Amount Of Substrate Research Articles

Использование побочных потоков товарного производства нефтепродуктов

Oily wastes, along with the problem of their disposal, comprise an inevitable factor in the processing and storage of oil and oil-derived products. Contemporary disposal methods such as landfill and incineration entail secondary pollution of environmental objects. However, since oily wastes contain valuable hydrocarbons, the search for new ways to extract them for use as components of the target products of oil refineries is an urgent task. The object of the study comprised oily wastes derived from an oilwell product of the commercial production of the Angarsk Petrochemical Company. According to the existing scheme, this product is combined with other oil-containing streams and sent for rectification. Thus, in 2017, 1,200 tonnes of secondary oil product were sent to the conversion unit. The transportation and processing of such a quantity of substrates leads to the release into the environment of more than 2 tonnes of harmful substances per year. The results of qualitative and quantitative analysis showed that the high content of gasoline fractions – predominantly n-alkanes C 5 –С 10 (more than 90% by weight) – in the hydrocarbon composition suggests the possibility of using the oilwell product as a component of motor gasolines without re-processing using the rectification method. However, the quality of the oilwell product, mainly in terms of water content and colour, is rather unstable. In order to select the preliminary preparation method for the oilwell product, tests of a bottom sample having a high water content (50% vol.) were carried out. It was established that sedimentation of the sample at a temperature of 22–23 °С for 4 hours leads to the effective separation of the water component. To reduce the influence of the colour factor of the oilwell product when adding it to motor gasolines, it is proposed to dilute it with other refinery by-products. The quality of laboratory samples of AI-92 and AI-80 gasolines obtained with the involvement of the prepared oilwell product complies with the requirements of GOST 32513. In order to scale the process of preparing the substation in order to use it as a component of motor fuels, Angarsk Petrochemical Company developed a simple, affordable technological scheme, based on mixing and separation processes using available equipment. The economic effect of the implementation of this measure will be about 3.7 million rubles per year. The proposed evaluation scheme and the method of separation of water-organic by-products for further use as a component of motor fuel are generic and can be applied to similar wastes from refineries and oil depots.

An electrochemical flow cell for the convenient oxidation of Furfuryl alcohols

Effecting oxidation reactions electrochemically dispenses with the need for reactive and potentially toxic reagents but barriers remain towards wide adoption of the technique, in part because of negative prior experiences with batch-mode reactions. Electrochemical flow set-ups fix the electrodes to maintain a uniformly narrow gap, and can operate continuously until a desired quantity of substrate has been processed. We describe the fabrication of an electrochemical flow cell and its application in the transformation of furfuryl alcohols into hydroxypyrones. The cell is simple to operate with inexpensive equipment under a constant current regime, flow rate being controlled by a standard laboratory syringe pump. With the addition of a trace of NaClO4 as electrolyte to provide a stable current flow, the oxidations proceed routinely with a current efficiency of around 60%.Graphical abstractᅟ

Stoichiometric constraints on the microbial processing of carbon with soil depth along a riparian hillslope

Soil organic matter (SOM) content is a key indicator of riparian soil functioning and in the provision of ecosystem services such as water retention, flood alleviation, pollutant attenuation and carbon (C) sequestration for climate change mitigation. Here, we studied the importance of microbial biomass and nutrient availability in regulating SOM turnover rates. C stabilisation in soil is expected to vary both vertically, down the soil profile and laterally across the riparian zone. In this study, we evaluated the influence of five factors on C mineralisation (Cmin): (i) substrate quantity, (ii) substrate quality, (iii) nutrient (C, N and P) stoichiometry, (iv) soil microbial activity with proximity to the river (2 to 75 m) and (v) as a function of soil depth (0–3 m). Substrate quality, quantity and nutrient stoichiometry were evaluated using high and low molecular weight 14C-labelled dissolved organic (DOC) along with different nutrient additions. Differences in soil microbial activity with proximity to the river and soil depth were assessed by comparing initial (immediate) Cmin rates and cumulative C mineralised at the end of the incubation period. Overall, microbial biomass C (MBC), organic matter (OM) and soil moisture content (MC) proved to be the major factors controlling rates of Cmin at depth. Differences in the immediate and medium-term response (42 days) of Cmin suggested that microbial growth increased and carbon use efficiency (CUE) decreased down the soil profile. Inorganic N and/or P availability had little or no effect on Cmin suggesting that microbial community growth and activity is predominantly C limited. Similarly, proximity to the watercourse also had relatively little effect on Cmin. This work challenges current theories suggesting that areas adjacent to watercourse process C differently from upslope areas. In contrast, our results suggest that substrate quality and microbial biomass are more important in regulating C processing rates rather than proximity to a river.

