查看更多>>摘要：Reuterin is a broad-spectrum antimicrobial agent widely used to control pathogenic bacteria. Antimicrobial properties of catechin have been well described. However, no information is available regarding their combination effects. The aim of the present study is to evaluate the antibacterial effects of reuterin and catechin alone or in combination against Streptococcus mutans (S. mutans). We found a clear synergistic effect of reuterin in combination with catechin on inhibiting growth of S. mutans. Combined treatment with reuterin and catechin resulted in reduced biofilm biomass and water-insoluble glucan content, and visibly damaged the biofilm structure. Moreover, the expression of biofilm-associated genes was significantly down-regulated after exposure to the combination. Our results demonstrate that the combination of reuterin and catechin exhibits synergistic antimicrobial activity against S. mutans by repressing growth, biofilm formation, water-insoluble glucan production, and virulence genes expression. These findings support this novel combination can be used as a natural antibacterial agent for the prevention of oral diseases.
查看更多>>摘要：The cryoprotective effect of ice structuring protein (ISP) on the microstructure and myofibrillar protein (MP) structure of mirror carp induced by freeze-thaw (F-T) processes was surveyed. The average diameter of ice crystals of those without ISP increased (from 130 to 220 mu m), and the carbonyl content and 20 value were also increased, meanwhile, the sulfhydryl, free amine, alpha-helix content, fluorescence intensity (FI) and peak intensity were significantly decreased after five F-T processes (P < 0.05). When the addition of ISP, the size of ice crystal and the change in MP structure of ISP-treated sample was smaller than those without ISP in a single F-T period. The average diameter of ice crystals of ISP-treated sample was 17.5% lower than those without ISP after three FT processes. The carbonyl content of ISP-treated sample was 16.5% lower than those without ISP after five F-T processes. The alpha-helix and FI of ISP-treated sample were 58.2% and 816 A.U., higher than those without ISP. The physical stability of the MP was increased after ISP treated. Hence, ISP could protect muscle fibers by inhibiting the extension of ice crystals, and improve the stability of the MP structure.
查看更多>>摘要：The formation and characterization of conjugates of soybean protein isolate (SPI) and dextran with varying molecular weights (4, 10, and 70 kDa) and their effects on quality of glucono-delta-lactone (GDL)-induced tofu were investigated. The extent of glycosylation was negatively related to the molecular weight of dextran. Thus, the SPI-dextran4 conjugate exhibited a darker color and a biggest decrease in whiteness from 70.49 to 45.51. SPI-dextran70 conjugate exhibited an increased surface hydrophobicity and free sulfhydryl content. Volume-average diameter of SPI-dextran70 conjugate-added soymilk and gel strength of the corresponding tofu ranged from 10.34 to 11.24 mu m and 0.068 to 0.083 N, respectively, which were lesser than those of the control (11.12 um and 0.133 N). However, SPI-dextran10 conjugate incubated for 6 days and SPI-dextran4 conjugate incubated for 2 days increased the gel strength of tofu to 0.146 and 0.143 N, respectively. Conjugates-added tofu exhibited an increased water holding capacity and a discontinuous and loose microstructure, but a lowered whiteness and a color change to yellow. Results demonstrated that the selection of dextran with an appropriate molecular weight and controlling the glycosylation degree were capable of improving the quality of SPI-dextran conjugate-added GDL-induced tofu.
