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The study aimed to assess the effects of different cooking temperatures (90, 93, 95, 98, and 100 ℃) and time (1, 3, 5, 7, and 9 min) on the physicochemical, textural, microstructural, and microbiological properties of fresh whole-limb crayfish. The differential scanning calorimetric (DSC) curve and heat transfer curves showed that the protein in the crayfish muscles was completely denatured after 3 min of heating. Meanwhile, increasing cooking temperatures could result in a faster heat transfer rate, better shell color, and more moisture loss. The hardness and chewiness of crayfish muscle increased significantly within 3 min of heating and then decreased slightly in the later phase (P > 0.05). Crayfish cooked at 93 to 95 ℃ for 3 to 5 min showed the highest hardness about 330–373 g. With increasing heating time, the microstructure of muscle fibers changed from a compact state to a loose state due to water loss and the damage to the endomuscular membrane. Higher temperature resulted in markedly lower TVC compared to 90 ℃. This research provided a reliable reference for cooking and processing crayfish. [ABSTRACT FROM AUTHOR]

This study discovered a novel chitosanase from Penicillium oxalicum M2 based on a new screening strategy. An extracellular chitosanase was isolated and purified from the fermentation broth of Penicillium oxalicum M2. A 19.34-fold purification was achieved on a cation exchange column. Using sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis, chitosanase was determined at approximately 42 kDa without any subunits. The sequence of peptide in the protein was identified as SALNKNYITNFSTLR by MALTI-TOF/TOF MS. The maximum catalytic activity of the purified enzyme was 60.45 U/mg at the optimum pH and temperature of 5.5 and 60 °C. The enzyme activity held stability in the range of 35–50 °C and pH 3–4.5. Ca2+, Mn2+, non-ionic surfactants (Tween 20/40/60/80 and Trition X-100) and some common reducing agents (DTT and β-ME) could significantly activate chitosanase. The purified enzyme showed rigorous specificity to chitosan as a substrate. The hydrolysate in the final stage of hydrolysis consisted of chitooligosaccharides with a degree of polymerization ranging from 2 to 5 and without glucosamine or acetylglucosamine. The monomeric enzyme obtained by one-step purification reveal applications potential in sugar industry, and expanded our understanding of the GH75 family chitosanases simultaneously. [ABSTRACT FROM AUTHOR]

The aim of the present study was to investigate the changes in the amino acid and fatty acid profiles of wheat flour noodles when supplemented with grass carp protein concentrate (GCPC) at levels of 0%, 10%, 20% and 30% (referred to as CN, GCPC10, GCPC20 and GCPC30). The protein quality of the products was also determined using the digestible indispensable amino acid score (DIAAS). The indispensable amino acids (IAA) content increased (347.93 to 417.03 mg/g protein) with the increasing levels of GCPC from 0 to 30%. The total IAA content of all the noodle formulations were above the recommended daily allowances for adults (277 mg/g). The content of dispensable amino acids in CN on the other hand was significantly the highest (636.67 mg/g protein) when compared to GCPC10 (611.82 mg/g), GCPC20 (587.19 mg/g) and GCPC30 (580.48 mg/g). The calculated DIAAS values with respect to young child and adult age patterns were 36% and 43% (lysine) for CN, which in both cases the protein quality is graded poor (< 75%). GCPC supplemented noodles were found to have DIAAS values from 72 to 99%, which in most cases were under the "good" (75–100%). The ratios of omega-6 (n-6) to omega-3 (n-3) fatty acids ratio was recorded 3.94, 3.62 and 3.53 for GCPC10, GCPC20 and GCPC30 respectively, all values being lower than the maximum recommended, 4.0. The polyunsaturated fatty acids (PUFA) to saturated fatty acids (SFA) ratio was recorded 2.05, 1.47, 1.36, and 1.34 for CN, GCPC10, GCPC20 and GCPC30 respectively, the minimum recommended ratio being 0.45. The study has thus concluded that incorporating GCPC into wheat flour noodles can upgrade the protein quality and balanced fatty acid content to promote healthy wheat flour noodle meals. [ABSTRACT FROM AUTHOR]

The aim of this work was to develop a novel, nontoxic, bioactive antimicrobial material based on a natural polymer, chitosan oligosaccharides (COS), a natural pyrone compound, kojic acid (KA), and piperazine. The COS-based polymer (COS-O-MB) has been synthesized by selective partial alkylation reaction to graft kojic acid, KA, and piperazine onto the COS molecular chain. Then, physicochemical properties and bioactivity of the COS-O-MBs were evaluated and it was characterized by FT-IR, NMR spectroscopy, Mw, PID, antimicrobial activity, hemolysis assay, biocompatibility, animal toxicity, and antimicrobial action mode studies. The results revealed that the alkylation reaction took place at the C-6 position of COS, and the as-prepared COS-O-MB significantly enhanced the antimicrobial activity and biocompatibility and reduced the hemolytic activity in vitro in comparison with that of the free COS and KA. Meanwhile, the antimicrobial action mode studies proved that COS-O-MB can pass through the anionic microbial membrane, destroy the cytomembrane integrity, and potentially affect protein denaturation, demonstrating that exposure to COS-O-MB results in the death of microbial cells. But importantly, COS-O-MB is not toxic to human cells. Hence, low hemolytic activity to human red blood cells, and nontoxic nature to female mice of SLAC KM strain, made this novel polymer material a promising and effective compound for food and pharmaceutical industries. [ABSTRACT FROM AUTHOR]

