查看更多>>摘要：Xinjiang is the main production area of figs in China. In this work, three different methods (SDE, SAFE, and SPME) were employed to extract the volatile compounds from Xinjiang dried figs. The exactions were then analyzed using aroma extract dilution analysis (AEDA) based on gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O). Seventy-five aroma-active compounds were identified with flavor dilutions (FD) factors ranging from 1 to 2187. Aroma compounds with odor activity value (OAV) greater than 10 were subsequently used in aroma reconstitution and omission experiments. Based on instrumental analysis and sensory evaluation, 22 compounds were identified as the key aroma compounds and eight of these were evaluated as the most important aroma contributors of Xinjiang dried figs, including heptanal, nonanal, linalool, benzyl benzoate, styrene, eugenol, 2-methoxy-4-vinylphenol, and vanillin. Moreover, three volatile components, including 2-methoxy-4-methylphenol, 2-methoxy-4-vinylphenol and ortho-guaiacol, were identified as key aroma compounds of dried figs and have not been reported previously.
Leca, Joao M.Pereira, VandaMiranda, AndreiaVilchez, Jose Luis...
6页
查看更多>>摘要：The occurrence of ethyl carbamate (EC) in fortified wines was studied testing different model wines under accelerated ageing (45 degrees C for 4 months and 70 degrees C for 1 month), to investigate the possibility of arginine (Arg) being a direct precursor of EC in fortified wines, comparing it with known major precursors, urea and citrulline (Cit). Wine main sugars were appraised as possible catalysts, as previously pointed out. Model wines showed that: Arg can induce the EC formation under accelerated ageing, even without being metabolised by microorganisms; although much less reactive, Arg can play a significant role since high residual levels can occur in young fortified wines; glucose (Glc) and fructose (Fru) suppressed the EC formation from urea and Cit pathways, in about 11-26%. Moreover, Madeira wine samples were investigated in order to appraise the eventual contribution of the alcoholic fortification. The results revealed that this step can promote a decrease of the amount of these EC precursors up to 46%. Despite preliminary, additional information about the EC formation in fortified wines was obrained namely for designing new mitigation strategies, which can pass through the reduction of residual Arg.
查看更多>>摘要：To tackle the issue of non-sugar compounds reduction in sugar beet molasses towards improved sugar recovery and complete molasses valorisation, various treatments were developed. As a step forward to sustainability, this study explores the applicability of alkaline hydrogen peroxide treated sugar beet pulp (AHPSBP) and commercial cellulose-based adsorbents for molasses purification by monitoring the changes in molasses colour, turbidity and sucrose content. Treatment conditions defined by Box-Behnken design were pH (3-7), molasses dry substance (30-50 degrees Brix), and adsorbent concentration (9-21 g/L) with constant treatment temperature. Favourable con-ditions for molasses colour reduction were acidic and neutral environment for commercial adsorbents (4.9-27.1%) and AHPSBP (20.3-32.7%), respectively. Turbidity reduction was higher than 90% in neutral environment regardless of applied adsorbent with minimal detected sucrose content reduction. AHPSBP exhibited greater potential regarding molasses colour and turbidity reduction compared to commercial adsor-bents obtained at favourable pH with lower applied concentrations.
查看更多>>摘要：Yersinia enterocolitica (Y. enterocolitica) is an important foodborne pathogen that causes gastrointestinal syndromes. The objectives of this study were to examine the incidence of Y. enterocolitica strains in food samples in China and determine their genotypes, in addition to assessing their antimicrobial resistance and pathogenic potential. From June 2015 to June 2016, a total of 1588 food samples were obtained, and 37 (2.33%) were found to be contaminated with Y. enterocolitica. A total of 51 different Y. enterocolitica strains were isolated. All isolates belonged to biotype 1A, and the predominant serotype was O:5. All strains lacked the ail, virF, ystA, and yadA virulence genes, but most strains (>75%) harbored the ymoA, sat, hreP, fepD, and fes genes. Over 85% of the 51 isolated strains were sensitive to tetracycline, trimethoprim/sulfamethoxazole, and chloramphenicol, whereas they were resistant to ampicillin and amoxicillin/clavulanic acid. Furthermore, all the strains were divided into seven clusters according to the results of the enterobacterial repetitive intergenic consensus-polymerase chain reaction. Our research emphasizes, for the first time, that more stringent cold storage methods may increase the risk of Y. enterocolitica contamination.
查看更多>>摘要：The aim of this work was to develop novel hybrid nanocarriers made of liposomes coated with chitosan (CS) cross-linked with sodium tripolyphosphate (TPP), named CS-TPP/liposomes, for fish-purified antioxidant peptide fractionated by RP-HPLC (F5). The produced nanodispersion (peptide-loaded CS-TPP/liposomes) was characterized by dynamic light scattering (DLS), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FT-IR) spectroscopy, and differential scanning calorimetry (DSC). The mean nanoparticle sizes of these uncoated and CS-TPP coated liposomes were found to be 409.2 and 687.4 nm, respectively, and the obtained polydispersity index (PDI) was <= 0.2. HRTEM revealed the spherical shape and smooth surface of the produced peptide-loaded nanovesicles. FT-IR spectroscopy revealed that the liposomes have been successfully coated by CS-TPP. In addition, DSC findings indicated enhanced electrostatic interactions among CS and lecithin molecules, leading to an increase in the melting (T-m) and decomposition temperature (T-d) in peptide-loaded CSTPP/liposomes hybrid system. Furthermore, the antioxidant activity of the loaded fish-purified antioxidant peptide to CS-TPP/liposomes was retained as confirmed by the employed free radical scavenging assay. The proposed hybrid system represents a promising idea for the delivery of protein hydrolysate and peptide fractions thereof in nutraceutical and functional foods applications.