查看更多>>摘要：The present research was designed with an aim to attempt enhancement of antimicrobial efficacy of bacteriocins against food-borne pathogens. Bacteriocin Bac23 was extracted from a lactic acid bacterium which was isolated from raw milk, and identified as Lactobacillus plantarum using 16S rRNA gene sequencing. The purified Bac23 was found to be stable over a broad temperature (20 degrees C - 100 degrees C) and pH (2-12) range, its molecular weight was estimated as 5.1 kDa using SDS-PAGE, and the amino acid sequence determined using LCMS/MS identified it as plantaricin. Bac23 exhibited antimicrobial response against only three (S. flexneri, S.aureus, and P.aeruginosa) out of a total of six test food-borne pathogens. The purified Bac23 was further used for green synthesis of bacteriocin-capped silver nanoparticles (SNPs), which displayed a particle size of 31 nm and a hydrodynamic diameter of 79.19 nm. The capped SNPs exhibited an antibacterial response against all the six test food-borne pathogens displaying MIC value as low as 4 mu g/ml for S flexneri and P.aeruginosa; thus, resulting into an almost 50% increase in the antimicrobial spectrum when compared with the antimicrobial activity of Bac23 alone. The present study therefore reports that the capping of a bacteriocin onto silver nanoparticles can enhance its antimicrobial response; hence aiding in combating food-borne pathogens.
查看更多>>摘要：Natural biopolymers such as food gums can be effective in improving the physical stability of colloidal particle dispersions. To improve the loading stability of curcumin in liposomes, liposomes with gum arabic (GA) or sodium alginate (SA) (0-2% w/v) were prepared and their physicochemical properties evaluated. Results showed that GA, which has a high surface activity, interacted more with the liposome surface resulting in smaller liposome size and polydispersity. However GA disrupted the internal lamellar structure of the liposomes at low concentrations, resulting in increased flocculation and was associated with poor retention of encapsulated curcumin. In contrast, SA formed a viscious continuous phase due to the gum network which reduced particle mobility and sedimentation, and increased curcumin retention, although this was associated with an increase in particle size and polydispersity index.
查看更多>>摘要：This study aimed to evaluate the effects of rice flour (RF) replacement with chickpea flour (CF) and their combinations with psyllium (PSY) on dough thermomechanical parameters by analyzing their relationship with the quality features of instrumental and sensory texture of gluten-free bread (GFB) during storage. Bread samples were evaluated for crumb moisture and firmness, texture profile analysis, texture acceptability, overall liking, and descriptive profile during 7 days of storage. The data were evaluated using regression vector (RV) coefficients and multiple factor analysis (MFA). The RV coefficients showed a high correlation among the data, and the sum between the two dimensions of MFA explained 96.58% of the total variation. Replacing RF by CF decreased the tendency for starch gelatinization, gel stability, and retrogradation, as well as the hardening rate, favoring acceptance of GFB, which was described as soft and fresh during the 7 days of storage. Adding PSY increased dough initial consistency, which explains the increased cohesiveness and springiness - aspects that inhibited bread crumbling during storage. The results indicate a promising use of Mixolab analysis to predict GFB quality and acceptability during 7 days of storage.
查看更多>>摘要：In the present study, it was reported that 3% casein modulated by the solution pH could be an outstanding stabilizer for oil-in-water Pickering HIPEs (80% oil phase). The zeta-potential and three-phase contact angle of casein at different pH were ranged from -29 to 19 and 77 degrees to 81 degrees, respectively. Casein particles were irreversibly anchored at the oil-water interface evidenced by CLSM and cyro-SEM. The rheological properties of the HIPEs depended on casein pH and the HIPEs stabilized by casein at pH 3 displayed the greatest viscoelasticity. All the HIPEs were outstanding stable against heating (100 degrees C for 15 min), but sensitive to the frozen-thawing treatment. Casein particles on the interface provided the electrostatic repulsion and steric hindrance to prevent the coalescence or flocculation of oil drops, and interacted with casein particles with nano size in water solution for stabilizing the Pickering HIPEs. Based on the particle size of casein and the resulting Pickering HIPEs, in-situ dispersion of casein to form the oil/water interface under high-speed shearing was proposed. Food-grade Pickering HIPEs were successfully fabricated using casein.
