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关键词： Bioflocculant   Flocculation   Proteoglycan RS-89   Rhodococcus opacus  

摘要： The water-soluble fraction of proteoglycan R_S-89 isolated from the Rhodococcus opacus FCL89 and composed of 64.6% polysaccharide and 9.44% protein has been studied as regards its flocculating activity. The R_S-89 polysaccharide component includes mannose, galactose and glucose at the molar ratio of 2.7: 1.3: 1. The basic factors affecting flocculating activity of the R_S-89 have been established. Additionally, the kinetics of kaolin sedimentation without and with the bioflocculant was investigated. The presence of divalent metal ions had a positive effect on the flocculating activity of the R_S-89. The addition of Ca²⁺ increased the R_S-89 flocculating activity in comparison to the other studied metals. It was proved that the proteoglycan R_S-89 achieved the highest flocculating activity at the concentration equal to 2 mg/L and in the presence of 10 mmol/L of Ca²⁺. The zeta potential values are less negative when there is an interaction between the kaolin particles and metal ions without the R_S-89 in the tested systems. Therefore, the proposed mechanism to describe the proteoglycan interaction with kaolin particles in the presence of divalent ions includes charge neutralization and a bridging mechanism. © 2021 The Authors

关键词： Ethanol extract of black soybean coat   Chitosan films   Antioxidant activity   Antimicrobial activity   Active packaging  

摘要： Chitosan (CS) with an ethanol extract of black soybean coat (EBSC) was prepared, and its physicochemical properties and antioxidant and antibacterial activities were tested. The results showed that EBSC significantly increased the thickness and UV-Vis light barrier ability of the CS-based films, while the swelling degree, water vapor permeability, and tensile strength decreased. The CS-EBSC films had smooth surfaces, compact cross-sections, and no cracks, and they had higher crystallinity than the CS film. Fourier transform-infrared spectroscopy indicated that there were noncovalent bonds (hydrogen bonds) between EBSC and CS. Furthermore, the CS-EBSC III film presented a stronger ABTS radical scavenging ability (66.58%) and could effectively inhibit Bacillus subtilis, Escherichia coli, and Staphylococcus aureus. The lipid oxidation test proved that CS-EBSC films significantly reduced the peroxide value of lard. The results above indicate that CS-EBSC films could be used as an active packaging material to improve the shelf life of food.

关键词： Heavy metals   Support vector machine (SVM)   Nitrogen and phosphorus nutrients   Physicochemical indicators   Prediction  

摘要： A novel method of predicting heavy metal concentration in lake water by support vector machine (SVM) model was developed, combined with low-cost, easy to obtain nutrients and physicochemical indicators as input variables. 115 surface water samples were collected from 23 sites in Chaohu Lake, China, during different hydrological periods. The particulate concentrations of heavy metals in water were much higher than the dissolved concentrations. According to Nemerow pollution index (Pi), pollution degrees by Fe, V, Mn and As ranged from heavy (2 <= Pi < 4) to serious (Pi >= 4). The concentrations of most heavy metals were the highest during the medium-water period and the lowest during the dry season. Non-metric Multidimensional Scaling Analysis confirmed heavy metal concentrations had slight spatial difference but relatively large seasonal variation. Redundancy Analysis indicated the close associations of heavy metals with nutrient and physicochemical indicators. When both nutrient and physicochemical indicators were used as input variables, the simulation effects for most elements in total and particulate were relatively better than those obtained using only nutrient or only physicochemical indicators. The simulation effects for As, Ba, Fe, Ti, V and Zn were generally good, based on their training R values of 0.847, 0.828, 0.856, 0.867, 0.817 and 0.893, respectively, as well as their test R values of 0.811, 0.836, 0.843, 0.873, 0.829 and 0.826, respectively;and meanwhile, in both the training and test stages, these metals also had relatively lower errors. The spatial distribution of heavy metals in Chaohu Lake was then predicted using the fully trained SVM models. (C) 2021 Elsevier Ltd. All rights reserved.

