The phosphorylation-deubiquitination positive feedback loop of the CHK2-USP7 axis stabilizes p53 under oxidative stress.

p53 regulates multiple signaling pathways and maintains cell homeostasis under conditions of DNA damage and oxidative stress. Although USP7 has been shown to promote p53 stability via deubiquitination, the USP7-p53 activation mechanism has remained unclear. Here, we propose that DNA damage induces reactive oxygen species (ROS) production and activates ATM-CHK2, and CHK2 then phosphorylates USP7 at S168 and T231. USP7 phosphorylation is essential for its deubiquitination activity toward p53. USP7 also deubiquitinates CHK2 at K119 and K131, increasing CHK2 stability and creating a positive feedback loop between CHK2 and USP7. Compared to peri-tumor tissues, thyroid cancer and colon cancer tissues show higher CHK2 and phosphorylated USP7 (S168, T231) levels, and these levels are positively correlated. Collectively, our results uncover a phosphorylation-deubiquitination positive feedback loop involving the CHK2-USP7 axis that supports the stabilization of p53 and the maintenance of cell homeostasis.

New progress in the identifying regulatory factors of exopolysaccharide synthesis in lactic acid bacteria.

The exopolysaccharides (EPSs) of lactic acid bacteria (LAB) have presented various bioactivities and beneficial characteristics, rendering their vast commercial value and attracting a broad interest of researchers. The diversity of EPS structures contributes to the changes of EPS functions. However, the low yield of EPS of LAB has severely limited these biopolymers' comprehensive studies and applications in different areas, such as functional food, health and medicine fields. The clarification of biosynthesis mechanism of EPS will accelerate the synthesis and reconstruction of EPS. In recent years, with the development of new genetic manipulation techniques, there has been significant progress in the EPS biosynthesis mechanisms in LAB. In this review, the structure of LAB-derived EPSs, the EPS biosynthesis basic pathways in LAB, the EPS biosynthetic gene cluster, and the regulation mechanism of EPS biosynthesis will be summarized. It will focus on the latest progress in EPS biosynthesis regulation of LAB and provide prospects for future related developments.

Formation of Nε-Carboxymethyl-Lysine and Nε-Carboxyethyl-Lysine in Heated Fish Myofibrillar Proteins with Glucose: Relationship with Its Protein Structural Characterization.

The formation of advanced glycation end products (AGEs), including Nε-carboxymethyl-lysine (CML) and Nε-carboxyethyl-lysine (CEL), in a fish myofibrillar protein and glucose (MPG) model system at 80 °C and 98 °C for up to 45 min of heating were investigated. The characterization of protein structures, including their particle size, ζ-potential, total sulfhydryl (T-SH), surface hydrophobicity (H0), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Fourier transform infrared spectroscopy (FTIR), were also analyzed. It was found that the covalent binding of glucose and myofibrillar protein at 98 °C promoted protein aggregation when compared with the fish myofibrillar protein (MP) heated alone, and this aggregation was associated with the formation of disulfide bonds between myofibrillar proteins. Furthermore, the rapid increase of CEL level with the initial heating at 98 °C was related to the unfolding of fish myofibrillar protein caused by thermal treatment. Finally, correlation analysis indicated that the formation of CEL and CML had a significantly negative correlation with T-SH content (r = -0.68 and r = -0.86, p ≤ 0.011) and particle size (r = -0.87 and r = -0.67, p ≤ 0.012), but was weakly correlated with α-Helix, ß-Sheet and H0 (r2 ≤ 0.28, p > 0.05) during thermal treatment. Overall, these findings provide new insights into the formation of AGEs in fish products based on changes of protein structure.

Formation of advanced glycation end products in sturgeon patties affected by pan-fried and deep-fried conditions.

