查看更多>>摘要：Isothiocyanates (ITCs) derived from Brassicaceae are potential food preservatives. Their antimicrobial ac-tivity is strongly influenced by their subclass and side chain. This is the first quantitative structure-activity relationships (QSAR) study of ITCs as antibacterials. Twenty-six ITCs covering 9 subclasses were tested against Escherichia coli and Bacillus cereus. Minimum inhibitory concentration (MIC) and growth inhibitory response (GIR) were determined and used to develop QSAR models. MIC of the most active ITCs was 6.3-9.4 mu g/mL. The QSAR models were validated with leave-one-out cross validation. The proposed models had a good fit (R-adj(2) 0.86-0.93) and high internal predictive power (Q(adj)(2) 0.80-0.89). Partial charge, polarity, reactivity, and shape of ITCs were key physicochemical properties underlying antibacterial activity of ITCs. Furthermore, ITC compositions and antibacterial activity of Sinapis alba, Brassica napus, B. juncea, B. oleracea, and Camelina sativa extracts were determined, after myrosinase treatment. B. oleracea ITC-rich extract showed promising activity (MIC 750-1000 mu g/mL) against both bacteria. C. sativa ITC-rich extract showed promising activity (MIC 188 mu g/mL) against B. cereus. The QSAR models successfully predicted activity of the extracts based on ITC compositions. The models are useful to predict antibacterial activity of new ITCs and ITC-rich mixtures. Brassicaceae ITC-rich extracts are promising natural food preservatives.
Guo, XiaojuanMcClements, David JulianChen, JunHe, Xuemei...
10页
查看更多>>摘要：A novel "industry-scale microfluidizer system" (ISMS) was used to prepare whole corn slurry (WCS). The impact of processing pressure (0-120 MPa) on the properties of WCS was examined. ISMS preserved the soluble solid content, stabilized the native pH (similar to 7.2), and retained the desirable yellow color of WCS. Moreover, it did not adversely impact the concentration of major nutrients, such as starch (similar to 50 g/100g), protein (similar to 13 g/100g), fat (similar to 8 g/100g) and dietary fiber (similar to 17 g/100g). ISMS also increased the polyphenol content and improved the in vitro antioxidant activity of WCS. Increasing the pressure led to an improvement in the physical stability of WCS, which was linked to the reduction in particle size, increase in viscosity, improved dispersion of the particulate matter and formed network with decreased dimensions. These results suggest that ISMS can be a new processing tool to create whole corn beverages with improved nutritional value, enhanced shelf life, and better functional performance.
查看更多>>摘要：Pouteria lucuma fruit is commonly used to prepare desserts, but it is also sold as pulp or flour. Then, huge amounts of its seeds are produced as agro-industrial waste, frequently eliminated. This study aims at analyzing the presence of all metabolites in Pouteria lucuma seed oil (LSO) by GC-MS and GC-FID. Several compounds were tentatively identified, such as fatty acids, fatty alcohols, carotenes, phytosterols and tocopherols from LSO. A representative result was the high amount of beta-sitosterol with 851.49 +/- 1.29 mg/100 g of LSO, followed by stigmasterol with 75.42 +/- 1.02 mg/100 g. Fatty acids with the highest content were oleic acid (13.57 +/- 1.50 g/100 g of LSO), 9E-octadecenoic acid (6.85 +/- 1.15 g/100 g of LSO), palmitic acid (5.44 +/- 1.18 g/100 g of LSO) and stearic acid (2.12 +/- 1.03 g/100 g of LSO). Therefore, metabolites tentatively identified in Pouteria lucuma seed oil have been linked to healthy properties based on a high amount of beta-sitosterol present. This evidence could determine this agro-industrial waste with having beneficial properties, thus providing great added value.
Rojas Lopez-Menchero, JorgeOgawa, MinamiMauricio, Juan C.Moreno, Juan...
9页
查看更多>>摘要：Yeast cell leakage from the matrix is one of the reoccurring inconveniences of most yeast immobilization systems. Yeast biocapsules are a cost-effective, spontaneous immobilization system whereby yeast cells are attached to the hyphae of a filamentous fungus, creating hollow spheres that allow recovery and reutilization. In an attempt to prevent yeast cell leakage from the fungal matrix, we coated the yeast biocapsules with a 0.2% (w/v) alginate layer and evaluated yeast cell immobilization and the potential to ferment synthetic high sugar medium and grape must. We concluded that alginate coating prevents cell leakage from yeast biocapsules but hinders alcoholic fermentation. In grape must fermentations, alginate coating does not affect wine acidity but impacts concentrations of some volatile compounds.
查看更多>>摘要：The enzyme immobilization process can address some problems associated with the free form (high price of enzyme production, difficulty in the separation of products from reaction media, and lack of reusability). In this study, alpha-amylase was covalently immobilized on the magnetic zeolite (MAZE) particles entrapped in the carboxymethyl cellulose (CMC) composite. The synthesized carrier and immobilized enzyme were fully characterized. The optimal temperature and pH for free enzyme were observed at 30 degrees C and 6.5, respectively. The optimal temperature for both forms of immobilized enzymes did not change after the immobilization process. The optimal pH for immobilized enzyme on MAZE particles had a shift towards basic region (pH 8). The immobilized enzyme into MAZE/CMC composite showed a broad optimum pH of 6.5-8.0 and high storage stability after 40 days of storage at 4 degrees C (78%). The reusability experiment indicated that approximately 45% of the initial activity of both immobilized enzymes remained after 12 times recycling. The K-m and V-max values were slightly changed after both immobilization processes. Finally, it can be proposed that the designed carrier in this study can be used in the industrial production of glucose syrup and electrochemical sensors.