关键词： Electron beams  

摘要： The aim of this work was to study the impact of electron-beam (e-beam) irradiation (0.5-2 kGy) on microbiological, physicochemical, and sensory quality of raspberries, over a storage period of 14 days at 4 degrees C. Results showed that irradiation had a significant effect (p < .05) on the reduction of the microbial population, weight loss, and the firmness of raspberries by slightly affecting the pH, TA, and TSS during storage. This effect depends on the used dose. The brightness of irradiated raspberries increased significantly by e-beam doses. The panel preferred raspberries irradiated with 0.5 and 1 kGy. In fact, untreated and treated at 2 kGy samples, showed a sensory degradation of stored raspberries. These results pointed out that e-beam irradiation can be considered as an environmentally friendly postharvest treatment suitable for conservation and preserving the quality of raspberries during storage. Novelty impact statement There is an ever-increasing consumer demand for food obtained by low-processed, more environmentally friendly, and greener preservation techniques to ensure food safety, guarantee high nutritional and organoleptic quality. E-beam irradiation at 0.5 and 1 kGy improved the color and some quality characteristics of raspberries better than control. E-beam irradiation at low doses is a method that may be a substitute and could be used along with conventional methods, providing raspberries quality.

关键词： Starch modification   High-pressure homogenization   Tamarind seed polysaccharide   Starch digestibility   Stability  

摘要： High-pressure homogenization (HPH) and Tamarind seed polysaccharide (TSP) are usually used to change structure and properties of native starch. In this study, native corn starch was treated by HPH at 0, 40, and 80 MPa, respectively, and physicochemical properties of the treated corn starch in the presence of TSP were analyzed. Results showed that TSP molecules interact with the high-pressure homogenized corn starch (40 MPa) to increase viscosity, thermal and freeze-thaw stability, and elasticity of starch paste, and limit starch digestion. After gelatinization, the homogenized starch formed a sponge-like network and stable gel with TSP inclusion. This resulted in a decrease in relative crystallinity from 6.77% to 3.22% (40 MPa treated starch with TSP inclusion) during the retrogradation process. This study showed that the addition of TSP to HPH treated corn starch can improve the thermal and freeze-thaw stability of the gel and delay the digestion and retrogradation of the starch.

关键词： Sensory analysis  

摘要： This study was conducted to investigate the functional properties of ice cream incorporated with encapsulated Nigella sativa seed oil (NSO). Incorporation of NSO microcapsules into ice cream at 3% and 5% (w/w) resulted in significant changes in the pH, acidity, antioxidant activity, and phenolic content of the samples. The most pronounced outcome of phenolic incorporation was a notable improvement in the antioxidant activity and the phenolic content of ice creams. The overrun, melting resistance, cohesiveness increased along with trace elements like Fe and Zn with high NSO microcapsules incorporation. In contrast, no notable change was observed in the firmness of the control and ice cream with 3% NSO microcapsules. SEM images of microcapsules showed slab-like irregular shapes. Given the functional and nutritional developments in ice cream with generally acceptable results of oxidative stability and sensory analysis, it is concluded that enrichment with NSO microcapsules up to 3% (w/w) can be functional. Novelty impact statement The interest in adding beneficial compounds such as antioxidants, phenolics, phytosterols, etc. to dairy products has been a global trend in recent years. Hence Nigella sativa seed oil microcapsules (up to 3% (w/w)) can be used as an ingredient in ice cream production because of providing functional and nutritional developments along with acceptable results of oxidative stability and sensory analysis.

关键词： Spinach powder   Dough and bread preparation   Rheological properties   Antioxidant activity  

摘要： An adequate intake of dietary fiber in baked foods with appropriate physiological functions is beneficial to human health. The spinach powder (1, 2, and 3 g/100 g) was supplemented with refined wheat flour to investigate its effect on physicochemical and antioxidant properties of bread. The mixing, pasting, and rheological properties of dough, as well as physical, antioxidant, and sensory properties of bread were analyzed. Results showed that water absorption%, stability and development time, protein weakening, and starch crystallinity of spinach samples increased to 62.40%, 5.92/min, 2.05/min, 0.76 Nm, and 0.21 Nm. The peak viscosity, final viscosity, setback, and breakdown values were significantly decreased to 2205.71, 2485.05, 1122.74, and 843.36 cP, respectively. Samples exhibited the highest elastic (218017 Pa) and viscous (94257.76 Pa) moduli and the lowest specific volume (3.12 cm3/g), color attributes, and sensorial properties. Furthermore, breads stored for different periods showed the minimum hardness (4151.67 N), chewiness (826.33 N), and resilience (0.08) compared to control. In addition, the 2,2-diphenyl-1-picrylhydrazyl, ferric reducing antioxidant power, and 2,2 '-azino-bis 3-ethylbenzothiazoline-6-sulfonic acid properties were also significantly improved in corresponding samples. Findings suggest that incorporating spinach into wheat flour could be a viable approach to produce healthy bread enriched with fiber, protein, and antioxidants.

