Search

Backgroud Zinc is an essential catalytic element in human health system but its absorption in intestinal system could be strongly affected by the gastrointestinal digestion. In this study, the food-derived potential zinc carrier, scallop adductor hydrolysates (SAHs), was produced and characterized. Results During the temporary storage in 4°C, the SAH decreased in zinc-chelating capacity in aqueous phase whereas the SAH-Zn complex exhibited high stability. Moreover, the secondary structure of SAH had no significant alteration. Zinc morphologically altered the surface structures of SAH, which was involving in carboxyl group of SAH. Results of in vitro gastrointestinal (GI) digestion suggested that the SAH-Zn maintained good stability in GI system and only proportion of high molecular weight cleaved. In addition, SAH could successfully carry and transport zinc while the fluorescence staining revealed free zinc accumulation inside the tissue. Finally, 3 representative absorbed peptides (around 600 Da) were identified and synthesized. Three synthetic peptides exhibit higher zinc-chelating capacity than SAH and could also successfully transported through the intestine. Conclusion This study provided a theoretical basis for the investigation of digestion and absorption of marine animal-derived peptides as zinc carriers. This article is protected by copyright. All rights reserved.

The effect of phlorotannin extracts (PTE) (from sporophyll of Undaria pinnatifida) added at different levels (0, 25, 125, 625 µmol/g protein) on the gel properties of mackerel (Scomberomorus niphonius) myofibrillar protein (MP) was studied with and without ultraviolet A (UVA) irradiation. The results showed that the gel strength and cooking yield increased in a PTE dose-dependent manner, and at the level of 625 µmol/g protein PTE, the highest gel strength of 308.43 ± 8.12 (mN·cm) and cooking yield of 76.16 ± 1.40% were obtained in the samples treated with UVA irradiation. The same samples also showed increased carbonyl content, decreased total sulfhydryl, unwinding of α-helix, and quenching of fluorescence intensity of endogenous tryptophan, all of which indicated that elevated protein oxidation in these samples led to enhanced protein cross-linking. Results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) indicated aggregation of myosin heavy chains (MHCs) in the UVA-treated gels with PTE, also evidenced by the dense three-dimensional network structure in these samples visualized by scanning electron microscopy (SEM). Electron spin resonance (ESR) and spin trapping results indicated that free radicals were produced during the gelation process, possibly originated from UVA-treated PTE, which played a critical role of oxidizing fish MPs, and eventually led to the improvement of the textural properties of the mackerel MP gel. PRACTICAL APPLICATION: Brown algae are a family of high-yield marine algae. Phlorotannin extracts are highly active natural substances extracted from brown algae that can have many applications. Ultraviolet A (UVA) as a green and environmentally friendly physical processing method has been widely used in food processing in recent years. The method proposed in this study could be utilized to improve properties of fish protein gel made from poorly performing low-priced fishes, and provide workable guidance for industry to expand the application of brown algae in food processing to better meet consumer's demand for high-quality marine foods.

The effects of phlorotannin extracts (PTE) (from sporophyll of Undaria pinnatifida) added at different concentration (0, 1.6, 8, and 40 mg/g protein) with and without ultraviolet A (UVA) irradiation treatment on gel properties of mackerel (Scomberomorus niphonius) mince (MM) were investigated. The results indicated that both the breaking force and water-holding capacity (WHC) of the MM gel increased with addition of PTE, and the highest breaking force and WHC were observed with 40 mg/g PTE under UVA irradiation. Low-field nuclear magnetic resonance revealed that free water significantly decreased in this PTE-MM gel as well. UVA irradiation treatment led to reduction of total sulfhydryls and free amines in the PTE-MM gel, indicating more cross-linking between proteins. Electrophoresis results indicated that myosin heavy chains were aggregated in the UVA-treated PTE-MM gel. The microstructure of the UVA-treated PTE-MM gel showed that protein formed more evenly distributed cross-linked structures and was more compact than the untreated control gel. As a conclusion, PTE addition with UVA irradiation is shown to improve gelling properties of mackerel mince.

Fucoxanthin is a xanthophyll carotenoid abundant in marine brown algae. The potential therapeutic effects of fucoxanthin on tumor intervention have been well documented, which have aroused great interests in utilizing fucoxanthin in functional foods and nutraceuticals. However, the utilization of fucoxanthin as a nutraceutical in food and nutrient supplements is currently limited due to its low water solubility, poor stability, and limited bioaccessibility. Nano/micro-encapsulation is a technology that can overcome these challenges. A systematic review on the recent progresses in nano/micro-delivery systems to encapsulate fucoxanthin in foods or nutraceuticals is warranted. This article starts with a brief introduction of fucoxanthin and the challenges of oral delivery of fucoxanthin. Nano/micro-encapsulation technology is then covered, including materials and strategies for constructing the delivery system. Finally, future prospective has been discussed on properly designed oral delivery systems of fucoxanthin for managing cancer. Natural edible materials such as whey protein, casein, zein, gelatin, and starch have been successfully utilized to fabricate lipid-based, gel-based, or emulsion-based delivery systems, molecular nanocomplexes, and biopolymer nanoparticles with the aid of advanced processing techniques, such as freeze-drying, high pressure homogenization, sonication, anti-solvent precipitation, coacervation, ion crosslinking, ionic gelation, emulsification, and enzymatic conjugation. These formulated nano/micro-capsules have proven to be effective in stabilizing and enhancing the bioaccessibility of fucoxanthin. This review will inspire a surge of multidisciplinary research in a broader community of foods and motivate material scientists and researchers to focus on nano/micro-encapsulated fucoxanthin in order to facilitate the commercialization of orally-deliverable tumor intervention products.

