Digestive characteristics of astaxanthin oil in water emulsion stabilized by a casein-caffeic acid-glucose ternary conjugate.

To overcome the barrier of poor oral bioavailability of astaxanthin, a stable oil-in-water emulsion was constructed using casein-caffeic acid-glucose ternary conjugates (CSC) to deliver astaxanthin, and its gastrointestinal behavior was evaluated in vitro with sodium caseinate (CSN) as a control. Results showed that, CSC-stabilized emulsion shower better resistance to the adverse conditions of the gastric environment than CSN-stabilized emulsion, and exhibited lower average particle size and aggregation (4972.33 nm, -5.93 mv) after simulated gastric digestion. Besides, after simulated intestinal digestion, the reducing capacity and astaxanthin transfer efficiency of CSC emulsion into the micellar phase were 686.74 µmol Trolox/100 mL and 26.2 %, which were 2.6 and 4.05-fold higher than that of CSN emulsion. The above results suggest that CSC can be used for better delivery of astaxanthin, which could be useful in designing foods such as functional beverages, pharmaceuticals and nutritional supplements for delivery of lipophilic bioactives.

The effects of mulberry polyphenols on the digestibility and absorption properties of pork myofibrillar protein in vitro.

The objective of the present study was to explore the effect of mulberry polyphenols on the digestibility and absorption properties of myofibrillar protein (MP) in vitro. MP was extracted from the Longissimus et thoracis muscle of 18 different pig carcasses and the MP-mulberry polyphenols complex was prepared. The antioxidant activity of digestive juice, degradation of both MP and polyphenols, and the metabolism of MP and the MP-polyphenols complex by intestinal microbial activity during digestion and fermentation in vitro were compared. The results showed that mulberry polyphenols significantly affect the digestibility of MP and the antioxidant activity of digestive juices during digestion (P < 0.05). After the modification of the polyphenols, the hydrolysis of MP increased from 55.4% to 64.0%, and the molecular weight of protein digestion product significantly decreased (P < 0.05). The scavenging rates of 2, 2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and 2,2-diphenyl-1-picrylhydrazyl in the final digestive juice were 350.1 µmol Trolox/mg protein and 34.0%, respectively, which were 0.34 and 0.47-fold higher than those of the control (P < 0.05). Furthermore, the release and degradation of phenolic compounds mainly occurred during intestinal digestion, and polyphenols that reached the colon after digestion, through the fermentation of intestinal microorganisms in vitro, enriched Lactobacillus and promoted the production of short-chain fatty acids which has obvious potential to improve intestinal health.

Improved physicochemical stability and bioaccessibility of astaxanthin-loaded oil-in-water emulsions by a casein-caffeic acid-glucose ternary conjugate.

In this study, the influence of casein-caffeic acid-glucose ternary conjugate (CSC) on the physicochemical properties and bioaccessibility of astaxanthin-loaded emulsion was investigated and compared with sodium caseinate (CSN), a synthetic emulsifier commonly used in the food industry. The CSC-stabilized emulsion exhibits droplet characteristics similar to CSN-stabilized emulsion, and can effectively resist the external forces that lead to the phase separation of the emulsion. Although phase separation also occurred at pH 4.0, CSC emulsion had a wider range of pH stability (pH 3.0, 5.0-8.0) and higher salt ion stability than CSN emulsion. Furthermore, CSC-stabilized astaxanthin emulsions showed better astaxanthin protection under different heat treatment conditions and storage temperatures compared with CSN. After 28 days of storage at 4 °C, astaxanthin residues in the CSC-stabilized emulsion reached 92.37 %. The bioaccessibility of astaxanthin in CSC-stabilized emulsion was 26.21 %, much higher than that in CSN (6.47 %). This research study provides a platform for designing astaxanthin-fortified food or beverage systems to achieve better stability and delivery to target sites.

Influence of Gelatin-Chitosan-Glycerol Edible Coating Incorporated with Chlorogenic Acid, Gallic Acid, and Resveratrol on the Preservation of Fresh Beef.

Chlorogenic acid (CA), gallic acid (GA), and resveratrol (RES) were added to a gelatin (GEL)-chitosan (CHI)-glycerol (GLY) edible coating, and their effects on the coating of fresh beef preservation were investigated. The results revealed that CA had the most significant improvement effect on fresh beef preservation. The combination of GEL-CHI-GLY-CA preserved the color of the beef better and delayed the increase of the total volatile base nitrogen, even though its total phenolic content decreased at a faster rate during beef preservation. GA also improved the preservation effect as on the 12th day of storage, the beef samples treated with GEL-CHI-GLY-GA had the lowest thiobarbituric acid reactive substances (0.76 mg Malondialdehyde (MDA)/kg) and total viable count (6.0 log cfu/g). On the whole, though RES showed an improvement on beef preservation, the improvement was not as good as the other two polyphenols. After 12 days of storage, the beef samples treated with GEL-CHI-GLY-RES had a higher pH value (6.25) than the other two polyphenol treatmed groups. Overall, the three polyphenol-added combinations increased the shelf life of beef by approximately 3-6 days compared to the control group (treated GEL-CHI-GLY with distilled water).