查看更多>>摘要：This work investigates the structure and behavior of model oil-in-water chocolate ganaches by comparing two systems differing in the nature of the dispersed (fat) phase: cocoa butter and cocoa mass (mix of cocoa butter and fibers). Significant differences regarding the textural properties and stability were evidenced. Concentrated liquid emulsions made with cocoa butter had a thick and homogeneous macroscopic aspect. Upon cooling, fat crystallization produced partial coalescence and the emulsions became solid. With molten cocoa mass, a homogeneous aspect was observed until 50 g/100 g of dispersed phase and a grainy texture was obtained at larger fractions. This textural transition was interpreted as being due to a jamming transition. Both conventional and fluorescence microscopy revealed that cocoa fibers were transferred from the fat phase to the aqueous phase and were partially anchored to the interfaces. Upon cooling, cocoa fibers acted as a physical barrier that limited the extent of partial coalescence.
Soares, Rodrigo de AraujoBorges, Soraia VilelaDias, Marali VilelaPiccoli, Roberta Hilsdorf...
6页
查看更多>>摘要：The effect of protein-based coating made with whey protein isolate (WPI), sodium montmorillonite nanoparticles (MMT-Na), and sodium metabisulfite (SMB) on the internal quality (weight loss, Haugh unit, yolk index, albumen pH, yolk pH, foam stability, and overrun) of eggs was evaluated for 8 weeks of storage at 25 +/- 3 degrees C and 70 +/- 5% RH. The coating was applied by immersion of eggs, followed by drying at room temperature. Uncoated eggs were used as a control. The coated eggs maintained grade A for up to 5 weeks, while the grade of the control eggs lasted about a week. Significant lower weight loss was observed for the coated eggs after 8 weeks of storage when compared to the control, with values of 11.65% and 14.50%, respectively. The protein-based coating improved foam stability (>75%) when compared to the control (43.45%) due to the small changes in pH of the albumen, after 5 weeks of storage. The control eggs lasted only 5 weeks under the storage conditions of this study, thus the internal quality was not determined after this period, while the coated eggs maintained integrity for up to 8 weeks.
Porto-Figueira, PriscillaPereira, Jorge A. M.Caldeira, HelenaCamara, Jose S....
8页
查看更多>>摘要：Food deterioration caused by microbial agents often involve the formation of biogenic amines (BAs), which can have harmful effects on human health. In this study a set of BAs - tryptamine, cadaverine, putrescine, spermine, histamine, tyramine, and spermidine, were simultaneously analysed to monitor their occurrence in different types of tuna samples. An improved extraction approach involving ultrasound-assisted microextraction (USA mu ET) followed by derivatization with dansyl chloride (DnsCl) and analysis by ultrahigh performance liquid chromatography (UHPLC) with fluorescence detection was validated for BAs quantification. The performance of the USA mu ET/UHPLC-FLD was assessed by studying the limits of detection (LOD) and quantification (LOQ), linear dynamic range (LDR), precision (intra and inter-day) and matrix effect (ME). Good linearity (r(2) > 0.98), LODs (from 0.98 to 8.57 mg kg(-1)) and LOQs (3.20-25.6 mg kg(-1)) were achieved for all BAs analysed. Recoveries ranged from 76% to 106%, with relative standard deviations (RSD) lower than 5.0%. ME was determined from 7.52 to 50% and the intra and inter-day precisions ranged from 4.7 to 11.6% and 5.5-14.2%, respectively. BAs levels varied significantly from 4.09 +/- 0.8 mg kg(-1) of putrescine in olive oil canned samples to 577.9 +/- 5.9 mg kg(-1) of cadaverine in natural canned samples. Tryptamine and tyramine were not detected in any of the samples analysed, while spermine and spermidine were found in 85.7% of the assayed tuna samples. Cadaverine was the most dominant BA with concentrations ranging from 54.3 +/- 2.5 mg kg(-1), in olive oil canned tuna, to 577.9 +/- 5.9 mg kg(-1), in natural canned samples, whereas putrescine had the lowest concentration (average 6.9 +/- 2.5 mg kg(-1)). The validated methodology revealed important improvements in terms of simplification of the experimental layout, expressed in the low sample and reagent amounts, in addition to less time-consuming and labour-intensive requirements that did not compromise the analytical performance.
NSTL
Elsevier