Fathead minnow reproduction: Implications for commercial culture

The fathead minnow,Pimephales promelas, is widely used as a bait, forage, and research fish in the United States. A hardy and fecund fish, this species has many attributes that are excellent for culture. Unfortunately, despite the widespread use of fathead minnows in toxicity testing and thousands of resulting publications, relatively little aquaculture‐related research has been conducted in support of commercial production. On the surface, current commercial fathead minnow production practices appear much the same as those of a decade ago. However, producers continue to refine culture methods, balancing broodfish stocking rates, spawning substrate quantity, and feeding rates in an attempt to meet both losses to predators and market demand. This review examines relevant reproduction‐related studies in the fields of ecology, behavior, toxicology, and aquaculture with the goal of advancing fathead minnow culture. In fathead minnow production, relative to the culture of food fish species, reproduction is vital, more so than rapid growth or a low feed conversion ratio. Fish numbers may exceed 1 million fish/ha, while feeding rates are relatively low and in feeder fish production, growth is deliberately restrained in order to maintain fish within market sizes year‐round. Underappreciated factors identified as affecting reproduction and with implications for commercial culture include: (a) poor egg adhesion to commonly used spawning substrates, (b) egg and fry cannibalism at high fish densities, and (c) the relatively short breeding period of individual males. Results highlight the importance of selecting an appropriate broodfish stocking rate based on fish size, anticipated pond fertility, and feeding program. New methods to improve reproductive performance will likely increase costs and will need to be accompanied by thorough economic analyses.

A mechanistic microbial underpinning for the size-reactivity continuum of dissolved organic carbon degradation

The reservoir of dissolved organic carbon (DOC) in the ocean is modified by multiple input and removal processes. Incubation experiments as well as measurements of oceanic DOC have demonstrated that the high molecular weight (HMW) fraction of DOC typically has a younger radiocarbon age and is more reactive biologically than the low molecular weight (LMW) fraction of DOC. These observations have been summarized as a ‘size-reactivity continuum’ of DOC reactivity, but mechanistic explanations for these observations have been lacking. Here we describe how our recent discovery of ‘selfish’ HMW organic matter uptake among bacteria in surface ocean waters may help explain the rapid removal of HMW DOC. ‘Selfish’ substrate uptake by bacteria encompasses rapid binding and partial hydrolysis of intact polysaccharides on the outer membrane of bacteria, seamlessly followed by the transport of large oligosaccharide fragments into the periplasm with little to no loss of LMW hydrolysis products. ‘Selfish’ bacteria therefore process HMW substrates in a manner distinct from bacteria that carry out extracellular hydrolysis that yields LMW hydrolysis products in the environment. Recognition of the presence and prevalence of selfish bacteria in the ocean has profound implications for carbon flow – the source and quantity of LMW substrates made available to non-extracellular-enzyme producing bacteria – as well as for efforts to model and measure bacterial interactions during organic matter degradation. This discovery also highlights the importance of targeted substrate binding and uptake as key (often understudied) factors in geochemical investigations of microbially driven carbon cycling in the ocean. We conclude with some speculative thoughts about the factors that may determine the prevalence of selfish substrate uptake in the environment.

Impact of pH and feeding system on black soldier fly (Hermetia illucens, L; Diptera: Stratiomyidae) larval development.

Black soldier fly (BSF) is a generalist species able to reduce large quantities of organic substrates and is thus considered as an interesting solution for waste management. Moreover, as BSF larvae accumulate high quantities of nutrients during their growth, they are valued because of their potential to produce products such as protein meal or fat for livestock feeds. Abiotic factors can influence larva growth, and a more detailed knowledge and control of these parameters can lead to the development of mass BSF breeding for the production of innovative products for animal feeds. As little information is available on the effects of the pH of substrates and feeding systems, the aim of this study was to evaluate the impact of these two factors on the activities of BSF larvae, prepupae, and adults. An experiment was performed with two fixed factors: i) pH (4.0; 6.1; 7.5; 9.5) and ii) feeding system (batch feeding system (TFS) or daily feeding system (DFS)). The pH treatments impacted larval weight on the first, third, and fifth day, but not at the end of the trial. Larval activity increased pH values from the fourth day onward, with final values of around 8.9–9.4 in all the treatments. The weight of the prepupae ranged from between 0.094 and 0.100 g. The final weight of the larvae and pupae, sex ratio, ingested food, larval mortality, percentage of emergence, and time to reach the pupa stadium were all affected by the feeding system. DFS showed the heaviest final larval weight (0.149 g), but required a longer time (11.3 d) than TFS to reach the prepupa stadium. The findings of this research could be useful for the mass production of BSF. Evaluation of an appropriate feeding system and initial pH value of the substrate are important parameters to reduce the time and to increase the weight in the production of larvae.

