Blanco-Morales, VirginiaGarcia-Llatas, GuadalupeYebra, Maria JesusSentandreu, Vicente...
9页
查看更多>>摘要：The impact of a plant sterol-enriched beverage on the sterol metabolism, organic acid production and microbiota composition was evaluated by means of a dynamic gastrointestinal and colonic fermentation model. After one week of fermentation, an absence of sterol metabolites was reported, in accordance with the lack of microbiota related to their metabolism. Although total organic acid content was lower in the ascending colon (AC) compared to the transversal (TC) and descending colon (DC) (28-57 mmol/L vs. 55-87 and 44-64 mmol/L, respectively), its increments, with respect to the initial value, were higher (2-fold vs. 1.6- and 1.5-fold). Increments of acetate, butyrate and propionate were observed in all colon vessels, whereas lactate production was only observed in the AC at the first hours of fermentation. Results showed a progressive increase in microbial species richness and evenness from the AC to the DC. Beverage fermentation also modulated certain members of the microbiota: Bifidobacterium (within 24 h) and Megasphaera genera were stimulated, and Mitsuokella was reduced in AC, while the growth of Klebsiella genus was promoted and Bacteroidetes phylum decreased in TC and DC. These results show that the beverage modulates the microbial community and activity, which could be physiologically relevant to the host.
查看更多>>摘要：Sugarcane juice contains unstable particles that readily undergo agglomeration and sedimentation. In this work, microfluidization was used as a processing tool to generate a possible solution to the sedimentation problem in sugarcane juice for the first time. Stoke's law was used to determine the particle sedimentation rate. Experiments were devised to explore the majority of the pressure range of microfluidization (50-200 MPa) with variation in processing cycles (1-7). Particle size and apparent viscosity of sugarcane juice were determined. Microscopic analysis was also carried out to visualize the effect of microfluidization on the particles in the juice. Microfluidization in the pressure range of 50-150 MPa with less than 7 cycles of processing reduced the size of suspended juice particles successfully. Results revealed that 150 MPa pressure with 5 cycles was suitable for sugarcane juice processing as it generates the lowest particle size (similar to 437 nm) and minimum particle sedimentation rate (4.91 x 10(-2) mm/day).
Azam, S. M. RoknulWang, YaoyaoZhou, JieQu, Wenjuan...
10页
查看更多>>摘要：This study endeavored to develop a method to evaluate the effect of ultrasound frequency on soybean protein extraction. In the ultrasonic frequencies range from 20 to 52 kHz, 28, 35, and 45 kHz were predicted to be the resonance frequencies in the ultrasound-assisted extraction (UAE) process of soybean protein by simulating the acoustic field distribution. The absolute sound pressure and the relative standard deviation could be wellcoordinated via frequency regulation. The extraction experiment of soybean protein showed that the extraction rate was improved significantly (p < 0.05) with the aid of ultrasound. The extraction effect was optimal at 28 kHz and the extraction rate was improved to 73.35 g/100 g from 46.09 g/100 g of control under the same condition. The structure of the extracted protein was analyzed by the spectrum to further explore the mechanism of the effect of ultrasonic frequency. Spectral analysis showed that 20, 28, and 35 kHz had a significant influence on the structure of protein molecules. Therefore, acoustic field simulation can be used as one effective method for selecting ultrasonic frequency, which could help to optimize equipment and improve efficiency.
查看更多>>摘要：Fresh-cut leafy greens are washed in water with antimicrobials such as free chlorine to mitigate risk of pathogen cross-contamination. Validation of the process in a commercial setting poses challenges, including the identification of effective surrogates that can be used directly on the processing line during commercial operation. The objective of this study was to evaluate the use of an abiotic, DNA-based indicator as a potential surrogate for Escherichia coli O157:H7 during the washing of spinach. E. coli O157:H7 and DBAS (DNA barcode abiotic surrogate) were inoculated onto spinach leaves and washed in water with free chlorine. E. coli O157:H7 and DBAS populations were enumerated by selective plate counting or qPCR, respectively, and by laser scanning confocal microscopy. DBAS displayed high sensitivity to free chlorine at concentrations >= 12.5 mg/L, similar to concentrations commonly used in leafy green washing. Linear regression analysis indicated that inactivation of E. coli O157:H7 and DBAS had comparable inactivation responses (R2 = 0.76). Microscopy analysis also showed similar rates of decontamination between the two analytes from the surface of spinach. These results show that DBAS is a promising abiotic surrogate for onsite validation of antimicrobial processes targeting foodborne pathogens such as E. coli O157:H7 on fresh produce.
