Emulsifying property,antioxidant activity,and bitterness of soybean protein isolate hydrolysate obtained by Corolase PP under high hydrostatic pressure

Enzymatic hydrolysis of proteins can enhance their emulsifying properties and antioxidant activities.However,the problem related to the hydrolysis of proteins was the generation of the bitter taste.Recently,high hydrostatic pressure(HHP)treatment has attracted much interest and has been used in several studies on protein modification.Hence,the study aimed to investigate the effects of enzymatic hydrolysis by Corolase PP under different pressure treatments(0.1,100,200,and 300 MPa for 1-5 h at 50℃)on the emulsifying property,antioxidant activity,and bitterness of soybean protein isolate hydrolysate(SPIH).As observed,the hydrolysate obtained at 200 MPa for 4 h had the highest emulsifying activity index(47.49 m^(2)/g)and emulsifying stability index(92.98%),and it had higher antioxidant activities(44.77%DPPH free radical scavenging activity,31.12%superoxide anion radical scavenging activity,and 61.50%copper ion chelating activity).At the same time,the enhancement of emulsion stability was related to the increase of zeta potential and the decrease of mean particle size.In addition,the hydrolysate obtained at 200 MPa for 4 h had a lower bitterness value and showed better palatability.This study has a broad application prospect in developing food ingredients and healthy foods.

Potential of high hydrostatic pressure in reducing the allergenicity of seafood

Seafood,as a primary high-quality protein source,plays an increasingly vital role in diets around the world,while seafood allergy is a worldwide health problem that affects the quality of life and may even threaten lives.High hydrostatic pressure(HHP),a novel non-thermal processing technology,shows the unique potential in alleviating seafood allergenicity.This comment provides a brief introduction of potential of high hydrostatic pressure in reducing the allergenicity of seafood.

The impact of high hydrostatic pressure treatment time on the structure,gelatinization and thermal properties and in vitro digestibility of oat starch

As a non-thermal processing technology,high hydrostatic pressure(HHP)can be used for starch modification without affecting the quality and flavour constituents.The effect of HHP on starch is closely related to the treatment time of HHP.In this paper,we investigated the impacts of HHP treatment time(0,5,10,15,20,25,30 min)on the microstructure,gelatinization and thermal properties as well as in vitro digestibility of oat starch by scanning electron microscopy,X-ray diffraction,Fourier transform infrared spectroscopy,13C NMR and differential scanning calorimeter.Results showed that 5-min HHP treatment led to deformation and decreases in short-range ordered and doublehelix structures of oat starch granules,and further extending the treatment time to 15 min or above caused the formation of a gelatinous connection zone,increase of particle size,disintegration of short-range ordered and double-helix structures,and crystal structure change from A type to V type,indicating gelatinization occurred.Longer treatment time also resulted in the reduction in both the viscosity and the stability of oat starch.These indicated that HHP treatment time greatly influenced the microstructure of oat starch,and the oat starch experienced crystalline destruction(5 min),crystalline disintegration(15 min)and gelatinization(>15 min)during HHP treatment.Results of in vitro digestibility showed that the rapidly digestible starch(RDS)content declined first after treatment for 5 to 10 min then rose with the time extending from 15 to 30 min,indicating that longer pressure treatment time was unfavourable to the health benefits of oat starch for humans with diabetes and cardiovascular disease.Therefore,the 500-MPa treatment time for oat starch is recommended not more than 15 min.This study provides theoretical guidance for the application of HHP technology in starch modification and development of health foods.

Optimization of Inactivation Conditions of High Hydrostatic Pressure Using Response Surface Methodology

Response surface methodology (RSM) was employed in the present work and a second orderquadratic equation for high hydrostatic pressure (HHP) inactivation was built. Theadequacy of the model equation for predicting the optimum response values was verifiedeffectively by the validation data. Effects of temperature, pressure, and pressureholding time on HHP inactivation of Escherichia coli ATCC 8739 were explored. Byanalyzing the response surface plots and their corresponding contour plots as well assolving the quadratic equation, the optimum process parameters for inactivation E. coliof six log cycles were obtained as: temperature 32.2℃, pressure 346.4 MPa, and pressureholding time 12.6min.