Olive Mill Industrial Waste as Co-substrate in Anaerobic Digestion with Aim at its Energetic Exploitation

The aim of this paper is to assess the feasibility of the co-digestion of olive mill industrial waste with urban sewage sludge from wastewater treatment plants (WWTP). These wastes include olive mill solid waste (OMSW) and olive mill effluent (OME). This co-digestion process enables the energetic exploitation of OMSW and/or OME and introduces an environmental solution for their highly pollutant compounds. The behaviour of both co-substrates was studied using biochemical methane potential assays. To determine the optimal proportions of each co-substrate, different quantities of OME and OMSW were added to a constant quantity of substrate (urban sewage sludge) and put to test. A small amount of digested sludge from WWTP was used as an inoculum to accelerate the pace of the reactions. Thus, the optimal proportions between substrate and co-substrate were defined. The samples containing OMSW showed a biodegradability around 23%, slightly above that of the substrate on its own (21.3%). Moreover, biogas production in samples containing OMSW was significantly superior to samples containing substrate only. Nevertheless, the samples containing OME as a co-substrate presented an inferior biodegradability (20.3%) to that of the substrate on its own. Similarly, biogas production in OME co-digestion remained within the usual values of urban sewage sludge biogas production. In all cases, the system remained stable and the energetic efficiency of the process was improved in comparison to the digestion of substrate only. Therefore, co-digestion with urban sewage sludge proves to be a cost-effective method for OMSW and OME environmental management.

Dynamics and diversity of the bacterial community during the spontaneous decay of açai (Euterpe oleracea) fruits.

The biodiversity and evolution of the microbial community in açai fruits (AF) between three geographical origins and two spontaneous decay conditions were examined by applying culture-independent methods. Culture-independent methods based on 16S rRNA from fifteen samples revealed that Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes and Acidobacteria were the most abundant phyla. At the genus level, Massilia (taxon with more than 50% of the sequences remaining constant during the 30 h of decay), Pantoea, Naxibacter, Enterobacter, Raoultella and Klebsiella were identified, forming the carposphere bacterial microbiota of AF. AF is fibre-rich and Massilia bacteria could find a large quantity of substrate for its growth through cellulase production. Beta diversity showed that the quality parameters of AF (pH, soluble solids, titratable acidity and lipids) and elemental analysis (C, N, H and C/N ratio) were unable to drive microbial patterns in AF. This research offers new insight into the indigenous bacterial community composition on AF as a function of spontaneous postharvest decay.

Iron(MCP) Complexes Catalyze Aziridination with Olefins As Limiting Reagents.

Herein described are the first efficient nitrogen-atom transfer reactions mediated by iron N, N'-dimethyl- N, N'-bis(2-pyridinylmethyl)cyclohexane-1,2-diamine- (MCP-) and 2-({1-[(pyridin-2-ylmethyl)pyrrolidin-2-yl]pyrrolidin-1-yl}methyl)pyridine-type (PDP-type) complexes. These catalysts affect styrene aziridination under mild conditions based on a limiting quantity of olefin substrate.

Mit dünnen Schichten durch vier Jahrzehnte

SummaryThin films through four decades – How they changed the worldThe 30th anniversary of the journal “Vacuum in research and practice” is accompanied by a brief journey through the world of thin films and their impact on our life during the past decades. Around 40 years ago coating processes had been ready to find their way into mass markets related to large areas and quantity of substrates. Reduction of friction, wear and corrosion on tools and machine components, architectural glass, optical and magnetic data storage media, displays, touch panels and solar cells have been the most important application areas during the past four decades. Often ecxiting new products (like the CD) caused a paradigm change in the design of coating machines, or a milestone in process technology (like Pulse Magnetron Sputtering) enabled new applications. In this contribution several decades of thin film technology will pass in fast motion. The article reflects the perception of someone having experienced 35 very exciting years in industrial development as well as applied research related to thin films and their deposition. Certainly this perception is subjective and incomplete.

