RESUMEN

The structural and functional changes of starch during hydrothermal treatment are influenced by its intrinsic properties. However, how the intrinsic crystalline structures of starch affect changes in structure and digestibility during microwave heat-moisture treatment (MHMT) has not been well understood. In this study, we prepared starch samples with varying moisture content (10 %, 20 %, and 30 %) and A-type crystal content (4.13 %, 6.81 %, and 16.35 %) and investigated the changes in their structures and digestibility during MHMT. Results showed that starch with a high A-type crystal content (16.35 %) and moisture levels of 10 % to 30 % exhibited less ordered structures after MHMT, while starches with lower A-type crystal content (4.13 % to 6.18 %) and moisture content of 10 % to 20 % showed more ordered structures after treatment; but less ordered structures when the moisture content was 30 %. All starch samples had lower digestibility after MHMT and cooking; however, starches with lower A-type crystal content (4.13 % to 6.18 %) and moisture content of 10 % to 20 % displayed significantly lower digestibility after treatment compared to modified starches. Accordingly, starches contained content of A-type crystals of 4.13 %-6.18 % and moisture of 10 %-20 % potentially had better reassembly behaviors during the MHMT to slow starch digestibility in a larger magnitude.

Asunto(s)

RESUMEN

It is highly desirable to improve the anti-slipping stability of the crimping structure for a reliable connection. This study innovatively presents a biomimetic strategy for designing a high-performance crimping structure for industrial hose assembly based on evidence that the special infundibulum dentis structure on the occlusal surface of ruminant molars has the potential of anti-slippage and can also reduce the risk of stress concentration. Utilizing reverse engineering technology, the three-dimensional (3D) digital model of the bovine molar was built as a representative prototype, and then corresponding characteristics of the infundibulum dentis were extracted with a fitting method for the bionic design of the crimping structure. Numerical simulations and experimental results both indicate that the bionic crimping structure has high resistance to slippage of hose body compared with the traditional type, and further, the formation mechanism of bionic anti-slipping performance was discussed.

RESUMEN

In this study, a comprehensive analytical method based on gas chromatography-tandem mass spectrometry (GC-MS/MS) was developed for the determination of nine N-nitrosamines in animal derived foods. There are many kinds of N-nitrosamines in foods that are harmful to human health. However, the national standard GB 5009.26-2016 pertains only to the detection of N-dimethylnitrosamine; there are many drawbacks of this method, such as complicated sample preparation, low recovery rate, and poor reproducibility. Hence, it is of practical significance to establish a method for the simultaneous determination of a variety of N-nitrosamines. The optimal extraction conditions for the developed method were as follows: 10.0 g aliquots of the sample were placed in a 50 mL centrifuge tube, followed by the addition of 10 mL acetonitrile and 200 µL internal working standard solutions. After 30 min of freezing treatment, 4 g magnesium sulfate and 1 g sodium chloride were added for dehydration, and the tube was centrifuged at 9000 r/min for 5 min. After vortex centrifugation, 5 mL of the clear supernatant was purified using 150 mg polystyrene divinylbenzene (PLS-A). The purified extracts were dewatered using 1.6 g MgSO4 and 0.4 g NaCl, and then filtered through a 0.22 µm membrane filter unit prior to GC-MS/MS analysis. Temperature-programmed was applied at an initial temperature of 50 ℃. After 0.16 min, the temperature was raised to 220 ℃ at the rate of 900 ℃/min for 5 min. N-Nitrosamines were separated on an HP-Innowax column (30 m×0.25 mm×0.25 µm). Identification and quantification were achieved using an electron impact ion (EI) source in positive ion mode with multiple reaction monitoring (MRM). The internal standard method was used to quantify the N-nitrosamines. Under the optimal conditions, the correlation coefficients of the standard calibration curves were not less than 0.99 in the range of 0.1-50.0 µg/L. The limits of detection were 0.03-0.30 µg/kg (S/N=3), and limits of quantification were 0.15-1.00 µg/kg (S/N=10). At spiked levels of 0.5, 1.0, and 3.0 µg/kg, the average recoveries of N-nitrosamines in spiked samples ranged from 80.4% to 98.5%, with relative standard deviations between 2.41% and 12.50%. This method was used to determine animal derived food products, except N-itrosomethylethylamine and N-nitrosomorpholine, others were founded. The results showed that N-nitrosamines levels in salted aquatic products were generally higher than those of the other samples. The method established in this study is simple to operate, and it does not require any time-consuming distillation extraction. Furthermore, there is minimal consumption of samples and reagents; consequently, the experiment cost is reduced, and the method is environmentally friendly. This method has theoretical and practical significance for the control of N-nitrosamines residues in animal derived foods, establishment of detection standards, and corresponding management measures.