This study compared the effects of pan-fried with low (LPF), high (HPF) amounts of oil and deep-fried (DF) on the profiles of advanced glycation end products (AGEs) in sturgeon patties. The surface color of the pan-fried patties, regardless of the amounts of oil used, visually presented more brown than deep-fried ones with higher internal temperature at the frying course of 3-9 min. Compared to LPF and HPF, DF significantly accelerated the furosine development for 6-9 min of frying, dynamically increased the accumulation of CML (Nε-carboxymethyl-lysine) and CEL (Nε-carboxyethyl-lysine) for up to 9 min of frying, and the level of CML in DF than LPF, HPF for 9 min of frying were increased by 209.6 % and 149.9 %, respectively. The oil level employed for pan-fried insignificantly influenced the formation of furosine and CML in patties. The principal component analysis further confirmed that DF patties had a greater influence on the formation of AGEs. The AGEs formation was positively associated with the temperature and amino groups, while remarkably negative correlation with moisture content. Therefore, pan-fried within 6 min of frying was recommended for the domestic cooking of sturgeon patties based on the potential formation of AGEs.

Mercury Contamination in Fish and Its Effects on the Health of Pregnant Women and Their Fetuses, and Guidance for Fish Consumption-A Narrative Review.

As a principal source of long-chain omega-3 fatty acids (3FAs), which provide vital health benefits, fish consumption also comes with the additional benefit of being rich in diverse nutrients (e.g., vitamins and selenium, high in proteins and low in saturated fats, etc.). The consumption of fish and other seafood products has been significantly promoted universally, given that fish is an important part of a healthy diet. However, many documents indicate that fish may also be a potential source of exposure to chemical pollutants, especially mercury (Hg) (one of the top ten chemicals or groups of chemicals of concern worldwide), and this is a grave concern for many consumers, especially pregnant women, as this could affect their fetuses. In this review, the definition of Hg and its forms and mode of entrance into fish are introduced in detail and, moreover, the bio-accumulation of Hg in fish and its toxicity and action mechanisms on fish and humans, especially considering the health of pregnant women and their fetuses after the daily intake of fish, are also reviewed. Finally, some feasible and constructive suggestions and guidelines are recommended for the specific group of pregnant women for the consumption of balanced and appropriate fish diets in a rational manner.

Formation of N ε-Carboxymethyl-Lysine and N ε-Carboxyethyl-Lysine in Pacific Oyster (Crassostrea gigas) Induced by Thermal Processing Methods.

Advanced glycation end products (AGEs) are important endogenous hazardous substances produced during the thermal processing of foods, which have attracted much attention due to the potential health risks. The current research first investigated the effect of different thermal processing methods (steaming, boiling, sous vide (SV), and sterilizing) on the formation of two typical markers of AGEs, including N ε-carboxymethyl-lysine (CML) and N ε-carboxyethyl-lysine (CEL), in Pacific oyster (Crassostrea gigas). The compositions, lipid oxidation, di-carbonyl compounds, and AGEs in 12 kinds of processed oysters were detected, and the Index values (total Z-score) were calculated. The SV treatment at 70°C caused higher processing yield and lower CEL level while sterilizing in oil at 121°C greatly resulted in the formation of CML. The Index value of SV-treated oysters was much lower than steamed, boiled, and sterilized ones. Correlation analysis showed that the CML and CEL levels were positively correlated with fat content, a* and b* value (p < 0.05), and negatively correlated with moisture content and L* value (p < 0.05). Besides, thiobarbituric acid reactive substances had a negative correlation with CML (r = -0.63, p < 0.05) while no significant correlation with CEL (p > 0.05), suggesting that lipid oxidation had a greater effect on the formation of CML but less on the formation of CEL. In summary, SV treatment at 70°C within 15 min was a recommended thermal processing method to reduce the formation of AGEs in oysters.

Physicochemical, microbiological and sensory quality changes of tissues from Pacific oyster (Crassostrea gigas) during chilled storage.

