查看更多>>摘要：The Cd and Pb are two typical heavy metal contaminants of agricultural products which have posed great threats to human health. The precise determination of Cd and Pb in agricultural products is extremely important for human health. In this paper, a simple and fast sample preparation method based on ionic liquid treatment was proposed to determine Cd and Pb in dried solid agricultural products by graphite furnace atomic absorption spectrometry (GFAAS). The samples were prepared by dissolving the tested agricultural products into the ionic liquid 1-butyl-3-methylimidazolium chloride. The temperature program and matrix modifiers for GFFAS analysis of these samples were optimized. The reliability of sample preparation was verified by comparing the between- and within-batch precision, which showed no significant differences at 95% confidence level. Detection limits were 0.019 mu g L-1 Cd and 0.042 mu g L-1 Pb for these samples. Results for determining Cd and Pb in these samples were in good agreement with those obtained from the conventional wet digested samples. Both the certified reference materials validation experiments and the spiked and recovery tests indicated this sample preparation for determining Cd and Pb had satisfactory accuracy and could be an alternative to traditional sample preparation.
查看更多>>摘要：Colorimetric indicators produced from nanofibers have a high contact surface area, allowing better interaction of the indicator with the external environment. In this context, this study aimed to develop time-pH indicator nanofibers with natural pigments for use as an emerging technology in the control of food quality. The polymeric solutions were prepared with 13% (w v(-1)) polycaprolactone (PCL) and 6% (w v(-1)) poly (ethylene oxide) (PEO). The natural dyes added to the polymeric solution were curcumin and quercetin (2%, w v(-1)) with the addition of 0.5 or 1% (w v(-1)) of phycocyanin. Solutions with curcumin, quercetin, and phycocyanin only (2% w v(-1)) were also studied. The color change monitoring was performed for 24 h, followed up every 1 h, using buffer solutions (pH 2 to 7). The condition with 2% (w v(-1)) phycocyanin showed a color variation (Delta E >= 5) noticeable to the human eye in the pH range 3-6 in 5 h of analysis. Thus, the indicator developed with PCL/PEO nanofibers containing 2% (w v(-1)) of phycocyanin is a promising alternative in monitoring the quality of perishable foods, as it can visually estimate changes in pH over time.
查看更多>>摘要：This study investigated the impact of air thawing (AT), water thawing (WT) and ultrasound-assisted immersion thawing (UT) at different power levels (200, 300, 400, and 500 W) on the emulsifying and gelling properties of the myofibrillar protein (MP). UT at 300 W (UT-300) significantly improved the solubility and the absolute.-potential value of MP, reduced the turbidity and the particle size of MP, lowered the loss of gel strength and water holding capacity, and promoted the formation of a stable emulsion (P < 0.05). Compared to the AT and WT samples, the UT-300 MP gels had shorter T-21 and T-22, which revealed that UT-300 had reduced mobility and losses of the immobilized and free water. The observation of the gel microstructure indicated that the UT-300 samples had compact and homogeneous MP gel network. As a result, appropriate ultrasonic power reduced the losses of the emulsifying properties (emulsifying activity index and the emulsion stability index) and gelling properties (gel water-holding capacity and gel strength) of MP.
查看更多>>摘要：Different winemaking practices have been tried to improve wine quality and differentiate wine styles. Low temperature fermentation has been proposed to enhance the aroma profile in young red wines. The aim of this work was to study how fermentation temperature affects the chemical composition, the concentration of yeast-derived volatile aroma compounds and the overall quality of young red wines. Thermomacerated Merlot grape must was fermented at 15 degrees C and 25 degrees C using five different Saccharomyces cerevisiae strains. Wines fermented at 15 degrees C displayed higher ethanol concentration, whereas differences in volatile acidity and colour were more related to the yeast strain used than the fermentation temperature. Sensory analysis could discriminate the wines fermented at two temperatures for each yeast tested. Low temperature fermentation produced wines with higher ester and lower terpene content compared to fermentation at 25 degrees C, whereas the fatty acids and higher alcohol concentraions were more associated to the yeast strain employed. In general, wines produced at low temperature were perceived as more aromatic, although this effect was strain-dependent. In summary, we were able to obtain red wines whit improved organoleptic characteristics, by combining thermomaceration and low temperature fermentation with cold adapted autochthonous yeast strains.
Meza, Barbara E.Fernandes, Rubens R.Zorrilla, Susana E.Wilson, D. Ian...
10页
查看更多>>摘要：Aerated icings are a sweet, fat-rich, and uncooked type of glaze material made by whipping sugar and fat together to form a bubbly fluid. The rheological behaviour of full-fat and reduced-fat aerated icings was characterised using rotational rheometry techniques. Control full-fat formulations were prepared using commercial icing sugar and unsalted butter (a viscoplastic fat-based continuous phase) in a 2:1 ratio. Reduced-fat samples were prepared by replacing 25% and 50% of butter by mass by a 50% w/w of native corn starch suspension (a potential carbohydrate-derived fat replacer). Icings with different air volume fractions were prepared by mixing in a planetary mixer for 3 min or 6 min (air volume fractions <= 0.17). The size distribution of sugar crystals and air bubbles were similar, with modal values near 10 mu m. The experimental data from flow curves and creep tests were described well by the Bingham and Burgers models, respectively. Flow behaviour and static yield stress values were affected by the mixing time and the butter replacement, whereas the viscoelastic behaviour was only influenced by the latter. The information obtained in this study can be used to assess whether these reduced-fat products are suitable for the flow and coating stages of manufacturing.
Urcan, Adriana CristinaCriste, Adriana DalilaDezmirean, Daniel SeverusBobis, Otilia...
