查看更多>>摘要：Effects of various fermentation conditions on fatty acid composition of single cell oil (SCO) from Trichosporon sp. F1-2 were investigated. Ten carbon sources clustered into two groups using hierarchical clustering algorithm and principal component analysis. Xylose and soluble starch from each group were further studied. SCO using xylose had a high oleic acid content, while the linoleic acid and alpha-linolenic acid content increased significantly in SCO using soluble starch especially at the sn-2 position. 20 and 31 triacylglycerol (TAG) types were detected, respectively. The increased types were rich in linoleic acid and alpha-linolenic acid. The effect of C/N ratios was the weakest (distance threshold 3.05), followed by inoculation amounts (3.08), fermentation time (4.30) and nitrogen sources (5.64). The optimum nitrogen source, C/N ratio, inoculation amount and fermentation time for SCO accumulation were ammonium sulfate, 60, 6% and 120 h, respectively. Two different SCOs were produced using xylose and soluble starch under optimum conditions, which were demonstrated to be potential substrates for synthesis of 1,3-distearoyl-2-oleoyl-glycerol (a cocoa butter improver) and MLM-type TAG (the dietary TAG with low caloric value) respectively. Therefore, changing the carbon source can help broaden application fields of SCOs and increase feedstock sources of structured TAG synthesis.
查看更多>>摘要：The main objective of this study was the investigation of different environmental growth conditions on the growth of chalk yeasts, Hyphopichia burtonii (HB), Wickerhamomyces anomalus (WA) and Saccharomycopsis fibuligera (SF). Through multiple methods, including radial growth, biocontrol assay, growth/no-growth modelling and a bread challenge test, the influence of pH (4.5-6.5), temperature (22-30 degrees C), propionic acid (0-0.3%) and presence of other spoilage fungi was assessed. This study showed that pH and temperature does not play a major role on the growth of HB, WA and SF. Only WA shows optimal growth at pH 4.5 and 30 degrees C on MEA. The likeliness of growth is the following: HB > SF > WA, except from WA at pH 4.5/30 degrees C. Biocontrol activity was observed against Aspergillus niger and Penicillium paneum in the presence of high concentrations of HB at 30 degrees C. Furthermore, this study showed that HB is most sensitive to propionic acid (PA), followed by SF and WA. The effectiveness of PA was also shown through bread challenge tests. The following order of sensitivity against PA was observed: HB > SF > WA. Breads inoculated with WA had a shorter shelf-life (2-3 days less).
查看更多>>摘要：Effects of adding resistant starch (RS), inulin (IN) and xylo-oligosaccharide (XOS) on the cooking properties, texture properties, ordered structure of starch, water mobility and in vitro digestion of Yiyang rice cake were investigated. The cooking loss of rice cake was reduced to 2.8-4.6% with the addition of XOS. Addition of these fermentable carbohydrates increased the hardness, viscosity, chewiness and order of starch. As the content of carbohydrates increased, the rice cakes gradually became smoother. RS and XOS promoted the starch retrogradation and the free movement of water in the rice cakes, and increased the ordered structure formed by the association between starch chains; IN had no obvious effect on the retrogradation. Compared with the control group, digestion rate and final digestibility level of the starch digestion model in RS and XOS groups decreased, especially the total amount of available starch of XOS120 decreased to 73.8%, indicating that they had a certain inhibitory effect on starch digestion. The crystallinity formation theories for high-moisture starch gels are not applicable to rice cakes.
Saad, Ahmed M.Mohamed, Alaa S.El-Saadony, Mohamed T.Sitohy, Mahmoud Z....