This study was designed to investigate the changes of physicochemical, microbiological and sensory properties of oyster tissues during chilled storage at 4 °C, including digestive gland (DG), the gonad and surrounding mantle area (GM), adductor muscle (AM). Sensory evaluation showed that the decrease of sensory scores of the three oyster tissues was more rapid than the whole oyster (WO). The drip loss of DG was more than other tissues and the WO. Moreover, the GM showed higher extent of lipid oxidation than other tissues and WO, while the AM showed higher TVB-N value and microbial counts than other tissues and WO. It is concluded that the spoilage of oyster during chilled storage greatly depended on the composition of oyster tissues. Overall, the findings may provide new insights to control the spoilage of oyster based on the changes of oyster tissues during storage.

Chitosan/sodium tripolyphosphate nanoparticles as efficient vehicles for enhancing the cellular uptake of fish-derived peptide.

Methodology to enhance the intestinal absorption of peptides is an important challenge due to their easily degradation and poor permeability across the intestinal epithelium. In this study, the fish-derived peptide (DGDDGEAGKIG)-loaded chitosan (CS) nanoparticles (CS/PEP-NPs) were prepared and investigated in Caco-2 monolayer model. The results indicated zeta potential of CS/PEP-NPs increased with the increase in molecular weight of CS (10-50 kDa). Transmission electron microscopy images revealed the CS/PEP-NPs were uniform spherical-shaped nanoparticles with a diameter of 50-200 nm (150 kDa). Compared to other CS/PEP-NPs, 150-kDa CS/PEP-NPs performed an outstanding apparent permeability coefficient (Papp, 2.29 × 10-5  cm s-1 ) and cumulative amount of peptide (120 min, 2,987 ng) in Caco-2 cells. CS/PEP-NPs could reduce the tight junction integrity of Caco-2 cells and enhance the intracellular fluorescence intensities of fluorescein isothiocyanate-labeled peptide. These findings suggest that chitosan nanoparticles are promising carriers to promote intestinal absorption of fish-derived peptide via paracellular pathway mediated by tight junctions. PRACTICAL APPLICATIONS: Chitosans are promising carriers to promote intestinal absorption of fish-derived peptide. The 150-kDa CS/PEP-NPs performed an outstanding apparent permeability coefficient (Papp, 2.29 × 10-5  cm s-1 ) and cumulative amount of peptide (120 min, 2,987 ng) in Caco-2 cells. CS/PEP-NPs could reduce the tight junction integrity of Caco-2 cells and enhance the peptide uptake by paracellular pathway. Chitosan nanoparticles can be developed as vehicles for enhancing the cellular uptake of peptide in food industry.

Glycated fish protein supplementation modulated gut microbiota composition and reduced inflammation but increased accumulation of advanced glycation end products in high-fat diet fed rats.

This study first investigates how the intake level of glycated fish protein (GP), enriched with Amadori products, affects gut health by modifying the fermentation of gut microbiota and accumulation of advanced glycation end products (AGEs) in rats fed a high-fat diet. Hyperlipidemic rats were fed a fish protein (FP) control diet, 6% low-level GP (L-GP) diet, and 12% high-level GP (H-GP) diet for four weeks. Compared to the FP diet, the GP diet greatly changed the pattern of protein fermentation and reduced inflammation markers and blood lipids, but increased the AGE plasma accumulation and fecal excretion. Furthermore, the GP supplementation significantly decreased Ruminiclostridium_6 and Desulfovibrio (p < 0.05), and the L-GP diet showed more effects on the increase of butyrate-producing Ruminococcus_1 and Roseburia, while the H-GP diet considerably decreased Helicobacter and Lachnospiraceae_NK4A136_group. Correlation-type principal-component analysis (PCA) clearly indicated that these biological effects of intake of GP were related to the modulation of gut microbiota composition and fermentation metabolite profiles. Overall, the low intake level of glycated fish protein may have a more beneficial effect on gut health.

Pea protein isolate-gum Arabic Maillard conjugates improves physical and oxidative stability of oil-in-water emulsions.