Optimal periodic control of the chemostat with Contois growth function

In this work, we examine the benefit of having periodic dilution rate in the chemostat model in terms of averaged conversion rate. We compare the effect of bringing a same substrate quantity by a periodic rate with a constant rate. We show that for the classical chemostat model with a Contois growth function, the performance of the averaged conversion rate can be improved under certain conditions. Using Pontryagin’s Principle, we characterize the extremals of the problem which minimizes the averaged substrate concentration among periodic trajectories of a given period.

Mesocricetus Auratus Preference for Substrate Quantity vs Enriched Commercial Housing Options: A Case Report

M. auratus is a common companion and laboratory animal in many countries around the world. Many guidelines recommend housing M. auratus in enriched enclosures that are as large as possible with a bedding depth of approximately 2.5 cm. However, given that wild M. auratus will build intricate burrows it is uncertain whether M.auratus would actually prefer to nest in an enclosure that provides enrichment relative to an enclosure that provides a greater substrate depth to facilitate natural behaviours. We provided a female M.auratus with an 8 m2 pen containing a 30L tub containing recycled paper bedding, an enriched 3-storey commercially available cage that included a running wheel and 2.5 cm of bedding in the bottom, and enrichment derived from a mixture of commercial products and recycled household products (RHPs; e.g. cardboard boxes). When randomly sampling the location of M. auratus during a 3-month study period, we found that virtually all nesting behaviour, including hoarding, sleeping, and burrow construction occurred within the tub. While approximately 31% of non-nesting behaviour centred around the cage, no nesting behaviour occurred there. Moreover, of the interactions with external enrichment in the pen, we found that over 90% of interactions were with RHPs rather than commercial products. We conclude that M. auratus is likely to prefer housing conditions that provide greater quantities of substrate in which they can emit their natural burrowing behaviours, that they value burrowing and nesting opportunities to a greater extent than even multi-level above-ground enriched areas, and those simple cardboard boxes may provide better enrichment than expensive commercial products.

An alternative polysaccharide uptake mechanism of marine bacteria

Heterotrophic microbial communities process much of the carbon fixed by phytoplankton in the ocean, thus having a critical role in the global carbon cycle. A major fraction of the phytoplankton-derived substrates are high-molecular-weight (HMW) polysaccharides. For bacterial uptake, these substrates must initially be hydrolysed to smaller sizes by extracellular enzymes. We investigated polysaccharide hydrolysis by microbial communities during a transect of the Atlantic Ocean, and serendipitously discovered—using super-resolution structured illumination microscopy—that up to 26% of total cells showed uptake of fluorescently labelled polysaccharides (FLA-PS). Fluorescence in situ hybridisation identified these organisms as members of the bacterial phyla Bacteroidetes and Planctomycetes and the gammaproteobacterial genus Catenovulum. Simultaneous membrane staining with nile red indicated that the FLA-PS labelling occurred in the cell but not in the cytoplasm. The dynamics of FLA-PS staining was further investigated in pure culture experiments using Gramella forsetii, a marine member of Bacteroidetes. The staining patterns observed in environmental samples and pure culture tests are consistent with a ‘selfish’ uptake mechanisms of larger oligosaccharides (>600 Da), as demonstrated for gut Bacteroidetes. Ecologically, this alternative polysaccharide uptake mechanism secures substantial quantities of substrate in the periplasmic space, where further processing can occur without diffusive loss. Such a mechanism challenges the paradigm that hydrolysis of HMW substrates inevitably yields low-molecular-weight fragments that are available to the surrounding community and demonstrates the importance of an alternative mechanism of polysaccharide uptake in marine bacteria.

