Calcium ion regulation of sodium alginate in pure buckwheat noodles shown by in vitro simulated digestion

The effects of calcium sodium alginate on quality and starch digestion of pure buckwheat noodles were investigated. The incorporation of calcium ions into noodles containing sodium alginate was found to reduce water absorption by the noodles during cooking, together with an increase of the turbidity. Calcium addition improved the noodle texture, as shown by the measurement of hardness, elasticity, adhesion, and chewability. In vitro simulations of digestion showed that calcium ion cross-linking with sodium alginate reduced glucose formation by approximately 23.3 mg/g. X-ray diffraction and Fourier transform infrared spectroscopy showed alterations in the crystal zone of the noodles induced by an alginate gel network, although no new chemical substances were generated. Noodles prepared by this exogenous method may be useful as functional foods for patients with diabetes

On-Site Quantification and Infection Risk Assessment of Airborne SARS-CoV-2 Virus Via a Nanoplasmonic Bioaerosol Sensing System in Healthcare Settings

On-site quantification and early-stage infection risk assessment of airborne severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with high spatiotemporal resolution is a promising approach for mitigating the spread of coronavirus disease 2019 (COVID-19) pandemic and informing life-saving decisions. Here, a condensation (hygroscopic growth)-assisted bioaerosol collection and plasmonic photothermal sensing (CAPS) system for on-site quantitative risk analysis of SARS-CoV-2 virus-laden aerosols is presented. The CAPS system provided rapid thermoplasmonic biosensing results after an aerosol-to-hydrosol sampling process in COVID-19-related environments including a hospital and a nursing home. The detection limit reached 0.25 copies/µL in the complex aerosol background without further purification. More importantly, the CAPS system enabled direct measurement of the SARS-CoV-2 virus exposures with high spatiotemporal resolution. Measurement and feedback of the results to healthcare workers and patients via a QR-code are completed within two hours. Based on a dose-responseµ model, it is used the plasmonic biosensing signal to calculate probabilities of SARS-CoV-2 infection risk and estimate maximum exposure durations to an acceptable risk threshold in different environmental settings

Comparison of Proteome Differences between Whole Milk and Skim Milk Based on High-throughput Quantitative Proteomics

Protein is an important nutrient in bovine milk, however, it is not clear about the effect of defatting on the protein content of bovine milk. In this paper, quantitative proteomics labeled with TMT (tandem mass tags) was used to analyze the proteome in whole milk and skim milk to investigate the effect of skimming on milk proteins. A total of 1352 proteins were identified in whole milk and skim milk, and 199 differentially expressed proteins were screened. Compared with whole milk, 67 proteins were up-regulated and 132 proteins were down-regulated after defatting. Among the major active proteins in bovine milk, κ-casein decreased in relative content after defatting, while β-lactoglobulin and lactoferrin increased in relative content after defatting. α-lactalbumin, αs1-casein, αs2-casein, β-casein, bovine serum protein and lactoperoxidase did not differ significantly in relative content. The relative levels of butyrophilin and lactadherin in milk fat globule membrane proteins decreased after defatting. Skimming also had effects on cytoskeleton, metabolism-related proteins in milk, changing the quality and nutritional value of the milk. The analysis of protein in whole and skim milk clarified the effect of skimming on bovine milk protein, which could provide a reference for the development of infant dairy products and the purchase of milk with different fat content by consumers

Recent Progress on Biosensors Based on Nanomaterials for Detection of Food Allergens

Food allergy has become one of the prominent issues in the fields of food safety and public health. Since there is no effective treatment for food allergy, avoiding dietary exposure to (or intake of) food allergens based on label information should remain the best option for allergy sufferers. The development of sensitive, accurate and efficient allergen detection technologies is crucial for protecting consumers’ safety and rights. As a multidisciplinary detection technology, biosensors have the advantages of high specificity, quick response and easy operation. The rapid development of nanomaterials has advanced the development of highly sensitive and high-throughput biosensors for the visual detection of food allergens. In order to provide more references for further research and application of biosensors in food allergen detection, this paper summarizes the general situation of food allergen detection by biosensors, and analyzes the latest development of various biological recognition elements and biosensors based on different nanomaterials in the field of food allergen detection

Quantitative Detection and Uncertainty Analysis of Low-level Presence of Genetically Modified Ingredient in Soybean