The present work investigated the impact of incubation time (0, 1, 3, and 5 day) on the properties and functionalities of conjugates formed between pea protein isolate (PPI) and gum Arabic (GA). The participation of both 11S and 7S to form conjugates with GA was proved by SDS-PAGE. The degree of conjugation reaction of conjugated was characterized by measuring the formation of Maillard reaction products, the loss of free amino groups, and color changes. The results suggested that PPI intimately incorporated into GA after 1 day incubation, giving a non-homogeneous microstructure with a reduction of nearly 18% available free amino and an increase of relative solubility to 15.5%. Additionally, emulsions prepared by PPI-GA conjugates showed smaller particle size, higher surface charge, and stronger steric hindrance to stabilize the emulsion droplets against environmental stresses and lipid oxidation. The findings provide a practical means to improve the functionality of pea proteins.

Modulation of Gut Microbiota by Soybean 7S Globulin Peptide That Involved Lipopolysaccharide-Peptide Interaction.

Soybean protein exhibits nutritional significance for the control of metabolic syndrome, and evidence suggests that gut microbiota are implicated in the control of metabolic disorders. This study aimed to investigate the modulation of pepsin-released peptides of soybean 7S globulin on gut microbiota and possible association between changes of gut microbiota composition and lipopolysaccharide (LPS)-peptide interaction. In vitro fermentation experiments showed that the extension region (ER) fragments of soybean 7S globulin selectively suppressed proinflammatory Gram-negative bacteria. ER peptides also promoted the highest production of short-chain fatty acids (SCFAs), which were associated with increase of the relative abundance of Lachnospiraceae and Lactobacillaceae. Isothermal titration calorimetry (ITC) and Langmuir monolayer studies demonstrated that ER peptides exhibited high affinity to LPS in the presence of Ca2+ and developed into ß-sheet-rich aggregate structures, thus weakening the stability of LPS monolayers. This finding supplies a possible explanation for improvement of the effects of soybean 7S globulin on metabolic disease.

Orally administered gold nanoparticles protect against colitis by attenuating Toll-like receptor 4- and reactive oxygen/nitrogen species-mediated inflammatory responses but could induce gut dysbiosis in mice.

BACKGROUND: Gold nanoparticles (AuNPs) are attracting interest as potential therapeutic agents to treat inflammatory diseases, but their anti-inflammatory mechanism of action is not clear yet. In addition, the effect of orally administered AuNPs on gut microbiota has been overlooked so far. Here, we evaluated the therapeutic and gut microbiota-modulating effects, as well as the anti-inflammatory paradigm, of AuNPs with three different coatings and five difference sizes in experimental mouse colitis and RAW264.7 macrophages. RESULTS: Citrate- and polyvinylpyrrolidone (PVP)-stabilized 5-nm AuNPs (Au-5 nm/Citrate and Au-5 nm/PVP) and tannic acid (TA)-stabilized 5-, 10-, 15-, 30- and 60-nm AuNPs were intragastrically administered to C57BL/6 mice daily for 8 days during and after 5-day dextran sodium sulfate exposure. Clinical signs and colon histopathology revealed more marked anti-colitis effects by oral administration of Au-5 nm/Citrate and Au-5 nm/PVP, when compared to TA-stabilized AuNPs. Based on colonic myeloperoxidase activity, colonic and peripheral levels of interleukin-6 and tumor necrosis factor-α, and peripheral counts of leukocyte and lymphocyte, Au-5 nm/Citrate and Au-5 nm/PVP attenuated colonic and systemic inflammation more effectively than TA-stabilized AuNPs. High-throughput sequencing of fecal 16S rRNA indicated that AuNPs could induce gut dysbiosis in mice by decreasing the α-diversity, the Firmicutes/Bacteroidetes ratio, certain short-chain fatty acid-producing bacteria and Lactobacillus. Based on in vitro studies using RAW264.7 cells and electron spin resonance oximetry, AuNPs inhibited lipopolysaccharide (LPS)-triggered inducible nitric oxide (NO) synthase expression and NO production via reduction of Toll-like receptor 4 (TLR4), and attenuated LPS-induced nuclear factor kappa beta activation and proinflammatory cytokine production via both TLR4 reduction and catalytic detoxification of peroxynitrite and hydrogen peroxide. CONCLUSIONS: AuNPs have promising potential as anti-inflammatory agents; however, their therapeutic applications via the oral route may have a negative impact on the gut microbiota.