Asunto(s)

RESUMEN

BACKGROUND: Rice is a typical monocotyledonous plant and an important cereal crop. The structural units of rice flowers are spikelets and florets, and floral organ development and spike germination affect rice reproduction and yield. RESULTS: In this study, we identified a novel long sterile lemma (lsl2) mutant from an EMS population. First, we mapped the lsl2 gene between the markers Indel7-22 and Indel7-27, which encompasses a 25-kb region. The rice genome annotation indicated the presence of four candidate genes in this region. Through gene prediction and cDNA sequencing, we confirmed that the target gene in the lsl2 mutant is allelic to LONG STERILE LEMMA1 (G1)/ELONGATED EMPTY GLUME (ELE), hereafter referred to as lsl2. Further analysis of the lsl2 and LSL2 proteins showed a one-amino-acid change, namely, the mutation of serine (Ser) 79 to proline (Pro) in lsl2 compared with LSL2, and this mutation might change the function of the protein. Knockout experiments showed that the lsl2 gene is responsible for the long sterile lemma phenotype. The lsl2 gene might reduce the damage induced by spike germination by decreasing the seed germination rate, but other agronomic traits of rice were not changed in the lsl2 mutant. Taken together, our results demonstrate that the lsl2 gene will have specific application prospects in future rice breeding. CONCLUSIONS: The lsl2 gene is responsible for the long sterile lemma phenotype and might reduce the damage induced by spike germination by decreasing the seed germination rate.

Asunto(s)

RESUMEN

Common wild rice (Oryza rufipogon Griff.) represents an important resource for rice improvement. Genetic populations provide the basis for a wide range of genetic and genomic studies. In particular, chromosome segment substitution lines (CSSLs) are most powerful tools for the detection and precise mapping of quantitative trait loci (QTLs). In this study, 146 CSSLs were produced; they were derived from the crossing and back-crossing of two rice cultivars: Dongnanihui 810 (Oryza sativa L.), an indica rice cultivar as the recipient, and ZhangPu wild rice, a wild rice cultivar as the donor. First, a physical map of the 146 CSSLs was constructed using 149 molecular markers. Based on this map, the total size of the 147 substituted segments in the population was 1145.65 Mb, or 3.04 times that of the rice genome. To further facilitate gene mapping, heterozygous chromosome segment substitution lines (HCSSLs) were also produced, which were heterozygous in the target regions. Second, a physical map of the 244 HCSSLs was produced using 149 molecular markers. Based on this map, the total length of substituted segments in the HCSSLs was 1683.75 Mb, or 4.47 times the total length of the rice genome. Third, using the 146 CSSLs, two QTLs for plant height, and one major QTL for apiculus coloration were identified. Using the two populations of HCSSLs, the qPa-6-2 gene was precisely mapped to an 88 kb region. These CSSLs and HCSSLs may, therefore, provide powerful tools for future whole genome large-scale gene discovery in wild rice, providing a foundation enabling the development of new rice varieties. This research will also facilitate fine mapping and cloning of quantitative trait genes, providing for the development of superior rice varieties.

RESUMEN

A rapid and sensitive method was developed for the determination of 23 phthalates in food samples including milk-based products, distilled liquor, wine, beverage, grain, meat, oil, biscuit (cookie), and canned food by liquid chromatography tandem mass spectrometry (LC-MS/MS). Liquid samples were exacted by acetonitrile, while solid samples were prepared by QuEChERS or glass-based SPE methods. The 23 phthalates were separated on Poroshell 120 EC-C18 column and followed by positive electrospray ionization as well as multi-reaction monitoring provided by a triple-quadrupole tandem mass spectrometer. To reduce contamination, the plastic materials were avoided in sample handling and preparation . The LODs were between 0.8 and 15 µg kg(-1) and LOQs were between 10 and 100 µg kg(-1). By using different concentrations: 100, 500, and 1000 µg kg(-1)) for DINP and DIDP; 50, 100, and 1000 µg kg(-1) for other 21 phthalate compounds, the spiked recoveries were within 75.5-115.2% and the relative standard deviations (RSDs) were in the range of 3.2-18.9%. The proposed protocol was then applied to the analysis of 623 real samples collected from the two sides of the Taiwan Straits, and the DEHP was found in almost all samples tested in this study, with levels ranging from 0.02 to 2685 mg kg(-1). The present study demonstrated a rapid, sensitive, and accurate method for determining 23 phthalates in foodstuffs.