Foodborne nanoparticles produced from food components during thermal processing have received attention due to their particular properties. Herein, the presence of fluorescent carbon dots (CDs) was reported from mackerel flesh roasted at 230 °C in an electronic oven, and the CD capability for free radical scavenging was investigated. The average size of the CDs was about 2.2 nm with a size distribution in the range of 0.9–3.5 nm as characterized with transmission electron microscopy (TEM). X-ray photoelectron spectroscopy (XPS) showed that the mackerel CDs mainly contain C, N and O. Fourier transform infrared (FTIR) analysis showed the existence of hydroxyl, amino, and carboxyl groups on the mackerel CD surface. The fluorescence lifetime was about 9.1 ns. Two absorption peaks at 277 and 328 nm were observed in UV–vis spectra, which are assigned to the π-π* and n-π* charge-transfer, respectively. The mackerel CDs showed excellent photostability in various metal ion solutions and pH environment. In addition, these CDs exhibited strong dose-dependent scavenging capability for hydroxyl radicals (·OH) and methyl radicals (·CH3) produced from methylene blue (MB)/visible-light photosensitization system. The free radical scavenging properties make the mackerel CDs capable of protecting against oxidative stress after they are exposed to biosystem.

Manufacturing of protein-enriched beverages is an interesting field which has attracted a lot of attention from the research community. In this study, polysaccharides extracted from a mushroom (Tremella fuciformis) were used to enhance the stability of 5% whey protein isolate (WPI) solution for enriched beverage development with excellent results. Rheological studies showed that the T. fuciformis polysaccharides (TP) enhanced WPI solution exhibited characteristics of pseudoplastic fluid. Microstructure studies showed that the WPI–TP complexes formed more orderly structures than that of the two monomers. A new limited proteolysis-coupled mass spectrometry technique was utilized to characterize the in vitro digestibility of WPI-TP complexes: the rate of digestion of WPI-TP was shown to be significantly lower than that of WPI, which would reduce gastric emptying time and increase satiety. In addition, the degree of digestibility of each protein and the potential binding regions of TP-WPI were also revealed by this new technique.

Nine transformants of Rhodosporidium toruloides with significant changes in the carotenoid profile were obtained by Agrobacterium tumefaciens-mediated transformation, including a white, three red, and four yellow mutants. A red mutant A1-15-BRQ that showed a high torularhodin production was selected for culture condition optimization. Results indicated that the torularhodin yield was boosted with glucose as the carbon source, at a carbon/nitrogen ratio of 22, a loading volume of 75 mL, and 28 °C. The torularhodin yield of 21.3 mg/L consisting of 94.4% total carotenoids was obtained by Box-Behnken design experiments. The torularhodin yield was 17.0-fold higher than that of the wild type, with time shortened from 9 to 3 days. This study reports an effective strategy for improving torularhodin production and provides a candidate R. toruloides strain for highly selective production of torularhodin.

Postmortem characteristics of Patinopecten yessoensis adductor muscle (PYAM) were evaluated by biochemical, chemical and textural changes during iced storage for 14 days. Triphosphate (ATP) and its breakdown products, K-value, total volatile basic nitrogen (TVB-N), pH, water-holding capacity (WHC), color, texture, protein degradation and cathepsin activities were monitored. K-value increased linearly from 5.9 ± 0.9% at day 0 to 28.1 ± 2.4% at day 2 and 70.2 ± 1.8% at day 12. Spoilage indicator TVB-N (mg/100 g) increased from 10.0 ± 0.6 to 34.6 ± 3.1 at day 12. Textural parameters (e.g., hardness, chewiness, springiness, adhesiveness, and shear force) followed a declining trend over the storage. The WHC decreased from 85.1 ± 3.1% at day 0 to 70.5 ± 1.8% at day 12. SDS-PAGE result indicated that proteolysis occurred in actin and myosin heavy chain (MHC) at day 14. Both cathepsin B and L increased throughout the iced storage, peaking at 1.47-fold and 1.08-fold, respectively, suggesting that cathepsin B and L played important roles in the deterioration of PYAM quality. The overall results indicated that PYAM was suitable to be consumed raw within the first 2 days, and to be processed in no more than 11 days.