Changes in Chlorophyll Fluorescence of Rice Mutants Induced by High Hydrostatic Pressure

Three mutants of rice (Oryza sativa L. ), Mutant 1, Mutant 2 and Mutant 3, which were selected by high hydrostatic pressure (75 MPa), and their parent Yuexiangzhan were used to study the changes in chlorophyll fluorescence during different growth stages. In all the three mutants, the function of PSⅡ was improved, F_v/F_m ratio of mutants increased compared to their parent at tillering and heading stage, and ΦPSⅡ also improved except for Mutant 2 at heading stage. Similar to their parent, the mutants exhibited slight photoinhibition at noon and almost complete recovery to initial levels of 6:00 after 18:00 at heading stage. At milking stage, the photoinhibition in the mutants was obvious, and recovered rapidly compared to the parent. Yields of individual plant and grain/straw ratio were also higher in three mutants than the parent. Results indicated that characteristics of chlorophyll fluorescence in leaves of mutants and their photoinhibition in the field had changed. It is suggested that high hydrostatic pressure induction could be applied as a new effective approach in high-yield rice breeding in the future.

Distinct influence of trimethylamine N-oxide and high hydrostatic pressure on community structure and culturable deep-sea bacteria

Trimethylamine N-oxide(TMAO)is one of the most important nutrients for bacteria in the deep-sea environment and is capable of improving pressure tolerance of certain bacterial strains.To assess the impact of TMAO on marine microorganisms,especially those dwelling in the deep-sea environment,we analyzed the bacterial community structure of deep-sea sediments after incubated under different conditions.Enrichments at 50 MPa and 0.1 MPa revealed that TMAO imposed a greater influence on bacterial diversity and community composition at atmospheric pressure condition than that under high hydrostatic pressure(HHP).We found that pressure was the primary factor that determines the bacterial community.Meanwhile,in total,238 bacterial strains were isolated from the enrichments,including 112 strains a ffiliated to 16 genera of 4 phyla from the Yap Trench and 126 strains a ffiliated to 11 genera of 2 phyla from the Mariana Trench.Treatment of HHP reduced both abundance and diversity of isolates,while the presence of TMAO mainly af fected the diversity of isolates obtained.In addition,certain genera were isolated only when TMAO was supplemented.Taken together,we demonstrated that pressure primarily defines the bacterial community and culturable bacterial isolates.Furthermore,we showed for the first time that TMAO had distinct influences on bacterial community depending on the pressure condition.The results enriched the understanding of the significance of TMAO in bacterial adaptation to the deep-sea environment.

Effect of High Hydrostatic Pressure Processing on the Structure and Property of Konjac Glucomannan–Casein Mixture

High hydrostatic pressure（HHP） processing is applied to a Konjac glucomannan（KGM）-casein（CS） mixture to explore the changes in the mixture＇s properties and microstructures.The mixture＇s viscosity increases by -18.1% at low HHP（200 MPa） and decreases by about 5.3-31.7% at high HHP（600 MPa）.Scanning electron microscopy analysis shows that low HHP induces a denser and more compact structure,and high HHP leads to a porous and reticular structure.X-ray diffraction shows that the mixture is amorphous without dramatic changes; only some small crystalline peaks appear under excessive pressure.Fourier transform infrared analysis indicates that the non-covalent interactions（hydrogen bonds,etc.） are probably the most important factors for the modification of mixture properties.Bonding enhances under low pressure,and weakens with increasing pressure and time.