Pork longissimus dorsi marinated with edible mushroom powders: Evaluation of quality traits, microstructure, and protein degradation.

In this study, we examined the effects of marination with five edible mushroom powders (3%, m/m) on the quality attributes and protein changes of pork longissimus dorsi compared to meat marinated with 0.2% papain and distilled water (control group). The results indicated that pork samples marinated with edible mushrooms displayed better water retention and lower shear force, especially in the 3% Hypsizygus marmoreus (HM) group (12.50 ± 0.73 N). Ultrastructural observation results showed that the Z-disk and M-line of the pork samples marinated with edible mushrooms were fractured and weakened. Furthermore, the degradation extent of desmin in the HM-marinated pork samples was obviously increased (43%) in comparison to the papain group (only 15%), which was further confirmed by the results of the myofibril fragmentation index. Overall, the pork samples marinated with 3% HM exhibited better quality traits among all groups and might be a potential strategy to improve tenderness.

Bioaugmentation combined with biochar to enhance thermophilic hydrogen production from sugarcane bagasse.

In this study, Thermoanaerobacterium thermosaccharolyticum MJ2 and biochar were used to enhance thermophilic hydrogen production from sugarcane bagasse. MJ2 bioaugmentation notably increased the hydrogen production by 95.31%, which was further significantly improved by 158.10% by adding biochar. The addition of biochar promoted the degradation of substrate, improved the activities of hydrogenase and electron transfer system, and stimulated microbial growth and metabolism. Microbial community analysis showed that the relative abundance of Thermoanaerobacterium was significantly increased by bioaugmentation and further enriched by biochar. PICRUSt analysis showed that MJ2 combined with biochar promoted metabolic pathways related to substrate degradation and microbial metabolism. This study provides a novel enhancement method for hydrogen production of the cellulolytic microbial consortium by exogenous hydrogen-producing microorganism combined with biochar and deepens the understanding of its functional mechanism.

Effects of mulberry pomace on physicochemical and textural properties of stirred-type flavored yogurt.

Adding functional ingredients is an important method to develop functional dairy products. Mulberry pomace (MPo), a byproduct of mulberry fruit processing, is rich in phenolic compounds and anthocyanins and can be served as the functional ingredient in functional dairy products. The aim of this work was to prepare a functional flavored yogurt by incorporating MPo into stirred yogurt and to investigate the effects of MPo on the physicochemical and textural properties of the product during cold storage. We supplemented MPo powder up to 3% (wt/wt) in fermented milk, and the changes in color, pH, titratable acidity (TA), total phenol content (TPC), total anthocyanin content (TAC), water-holding capacity, rheological behavior, texture, and microstructure of the functional flavored yogurt were monitored during storage under 4°C for 28 d. The MPo powder brought a pink to dark red color to the yogurt, decreased the lightness (L*) and yellow-blue color (b*) values, increased the red-green color (a*) values, decreased the pH value, and increased the contents of TA, TPC, and TAC in a dose-dependent manner. The addition of MPo at 1%, 2%, and 3% (wt/wt) significantly increased water-holding capacity, consistency, viscosity, and viscosity index, and reduced firmness of yogurt samples. Supplementation of MPo significantly reduced the pore spaces and channels inside the samples and improved microstructure of the functional yogurt. During the 28 d of cold storage, MPo-fortified yogurt samples kept relatively constant color, although their L*, a*, and b* showed a decreasing tendency. The pH of all yogurt samples gradually decreased with increasing of TA. Interestingly, TPC and TAC contents and the texture parameters of MPo-fortified yogurt increased gradually and continuously during the 28 d of cold storage. Mulberry pomace is beneficial to improve the physicochemical and textural properties of yogurt and has the potential as a natural stabilizer to be used in functional yogurt rich in phytochemicals.

Biochar boosts dark fermentative H2 production from sugarcane bagasse by selective enrichment/colonization of functional bacteria and enhancing extracellular electron transfer.