A Novel Natural Influenza A H1N1 Virus Neuraminidase Inhibitory Peptide Derived from Cod Skin Hydrolysates and Its Antiviral Mechanism.

In this paper, a novel natural influenza A H1N1 virus neuraminidase (NA) inhibitory peptide derived from cod skin hydrolysates was purified and its antiviral mechanism was explored. From the hydrolysates, novel efficient NA-inhibitory peptides were purified by a sequential approach utilizing an ultrafiltration membrane (5000 Da), sephadex G-15 gel column and reverse-phase high-performance liquid chromatography (RP-HPLC). The amino acid sequence of the pure peptide was determined by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) was PGEKGPSGEAGTAGPPGTPGPQGL, with a molecular weight of 2163 Da. The analysis of the Lineweacer⁻Burk model indicated that the peptide was a competitive NA inhibitor with Ki of 0.29 mM and could directly bind free enzymes. In addition, docking studies suggested that hydrogen binding might be the driving force for the binding affinity of PGEKGPSGEAGTAGPPGTPGPQGL to NA. The cytopathic effect reduction assay showed that the peptide PGEKGPSGEAGTAGPPGTPGPQGL protected Madin⁻Darby canine kidney (MDCK) cells from viral infection and reduced the viral production in a dose-dependent manner. The EC50 value was 471 ± 12 µg/mL against H1N1. Time-course analysis showed that PGEKGPSGEAGTAGPPGTPGPQGL inhibited influenza virus in the early stage of the infectious cycle. The virus titers assay indicated that the NA-inhibitory peptide PGEKGPSGEAGTAGPPGTPGPQGL could directly affect the virus toxicity and adsorption by host cells, further proving that the peptide had an anti-viral effect with multiple target sites. The activity of NA-inhibitory peptide was almost inactivated during the simulated in vitro gastrointestinal digestion, suggesting that oral administration is not recommended. The peptide PGEKGPSGEAGTAGPPGTPGPQGL acts as a neuraminidase blocker to inhibit influenza A virus in MDCK cells. Thus, the peptide PGEKGPSGEAGTAGPPGTPGPQGL has potential utility in the treatment of the influenza virus infection.

Glycation of fish protein impacts its fermentation metabolites and gut microbiota during in vitro human colonic fermentation.

The aim of this study was to investigate the fermentation properties of fish protein (FP) glycated with glucose at two different heating time (24 h and 48 h, 50 °C, GFP24 and GFP48), using an in vitro batch fermentation model of human distal colon. The heated fish protein in absent of glucose was also as controls. The lower glycation extent of fish protein, with a lower browning intensity and bound sugar, enhanced the production of acetate and propionate. The formation of indole and ammonia was inhibited by the glycation of fish protein, but less affected by its glycation extent. Compared to FP, the glycation of fish protein significantly increased (p < .05) the relative abundance of genera Lactococcus for GFP24 (47%) and GFP48 (71%), whereas decreased dominant genera Bacteroides for GFP24 (32%) and GFP48 (23%). Compared to GFP24, GFP48 indicated significantly higher relative abundance of Holdemania, Streptococcus, Enterococcus and Lactobacillus, and lower amounts of Parabacteroides (p < .05). In the meantime, the heated treatments in the absent of glucose resulted in the increase of some genera Dialister, Arobacter, Clostridium_sensu_stricto_1, Phascolarctobacterium and Veillonella, and also ammonia production. Furthermore, the correlation analysis confirmed that the glycation of fish protein for the decrease of ammonia and indole production was associated with the changes of some proteolytic bacteria genera, including Bacteroides, Dialister and Parabacteroides. Thus, the glycated fish protein rich in Amadori products greatly change the profiles of fermentation metabolite and gut microbiota, and these changes can have a potential impact on host health.