10页
查看更多>>摘要：This study aimed to produce a palatable functional cucumber juice: non-supplemented cucumber juice, control juice (J-con), and supplemented with different herbal extracts. Four juices were prepared and evaluated, as supplemented with the ethanolic extracts of cinnamon, mint, ginger, and clove denoting as; J-cin, J-min, J-gin, and J-clov, respectively as compared to J-con. HPLC analysis indicated that J-clov followed by J-min were the richest juices in the phenolic and flavonoid compounds compared to control. Pyrogallol, catechin, gallic, and chlorogenic acid were the most prominent phenolics in J-clov, while hesperidin and apigenin-6-arabinose were the most abundant flavonoids. Clove extract showed the highest (p < 0.05) antioxidant activity (80%), followed by the mint extract. Clove and mint extracts significantly reduced the growth of the tested bacteria and fungi. The antioxidant activities in all juices significantly (p < 0.05) decreased during the storage period (0, 2, 4, and 6 months) at 25 degrees C as polyphenols and flavonoids content declined. The pH and vitamin C significantly decreased; however, the titratable acidity increased. Clove and mint extracts (p < 0.05) reduced the decay of total sugars by reducing the microbial load. J-clov showed the highest sensorial taste and flavor scores; however, J-min and Jcin were the best colors.
查看更多>>摘要：Effects of ultrasound (US, 100, 200, 300, 400, and 500 W) and hot water (HW, 25, 40, and 55 degrees C) treatment combination on Rhizopus stolonifer in sweet potato tuberous roots (TRs) were investigated. US (300, 400, and 500 W) simultaneous HW (55 degrees C) for 10 min significantly inhibited colony diameters (from 90 mm to 80.08, 65.60, and 6.00 mm) and spores germination (p < 0.05). US+HW treatment significantly increased the leakage of nucleic acids and proteins (p < 0.05). Scanning and transmission electron microscopy analyses showed that US+HW led to significant damage on the appearance and ultrastructure of R. stolonifer. These damages resulted in crumpled hyphae, thickened cell walls, disappeared membranous organelles, massive vacuolation of the cytoplasm. US500+HW55 treatment could lead to cell membrane permeability increase and mitochondrial membrane potential decrease of R. stolonifer. In addition, US500+HW55 controlled the R. stolonifer development in sweet potato TRs during 20 days of storage at 28 degrees C, suggesting that US500+HW55 effectively inhibited the infection of R. stolonifer. Therefore, US500+HW55 treatment could be an efficient alternative method for storing and preserving sweet potato TRs.
查看更多>>摘要：Wheat Qu contains various microorganisms and is the fermentation starter for rice wine. The impact of geographic location on the volatile compounds and microbial communities in wheat Qu remains unknown. This study demonstrated significant differences in the volatile compound profiles of wheat Qu from different regions of China. Phenylethyl alcohol, hexadecanoic acid methyl ester, 9-octadecenoic acid methyl ester, and 2-octanone were the main volatile compounds detected. The bacterial and fungal communities in wheat Qu also differed significantly according to geographic location with both communities explaining the variation in volatile compounds (bacteria making the greater contribution). The bacterial community was dominated by Pediococcus, Weissella, and Lactobacillus while the fungal community was dominated by Saccharomycopsis and Rhizopus. Bacteria exhibited more significant associations with volatile compounds than fungi did. Prediction of metabolic function demonstrated significantly different profiles for the bacterial communities from different regions. These data showed that geographic location considerably affects the composition of volatile compounds and microbial communities in wheat Qu, with the bacterial community being the main contributor to variation of volatile compounds.
查看更多>>摘要：In this study, we developed a highly sensitive glutamate biosensor based on Pt nanoparticles (PtNP) decorated two-dimensional nanomaterial MXene-Ti3C2Tx for sensitive analysis of monosodium glutamate (MSG) in food samples. The morphology of PtNP@MXene-Ti3C2Tx was characterized by SEM, which confirmed the successful synthesis of the nanocomposite. The electrochemical experiments were carried out after optimizing working conditions, and a linear relationship was established between the current response and MSG content. The biosensor exhibited a good linear relationship with a correlation coefficient (R2) of 0.9948 in a range of 10-110 mu mol/L, and it also had excellent sensitivity (1.5906 nA/(mu mol/L)) and a low detection limit (0.45 mu mol/L). The biosensor exhibited high selectivity towards glutamate, and it could hold over 70% of its initial sensitivity for 28 days when stored under optimal conditions. The analytical recovery of added MSG (50 and 100 mu mol/L) in the vegetable soup was 87.04 and 106.81 g/100 g, respectively. The biosensor was also used successfully to test MSG content in soy sauce, stock cube, and mushroom seasoning. Hence, the constructed glutamate biosensor would be a suitable method for rapid detection of MSG in foodstuffs.