查看更多>>摘要：There is an urgent need to increase the daily intake of insoluble dietary fiber, and at the same time to find new sources and new production technologies. We hypothesized that fungal enzymes directly involved in lignocellulosic material hydrolysis (Aspergillus and Trichoderma enzyme cocktails) will change the fiber structure particularly efficiently after the action of laccase (Trametes versicolor enzyme cocktail). Enzymes production on an inducing substrate (same as starting material for obtainment of insoluble dietary fibers) and their usage resulted in obtainment of novel insoluble dietary fibers with better characteristics, 24% higher swelling, 43% higher WRC and 57% higher ORC compared to insoluble dietary fibers from triticale (already proven to be a good food additive). Changes in structure were analyzed by FTIR and microscopic analysis. Antioxidative performance of the obtained products, new insoluble and released soluble dietary fibers, was analyzed in detail. Newly obtained soluble dietary fibers demonstrated up to 20 times higher antioxidant activity compared to untreated fibers (ABTS and DPPH tests). These results suggest their good performance as a future food additive. At the same time, they prove the hypothesis that the use of enzyme cocktails rich in laccase is a good choice for biological pretreatment in this process.
查看更多>>摘要：An effective method for the selection of active compounds from cranberry based on counter-current fractionation and bioassay-guided separation was established. Cranberry extract showed potential alpha-glucosidase inhibitory activity. The active compounds were extracted by different solvents and enriched in water. The water extract was divided into eight fractions via high-speed counter-current chromatography to further track the active compounds. Results indicated that the alpha-glucosidase inhibitory activity of F7 was remarkable higher than the other fractions. Four compounds, including delphinidin-3-glucoside (D3G), cyanidin-3-glucoside, cyanidin-3-rutinoside, and pelargonidin-3-glucoside, were separated from F7 through column chromatography, and their structures were identified by high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry, 1H nuclear magnetic resonance (NMR), and 13C NMR. D3G showed the strongest alpha-glucosidase inhibitory activity among the compounds. Moreover, the interaction mechanism between alpha-glucosidase and D3G was clearly characterized and described by spectroscopic analyses and molecular docking. D3G could spontaneously bind with alpha-glucosidase to form complexes through hydrophobic interaction. The secondary structure of alpha-glucosidase changed in varying degrees after complexation with D3G. The alpha-helix and beta-turn contents of alpha-glucosidase markedly decreased, whereas the irregular coil increased. These findings provide a new insight into the interaction between alpha-glucosidase and D3G.
查看更多>>摘要：Refractance Window (RW) is a relatively new drying technique for producing dried powders, slices or leathers from fruits and vegetables. In the present study, the effect of temperature (70, 80 and 90 degrees C) and thickness of puree (2 and 3 mm) on drying characteristics, mass transfer and quality attributes of RW dried banana puree were investigated. Results showed that drying at 90 degrees C reduced drying time (-61-64%) and energy consumption (-30-44%), as compared to drying at a lower temperature (70 degrees C) for both the thickness. The effective diffusion coefficient (Deff) values obtained (2.89 x 10-9 to 8.84 x 10-9 m2/s) using Dincer and Dost analytical approach had higher R2 (0.980-0.991) and lower RMSE (0.029-0.053) values. RW drying at 90 degrees C resulted in higher ascorbic acid retention (-76-78%) with the least total colour change (3.4-6.9) compared to other studied conditions. Besides, retention of total phenolic (10.3 mg GAE/g dm) and flavonoid contents (3.4 mg QE/g dm), as well as antioxidant capacity (58.8 mM TE/g dm), were also better in samples dried at 90 degrees C. The study suggested that drying at a higher temperature during RW not only reduces drying time but also improves retention of quality attributes.
查看更多>>摘要：One significant challenge during the conjugation between protein and polysaccharide via Maillard reaction is to achieve high grafting degree and low browning degree. We developed a novel method called cyclic continuous reaction to resolve this challenge. We prepared soy protein isolate (SPI)-dextran conjugate and used the conjugate to encapsulate curcumin to form nanoparticles to improve curcumin's solubility for enhanced antioxidant capacity. The obtained SPI-dextran conjugates showed a higher grafting degree (42%) and a lower level of browning (0.053 cm-1). Chemical reaction kinetics modeling suggested that Maillard reaction during SPIdextran conjugation is a pseudo zero order chemical reaction. The secondary structure analysis of conjugates suggested that the content of random coil structure increased, indicating that conjugation with dextran increased protein's structural disorder. The tertiary structure analysis indicated that the surface of conjugate molecules showed enhanced hydrophilicity. The curcumin was indeed encapsulated by SPI-dextran conjugate and the formed nanoparticles were stable and possessed a uniform particle size (polydispersity index 0.148). The antioxidant capacity of conjugate-curcumin nanoparticles was more than double of curcumin alone. This novel method opens up tremendous opportunities for the broad protein-polysaccharide synthesis community.
NSTL
Elsevier