Asunto(s)

RESUMEN

The yield and quality of rice are directly impacted by floral organ development in rice. Understanding of the floral development mechanism will be useful in genetic improvement of yield and quality. In this study, a rice mutant palea degradation 2 (pd2) in an indica cultivar '8PW33' was obtained after 60Co γ-ray treatment. Analysis of the mutant showed that, compared to the wild type, plant height, total grain number per panicle, and sword leaf width were significantly increased, but the seed setting rate were significantly decreased. The florets of the mutant exhibited degraded palea and sickle-shaped tortuous lemma. Detail examination using scanning electron microscopy revealed that when epidermis of the vane and lemma were normal, epidermis of the palea were arranged tightly, which might result from degraded palea. Genetic analysis supported that this mutation phenotype was controlled by a single recessive gene. Polymorphic analysis of simple sequence repeat markers demonstrated that PD2 gene is located on chromosome 9. With a larger mapping population and more indel markers, we further mapped PD2 gene between 2 indel markers with a physical region of about 82 kb. Within this region, there is a cloned gene REP1 known to control rice palea development. By comparing the DNA sequences of REP1 from pd2 and 8PW33, in combination with the results of phenotypic analysis, we concluded that PD2 is an allele of REP1.

Asunto(s)

RESUMEN

A method for the simultaneous determination of 23 phthalate esters in food samples by solid-phase extraction coupled with gas chromatography-mass spectrometry (SPE-GC-MS) was developed and evaluated. The samples were extracted with hexane or acetonitrile, and cleaned up with a glass ProElut PSA SPE column. The identification and quantification were performed by GC-MS in selected ion monitoring (SIM) mode. The extraction processes of different foods were investigated. The calibration curves of phthalate esters showed good linearity in the range of 0.05-5 mg/L (0.5-5 mg/L for diisononyl phthalate (DINP), diisodecyl-phthalate (DIDP)) with the correlation coefficients (r) between 0.984 8 and 0.999 6. The limits of detection of phthalate esters in food samples ranged from 0.005 to 0.05 mg/kg (S/N = 3) and the limits of quantification ranged from 0.02 to 0.2 mg/kg (S/N = 10). The average recoveries of 23 analytes spiked in 10 kinds of food matrices ranged from 77% to 112% with the relative standard deviations (RSDs, n = 6) of 4.1%-12.5%. The method is suitable for the determination of 23 phthalate esters simultaneously in foodstuffs with easy operation, high accuracy and precision.

Asunto(s)

RESUMEN

An effective multi-residue method for the trace analysis of fipronil and four metabolites (fipronil-desulfinyl, fipronil-sulfide, fipronil-sulfone and fipronil-carboxamide) in tea was developed based on solid-phase microextraction coupled with gas chromatography (SPME-GC). The targets were extracted with a fused-silica fiber coated with 85 microm polyacrylate (PA). The extraction was performed in a pH 9 buffer (containing 0.1 mol/L boracic acid, 0.1 mol/L KCI and 0.1 mol/L NaOH) at 60 degrees C and under 2500 r/min for 30 min. With the concentration range of 2-10 microg/kg, the recoveries ranged from 71.2% to 109.3% and the relative standard deviations (RSDs) were lower than 10% (n = 6). The limits of detection (LODs) and limits of quantitation (LOQs) of the studied compounds ranged from 0.3 microg/kg to 1.2 microg/kg and 1.0 microg/kg to 4.0 microg/kg, respectively, with the values well below the residue limits set by Japan, European Union and China. By the proposed method, 1 positive samples of 30 tea samples were found with fipronil and fipronil-sulfone. The identification of the method was done by gas chromatography-mass spectrometry (GC-MS). The method can be applied as a monitoring tool for tea, in the investigation of food to fipronil and its metabolites.

Asunto(s)

RESUMEN

A pH sensitive polymer was prepared by copolymerization of methacrylic acid as monomer, diethylene glycol dimethacrylate as cross-linking reagent, heptane as porogen, and fluorescent dye eosin as indicator. The factors of influence on the preparation, and the character of the pH sensitive polymer for pH were studied. The maximal emission wavelength of eosin was red shifted in the polymer than in solution, the apparent Ka largened, and the dissociation equilibrium of indicator was shifted to acidity direction, because the polarity of polymer diminished. Under the optimal condition, the calibration curve of the pH sensitive polymer covered the range of pH 0-3.0 with good reproduction and reversibility.

Asunto(s)