Different heating conditions could change water absorption capacity of sea cucumbers body wall (SCBW), and subsequently affect the sensory quality of the rehydrated sea cucumbers. In this study, fresh SCBWs were boiled for 30, 60, 90, 120, 150, 180 min, respectively. The boiled SCBWs were then soaked in deionized water for 48 hr. The changes in water absorption ratio (Wabs ), water holding capacity, water distribution, texture and ultrastructure of the SCBW were investigated. With increasing cooking time (from 30 to 180 min) the water absorption capacity is significantly enhanced (from 1.84 times to 3.37 times). The absorbed water was found to exist inside the SCBW in two forms, physisorbed water, which entered the SCBW via diffusion and could be easily removed, and associated water, which formed association with the SCBW structure, evidenced by the difference in mobility determined by low field nuclear magnetic resonance (LF-NMR) spectroscopy. Study of the microstructure of the SCBW showed that the collagen fibers in the SCBW gradually depolymerized and degraded, resulting in the formation of inter-fiber pores and gaps which became internal space that could accommodate more and more water as the cooking time increased. This water was mainly physisorbed with high mobility. The texture characteristics of the SCBW negatively correlated with the accumulation of physiosorbed water. These findings suggest that proper control of heating time could be critical in determining the sensory/eating quality of sea cucumbers. PRACTICAL APPLICATION: Different heating conditions allows sea cucumbers to have different water absorption capacity during the subsequent soaking process, which could greatly affect sea cucumber sensory quality. Understanding the effects of heating on the water absorption characteristics and texture characteristics of sea cucumber body wall will provide knowledge basis and guidelines to optimize the processing parameters for the emerging ready-to-eat sea cucumber industry.

Profiling of polyphenolics in four types of brown macroalgae, namely Laminaria japonica (L. japonica), Undaria pinnatifida (U. pinnatifida), Sargassum fusiforme (S. fusiforme), and Ascophyllum nodosum (A. nodosum), and their effect on oxidation resistance were investigated for the first time. Polyphenolic extracts from marine brown macroalgae were shown to effectively remove oxidants from cells and cellular systems. A. nodosum showed the highest antioxidant activity among evaluated brown macroalgae, showing a better scavenging effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical and alleviating oxidative damage caused by hydrogen peroxide to human keratinocytes (HaCaT) cells. Through Q-Exactive HF-X mass spectrometry analysis, 12 polyphenolic compounds were preliminarily identified, including phlorotannins, phenolic acids, and flavonoids. Significant differences in content and variety of polyphenolics were found in evaluated brown macroalgae, which could be related to differences in antioxidant activity in vivo and in vitro. Moreover, the antioxidant activity might be related to the total phenolic content and the types of polyphenolics, especially phlorotannins. The findings presented in this study indicate that A. nodosum could be used as an important substitute for functional ingredients in foods and pharmaceutical preparations, as well as a raw material for phlorotannins research.

BACKGROUND Oxidized phlorotannin can be used as a protein crosslinking agent to produce high-quality fish gel products. Phlorotannin can be easily induced to form quinone compounds in an oxidizing environment, while o-quinone has been proven to be a reactive, electrophilic intermediate that easily reacts with proteins to form rigid molecular crosslinking networks. The objective of this study was to investigate the synergistic effects of ultraviolet A (UVA) irradiation (1 h, 15 W m-2 ) and various concentrations of Laminaria japonica phlorotannin extracts (PTE) on the gel properties of grass carp myofibrillar protein (MP). RESULTS UVA treatment and PTE could synergistically improve the MP gel properties more than PTE alone (P

Phlorotannins are a group of major polyphenol secondary metabolites found only in brown algae and are known for their bioactivities and multiple health benefits. However, they can be oxidized due to external factors and their bioavailability is low due to their low water solubility. In this study, the potential of utilizing nanoencapsulation with polyvinylpyrrolidone (PVP) to improve various activities of phlorotannins was explored. Phlorotannins encapsulated by PVP nanoparticles (PPNPS) with different loading ratios were prepared for characterization. Then, the PPNPS were evaluated for in vitro controlled release of phlorotannin, toxicity and antioxidant activities at the ratio of phlorotannin to PVP 1:8. The results indicated that the PPNPS showed a slow and sustained kinetic release of phlorotannin in simulated gastrointestinal fluids, they were non-toxic to HaCaT keratinocytes and they could reduce the generation of endogenous reactive oxygen species (ROS). Therefore, PPNPS have the potential to be a useful platform for the utilization of phlorotannin in both pharmaceutical and cosmetics industries.

In this study, effects of different steaming conditions (temperature-time scales) on quality characteristics of cooked whitefish (Coregonus peled) were characterized to guide product development. Investigation of three cooking conditions, including 60°C (3-20 min) 80°C (1-12 min) and 100°C (1-6 min) indicated that properties including textural properties, cooking loss, color change, water holding capacity (WHC), and protein content were all significantly correlated to the cooking condition. It was observed that the color changes of fish meat, especially the brightness L* were strongly correlated to the relative extraction rate (RER) of myofibrillar proteins (MFPs), which could be considered as a marker for the doneness of the cooked whitefish. Our results indicated that during the steaming process, the water holding capacity of the fish continued to decline, and the cooking loss continued to increase. However, a sudden jump in cooking loss occurred when the fish sample became overcooked. To minimize cooking loss, a good control of the doneness hence is needed to avoid overcooking. Moreover, results of this study demonstrated that low-temperature steaming could better maintain the springiness and cohesiveness of the fish as the myofibrillar proteins experienced less sudden swelling and shrinkage. Hence, low temperature steaming should be the preferred method for whitefish processing to minimize the negative impact on fish sensory qualities.