Hierarchically structured carbon/carbon nanocomposites with adjustable porosity fabricated by twin polymerization

Carbon materials with a complex core-shell structure and adjustable porosity are fabricated by subsequent surface polymerization of twin monomers on carbon black and silica particles. The twin monomers 2,2’-spirobi[4H-1,3,2-benzodioxasiline] (Spiro) and tetrafurfuryloxysilane (TFOS) are polymerized in one step to an inorganic/organic hybrid material, which contains nanostructured silica and phenolic resin or poly(furfuryl alcohol), respectively, as organic polymer. After carbonization and the removal of silica, a porous carbon shell with defined porosity is obtained. In this process, Spiro based materials produce microporous carbon and TFOS based materials produce a mesoporous carbon. Quantities of monomer, catalyst and substrate can be varied. This allows to create a library of porous carbon materials with different properties such as controlled porosity, morphology and hierarchically structuring. Thus, mesoporous carbon with a microporous shell can be achieved by using carbon black particles as substrate and Spiro as twin monomer. Furthermore, carbon hollow spheres with a double shell with hierarchically structuring can be synthesized by subsequent polymerization of TFOS and Spiro on silica particles. The porous carbon materials were characterized by quantitative elemental analysis, thermogravimetric measurements, SEM/EDX, TEM, nitrogen sorption isotherms and mercury porosimetry.

Impact of an experimental eutrophication on the processes of bioerosion on the reef: One Tree Island, Great Barrier Reef, Australia

The components of bioerosion were investigated during ENCORE (The Effect of Nutrient Enrichment on Coral Reefs) over 2years of controlled additions of dissolved inorganic nitrogen and phosphorus. The study was carried out at One Tree Island, southern Great Barrier Reef, Australia. Rates of microbioerosion and external erosion by grazing were significantly higher at the enriched sites than at the control sites. Rates of accretion by coralline algae were also significantly higher at enriched sites. In contrast, rates of macroboring were not significantly different between enriched and control sites.This study highlights the importance of improving water quality on the reef to reduce rates of bioerosion given that quantities of dead coral substrates have recently substantially increased as a result of coral bleaching (Hughes et al., 2015) and several Crown of Thorns plagues (Fabricius et al., 2010; De'ath et al., 2012), on the Great Barrier Reef.

Screening of low cost agricultural wastes to maximize the fructosyltransferase production and its applicability in generation of fructooligosaccharides by solid state fermentation

Production of fructosyltransferase by Aspergillus flavus NFCCI 2364 was exploited in solid state fermentation using low cost agricultural wastes for their ability to generate fructooligosaccharides. Among sixteen screened agro wastes, sugar cane bagasse was remarked as the most promising substrate suited for excellent growth and adequate production of fructosyltransferase (FTase) in 96 h of fermentation. The fermentation attempted in one variable executed yeast extract 0.2 g/gds (gram per gram dry substrate) as the most applicable nitrogen source and inoculum size 1 × 108 spores/gds resulted FTase activity of 197.10 U/gds (unit per gram dry substrate). The recuperated FTase activity of 423.18 U/gds was executed by rotable central composite design RCCD) approach of response surface methodology by validated process variables viz. pH 5.0, substrate particle size 2.5 mm, substrate moisture ratio 1:1.4 and substrate quantity of 7.0 g respectively. The study signifies excellent stability and compatibility of A. flavus NFCCI 2364 using sugarcane baggase as an economical substrate for industrial production of fructosyltransferase.

Effect of Crude Oil Polluted Soil and Substrate Quantity on Some Morphological Characters of Pleurotus ostreatus (Jacq.) P. Kumm and Pleurotus pulmonarius (Fries) Quel Fruit Bodies

The study was conducted to determine the influence of different levels of crude oil pollution on some morphological characteristics of P. ostreatus and P. pulmonariusfruit bodies. Crude oil treatment was done at 2%, 4% and 6% levels to 2,500 g/kg of garden soil. A.gayanus substrate was used in two quantity layers of 150 g/kg (4 cm) and 300 g/kg (8 cm) and placed on top of the polluted soil before spawn inoculation. The Cap Size (C.S cm), Stipe Length (S.L cm) and Weight (Wt. g/kg) of each mature mushroom fruit body were determined. Data collected were analysed using Analysis of Variance (ANOVA), while mean separation was done using Duncan Multiple Range Test (DMRT). Results showed that mean and standard error mean (mean± SEM) of C.S, S.L, and Wt of fruit bodies of both oyster mushrooms were not significantly different at p<0.05. Therefore, the various levels of crude oil pollution (2%, 4%, and 6%), as well as A.gayanus substrate layers/quantities of 4 cm/150 g/kg and 8 cm/300 g/kg did not affect some of the morphological characters of the Oyster mushroom species studied.