关键词： Pistachio milk   Pistachio slurry   Ultrasonic power   RSM   Freeze-thaw   Oxidative stability  

摘要： Pistachio milk, as a non-dairy nutraceutical beverage, is a thermodynamically unstable colloidal system. So, this study aimed to optimize pistachio milk production in terms of pistachio slurry (20-40%), emulsifier content (0.5-1%), and ultrasonic power of 200-400 W as independent variables using response surface methodology based on particle size and polydispersity index (PDI) as responses. Moreover, the influence of environmental treatments (pH variation, freeze-thaw cycles, and different temperatures) and 28-day storage (at 4 and 20 degrees C) was evaluated on physicochemical properties of the optimum formula. The results showed an increment in pistachio slurry (%) had a positive relationship with particle size and its PDI, despite the emulsifier enhancement. The software, based on central composite design, selected the pistachio milk containing 28.5% pistachio slurry, 1% emulsifier produced by 200 w ultrasonic power as the best sample. It found that the acidic pH, continuous freeze-thaw cycles, and temperature increment decreased the particle charge and elevated the size and PDI of the sample leading to low colloidal stability. Furthermore, the storage data showed the colloidal and oxidative stability of the specimen reduced during the time, even though the samples stored at 4 degrees C were more stable.

摘要： Perilla seed oil (PSO) has a special aromatic odor, which is unpleasant to the personal preferences of some consumers. To this end, this article evaluated the differences in volatile organic compounds (VOCs), physicochemical characteristics, and fatty acid composition of PSO treated with ethanol (PSO-EA), activated carbon (PSO-AC), and activated kaolin (PSO-AK). The results showed that in the PSO, PSO-EA, PSO-AC, and PSO-AK samples, the content of linolenic acid, oleic acid, and linoleic acid hardly changed. Among the physicochemical characteristics of the four samples, the color difference between PSO and PSO-EA was greater than the color difference between PSO and PSO-AC, PSO-AK. The three treatment methods had the greatest impact on the PSO peroxide value but had little effect on other indicators. Gas chromatography-ion mobility spectrum results identified 28 known volatiles, of which aldehydes, alkenals, alcohols, ketones, and esters were the main groups. Fingerprint analysis found that PSO had an aromatic odor, which includes 1-hexanol, hexanal, and 2-pentylfuran;the removal effect of ethanol on VOCs in PSO was better than that of activated carbon and activated kaolin. The difference between the four oil samples was found from the strength of the VOCs' signals in a two-dimensional map. From the principal components analysis and the "nearest neighbor" fingerprint analysis, it was found that PSO is generally quite different from PSO-EA, PSO-AC, and PSO-AK, while in the "nearest neighbor" fingerprint analysis, PSO-AC and PSO-AK are similar in general. In short, PSO will have better applications in the food field. Practical Application Treatment of PSO with ethanol, activated carbon, and activated kaolin is conducive to the comprehensive utilization of edible resources. In this work, ethanol, activated carbon, and activated kaolin were used to remove VOCs in PSO, and PSO-EA, PSO-AC, and PSO-AK were obtained. The perilla seed oil after these three treatment methods

关键词： Poly (vinyl alcohol)   Guar gum   AgNPs   Antibacterial   Degradable packaging  

摘要： In this study, we prepared Poly (vinyl alcohol) (PVA)/Guar gum (GG) based nanocomposite films with a different weight ratio of silver nanoparticles (AgNPs) via in situ approach using GG itself as a reducing agent and PVA as a capping as well as stabilizing agent at room temperature. The in situ synthesized AgNPs in the PVA/GG matrix was confirmed by surface plasmon resonance (420 150 nm) and SEM-EDAX analysis. The average size of AgNPs was found to be 10 nm determined by XRD. The light transmittance is greatly influenced by the AgNPs. At an optimal concentration of AgNPs (6.8 mg), PVA/GG/Ag nanocomposite films showed improved tensile properties (Ts-23.93 MPa) and the water vapor transmission rate. The incorporation of AgNPs has significantly enhanced the hydrophobicity (similar to 77%) as well as the thermal stability (similar to 61.39%) of the PVA/GG film. The overall migration rate of the nanocomposite films with the three food simulants was shown significantly below the permitted limit of 10 mg/dm(2). Further PVA/GG/Ag nanocomposite films showed a lower soil burial degradation rate than PVA/GG film and good antibacterial properties against environmental microorganisms such as S. aureus and E. coli bacteria. The results suggest that the prepared films can be used as promising food packaging materials. [GRAPHICS] .