In this study, κ-carrageenan was used as an additive to improve the quality of Hypophthalmichthys molitrix-sea cucumbers (HM-SC) compound surimi gel. The effects of κ-carrageenan on rheological properties, gel strength, textural and moisture characteristics, as well as microstructure of the HM-SC surimi gel were investigated, alongside with Fourier transform infrared (FT-IR) spectroscopic characterization and SDS-PAGE analyses of the compound materials. Rheological tests showed that addition of κ-carrageenan increased the storage modulus of the HM-SC compound materials in a dosage-dependent way, which led to superior shape-forming and shape-keeping abilities in 3D printed products. The best gel strength of 1236.04 g mm was obtained in samples with κ-carrageenan addition at 1.5% (w/w). The microstructure of the HM-SC compound surimi gel became more compact and denser, with improved connectivity. These samples also had reduced cooking loss and improved water holding capacity, confirmed by changes in water mobility characterized through Low-field nuclear magnetic resonance (LF-NMR). Moreover, κ-carrageenan addition did not change protein configuration much, neither was it contributed to the aggregation and degradation of proteins. These results showed that the quality of the HM-SC compound material could be improved with the κ-carrageenan addition, which could make it suitable for 3D printing based novel product development.

In the present study, effects of riboflavin (RF) and kelp polyphenol extracts (KPE) on mackerel (Scomberomorus Niphonius) myofibrillar protein (MP) gel were studied with or without ultraviolet A (UVA) irradiation treatment. The gel strength was increased with the addition of RF and KPE under UVA irradiation. Analysis of the proteins in the gel indicated that the carbonyl content increased, while the contents of total sulfhydryl and amino groups decreased. The proteins appeared to have no α-helix structures, and the endogenous tryptophan content appeared to decrease. The results of SDS-PAGE indicated that the RF and KPE treated samples under UVA irradiation showed massive MP cross-linking by covalent bonds. Electron spin resonance (ESR) results indicated that UVA irradiation generated free radicals in RF and KPE, which ultimately led to an improvement in MP gel properties. It also indicated that KPE could prevent the occurrence of peroxidation to improve the gel properties.

The effects of temperature/time pretreatments on the texture and microstructure of abalone (Haliotis discus hanai) meat with the same myofibril extraction rate (60-66.7%) were investigated. The abalone samples were categorized into control and four treatment groups of different heating temperature/heating time combinations as 50°C/120 min, 60°C/10 min, 70°C/5 min, and 80°C/2 min, respectively. Compared to the control samples, the abalone samples heated at 60°C/10 min were the most tender (minimum shear force). It is clear that a sharp reduction in hardness was observed in heat treated abalone meat samples, compared to the raw samples. Nuclear magnetic resonance (NMR) showed that the water distribution pattern in abalone samples changed as they were experiencing different heat treatments. Particularly, the immobilized water components in samples heated at 60°C/10 min increased significantly. The textural properties of these samples evaluated after an 80 s-reheating by microwave were of superior quality. It is concluded that the optimal condition for pretreatment abalone was 60°C/10 min, which could significantly improve the textural properties of preprocessed abalones.Ready-to-eat foods can either be consumed directly, or further prepared according to consumers' preference. They are processed and packed following scientifically defined criteria to meet ready-to-eat requirements. For consumers, the quality of the food is one of the most important factors affecting purchasing decisions. Pretreatment through heating plays a key role in determining the eating quality of the product. Our study investigated the effects of pretreatment temperature and time on the food quality. These findings will establish optimal conditions for pretreating abalone to develop high-quality ready-to-eat food products.

The effect of salt concentration on the processing and characteristics of turbot muscle was investigated in this study. The turbot muscle samples were salted with 1%, 5%, 10%, 15%, or 20% w/w salt at 4°C for 3 h. Low-field nuclear magnetic resonance was utilized to characterize water distribution and water holding capacity in the samples. Nuclear magnetic resonance transverse (T2) relaxation identified three water components (T21, T22, and T23) which all exhibited characteristics correlated with water holding capacity. Textural analysis indicated that hardness and elasticity increased with increasing salt concentration. Histological imaging showed that with the increase of salt concentration, the muscle fiber diameter and area increased first and then decreased. The porosity of salted samples was higher than that of fresh ones. It was shown that salting at lower salt concentrations would lead to partial degradation of the fibrin in the tissue samples and the swelling of proteins. In treated samples, 5% w/w salt was shown to produce the best results. This study provides theoretical basis for the development of salted turbot meat products.

In this study, the effects of five cooking methods on nutritional value and flavor of turbot muscle were evaluated. Chemical compositions of samples were determined using AOAC methods, and the fatty-acid composition was determined by gas chromatography–mass spectrometry (GC–MS). Flavors of samples cooked using different methods were characterized by electronic nose. Volatile compounds were determined using solid-phase microextraction (SPME) followed by gas GC–MS. All the samples were investigated before/after cooking. The results showed that the fatty acids found in abundance in the raw sample were C22:6n-3, C16:0, C18:1n-7, and C20:5n-3. All of the fatty acids were detected in steamed samples, while some of the fatty acids were degraded in other cooking methods. Electronic nose can be used to distinguish samples cooked differently. 20, 17, 34, 20, and 23 compounds were detected in samples cooked by frying, baking, microwave heating, boiling in vacuum-sealed bag (BIVSB) and steaming, respectively. Aldehydes, ketones, alcohols, acids, and hydrocarbons were the main volatile components detected. In summary, steaming preserves water, protein, lipids and fatty acids the best in cooked samples while generates desirable flavor, it is recommended as the choice of cooking for turbot.