The influence of biochar (BC) on anerobic digestion (AD) of organic wastes have been widely studied. However, the effect of BC on rate-limiting step during AD of lignocellulosic waste, i.e. the hydrolysis and acidogenesis step, is rarely studied and the underlying mechanisms have not been investigated. In this study, the benefits of BC with respect to dark fermentative hydrogen production were explored in a fermentation system by a heat-shocked consortium from sewage sludge (SS) with pretreated sugarcane bagasse (PSCB) as carbon source. The results showed that biochar boosted biohydrogen production by 317.1% through stimulating bacterial growth, improving critical enzymatic activities, manipulating the ratio of NADH/NAD+ and enhancing electron transfer efficiency of fermentation system. Furthermore, cellulolytic Lachnospiraceae was efficiently enriched and electroactive bacteria were selectively colonized and the ecological niche was formed on the surface of biochar. Synergistic effect between functional bacteria and extracellular electron transfer (EET) in electroactive bacteria were assumed to be established and maintained by biochar amendment. This study shed light on the underlying mechanisms of improved performance of biohydrogen production from lignocellulosic waste during mesophilic dark fermentation by BC supplementation.

The dose-dependent effects of polyphenols and malondialdehyde on the emulsifying and gel properties of myofibrillar protein-mulberry polyphenol complex.

The effects of mulberry polyphenols and malondialdehyde (MDA) on the emulsifying and gel properties of myofibrillar protein (MP) were studied. Emulsibility and gel properties of MP were compared in range of mulberry polyphenol/MDA concentrations by particle size, Zeta potential, antioxidant capacity, gel strength, water-holding capacity (WHC), rheological properties and microstructure. Mulberry polyphenols enhanced the inoxidizability of MP emulsion but decreased its emulsifying property. MDA at intermediate concentrations (5-20 mM) improved the elasticity, strength, and WHC of polyphenols-modified MP emulsion gel, while at high concentration (40 mM) it destroyed the emulsion gel, resulting in "oil leakage". Polyphenol is not conducive to the gelation but weaken the oxidative damage of MDA to protein. The gel structure of MP emulsion collapsed after high dose of polyphenols or MDA treated. Thus, to maintain uniform textural and antioxidant activity of meat product, both polyphenols addition and oxidation intensity should be controlled simultaneously.

Regulation of protein oxidation in Cantonese sausages by rutin, quercetin and caffeic acid.

The effects of rutin, quercetin, and caffeic acid on protein oxidation in Cantonese sausage during 60 days of storage at room temperature (25 ± 1 °C) were investigated. The results showed that the three phenolic compounds played different roles in inhibiting the oxidation of sarcoplasmic and myofibrillar protein. All of them inhibited sarcoplasmic protein oxidation by retarding carbonylation, the conversion of SH to S-S groups, and the formation of dimeric tyrosine and Schiff bases, of which rutin is the most effective. For myofibrillar protein, all of them suppressed the conversion of SH to S-S groups, only caffeic acid inhibited the accumulation of Schiff bases instead of carbonyls while both quercetin and caffeic acid inhibited the formation of dimeric tyrosine. In addition, quercetin had an inverse dosage effect on the oxidation regulation of MP, 0.16 g/kg quercetin had better inhibit effect on protein oxidation than 0.32 g/kg quercetin.

Enhanced lignin removal and enzymolysis efficiency of grass waste by hydrogen peroxide synergized dilute alkali pretreatment.

Pretreatment process plays a key role in biofuel production from lignocellulosic feedstocks. A study on dilute NaOH pretreatment supplemented with H2O2 under mild condition was conducted to overcome the recalcitrance of grass waste (GW). The optimized process could selectively increase lignin removal (73.2%), resulting in high overall recovery of holocellulose (73.8%) as well as high enzymolysis efficiency (83.5%) compared to H2O2 or NaOH pretreatment. The analyses by Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) revealed that supplementary H2O2 disrupted the structure of GW to facilitate the removal of lignin by NaOH, and exhibited synergistic effect on lignin removal and enzymolysis with dilute NaOH. Moreover, high titer of ethanol (100.7 g/L) was achieved by SSCF on 30% (w/v) pretreated GW loading. The present study suggests that the established synergistic pretreatment is a simple, efficient, and promising process for GW biorefinery.

Effects of mulberry polyphenols on oxidation stability of sarcoplasmic and myofibrillar proteins in dried minced pork slices during processing and storage.