Seinat seed oil was blended with peanut oil for the enhancement of stability and chemical characteristics of the blend. The physicochemical properties (relative density, refractive index, free fatty acids, saponification value, iodine value and peroxide value) of seinat seed and peanut oil blends in ratios 95:5, 85:15, 30:70 and 50:50 proportions were evaluated, as well as oxidative stability index, deferential scanning calorimetric (DSC) characteristics and tocopherols content. Results of oil blend showed that there was no negative effect by the addition of seinat seed oil to peanut oil and also had decreased percentages of all saturated fatty acids except stearic acid, conversely, increased the levels of unsaturated fatty acids. As for the sensory evaluation, the panelist results showed that seinat seed oil blends had no significant differences ( p < 0.05) in all attributes except the purity. The results indicated that the blending of seinat seed oil with peanut oil had also increased the stability and tocopherols content. As Sudan is the first producer of seinat oil, blending of seinat seed oil with traditional oil like quality, and may decrease the consumption of other expensive edible oils. [ABSTRACT FROM AUTHOR]

Cysteine cathepsin-associated degradation of muscle proteins have been assumed to be crucial to the softening of chilled fillet. The effect of aqueous extract of Alliums on cathepsin-induced proteolysis and texture deterioration of ice-stored carp fillets was evaluated. Among all treatments, extracts of scallion and garlic were the most effective inhibitor of cathepsin B, reducing the enzyme activity by more than 40 % after storage of 3 days, whereas extracts of scallion and leek had the greatest inhibitory effects on the cathepsin L activity, resulting in corresponding reduction in enzyme activity of 65 and 57 %, respectively. Extracts of scallion and garlic were the most effective treatments in impeding accumulation of TCA-soluble peptides and breakdown of myofibrillar proteins as validated by SDS-PAGE pattern. After storage of 21 days, the shear force of fillets treated with scallion and garlic extracts were approximately 30 % higher than those of control, whereas the treatments with other Allium extracts showed no inhibitory effect on textural deterioration. The results demonstrated that the treatment of grass carp fillets with extract of scallion and garlic has the potential to mitigate the endogenous cathepsin-induced softening of ice-stored grass carp fillets. [ABSTRACT FROM AUTHOR]

In this paper, a novel chitosan oligosaccharides derivative-chitosan oligosaccharides-kojic acid graft copolymer (COS/KA), COS, and KA were selected to investigate the binding to bovine serum albumin (BSA) using UV-Vis spectroscopy, fluorescence, synchronous fluorescence, and circular dichroism (CD) at pH 7.4. The results indicated that the tryptophan residues of BSA to the distance of COS/KA, COS, and KA were <8 nm, the quenching constants K were decreased, and the value of Kq were much >2.0 × 10 L mols for COS/KA-BSA, COS-BSA, and KA-BSA at 298, 302, 306, 310 K, respectively, those confirmed that the quenching process belongs to static quenching. The thermodynamic parameters ∆H°, ΔG°, ΔS° at different temperatures were calculated and indicated that hydrophobic and electrostatic forces played important roles in the binding process, and the enhanced binding affinity mainly associated with the increase of the hydrophobicity. Moreover, the CD data demonstrated that the secondary structure of BSA was slightly altered in the presence of COS/KA, COS, and KA, with different reduced α-helix contents (46.30 ± 0.20, 48.60 ± 0.40, 50.70 ± 0.20), respectively. The work provides basic data for the binding mechanism of COS/KA with BSA in vitro. [ABSTRACT FROM AUTHOR]

Silver carp ( Hypophthalmichthys molitrix) is one of the major species of freshwater fish in China. Modification of myofibrillar proteins induced by high pressure processing (HPP) has been investigated at pressures ranging from 200 to 500 MPa for 10 min at 20 °C. Influence of high pressure on conformational changes of myofibrils was studied by means of differential scanning calorimetry (DSC), surface hydrophobicity measurement, ultraviolet absorption spectra and second-derivative spectroscopy, intrinsic spectrofluorimetry, Raman spectroscopic analysis and circular dichroism (CD). DSC analyses revealed that the conformational stability of myofibrils is reduced to different extents when they are exposed to a pressure over 200 MPa. More sulfydryl groups as well as hydrophobic regions and amino acid residues which had ultraviolet absorbance had been found significantly after HPP (≥300 MPa). Changes in the Raman spectra were interpreted as the occurrence of secondary structural changes in pressure-induced myofibrillar proteins. CD analysis results demonstrated that α-helix was destroyed after processed at 400 MPa for 10 min. The results implicated that HPP can be used as a possible means of improving the functional properties for growing demand for healthier fish products. [ABSTRACT FROM AUTHOR]

