Sulfolobus tokodaii strain 7高温酸性α-淀粉酶基因在大肠杆菌中克隆表达及其酶学性质

以超嗜热古菌Sulfolobus tokodaii strain 7基因组DNA为模板,通过PCR扩增高温酸性α-淀粉酶基因ST0817,将此基因克隆至表达载体pET15b,并转化大肠杆菌Escherichia coli BL21-CodenPlus(DE3)-RIL,获得重组大肠杆菌工程菌。通过热处理、镍柱亲和层析和分子筛层析,得到纯化重组酶,SDS-PAGE分析表明,该酶分子量为53.0 kDa。酶学性质研究表明,该酶最适温度和pH分别为75℃和5.5;具有较强的热稳定性和pH稳定性,在85℃处理8 h保持50%左右活力,在pH 5.2处理120 min仍保持50%活力。此酶对不同底物水解活性不同,直连淀粉>可溶性淀粉>支链淀粉>β-极限糊精>糖原>环糊精>普鲁兰糖;该酶对有机溶剂、变性剂和金属离子具有一定抗性。     

CATHEPSIN D AND ITS EFFECTS ON MYOFIBRILLAR PROTEINS: A REVIEW1

The molecular and enzymatic properties of the extensively studied enzyme cathepsin D are reviewed and additional information concerning its activity presented. Cathepsin D at pH 5.5 (37°C) degraded several myofibrillar proteins. The most rapidly hydrolyzed included titin and perhaps nebulin, myosin heavy chain, and M and C-proteins. The effects of cathepsin D on myofibrillar structure under these conditions included reduction in A band width, cleared central region in the A band, and dislocation of the Z line. Temperature was found to exert a strong influence on activity of cathepsin D and maximum activity was observed at 45°C with both muscle and hemoglobin substrates. Activity was evident at even higher temperatures and approximately 49% remained at 55°C (hemoglobin assay). Low temperature (i.e., < 15°C) however, has been observed to result in almost complete inactivity of the enzyme. The implications of this information for involvement of cathepsin D in postmortem proteolysis and tenderization were discussed.     

Production and Application of a Maltogenic Amylase by a Strain of Thermomonospora viridis TF-35

An extracellular and thermostable maltogenic amylase-producing moderate thermophile (Thermomonospora viridis TF-35), which grew well at 28–60°C, with optima at 45°C and pH 7, was isolated from soil. Maximal enzyme production was attained after aerobical cultivation for 32 h at 42°C with a medium (pH 7.3) composed of 2% (w/v) soluble starch, 2% gelatin hydrolyzate, 0.1% K₂HPO₄ and 0.02% MgSO₄ · 7H₂O. The partially purified enzyme, which was most active at 60°C and pH 6.0 and stabilized with Ca²⁺, converted about 65, 80, 75, 75, 65 and 60% of maltotriose, maltotetraose, maltopentaose, amylose, amylopectin and glycogen into maltose as a major product under the conditions used, respectively. Glucose and small amounts of maltooligosaccharides were also formed concomitantly as by-products. The molar ratio of maltose to glucose from maltotriose were larger than 1 during all stages of the hydrolysis. About 70 and 76% of 25% (w/v) potato starch liquefites having a 3.5 DE value were converted into maltose by the enzyme in the absence and presence of pullulanase during the saccharification, respectively. About 90 and 94% of the starch liquefites were also converted into maltose with relatively low contents of maltooligosaccharides by the cooperative 2 step reaction with the enzyme after obtaining starch hydrolyzates containing about 85 and 90% maltose by the simultaneous actions of soybean ß-amylase and debranching enzymes.     

Preliminary Characterization of Novel Extra-cellular Lipase from Penicillium crustosum Under Solid-State Fermentation and its Potential Application for Triglycerides Hydrolysis

Current studies about lipase production involve the use of agro-industrial residues and newly isolated microorganisms aimed at increasing economic attractiveness of the process. Based on these aspects, the main objective of this work is to perform the partial characterization of enzymatic extracts produced by a newly isolated Penicillium crustosum in solid-state fermentation. Lipase extract presented optimal temperature and pH of 37?°C and 9?C10, respectively. The concentrated enzymatic extract showed more stability at 25?°C and pH?7. The enzymes kept 100% of their enzymatic activity until 60?days of storage at 4 and ?10?°C. The stability under calcium salts indicated that the hydrolytic activity presented decay with the increase of calcium concentration. The specificity under several substrates indicated good enzyme activities in triglycerides from C4 to C18.