查看更多>>摘要：Plasticised cassava starch films with 1-2% ferulic or cinnamic acid were obtained by melt blending and compression moulding. Partial losses (about 40%) of the more thermo-sensitive ferulic acid occurred during processing. Incorporation of phenolic acids did not provoke remarkable changes in the oxygen and water vapour permeability of starch films, but these became less water soluble (13-25% reduction), more extensible and less resistant to break, especially with the highest concentration of ferulic acid. Films with 2% of either acid effectively inhibited the growth of E. coli and L. innocua in tests carried out in culture medium; being cinnamic acid more effective than ferulic and L. innocua more sensitive than E. coli; a Log CFU reduction, with respect to the control, higher than 6 was obtained for L. innocua with 2% of cinnamic acid in the films. The growth of both strains was also inhibited in chicken breast (log CFU reduction>2) with 2% of either acid. In fresh-cut melon, the L. innocua growth was significantly inhibited by films with 2% cinnamic acid, but lower growth inhibition of E. coli in fresh-cut melon was observed.
查看更多>>摘要：Polysaccharides extracted from fruits and leaves of baobab tree (Adansonia digitata) were assessed for their emulsifying capacity. Emulsions were formed at acidic pH (pH 2.0 and phi = 0.1) and were investigated by means of droplet size distribution analysis, zeta-potential measurements, and interfacial composition analysis. Despite the macromolecular differences of baobab polysaccharides all emulsions were formulated at concentrations resulting in comparable zero shear viscosity of the continuous phase allowing structure vs. function relationships to be made. Emulsions made with fruit polysaccharides formed finer droplets and exhibited good long term stability than those formulated with leaf polysaccharides. Stability was achieved by formation of thick interfacial layers, as evidenced by the large polysaccharide interfacial loading (Gamma(polysaccharide) 13.8 or 20.7 mg m(-2)) that created an effective steric barrier against droplet growth, whereas proteins did not seem to play central role. Fruit polysaccharide emulsification performance at acidic pH was attributed to their compact conformation at the interface that is linked to their structure. Conversely, the presence of rhamnogalacturonan segments in leaf polysaccharides resulted in chain desorption and poor emulsion stability. Overall, it has been shown that baobab fruit polysaccharides could be suitable emulsifiers for a range of technological applications that require low pH stability.
Siaw, Michelle OppongWang, Ya-JaneMcClung, Anna M.Mauromoustakos, Andy...
8页
查看更多>>摘要：Rice kernel hardness is an important characteristic to the rice industry because of the greater economic value of whole kernels over brokens. Rice hardness may be weakened by increased porosity, i.e., void spaces formed from loose interaction between chemical components like starch, proteins and lipids. The objective of this study was to elucidate the impacts of rice proteins and lipids on porosity and hardness via heat treatment and solvent extraction. Brown rice kernels of similar thickness from four cultivars with varying protein and lipid contents were subjected to protein denaturation by heat treatment and/or lipid removal by hexane extraction and then characterized for protein solubility, residual lipids, porosity and breaking force. The results show that although porosity is generally negatively correlated with kernel hardness, porosity was primarily influenced by the quantity of proteins and lipids, whereas kernel hardness was primarily affected by their compositions. The continuity of the protein-starch matrix was the dominant factor that governed kernel hardness. This matrix is proposed to be strengthened by an increase in glutelin content and a decrease in non-polar lipids. This study demonstrates the importance of chemical composition on kernel hardness and elucidates the relationship between porosity and breaking force in rice kernels.
查看更多>>摘要：Aspergillus flavus contamination is of great concern to food safety. Our previous studies demonstrated that recombinant Puroindoline B protein (rPINB) has an inhibitory effect on A. flavus mycelium development. However, fungal contamination often begins with spore germination within food shelf life. Here, rPINB was evaluated for its antifungal properties against A. flavus spores in vivo and in vitro. The results showed that rPINB could inhibit spore formation and aflatoxin B1 of A. flavus on maize. In vitro analysis revealed its dose-dependent antifungal effect on spore germination and germ tube growth of A. flavus. Scanning electron microscopy revealed that rPINB exposure altered spore morphology, indicating it damaged the cell wall. Transmission electron microscopy and the inhibition of ergosterol synthesis further revealed that rPINB exposure significantly damaged the cell membrane. The mitochondrial membrane potential decreased, and DNA fragments were scattered in the cytoplasm as detected using 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolocarbocyanine iodide and 4',6-diamidino-2-phenylindole staining. The direct antifungal activity of rPINB observed both in vivo and in vitro suggests that rPINB may be used to prevent fungal contamination of stored foods and agricultural products in the future.
NSTL
Elsevier