It is difficult to maintain the high quality of sea cucumber Stichopus japonicus (S. japonicus) during regular thermal processing due to the special physiochemical makeup of S. japonicus body wall (SJBW) that affects its textural properties. Hence, it is very necessary to understand the parameters controlled textural alteration and the potential mechanisms during thermal processing of SJBW. In the present study, morphology, hardness and chewiness of SJBW gradually changed starting from 3 h during thermal processing. SDS-PAGE analysis indicated that notable proteolysis occurred in actin and other proteins with molecular weight of 200 kDa in a time-dependent manner. DNA fragmentation, cathepsin L and caspase-3-like activities also increased in SJBW. Within 1 h of incubation, both phosphorylated p38 and c-jun N-terminal kinase (JNK) and reactive oxygen species (ROS) production in SJBW reached the highest levels, and then returned back to the original levels after 3 h. A plausible signaling pathway in SJBW during low-temperature treatment is as follows: ROS produced, Mitogen-activated protein kinases (MAPK) phosphorylation, endogenous enzyme activation, DNA damage, protein degradation, and textural tenderization. Understanding the molecular mechanism underlying physiochemical changes during low-temperature treatment would be essential to achieve better control of the texture and quality of SJBW.

Undaria pinnatifida (UP) is a brown algae commonly consumed as food in Asian countries. The purpose of this study was to compare the effects of different domestic cooking methods (i.e., air frying (AF), microwaving, and high temperature and pressure (HTP) cooking) on the nutritional and bioactive substances in UP, as well as on UP color and texture, in order to identify methods to retain beneficial components better. In this study, microwave treatment resulted in better retention of color, polysaccharide (4.17 ± 0.07 mg glucose equivalents (GE)/g dry weight (dw) ), total phenol content (TPC) (1.50 ± 0.0062 mg gallic acid equivalents (GAE)/g dw) as well as chlorophyll a (18.18 ± 0.41 mg/g fresh weight (fw) ) and fucoxanthin (281.78 ± 17.06 μg/g dw). HTP treatment increased the TPC of UP (1.69 ± 0.0075 mg GAE/g dw), and AF treatment resulted in a lower loss of total amino acids (2.14 ± 0.15%). Overall, microwave cooking appeared to be the best among the three in producing cooked UP with high quality. This study provided a useful guideline in selection of cooking for UP which could retain more health-beneficial substances and yield products with better eating qualities to improve human diet.

In this study, the effects of low-temperature long-time (LTLT) processing on the quality of Patinopecten yessoensis adductor muscle (PYAM) were investigated at 55°C. The texture of processed PYAM was characterized by textural profile analysis (TPA), and significant increases of cook loss, hardness, and shear force with time during LTLT processing were observed. The degradation of structural proteins was analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and fragments with molecular weights of 208 kDa (myosin heavy chain, MHC), 97 kDa (paramyosin) and 35–40 kDa, respectively, were among the main products. Chemical characterization revealed elevated levels of activity in cathepsin L and caspase-3 and oxidation of proteins and lipids. Electron spin resonance spin trapping indicated reactive oxygen species (ROS) production in the PYAM during LTLT processing. Based on these results, it is proposed that the sequence of events in PYAM during LTLT processing includes ROS→ en...

This study elucidated thermal denaturation profile of myosin in sea cucumber longitudinal muscle. Sea cucumber myosin structure was different from fish at its head/tail junction which could not be cleaved by EDTA. However, sea cucumber myosin in salt-dissolved form could be cleaved into heavy meromyosin (HMM) and light meromyosin (LMM) segments. Although sea cucumbers lived in cold water, its myosin stability was comparable to tropical tilapia, more stable than rainbow trout (a cold water fish). Upon heating, the sea cucumber myosin lost its salt-solubility rapidly, even before losing its ATPase activity. The quick loss of salt-solubility suggested a quick denaturation at light meromyosin region as revealed by chymotryptic digestion. These results suggested that sea cucumber myosin is consisted of very stable head region and unstable tail region, which is important for choosing proper heating conditions for sea cucumber processing.

Background: Sea cucumber is a seafood of high nutritional value. During its processing, sea cucumber processing liquor is routinely produced, and usually discarded as waste. The chemical composition of this processing liquor is similar to sea cucumbers themselves. Hence, valuable ingredients, such as functional polysaccharides, could be enriched from them. Results: Biologically active polysaccharides from sea cucumber processing liquor were extracted through protease hydrolysis and electroosmosis. The analysis reveals that these polysaccharides extracts from sea cucumber processing liquor (PESCPL) are predominantly composed of mannose, alongside with some glucose and fucose. The antioxidant activity of PESCPL was analyzed using electron spin resonance in vitro . It was demonstrated that PESCPL could scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, hydroxyl radicals and superoxide anion radicals effectively. The effect of PESCPL was investigated in vivo by using mice model fed with high fat diets with/without PESCPL supplement, it was shown that PESCPL could increase the catalase and superoxide dismutase activity in the serum, and decrease its MDA content. Furthermore, the mice fed with PESCPL diet showed a considerable decrease in the serum cholesterol and triglyceride, and an increase in high-density lipoprotein cholesterol levels. Conclusions: Our research highlights that polysaccharide extracts from the sea cucumber processing liquor are natural antioxidants, and it could be utilized as therapeutic supplement for dyslipidemia. Normal 0 false false false EN-US ZH-CN X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabla normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri",sans-serif; mso-bidi-font-family:"Times New Roman"; mso-fareast-language:ZH-CN;}