The physicochemical and functional properties of seinat seed flour (SSF), defatted seinat flour (DSSF), and protein isolates were studied. Protein was extracted from DSSF using an alkali solution with isoelectric precipitation and freeze drying. Freeze dried seinat seed protein isolates (FSSPI), SSF, and DSSF were evaluated for their physicochemical and functional properties. SSF contained high levels of crude fat and fiber (31.13% and 24.75%, respectively). FSSPI contained 91.83% protein versus 28.58% for SSF. The amounts of potassium, the mineral with the highest content, were 9,548.33, 6,439.03, and 1,029 mg/100 g in SSF, DSSF, and FSSPI, respectively. The functional properties were variable among samples. The protein solubility of FSSPI was significantly higher ( p<0.05) than for DSSF and SSF. FSSPI has a significantly better ( p<0.05) foaming capacity, water/fat absorption capacity, and bulk density than SSF and DSSF. FSSPI also showed an emulsifying capacity comparable to commercial soy protein isolates. [ABSTRACT FROM AUTHOR]

In this paper, the sensitivity of food spoilage organisms ( Bacillus cereus; Escherichia coli) to natural antimicrobial peptides (surfactin; polylysine; nisin) from microorganism was observed, and the optimization of antimicrobial effect in meat evaluated by a RSM was studied. Results showed that these strains were sensitive to them. MICs of surfactin and polylysine and nisin were 31.25 and 312.5 and 312.5 μg/mL respectively against B. cereus, and MIC were 15.625 and 156.25 and 2,500 μg/mL respectively against E. coli. The optimization result indicated that B. cereus and E. coli could be sterilized by six log cycles when the temperature was 14.05 °C, the action time was 10.95 h, and the concentration (surfactin/polylysine/nisin weight ratio 0.1:1:2) was 379.53 μg/mL. [ABSTRACT FROM AUTHOR]

Differentiation of tobacco leaves in different plant stalk positions in China was achieved based on basic chemical compounds and neutral volatiles by principal component analysis (PCA). The continuous flow analysis method was used to determine the quantity of the basic chemical compounds (sugars, total nitrogen and nicotine) of 30 samples. The neutral volatiles of tobaccos were analyzed by GC-MS. It was found that the disparity in basic chemical components was not enough to assess the different quality of tobacco leaves. PCA was used to reveal the differences among these three species based on neutral volatile compounds. Tobacco leaves in different positions were differentiated according to the results of PCA. Four principal components were extracted and altogether accounted for exceeding 80 % of the total variances. The first principal component explained 48.1 % of the total variation and was mainly defined by solanone, megastigmatrienone, 5-methylfurfural, furfuralcohol, phenylethylalcohol and benzylalcohol. The second principal component explained 18.1 % of the total variation and was mainly defined by β-ionone and farnesylacetone. The plots of sample loadings showed that a good differentiation on the basis of concentrations of neutral volatiles was achieved. These results demonstrated that neutral volatiles can be used as the useful variables to characterize the tobacco leaves in different positions. [ABSTRACT FROM AUTHOR]

The surface properties of monoacyl trehaloses with different acyl chains were investigated at 30°C, 40°C, 50°C, and 60°C. Monoacyl trehaloses were enzymatically synthesized and purified with silica gel column chromatography and semi-preparative high-performance liquid chromatography (HPLC), and the purity of products was identified by mass spectrometry (MS) and nuclear magnetic resonance (NMR). The surface tension of monoacyl trehalose in pure water was measured using Douy ring method at different temperatures. The critical micelle concentrations (CMC), surface tension at the CMC, γCMC, and residual area per molecule, a, were estimated from the curves. The CMC value of unsaturated monoacyl trehalose was affected by both the degree of unsaturation and the acyl chain length, and the effect of chain length on the CMC value was much stronger than that of the unsaturation degree. However, there was no significant dependency of the γCMC value and a values on the chain length or the unsaturated degree. [ABSTRACT FROM AUTHOR]

Chinese olive ( Canarium album L.), a native and a well-known tropical fruit tree in the southeast of China, contains large amount of phenolics and possesses great pharmacological activities. In this study, phenolics were extracted from Chinese olive fruit pulp using 80% (v/v) aqueous acetone, and acetone extracts were further fractioned with petroleum ether, ethyl acetate and n-butanol sequentially. From n-butanol fraction, a new phenolic compound was isolated and purified through AB-8 adsorption resin column chromatography, polyamide column chromatography and TSK Toyopearl HW-40 (S) column chromatography, and the structure of the new compound was established as 3- O-galloyl quinic acid butyl ester by electrospray ionization mass spectrometry (ESI-MS), 1D- and 2D-NMR (DEPT, COSY, HMBC, HMQC) and UV–vis techniques. [ABSTRACT FROM AUTHOR]