X-ray diffraction investigation of amorphous calcium phosphate and hydroxyapatite under ultra-high hydrostatic pressure

The changes in the crystal structures of synthetically prepared amorphous calcium phosphate（ACP） and hydroxyapatite（HAP） in water（1：1 mass ratio） were studied by synchrotron X-ray diffraction（XRD） under ultra-high hydrostatic pressures as high as 2.34 GPa for ACP and 4 GPa for HAP. At ambient pressure, the XRD patterns of the ACP and HAP samples in capillary tubes and their environmental scanning electron micrographs indicated amorphous and crystalline characteristics for ACP and HAP, respectively. At pressures greater than 0.25 GPa, an additional broad peak was observed in the XRD pattern of the ACP phase, indicating a partial phase transition from an amorphous phase to a new high-pressure amorphous phase. The peak areas and positions of the ACP phase, as obtained through fitting of the experimental data, indicated that the ACP exhibited increased pseudo-crystalline behavior at pressures greater than 0.96 GPa. Conversely, no structural changes were observed for the HAP phase up to the highest applied pressure of 4 GPa. For HAP, a unit-cell reduction during compression was evidenced by a reduction in both refined lattice parameters a and c. Both ACP and HAP reverted to their original structures when the pressure was fully released to ambient pressure.

Extraction of β-Carotene,Vitamin C and Antioxidant Compounds from Physalis peruviana(Cape Gooseberry)Assisted by High Hydrostatic Pressure

High hydrostatic pressure assisted extraction (HHPE) has several advantages when compared to traditional extraction methods, which frequently cause degradation and loss of target components and might consume large volumes of environmentally unfriendly solvents. The aim of this study was to develop an assisted extraction method using high hydrostatic pressure (HHPE) and to evaluate both HHPE and conventional extraction methods for β-carotene, antioxidant compounds and vitamin C from cape gooseberry. β-carotene and compounds with antioxidant activity (2,2-diphenyl-1-picrylhydrazyl radical assay (DPPH*) or radical scavenging activity;ferric reducing antioxidant power assay (FRAP)) were extracted using HHPE for 5 min, 10 min and 15 min at 500 MPa, while vitamin C was extracted at 500 MPa for 30 s, 60 s and 90 s. Processing significantly affected (p ≤ 0.05) the β-carotene content of all samples, increasing retention by 8%, 14% and 15% at 500 MPa after 5 min, 10 min and 15 min of HPPE, respectively. The highest antioxidant content determined by DPPH* and FRAP assays was obtained in a sample treated at 500 MPa for 15 min, showing increases of 26% and 51%, respectively, compared with an untreated sample. The ascorbic acid content of fresh cape gooseberry was 26.31 mg·100 g-1. In fact, the ascorbic acid levels were significantly higher for all high-pressure-treated samples compared to this of conventionally extracted sample (p ≤ 0.05), exhibiting increases of 9%, 41% and 53% at 500 MPa after 30 s, 60 s and 90 s of HPPE, respectively. Thus, the application of HHPE produced higher β-carotene content, antioxidant compounds and vitamin C content and required less extraction time compared to other extraction methods. The pharmaceutical and food industries can benefit by using high pressure extraction technology.

Widespread and active piezotolerant microorganisms mediate phenolic compound degradation under high hydrostatic pressure in hadal trenches

Phenolic compounds,as well as other aromatic compounds,have been reported to be abundant in hadal trenches.Although high-throughput sequencing studies have hinted at the potential of hadal microbes to degrade these compounds,direct microbiological,genetic and biochemical evidence under in situ pressures remain absent.Here,a microbial consortium and a pure culture of Pseudomonas,newly isolated from Mariana Trench sediments,efficiently degraded phenol under pressures up to 70 and 60 MPa,respectively,with concomitant increase in biomass.By analyzing a high-pressure(70 MPa)culture metatranscriptome,not only was the entire range of metabolic processes under high pressure generated,but also genes encod-ing complete phenol degradation via ortho-and meta-cleavage pathways were revealed.The isolate of Pseudomonas also contained genes encoding the complete degradation pathway.Six transcribed genes(dmpKLMNOP_(sed))were functionally identified to encode a multicomponent hydroxylase catalyzing the hydroxylation of phenol and its methylated derivatives by heterogeneous expression.In addition,key catabolic genes identified in the metatranscriptome of the high-pressure cultures and genomes of bacterial isolates were found to be all widely distributed in 22 published hadal microbial metagenomes.At microbiological,genetic,bioinformatics,and biochemical levels,this study found that microorganisms widely found in hadal trenches were able to effectively drive phenolic compound degradation under high hydrostatic pressures.This information will bridge a knowledge gap concerning the microbial aromatics degradation within hadal trenches.