The aim of this work was to investigate the effects of initial C/N ratio on the total losses of N and C during composting of cattle manure/corn stover mix, and to analyze how the initial C/N ratio impacts the successive progression of the microbiota to affect losses of N and C during the composting. Results indicated that the least of C-loss and N-loss occurred in 35:1 of initial C/N ratio. The succession of predominant bacteria in the composting mix was significantly affected by the temperature and the initial C/N ratio. Redundancy analysis showed that significant negative correlations existed between nitrogen fixing bacteria and N- and C-losses, and significant positive correlations existed between denitrifying bacteria and N- and C-losses. Higher initial C/N ratio appeared to promote growth of nitrogen fixing bacteria while compress the denitrifying bacteria. These results indicated that adjustment of the initial C/N ratio is an important way to control the losses of N and C in the compost. In addition, beneficial nitrogen fixing bacteria could potentially be screened and used as composting supplements to improve the quality of the compost.

The aim of this work was to investigate how the initial C/N ratio during composting of chicken manure/corn stover mix affected the succession of dominant bacteria in the mix which led to the reduction of the total losses of N and C in the composting process. 16S rDNA sequencing indicated that the succession of predominant bacteria was significantly affected by the temperature and the initial C/N ratio during composting. Redundancy analysis showed that higher C/N appeared to promote the relative abundance of nitrogen fixing bacteria Thermoactinomyces, Planifilum, Flavobacterium, Bacillaceae, Pseudomonas, Sphingobacterium, Paenibacillus, Bacillus and Thermobifida, while compressing the denitrifying bacteria Pusillimonas, Ignatzschineria, Alcanivorax, Cerasibacillus, Truepera and Erysipelothrix. C/N ratio of 30:1 yielded the least C/N losses in the composting process, indicating that adjustment to the initial C/N ratio could affect nitrogen transforming bacteria to reduce the total losses of N and C and improve compost quality.

In this study, three synthetic zinc-chelating peptides (ZCPs) derived from sea cucumber hydrolysates with limited or none of the common metal-chelating amino-acid residues were analyzed by flame atomic absorption spectroscopy, circular dichroism spectroscopy, size exclusion chromatography, zeta-potential, Fourier transform infrared spectroscopy, Raman spectroscopy and nuclear magnetic resonance spectroscopy. The amount of zinc bound to the ZCPs reached maximum values with ZCP:zinc at 1:1, and it was not further increased by additional zinc presence. The secondary structures of ZCPs were slightly altered, whereas no formation of multimers was observed. Furthermore, zinc increased the zeta-potential value by neutralizing the negatively charged residues. Only free carboxyl in C-terminus of ZCPs was identified as the primary binding site of zinc. These results provide the theoretical foundation to understand the mechanism of zinc chelation by peptides.

Sea cucumber Stichopus japonicus (S. japonicus) shows a strong ability of autolysis, which leads to severe deterioration in sea cucumber quality during processing and storage. In this study, to further characterize the mechanism of sea cucumber autolysis, hydroxyl radical production induced by ultraviolet A (UVA) irradiation was investigated. Homogenate from the body wall of S. japonicas was prepared and subjected to UVA irradiation at room temperature. Electron Spin Resonance (ESR) spectra of the treated samples were subsequently recorded. The results showed that hydroxyl radicals (OH ) became more abundant while the time of UVA treatment and the homogenate concentration were increased. Addition of superoxide dismutase (SOD), catalase, EDTA, desferal, NaN3 and D2O to the homogenate samples led to different degrees of inhibition on OH production. Metal cations and pH also showed different effects on OH production. These results indicated that OH was produced in the homogenate with a possible pathway as follows: O2− → H2O2 → OH , suggesting that OH might be a critical factor in UVA-induced S. japonicus autolysis.

Chouguiyu (stinky Mandarin fish), a traditional spontaneously fermented fish in China, is famous for its unique aroma and pleasant taste. However, the relationships between the succession of microorganisms during the fermentation and the formation of Chouguiyu's unique aroma and taste remain to be characterized. In this study, 16S rRNA gene amplicon sequencing was done to investigate the evolving microbiota during Chouguiyu fermentation, and the volatile compounds and amino acids profiles were measured alongside with chemical characterization of the samples (e.g., determination of pH, TVB-N, TBARS, and TCA-soluble peptides). Based on the changes of the microbiota, the fermentation was categorized into two stages: early-fermentation, 1st-3rd days; and late-fermentation, 4th-7th days. Linalool, piperitone, anethole, 1-octen-3-ol, 2-methyl-3-octanone and indole were identified as characteristic volatile compounds in Chouguiyu. According to the sensory evaluation results, the flavor of the Chouguiyu was reinforced in the late-fermentation stage. Redundancy analysis showed the relationships between evolving microbiota and the formation of Chouguiyu's aroma and taste, and Psychrilyobacter was identified to be the most important bacterial genus contributing to flavor and aroma development, followed by Fusobacterium, Arcobacter and Oceanisphaera. These genera were positively correlated with Glu, Met, Tyr, Pro, linalool, piperitone, indole, TBARS, TVB-N, and TCA, and influenced the flavor and aroma of the Chouguiyu. The results of this study provided a scientific basis to further improve Chouguiyu production.