Biogenic Polyphosphate Nanoparticles from a Marine Cyanobacterium Synechococcus sp. PCC 7002: Production, Characterization, and Anti-Inflammatory Properties In Vitro.

Probiotic-derived polyphosphates have attracted interest as potential therapeutic agents to improve intestinal health. The current study discovered the intracellular accumulation of polyphosphates in a marine cyanobacterium Synechococcus sp. PCC 7002 as nano-sized granules. The maximum accumulation of polyphosphates in Synechococcus sp. PCC 7002 was found at the late logarithmic growth phase when the medium contained 0.74 mM of KH2PO4, 11.76 mM of NaNO3, and 30.42 mM of Na2SO4. Biogenic polyphosphate nanoparticles (BPNPs) were obtained intact from the algae cells by hot water extraction, and were purified to remove the organic impurities by Sephadex G-100 gel filtration. By using 100 kDa ultrafiltration, BPNPs were fractionated into the larger and smaller populations with diameters ranging between 30⁻70 nm and 10⁻30 nm, respectively. 4',6-diamidino-2-phenylindole fluorescence and orthophosphate production revealed that a minor portion of BPNPs (about 14⁻18%) were degraded during simulated gastrointestinal digestion. In vitro studies using lipopolysaccharide-activated RAW264.7 cells showed that BPNPs inhibited cyclooxygenase-2, inducible nitric oxide (NO) synthase expression, and the production of proinflammatory mediators, including NO, tumor necrosis factor-α, interleukin-6, and interleukin-1ß through suppressing the Toll-like receptor 4/NF-κB signaling pathway. Overall, there is promise in the use of the marine cyanobacterium Synechococcus sp. PCC 7002 to produce BPNPs, an anti-inflammatory postbiotic.

Novel Natural Angiotensin Converting Enzyme (ACE)-Inhibitory Peptides Derived from Sea Cucumber-Modified Hydrolysates by Adding Exogenous Proline and a Study of Their Structure⁻Activity Relationship.

Natural angiotensin converting enzyme (ACE)-inhibitory peptides, which are derived from marine products, are useful as antihypertensive drugs. Nevertheless, the activities of these natural peptides are relatively low, which limits their applications. The aim of this study was to prepare efficient ACE-inhibitory peptides from sea cucumber-modified hydrolysates by adding exogenous proline according to a facile plastein reaction. When 40% proline (w/w, proline/free amino groups) was added, the modified hydrolysates exhibited higher ACE-inhibitory activity than the original hydrolysates. Among the modified hydrolysates, two novel efficient ACE-inhibitory peptides, which are namely PNVA and PNLG, were purified and identified by a sequential approach combining a sephadex G-15 gel column, reverse-phase high-performance liquid chromatography (RP-HPLC) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS), before we conducted confirmatory studies with synthetic peptides. The ACE-inhibitory activity assay showed that PNVA and PNLG exhibited lower IC50 values of 8.18 ± 0.24 and 13.16 ± 0.39 µM than their corresponding truncated analogs (NVA and NLG), respectively. Molecular docking showed that PNVA and PNLG formed a larger number of hydrogen bonds with ACE than NVA and NLG, while the proline at the N-terminal of peptides can affect the orientation of the binding site of ACE. The method developed in this study may potentially be applied to prepare efficient ACE-inhibitory peptides, which may play a key role in hypertension management.

Preparation of a fermentation solution of grass fish bones and its calcium bioavailability in rats.