10页
查看更多>>摘要：Beebread (BB) is a fermented bee product made from plant pollen, honey and bee saliva. The nutritive and biological compounds of BB vary greatly depending on the diversity of flora and the season of pollen collection by bees. In order to evaluate this valuable bee product potential, thirteen BB samples were analyzed on the nutritive proprieties and biologically active compounds, correlated with their botanical origin. The obtained results shows that BB comes with a high content of proteins with values ranging between 18.96 and 23.11 g/100 g, lipids ranging between 4.89 and 14.74 g/100 g, and free sugars, fructose being present in the highest amount (17.27 g/100 g). Analyzed samples contain all the essential amino acids, methionine being the most abundant, 86.93-12.38 mg/100 g, mono- and polyunsaturated fatty acids, omega-6/omega-3 ratio varying between 0.02 - 1.07. BB samples have also high amount of natural antioxidants, from the class of polyphenols and flavonol glycoside derivative. These findings suggest that BB could be used as a source of potential value-added nutrients and bioactive compounds and contributes to the chemical knowledge of this natural product.
查看更多>>摘要：The present study focused on the antimicrobial assessments of Centella asiatica for different extracts (ethanol, methanol, water, and hexane) against Bacillus cereus, Escherichia coli O157: H7, Salmonella enterica serovar Typhimurium, Staphylococcus aureus, Aspergillus niger, and Candida albicans. Ethanol achieved the highest extraction yields, total phenolic, and flavonoids contents, followed by those achieved with methanol, water, and hexane. The ethanolic extract exhibited the highest antimicrobial activity in agar disc diffusion assays. The minimum inhibitory concentrations (MIC) ranged from 7.81 for C. albicans to 125 mg/mL for A. niger. The minimum bactericidal concentration (MBC) was ranged from 15.63 for S. aureus and S. Typhimurium to 62.50 mg/mL for E. coli O157: H7. The minimum fungicidal concentration (MFC) was ranged 7.81 for C. albicans and 250 mg/mL for A. niger. No MBC and MFC could be established for the methanolic and aqueous extract, and the hexane extract did not show any antimicrobial activity. Ethanolic extract could potentially be an alternative for synthetic preservatives against foodborne pathogens.
查看更多>>摘要：The antioxidant activities of protein obtained from selenium-enriched germinated brown rice (Se-GBR) and germinated brown rice (GBR) were evaluated by measuring their ABTS center dot(+) radical scavenging activities and reducing power. Results showed that the antioxidant activity of the Se-GBR protein is higher than that of GBR under all treatment conditions. Heating improved the antioxidant activity of proteins. However, the addition of citric acid, metal ion and salt ion remarkably reduced the antioxidant activities of protein. The ABTS center dot(+) radical scavenging capacity under the conditions of light and sterilization were relatively stable, but the reduction capacity was remarkably reduced. Effects of different cooking methods (normal cooking, microwave cooking and high-pressure cooking) on protein contents, digestibility and interactions of Se-GBR and GBR were investigated. No significant change in protein content was observed after different cooking methods. However, high pressure and microwave cooking weakened the hydrophobic interactions of proteins, which led to the exposure of hydrophobic groups, as well as aggregates and precipitates of protein. Therefore, protein digestibility was decreased. The food processing methods should be considered to maintain the nutritional properties of Se-GBR and GBR proteins effectively.
查看更多>>摘要：The structure and physicochemical properties of a protein have significant effects on its molecular flexibility. Herein, different flexible protein molecules are obtained after ultrasound treatment at different power conditions (0, 200, 400, and 600 W), and the structural and functional changes in the soybean protein isolate (SPI) are determined. The correlation between flexibility (F), surface hydrophobicity (H-0), and emulsifying properties is established. It is demonstrated that ultrasound decreases the alpha-helical content and increases the beta-sheet content of the SPI, thereby increasing its flexibility and sulfhydryl content, and unfolding its tertiary structure. The SPI affords the best solubility, turbidity, surface hydrophobicity, emulsifying activity (EA), and emulsifying stability (ES) when subjected to an ultrasound power of 400 W. The correlation coefficients between flexibility and emulsification performance (0.938 (F:EA) and 0.958 (F:ES)) are significantly higher than those between the surface hydrophobicity and emulsification performance (0.772 (H-0:EA) and 0.883 (H-0:ES)). Therefore, the conformational flexibility of SPI, rather than its surface hydrophobicity, determines its emulsification properties. These findings provide a theoretical basis for understanding the emulsification mechanism of ultrasound-modified proteins, which is important in the food industry.
Phuong Hong LeParmentier, NillsThien Trung LeRaes, Katleen...
9页
查看更多>>摘要：The production of fermented foods enriched with gamma-aminobutyric acid (GABA) is a current trend in the food industry. In this study, the release of free glutamic acid (Glu) and its conversion to GABA in soymilk were conducted through enzymatic hydrolysis using Alcalase (Al) and Flavourzyme (Fl), following by the fermentation using Lb. plantarum LMG6907 (at 30 degrees C for 96 h). Results showed that a degree of hydrolysis of 90% was achieved when soymilk was treated with a mixture of Al:Fl in a ratio 1:1 (final enzyme concentration of 2 mL/100 mL). Both the free Glu and the GABA content were significantly increased in soymilk hydrolysate, which is a product obtained after enzymatic hydrolysis of soymilk. After 72 h of fermentation, the GABA content in soymilk hydrolysate reached 859 mg/L while the remaining Glu was 2467 mg/L. Fermentation of soymilk hydrolysate at the optimal conditions for glutamate decarboxylase activity (initial pH 4.7, 50 degrees C), the enzyme catalyzing the conversion of Glu to GABA, also did not show a higher GABA production.
NSTL
Elsevier