Three strains of lactic acid bacteria (LAB), including two strains of Lactobacillus plantarum and one strain of Lactococcus lactis isolated from spontaneously fermented Yucha, a traditional Chinese home-made fermented fish product, were evaluated as starter cultures for Yucha production. All three starter cultures could drive Yucha fermentation processes by rapid colonizing and fast acidifying the raw fish materials, and restricting the growth of undesirable bacteria. As a result, the starter-inoculated Yucha products were safer than their spontaneously-fermented counterpart, and fewer biogenic amines were detected in them. During the late stage of Yucha fermentation, the initial L. lactis was gradually replaced by endogenous L. plantarum, indicating that Yucha environmental condition is a favorable niche of L. plantarum. Volatile compounds profiling combined with cluster analysis demonstrated that the competition between the two species significantly shaped the development of aroma and flavor compounds in Yucha. Besides, correlation analysis suggested that 1-methyl-naphthalene could be a potential indicator to evaluate the degree of ripeness in Yucha products.

During thermal tenderization of sea cucumber body wall, protein oxidation always happens which disrupts its structural integrity. In this study, we investigated the effects of (−)-epigallocatechin gallate (EGCG, at 0, 5, 50, 125, 250 μg/mL) to protect the structure of heated collagen fibers (CFs) in sea cucumber Apostichopus japonicus body wall. Many disintegrated collagen fibrils and fibril bundles were observed in samples with no EGCG by scanning electron microscope, while the integrity of CFs was protected in samples with 125 μg/mL EGCG. Electron paramagnetic resonance results indicated heat-induced •OH in heated CFs were neutralized by EGCG, up to 83% in samples with 250 μg/mL EGCG. Chemical analysis of the soluble fragments in heated CFs showed plenty of proteins and glycosaminoglycan were released in heated CFs, and the addition of EGCG into the samples reduced their dissolution. Analysis of differential scanning calorimetry and thermogravimetry indicated EGCG could enhanced the thermostability of CFs. Fourier transform infrared spectroscopy results showed EGCG at 125 μg/mL prevented the conversion of α-helixes to β-sheets, and affected N–H bending coupled with C–N stretching. In conclusion, EGCG could protect the structure of CFs in a dosage dependent way, and 125 μg/mL was the most effective.

Biochemical, chemical and textural changes in postmortem Stichopus japonicus body wall (SJBW) were evaluated during iced storage for 8 days. Triphosphate (ATP) and its breakdown products, K-value, total volatile basic nitrogen (TVB-N), microbiological,pH, water-holding capacity (WHC), texture, protein degradation and cathepsin activities were monitored. K-value increased linearly from 4.83 ± 0.57% at day 0–18.85 ± 2.09% at day 2, 28.15 ± 2.05% at day 4, and 48.16 ± 1.91% at day 8. Spoilage indicator TVB-N (mg/100 g) increased from 4.03 ± 0.28 to 12.68 ± 0.56 during the same time span. Textural parameters (e.g., hardness, chewiness, springiness and adhesiveness) all followed a declining trend over the storage duration. The WHC decreased from 67.71 ± 4.03% at day 0–54.60 ± 6.14% at day 2 and 48.57 ± 12.68% at day 8. SDS-PAGE results indicated that actin was degraded at day 6. Both cathepsin B and L increased throughout the iced storage, suggesting that cathepsin B and L played important roles in the deterioration of SJBW quality. The overall results indicated that SJBW was suitable to be consumed raw within the first 2 days, and to be processed in no more than 4 days.

Foodborne nanostructures have gained more and more attention in recent years. In this paper, the presence and physicochemical properties of carbonaceous nanostructures (CNSs) from roasted pike eel ( Muraenesox cinereus) were reported. The monodispersed CNSs are strongly photoluminescent under the illustration of ultraviolet (UV) light, with a fluorescent quantum yield of 80.16%, and display excitation-dependent emission behavior. The formation of CNSs is believed to go through a process of morphology evolution, including polymerization, pyrolysis, nucleation, growth, emergence, and blossom. The optical properties of the CNSs were shown to be affected by the roasting temperature. Furthermore, cellular uptake of the CNSs was investigated, and it is shown that the CNSs were clearly absorbed into live cells and were mainly distributed within the cell cytoplasm and not in the cell nucleus. This work is among the very first reports on CNSs present in roasted fish, providing valuable insights into the formation mechanism of such nanostructures and showcasing the biodistribution of these food-originated CNSs in live cells.

Undaria pinnatifida sporophyll (U. pinnatifida) is a major byproduct of U. pinnatifida (a brown algae) processing. Its phenolic constituents, phlorotannins, are of special interest due to their intrinsic ability to precipitate proteins. Herein, a high-temperature extraction procedure was used to isolate these biologically active compounds. The heating temperature, heating time, and extraction solvent (ethanol) concentration were examined with response surface analysis to determine the optimal conditions to achieve the maximum extraction rate. The analysis revealed the optimal conditions to be: 170 &deg, C of heating temperature, 5.2 h of heating time, and 52% ethanol concentration for a yield of 10.7 &plusmn, 0.2 mg gallic acid equivalent/g dry weight (GAE/g DW) of sample. Compared to epigallocatechin gallate (EGCG), the extracted phlorotannins displayed higher antioxidant activity on H2O2-induced RAW 264.7 cells with improved efficiency. Furthermore, the compounds exhibited strong anti-inflammatory activity. These findings potentially can be utilized to guide development of novel functional foods and food supplements from sea-originated resources such as brown algae.