This experiment was designed to evaluate the influence of mulberry polyphenols (MP) on oxidation stability of sarcoplasmic and myofibrillar proteins in dried minced pork slice during processing and storage. Composition, amino acid side chain modification, average particle size, hydrophobicity and solubility of proteins in the slices were investigated. MP displayed protective effects on oxidation stability of sarcoplasmic and myofibrillar proteins in slices, considering carbonyl formation and transformation from SH group to SS group were remarkably retarded by MP. Proteins in MP-treated slices possessed larger average particle size but lower aggregation during processing and storage. Meanwhile, the strengthened ionic bonds and weakened hydrogen, hydrophobic and disulfide bond could be responsible for the improved protein stability of slice with MP. All these results suggested that mulberry polyphenol could improve protein oxidation stability in meat products.

Insight into the conformational and functional properties of myofibrillar protein modified by mulberry polyphenols.

This paper investigated the conformational and functional properties of myofibrillar protein modified by five phenolic compounds, including cyanidin 3-O-glucoside, cyanidin 3-O-rutinoside, caffeic acid, quercetin and rutin, dominantly presented in mulberry polyphenols-enriched sausage. These phenolic compounds significantly affected the structure of myofibrillar protein as indicated by the remarkable losses of carbonyl and ε-NH2 and the obviously fluorescence quenching effect (P < 0.05). Modified myofibrillar protein increased antioxidative activity but decreased thermal stability. Myofibirllar protein modified with rutin had no change in thermal stability but improved emulsifying properties. Quercetin has little effect on secondary structure of myofibirlliar protein. Caffeic acid triggered the conversion of α-helix to ß-sheet in myofibrillar protein, and the resulted protein exhibited the strongest fluorescence quenching, solubility and antioxidant activity among all samples. Overall, the results suggested that all phenolic compounds involved in the changes of meat product quality, with caffeic acid and rutin being the most critical ones.

Enhancing hemoglobin peptide production from chicken blood fermentation by food-grade nonionic surfactant.

This study is focused on employing a potential process technology for enhancing hemoglobin peptides production from chicken blood. Effects of surfactants on chicken blood biodegradation and hemoglobin polypeptide accumulation were evaluated and the bioconversion conditions were optimized. Results suggested that surfactants exhibited the positive effect on hemoglobin peptides production during chicken blood bioconversion by Aspergillus niger. Dodecyl glucopyranoside was selected as the optimal surfactant and added at the 48th hour of the fermentation process (64 H) at the concentration of 6.0 g/L. Under the optimized conditions, 104.5 mg·N/mL amino nitrogen, 638.3 mg·N/mL nonprotein nitrogen, and 766.3 mg·N/mL soluble nitrogen were detected, which increased by approximately 0.7-, 3.7-, and 3.8-fold, respectively, compared with the control. Furthermore, the acid protease stability was remarkably intensified and the accumulated peptides were mainly distributed at 500-2,000 Da. Results from this work corroborate the potential of applying dodecyl glucopyranoside in hemoglobin polypeptide production from chicken blood.

Effect of Flammulina velutipes on the physicochemical and sensory characteristics of Cantonese sausages.

The effects of fresh and dried Flammulina velutipes (FFV and DFV) on quality and sensory characteristics of Cantonese sausages were investigated. Sausage samples were prepared by adding 0% (control), 2.5% FFV, 2.5% and 5.0% DFV, respectively, and their nutritional compositions, free amino acid profiles, lipid and protein oxidation, color and texture properties were determined. Addition of F. velutipes significantly decreased fat content while increased free amino acid contents of Cantonese sausages. Total free amino acid contents of 2.5% FFV, 2.5% DFV and 5.0% DFV incorporation were 2.8-, 2.4- and 3.5-fold as compared to control, respectively. Lipid and protein oxidation of Cantonese sausages were effectively inhibited by the addition of F. velutipes. Both FFV and DFV addition decreased hardness and chewiness while showed different effect on yellowness of samples. DFV added at 2.5% exhibited the best overall sensory acceptance. Therefore, appropriate addition of F. velutipes may be an effective way to improve meat product quality and function.

Use of straw mushrooms (Volvariella volvacea) for the enhancement of physicochemical, nutritional and sensory profiles of Cantonese sausages.

The aim of this work was to evaluate the quality and sensory properties of Cantonese sausages incorporated with dried straw mushrooms. Five types of sausage with the addition of 0%, 1%, 2%, 3%, and 4% straw mushrooms were prepared, and their physicochemical traits and sensory acceptance were investigated. The results showed that incorporation of straw mushrooms improved the physical properties, significantly decreased peroxide value, increased the amount of amino acids and volatile compounds, and introduced new volatiles (aldehyde and ester compounds) to Cantonese sausages. Compared to sausages without addition of straw mushrooms, the amount of essential amino acids increased 8-fold, the P/S ratio of fatty acid increased to 0.46 similar to the recommended nutritional value, and the lipid peroxide value reduced 10-fold in Cantonese sausages with addition of 4% straw mushrooms. These results indicate that incorporation of straw mushrooms could be an efficient way to obtain nutritional and healthy Cantonese sausages.