Changes in structure and functional properties of whey proteins induced by high hydrostatic pressure:A review

High hydrostatic pressure(HHP)is an alternative technology to heat processing for food product modifications.It does not cause environmental pollution and eliminates the use of chemical additives in food products.This review covers the research conducted to understand the effect of HHP on structure and functional properties of whey proteins.In this paper,the mechanism underlying pressure-induced changes inβ-lactoglobulin andα-lactabumin is also discussed and how they related to functional properties such as hydrophobicity,foam stability,and flavor-binding capacity.

Characterization of Fe(Ⅲ)-Reducing Enrichment Cultures and Isolation of Enterobacter sp. Nan-1 from the Deep-Sea Sediment, South China Sea

To characterize the Fe(III)-reducing bacteria,enrichment cultures were initiated by inoculating deep-sea sediment from the South China Sea(SCS)into the media with hydrous ferric oxide(HFO)as the sole electron acceptor.As indicated by Meta 16S rDNA Amplicon Sequencing,the microorganisms related to Fe(III)-reduction in the enrichment cultures were mainly Shewanella and Enterobacter.A new facultative Fe(III)-reducing bacterium was obtained and identified as Enterobacter sp.Nan-1 based on its 16S rRNA gene sequence and physiological characterizations.Enterobacter sp.Nan-1 was not only a mesophilic bacterium capable of reducing HFO with a wide range of salinity(4,34,40,50 and 60 g L−1)efficiently,but also a piezotolerant bacterium that can proceed Fe(III)-reduction sustainedly at hydrostatic pressures between 0.1 and 50 MPa using glucose and pyruvate as carbon source.Furthermore,the geochemical characteristics of deep-sea sediment indicated that the microbial metabolism and iron reduction both remain active in the well-developed Fe(III)-reducing zone where the strain Nan-1 was obtained.To our knowledge,Enterobacter sp.Nan-1 could serve as a new applicative Fe(III)-reducing bacterium for future investigation on the iron biogeochemical cycle and diagenetic process of organic matter in the deep-sea environment.

Pseudo-chromosome–length genome assembly for a deep-sea eel Ilyophis brunneus sheds light on the deep-sea adaptation

High hydrostatic pressure,low temperature,and scarce food supply are the major factors that limit the survival of vertebrates in extreme deep-sea environments.Here,we constructed a high-quality genome of the deep-sea Muddy arrowtooth eel(MAE,Ilyophis brunneus,captured below a depth of 3,500 m)by using Illumina,Pac Bio,and Hi-C sequencing.We compare it against those of shallow-water eel and other outgroups to explore the genetic basis that underlies the adaptive evolution to deep-sea biomes.The MAE genome was estimated to be 1.47 Gb and assembled into 14 pseudo-chromosomes.Phylogenetic analyses indicated that MAE diverged from its closely related shallow-sea species,European eel,~111.9 Mya and experienced a rapid evolution.The genome evolutionary analyses primarily revealed the following:(i)under high hydrostatic pressure,the positively selected gene TUBGCP3 and the expanded family MLC1 may improve the cytoskeleton stability;ACOX1 may enhance the fluidity of cell membrane and maintain transport activity;the expansion of ABCC12 gene family may enhance the integrity of DNA;(ii)positively selected HARS likely maintain the transcription ability at low temperatures;and(iii)energy metabolism under a food-limited environment may be increased by expanded and positively selected genes in AMPK and m TOR signaling pathways.