An alkaline phosphatase was purified from the gut of sea cucumber Stichopus japonicus by n-butyl alcohol extract, ammonium sulfate precipitation, ion exchange chromatography with diethylaminoethyl cellulose, gel filtration chromatography with Sephacryl S-200 and preparative electrophoresis with polyacrylamide gel electrophoresis. The native enzyme was estimated to be 166 ± 9 kDa and produced a single predominant band corresponding to active enzyme on nondenaturing electrophoresis, but showed 2 bands of 97 and 35 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, suggesting that the native enzyme is composed of two dissimilar subunits. The enzyme displayed maximum activity at pH 11 and 40 °C, showing narrow pH stability (pH 10–12) and thermal instability at temperature higher than 30 °C. The activity of the purified alkaline phosphatase was enhanced by Mg2+, whereas inhibited by Zn2+, Ca2+ and EDTA at 1 and 10 mM, suggesting its activity is in a magnesium ion-dependent manner. The product-analog WO42− and product HPO42− showed strong inhibitory effects on the enzyme activity. Using p-nitrophenyl phosphate as substrate, the Vmax and Km values were 24.45 μmol/L min and 5.76 mM, respectively.

Pepsin-solubilized collagen (PSC) was successfully prepared from the body wall of sea cucumber Stichopus japonicus . Ultraviolet–visible and Fourier transform infrared spectroscopic analyses showed that the PSC was a high-purity collagen that maintained the intact triple-stranded helices. Physical and chemical characterization of the PSC showed a isoelectric point of 4.14, a superior moisture-absorption and retention capacities comparing to glycerol, a minimum solubility at pH 5.0 in 0.5 M acetic acid, and a sharp decrease in solubility in the presence of low concentration of NaCl. The viscosity of PSC was shown to decrease continuously as the temperature was increased. The radical scavenging activity of the PSC was characterized with two model systems: for hydroxyl radicals, the PSC was more active than vitamin C but less active than sulfourea; for 1,1-diphenyl-2-picrylhydrazyl radicals, the PSC was more active than vitamin E.

The texture and microstructure of edible abalone meats were studied during heat treatments from 50 to 100°C for 60 min. No increase in extractable soluble collagen content was observed below 80°C, but a 9-fold increase was observed at 100°C. SDS-PAGE showed that extractable myosin heavy chains and paramyosin contents reduced significantly at 80°C, and disappeared completely at 100°C. The shear force increased slowly from 50 to 70°C, but relaxed back to the initial level at 100°C. Rapid reduction of hardness was observed at 50°C, minimum hardness was obtained at 100°C. Springness, cohesiveness, chewiness, and resilience were enhanced to maximum levels at 70, 90, 70, and 90°C, respectively. Optical micrographs and transmission electron microscope showed a significant increase of intermyofibrillar gaps at 90°C and broken fibers at 100°C. Results suggested that 80°C might be a suitable temperature to produce ready-to-eat abalone products.

A fast and easy-to-operate Fourier Transform Infrared (FTIR) spectrometry-based approach was developed for microbial differentiation and quantiffcation in apple juice. Eight different microorganisms were eevaluated. Enterobacter cloacae, Salmonella typhimurium, Enterobacter aerogenes, Salmonella choleraesuis, Serratia marcescens, Pseudomonas vulgaris, Vibria cholerae, and Hafnia alvei. FTIR spectrascopy combined with chemometrics could differentiate the microorganisms studied at low concentration level of 10° colony-forming units (CFU)/mL in apple jeice. The chemometric models developed to count microorganisms in apple juice were valldated by an indepen dent test set consisting of 18 samples and correlated against plate counts satisfactorily up to a detection limit of 10 3 CFU/mL.

Routine identification of pathogenic microorganisms predominantly based on nutritional and biochemical tests is a time-consuming process. In this study, a method based on FTIR spectroscopy was developed to detect and identify the presence of five possible pathogenic bacteria in ten different microorganism mixtures with each cocktail containing up to three different species at a concentration of 109 CFU/mL. A mathematical approach based on factoring out the common features in the spectral fingerprints was developed and implemented in conjunction with discriminant analysis. FTIR spectra of the mixtures were directly obtained and analyzed using canonical variate analysis based on the discriminant model for the presence of particular species in the pathogenic bacteria mixtures. In nine out of ten mixtures, the predictions were 100% accurate; in one mixture, only one false negative was reported, with no false positives. Results suggest that FTIR spectroscopy combined with a suitable analytical procedure has excellent potential as a fast, powerful, and reliable alternative for identifying a specific foodborne pathogen in a complex and/or competing system.

Seven selective differential plating media were evaluated for their effectiveness in recovering eight serotypes (0:3; 0:8; 0:9; 0:11,24; 0:12,25; 0.16; 0:17; and 0:28) of Y. enterocolitica from pure cultures and from artificially inoculated fresh ground pork homogenate. Cefsulodin-irgasan-novobiocin (CIN) agar was the most effective medium for the recovery of Y. enterocolitica. However, Y. enterocolitica 0:12,25 was slightly inhibited on CIN agar. Bismuth sulfite agar, MacConkey, and MacConkey-Tween 80 agars were acceptable; cellobiose-arginine-lysine, desoxycholate citrate, and Salmonella-Shigella agars were the least effective media.