查看更多>>摘要：In this study, SERS coupled with chemometric algorithms like PLS (partial least square), Si-PLS (synergy intervalPLS), GA-PLS (genetic algorithm-PLS) and UVE-PLS (uninformative variable elimination-PLS) were applied for the detection of 2,4-D and imidacloprid in milk. The fabricated gold and silver core-shell nanoflowers (Au@Ag NFs) were used as SERS nanosensor which exhibited strong signal over the concentration range of 1.0 x 10(-3) to 1.0 x 10(2) ng/mL. Performances of the models were evaluated based on the attained correlation coefficients of the prediction (R-p) and calibration (R-c), root mean square error in calibration (RMSECV) and prediction (RMSEP), and the ratio of sample standard deviation to RMSEP (RPD). The models exhibited improved results in the order of PLS < Si-PLS < GA-PLS < UVE-PLS. The UVE-PLS model showed superior performance, yielded R-c = 0.9801 and R-p = 0.9878 with RPD = 6.32 for 2,4-D, and R-c = 0.9732 and R-p = 0.9726 with RPD = 4.30 for imidacloprid. The strategy could be employed for safety and quality monitoring of milk.
Araujo-Rodrigues, Helenados Santos, Maria Teresa P. G.Martins, Antonio P. L.Alvarenga, Nuno...
10页
查看更多>>摘要：Serpa is an ovine raw milk cheese widely appreciated by the consumers. However, raw milk products may be seen with reservations in terms of safety or technological defects. To overcome that, the addition of an autochthonous starter culture may ensure the cheesemaking process optimization and microbiota dominance. In this work, the technological and protective performance of eleven lactic acid bacteria strains, isolated from Serpa Protected Designation of Origin cheese and reported as generally recognized as safe, were screened. The integration of technological and protective properties studied in the PCA plot, coupled with the proteolytic and lipolytic analysis suggested that Lb. plantarum PL1 and PL4 strains may be the best candidates. These strains showed both proteolytic and lipolytic activities, a good acidification potential, low D-lactic acid production and were well adapted to the salt and temperatures used. PL1 strain also exhibited a higher antimicrobial effect against the pathogenic bacteria studied. Although Lb. paracasei strain showed lower acidification capacity, due to their technological and protective properties, it could be combined with other more acidifying strains. As future work, it is important to establish cheese model systems to complement this screening and implement an autochthonous starter culture.
查看更多>>摘要：Increased consumer demand to reduce or replace animal-derived food products with more sustainable plant options has created new opportunities for pulse research. Pulses are important sources of proteins and fiber but widespread applications in Western diets have been limited due to the presence of off-flavours. Volatile and nonvolatile off-flavour compounds contribute to beany and grassy aromas that are unacceptable to consumers. Research focused on studying off-flavours has primarily utilized high performance liquid chromatography and gas chromatography to help characterize these compounds. Recent reviews on pulses have summarized the development and classification of off-flavours in pulses, but to date no systematic reviews have focused on the analytical instruments used to evaluate off-flavours compounds in pulses and their by-products. In this review, the main chromatography approaches used to study off-flavour compounds present in pulses and their byproducts will be discussed. Special emphasis will be paid to analytical instrument and method variation between studies. Complexities in the off-flavour analysis of pulses will also be addressed. Lastly, gaps in the literature and opportunities for future research will be suggested.
查看更多>>摘要：Understanding fat structure and mechanical properties is crucial for the processing and mouthfeel of fat-rich foods. In this study, we systematically explored the impact of changes in the composition of fully hydrogenated palm kernel oil (FHPKO) on its crystallization behavior, nano/microstructure, and mechanical properties by blending with 1, 2, 3, 4, 5, 10, and 20% triolein (OOO). Changes in the triglycerides (TAGs) composition of FHPKO affected its crystal habit and therefore its functionality. The lower melting unsaturated OOO remarkably increased the onset of crystallization temperature and time of FHPKO, particularly with the addition of 10% and 20% OOO. The addition of OOO also slowed down the nucleation and crystal growth rate owing to the dilution of the high-melting point TAGs. X-ray diffraction analysis showed a similar lamellar longitudinal size for all fat blends. However, the crystal domain size increased with the addition of OOO, which was caused by an increase in the amount of liquid oil between the lamellae. In addition, large crystal particles were observed with an increase in OOO content, leading to a weak interaction between the clusters with a low fractal dimension, thus reducing the strength of the mechanical properties of the fat crystal network.
查看更多>>摘要：Diacylglycerol (DAG) is functional oil with many beneficial effects. However, the current approaches for DAG preparation face the problems of the low utilization rate of substrates and producing large amounts of by-product. Here, we report a novel approach for simultaneous preparation of edible quality medium and high purity DAG by combining enzymatic partial hydrolysis and a novel partial glyceride lipase (PGL)-catalyzed esterification. Firstly, four lipases were screened for their capability in DAG preparation by partial hydrolysis and Lipase DF "Amano" 15 was the best. Under the optimal conditions, scale-up reaction was performed and residues containing 55.2% DAG were obtained after molecular distillation. Subsequently, the collected distillates were used as substrate for DAG synthesis by a novel PGL-catalyzed esterification and PGL AOL-V269D was selected. Under the optimized conditions, scale-up reaction was performed and residues containing 99.3% DAG were obtained after molecular distillation. The collected distillates were recycled for further DAG synthesis. Finally, the obtained medium and high purity DAG were characterized, lacking glycidyl esters and 3-chloro-1,2-propane-diol esters, and with low acid and peroxide value reaching the edible quality. Overall, the proposed novel procedure enabled the substrates to be used extensively without by-product production.
NSTL
Elsevier