In this study, with grass fish bones as the substrate, after flavourzyme treatment, and fermentation with Leuconostoc mesenteroides, a fermentation solution with a high content of soluble calcium was obtained. High performance liquid chromatography and GC-MS analysis indicated that free calcium (11.29 mmol L-1) in the fermentation solution was composed of calcium lactate (3.89 mmol L-1), calcium acetate (6.21 mmol L-1), calcium amino acids and small peptide calcium. Animal experiments show that the fermentation solution of grass fish bones could promote the growth and development of calcium-deficient rats. Complex organic calcium could be well absorbed and utilized by rats so that serum calcium, alkaline phosphatase levels, femur weight and other indicators in calcium-deficient rats could be returned to normal levels. The fermentation solution of grass fish bones can avoid the waste of aquatic proteins and fish bone calcium, and it exhibited high calcium bioavailability. Therefore, the fermentation solution of grass fish bones might be used as a new efficient calcium supplement.

Modifications in gut microbiota and fermentation metabolites in the hindgut of rats after the consumption of galactooligosaccharide glycated with a fish peptide.

The aim of this research was to investigate the impact of a diet containing galactooligosaccharide (GOS)-fish peptide (FP) conjugates prepared via Maillard reaction on the colonic fermentation properties and the composition of gut microbiota in Sprague-Dawley rats. The rats were fed the GOS diet, FP diet, GOS and FP mixture (GOS/FP) diet, GOS glycated with FP (80 °C for 120 min, G-GOS/FP) diet, or control (CK) diet for three weeks. Compared to the GOS/FP diet, the G-GOS/FP diet greatly changed the pattern of SCFA production in the hindgut of rats, by increasing the total SCFA (44%), butyrate (55%) and propionate (1.23-fold) levels in the proximal colon, and the butyrate levels (74%) in the distal colon, and decreased the production of ammonia in feces (P < 0.05). The G-GOS/FP altered the colonic microbiota by increasing (P < 0.05) the relative abundance of Anaerovibrio (7.43-fold) and Prevotella-9 (2.47-fold), and by decreasing (P < 0.05) the relative abundance of Alloprevotella (0.57-fold) and Holdemanella (0.64-fold), and showed a similar relative abundance of Bifidobacterium, when compared with GOS/FP. The GOS/FP diet increased the number of Lactobacillus and the intensity of fermentation in the cecum, but the G-GOS/FP diet and GOS diet did not have these effects, showing that the glycation clearly altered the fermentability of the fish peptide. It is concluded that the glycation-induced modification of GOS by mild thermal treatments showed its fermentation persistence in the colon of the host, and improved some prebiotic activities of GOS. These results may provide new strategies for oligosaccharides in combination with peptides to modulate the intestinal environment to promote human health.

Effect of different cooking conditions on the profiles of Maillard reaction products and nutrient composition of hairtail (Thichiurus lepturus) fillets.

Much attention has been given to investigate the formation of Maillard reaction products in thermal processing food due to potential health risks. This study aimed to the profiles of Maillard reaction products (MRPs) and changes of nutrient composition in hairtail (Thichiurus lepturus) fillets prepared by three cooking method: boiling, baking and frying. The Nε-carboxymethyllysine (CML) level ranged from non-detectable to 4.24mg/100g protein and furosine ranged from 4.25 to 20.95mg/100g protein. The levels of CML and furosine in boiled hairtail fillets were much lower than baked and fried ones. The formation of CML was only affected by the cooking method. The changes of the lipid and moisture content, and thiobarbituric acid-reactive substances (TBARS) content in cooked hairtail fillet had different effects on the formation of different stages of Maillard reaction. Furosine level significantly correlated with absorbance in 420nm (r=0.74, p<0.05) and 280nm (r=0.73, p<0.05) and fluorescence Intensity (FI) (r=0.65, p<0.05), but did not correlate with CML. The CML level linearly correlated with the moisture (r=0.79, p<0.01) and lipid content (r=0.73, p<0.05), and the formation of TBARS value (r=0.92, p<0.01), but did not correlate with the FI. Overall, the findings may help to better control the cooking conditions of hairtail meat based on the profiles of MRPs.