Cobalt-Catalyzed C(sp(2))-H Borylation: Mechanistic Insights Inspire Catalyst Design.

A comprehensive study into the mechanism of bis(phosphino)pyridine (PNP) cobalt-catalyzed C-H borylation of 2,6-lutidine using B2Pin2 (Pin = pinacolate) has been conducted. The experimentally observed rate law, deuterium kinetic isotope effects, and identification of the catalyst resting state support turnover limiting C-H activation from a fully characterized cobalt(I) boryl intermediate. Monitoring the catalytic reaction as a function of time revealed that borylation of the 4-position of the pincer in the cobalt catalyst was faster than arene borylation. Cyclic voltammetry established the electron withdrawing influence of 4-BPin, which slows the rate of C-H oxidative addition and hence overall catalytic turnover. This mechanistic insight inspired the next generation of 4-substituted PNP cobalt catalysts with electron donating and sterically blocking methyl and pyrrolidinyl substituents that exhibited increased activity for the C-H borylation of unactivated arenes. The rationally designed catalysts promote effective turnover with stoichiometric quantities of arene substrate and B2Pin2. Kinetic studies on the improved catalyst, 4-(H)2BPin, established a change in turnover limiting step from C-H oxidative addition to C-B reductive elimination. The iridium congener of the optimized cobalt catalyst, 6-(H)2BPin, was prepared and crystallographically characterized and proved inactive for C-H borylation, a result of the high kinetic barrier for reductive elimination from octahedral Ir(III) complexes.

Impact of agricultural management on bacterial laccase-encoding genes with possible implications for soil carbon storage in semi-arid Mediterranean olive farming.

Background: In this work, we aimed to gain insights into the contribution of soil bacteria to carbon sequestration in Mediterranean habitats. In particular, we aimed to use bacterial laccase-encoding genes as molecular markers for soil organic C cycling. Using rainfed olive farming as an experimental model, we determined the stability and accumulation levels of humic substances and applied these data to bacterial laccase-encoding gene expression and diversity in soils under four different agricultural management systems (bare soils under tillage/no tillage and vegetation cover under chemical/mechanical management).Materials and Methods: Humic C (> 104 Da) was subjected to isoelectric focusing. The GC-MS method was used to analyze aromatic hydrocarbons. Real-Time PCR quantification and denaturing gradient gel electrophoresis (DGGE) for functional bacterial laccase-like multicopper oxidase (LMCO)-encoding genes and transcripts were also carried out.Results: Soils under spontaneous vegetation, eliminated in springtime using mechanical methods for more than 30 years, showed the highest humic acid levels as well as the largest bacterial population rich in laccase genes and transcripts. The structure of the bacterial community based on LMCO genes also pointed to phylogenetic differences between these soils due to the impact of different management systems. Soils where herbicides were used to eliminate spontaneous vegetation once a year and those where pre-emergence herbicides resulted in bare soils clustered together for DNA-based DGGE analysis, which indicated a certain amount of microbial selection due to the application of herbicides. When LMCO-encoding gene expression was studied, soils where cover vegetation was managed either with herbicides or with mechanical methods showed less than 10% similarity, suggesting that the type of weed management strategy used can impact weed community composition and consequently laccase substrates derived from vegetation decay.Conclusions: We suggest that the low humic acid content retrieved in the herbicide-treated soils was mainly related to the type (due to vegetal cover specialization) and smaller quantity (due to lower vegetal biomass levels) of phenolic substrates for laccase enzymes involved in humification processes. We also found that spontaneous vegetal cover managed using mechanical methods could be the best option for achieving C stabilization in rainfed Mediterranean agroecosystems.

Antioxidant properties of protein hydrolysate from Douchi by membrane ultrafiltration

ABSTRACTProtein extracted from Douchi was hydrolyzed by alcalase based on a single-factor experiment and response surface methodology was employed to optimize hydrolysis conditions. The optimum conditions were determined to be: 63℃ extraction temperature, 1.4% quantities of enzyme and substrate, and 1.7 h extraction time. The optimal protein hydrolysate was subsequently subjected to ultrafiltration, and the fraction of molecular weight 10–50 kDa was identified as the most potent contributor to antioxidant activity. Amino acid analysis indicated that acidic amino acids were the most abundant in all fractions of the protein hydrolysate. Infrared spectroscopy showed there were no significant differences in secondary structure between fractions.