Protective effects of Momordica grosvenori extract against lipid and protein oxidation-induced damage in dried minced pork slices.

The experiment was conducted to assess the protective effects of Momordica grosvenori extract (MGE) against lipid and protein oxidation-induced damage in vacuum-packed dried minced pork slices stored at room temperature for 21days. Antioxidant activity of MGE was evaluated by measuring its radical scavenging activities and reducing power with progressive concentrations from 40 to 200g/L. MGE was added to the dried minced pork slices at 7, 10 or 15g/100g. Results showed that inclusion of MGE in dried minced pork slice significantly delayed the formation of hexanal, thiobarbituric acid-reactive substances and carbonyls and reduced the sulfhydryl loss in a dose-dependent manner (P<0.05), indicating that MGE exerted a protective effect against lipids and protein oxidation. Concomitantly, an intense increase of redness and loss of lightness and yellowness was found to take place (P<0.05), though it exhibited little negative effects on the sensory properties of slices. Mogrosides, the main bioactive components in M. grosvenori, decreased primarily during processing while they were relatively stable during storage under vacuum condition, room temperature. All these results demonstrated MGE had great potential as a natural antioxidant used in meat products.

Influence of hydrolysis behaviour and microfluidisation on the functionality and structural properties of collagen hydrolysates.

The functionality and structural properties of pig skin hydrolysates with different degrees of hydrolysis (DH, 10% and 20%) and microfluidisation (120MPa), prepared by pepsin and Alcalase® have been investigated in this study. Extensive hydrolysis can significantly improve the absolute value of the zeta potential and surface hydrophobicity. The particle distribution of hydrolysates decreased with increasing DH. The numbers of free sulfhydryl (SH) and disulfide bonds (SS) were significantly increased with increasing DH (p<0.05). Hydrolysates with a lower DH showed a better emulsifying property than those with a higher DH. Microfluidisation led to the transformation of structural and interfacial properties of the hydrolysates and increased the value of the zeta potential, S0, and gel strength. Microfluidisation results in limited breakage of chemical bonds, the number of SS and SH bonds unchanged in the treatment. These results reflect the functionality and structural properties of collagen-rich pig skin hydrolysates.

Mulberry anthocyanin biotransformation by intestinal probiotics.

This study was designed to evaluate mulberry anthocyanins bioconversion traits for intestinal probiotics. Five intestinal beneficial bacteria were incubated with mulberry anthocyanins under anaerobic conditions at 37°C, and bacterial ß-glucosidase activity and anthocyanin level were determined. Results demonstrated that all strains could convert mulberry anthocyanins to some extent. With high ß-glucosidase production capacity, Streptococcus thermophiles GIM 1.321 and Lactobacillus plantarum GIM 1.35 degraded mulberry anthocyanins by 46.17% and 43.62%, respectively. Mulberry anthocyanins were mainly biotransformed to chlorogenic acid, crypto-chlorogenic acid, caffeic acid, and ferulic acid during the anaerobic process. Non-enzymatic deglycosylation of anthocyanins also occurred and approximately 19.42% of the anthocyanins were degraded within 48h by this method.

A Novel Mesophilic Anaerobic Digestion System for Biogas Production and In Situ Methane Enrichment from Coconut Shell Pyroligneous.

A novel mesophilic anaerobic digestion process with detoxification-treated coconut shell pyroligneous was established, exhibiting an effective advantage in biogas production. The pyroligneous collected contained 166.2 g l(-1) acetic acid, indicating great potential for biogas production. Detoxification was an effective way of simultaneously enriching biodegradable ingredients and removing inhibitors (mainly as phenols and organic acids) for digestion process. The digestion process lasted 96 h and fermentation characteristics (chemical oxygen demand (COD) removal ratio, volatile fatty acid (VFA) consumptions, pH, total gas, methane yield, and phenol removal efficiency) were measured. The experiments successfully explored the optimum detoxification parameters, oxidized with 10 % H2O2 followed by overliming, and demonstrated 89.3 % COD removal, 91.4 % methane content, 0.305 LCH4/g COD removed CH4 yield, and 88.81 % phenol removal ratio. This study provided clues to overcome the negative effects of inhibitors in pyroligneous on biogas production. The findings could contribute to significant process in detoxified pretreatment of pyroligneous and develop an economically feasible technology for treating pyroligneous after producing charcoal.