查看更多>>摘要：This study aimed to assess the protective effects of the main components of Zanthoxylum bungeanum Maxim. essential oil (ZBMEO) on the characteristics of rabbit meat myofibrillar protein (MP) under MDA (malondialdehyde) induced oxidation. The MP suspensions were mixed with various concentrations (5 mM, 25 mM and 50 mM) of linalool, limonene, sabinene under MDA-induced oxidation. The retained MDA contents were determined, and the thermal stability and structure of rabbit meat myofibrillar protein were analyzed. Linalool, limonene and sabinene can prevent MDA from binding to MP effectively. The addition of linalool, limonene and sabinene led to the increase in the sulfhydryl and free amine contents, and the decrease in the carbonyl content and surface hydrophobicity compared to control MP. Also, the addition had protective effects on maintaining the secondary structure and morphology of MP under MDA-induced oxidation. The Differential scanning calorimetry (DSC) and SDS-PAGE analysis indicated that linalool, limonene, sabinene had an obvious protective effect on MHC and actin. The above results suggest that linalool, limonene and sabinene could reduce the oxidative damage of MDA to MP, which might have the potential in protecting the structure and physicochemical properties of the protein in foods.
查看更多>>摘要：The effects of cellulose powder and water activity (a(w)) on the equilibrium water content, glass transition temperature (T-g), mechanical relaxation, and caking of freeze-dried amorphous carbohydrate blend powders (dextrin-glucose mixture) were investigated. Water sorption isotherm and T-g-curve were obtained, and critical water activity (a(wc)) was determined as the a(w) at T-g = 25 degrees C. There was a minor effect of cellulose powder on the a(wc). The degree of caking was negligible below the a(wc) (glassy state), but increased remarkably above the a(wc) (rubbery state). Cellulose powder played a dispersive role in the powder, and thus diminished the degree of caking. The caking behavior could be described by a stretched exponential function, and an experimental formula to predict the degree of caking as a function of a(w)/a(wc) was obtained. The results for a food powder, with a more complex composition, largely deviated from the formula. Mechanical relaxation was evaluated as a force-reduction during isothermal compression. It was found that the relationship between the degree of caking and force-reduction could be described as a linear function independent of a(w) and cellulose powder content. The results for the food powder partially followed the linear relationship.
Darmawan, K. KevionKaragiannis, C. TomHughes, G. JeffSmall, M. Darryl...
9页
查看更多>>摘要：This study employs computational techniques to investigate whether the inclusion of beta-lactoglobulin and alpha-lactalbumin can enhance the molecular stability of apo-lactoferrin in conditions of gastric pH. Atomistic molecular dynamics simulations reveal that acidic pH results in weakened interactions between lactoferrin and the other proteins compared to those under neutral pH. Nevertheless, protein-protein dissociation free energy calculations using the umbrella sampling calculations confirm that some contacts are maintained between apolactoferrin and the other whey proteins, specifically the beta-lactoglobulin units. This is manifested as a broad energy minimum at the intermediate inter-molecular distance of the inter-protein free energy profiles; thereby, demonstrating the formation of a nano-scale flocculant, followed by a potential gel, composed of protein particles. Practically, this property could be exploited to entrap further bioactive components within the protein matrix for novel engineered food materials. Furthermore, it was found that the anti-bacterial peptide regions of apo-lactoferrin are unaffected by the acidic pH, indicating the potential capability of apo-lactoferrin to act against harmful bacteria. Overall, this work unveils an understanding at a molecular level regarding the structural changes of the aforementioned proteins that maybe beneficial for future advancement of nutraceuticals.
NSTL
Elsevier