In this study, the low-level presence of genetically modified (GM) soybean event GTS-40-3-2 was quantitatively detected and the measurement uncertainty was estimated. Within 95% confidence interval, the quantitative method developed using real-time polymerase chain reaction (PCR) and digital PCR could stably detect 0.01% GTS-40-3-2 content with acceptable cost and uncomplicated operation, while the digital PCR method could quantify 0.1% GTS-40-3-2 content accurately, and the quantitative error did not exceed 50% even at GTS-40-3-2 content as low as 0.05%. The sources of uncertainty in quantitative digital PCR analysis were analyzed, and the calculation formula for uncertainty was derived from calculation models in analytical chemistry. Furthermore, GTS-40-3-2 was used for laboratory verification. The expanded uncertainty in quantitative analysis of 0.1% and 0.05% GTS-40-3-2 contents was calculated as 23.56% and 107.29% (k = 2), respectively

A 3D-cascade-microlens optofluidic chip for refractometry with adjustable sensitivity†

Refractive index (RI) sensing as a label-free and non-invasive method has been playing an important role in industrial metrology, biochemical detection, and environmental analysis. Due to the combined advantages of microoptics and microfluidics, optofluidic RI sensors have attracted growing interest. Despite a variety of prototypes of optofluidic RI sensors, comprehensive improvement in sensitivity, detection range, fabrication procedures and cost can still bring substantial benefits to the field. In this work, we fabricated a 3D-cascade-microlens optofluidic chip (3DCMOC) for RI sensing. Two-photon stereolithography was employed to fabricate the chip mold, with which the 3DCMOC could be easily manufactured via mold replication. By virtue of integrating four detection channels configured with different numbers (1, 3, 5, and 7) of cascaded microlenses within the 3DCMOC, adjustable sensitivity for RI sensing has been demonstrated through measuring standard sucrose solutions. It was found that the seven-microlens configuration achieved an excellent sensitivity (mean: 21 ± 5 AU·RIU (refractive index unit)−1) and resolution (mean: 3.8 × 10−5 ± 0.9 × 10−5 RIU) at a cost of a narrow linear dynamic range (LDR, 1.3326–1.3548). In contrast, the single-microlens configuration led to an extended LDR (1.3326–1.5120 tested) despite the lower sensitivity (mean: 2.6 ± 0.2 AU·RIU−1) and resolution (mean: 1.5 × 10−4 ± 0.1 × 10−4 RIU). Furthermore, the use of the 3DCMOC was investigated via real-time salinity sensing and analysis of urine specific gravity.ISSN:1473-0197ISSN:1473-018

Self-aligned 3D microlenses in a chip fabricated with two-photon stereolithography for highly sensitive absorbance measurement

Absorbance measurement is a widely used method to quantify the concentration of an analyte. The integration of absorbance analysis in microfluidic chips could significantly reduce the sample consumption and contribute to the system miniaturization. However, the sensitivity and limit of detection (LoD) of analysis in microfluidic chips with conventional configuration need improvements due to the limited optical pathway and unregulated light propagation. In this work, a 3D-microlens-incorporating microfluidic chip (3D-MIMC) with a greatly extended detection channel was innovatively fabricated using two-photon stereolithography. The fabrication was optimized with a proposed hierarchical modular printing strategy. Due to the incorporation of 3D microlenses, the light coupling efficiency and the signal-to-noise ratio (SNR) were respectively improved approximately 9 and 4 times. An equivalent optical path length (EOL) of 62.9 mm was achieved in a 3.7 μl detection channel for testing tartrazine samples. As a result, the sensitivity and LoD of the 3D-MIMC assay were correspondingly improved by one order of magnitude, compared with those of the 96-well plate assay. Notably, the 3D-MIMC has the potential to be integrated into a general microanalysis platform for multiple applications.ISSN:1473-0197ISSN:1473-018

Colorimetric immunodetection of bacteria enriched on membranes within a compact multichannel filtration device

Colorimetric immunoassay is a widely used method for pathogen detection. The conventional implementation of immunoassays in 96-well plates often encounters difficulties for samples with low concentrations. In this study, the detection performance has been improved using a cellulose acetate membrane for target enrichment and immunodetection. For this end, a compact multichannel filtration device was fabricated using a 3D printer for sample loading. Background effects of the membrane were greatly minimized after pretreatment with a sodium hydroxide solution to significantly reduce non-specific binding. The colorimetric result of the immunodetection of Escherichia coli strain K12 (E.coli K12) was recorded and quantitatively analyzed with a smartphone camera. A limit of detection was calculated as 40 cfu (colony forming unit)/ml, two orders of magnitude more sensitive than that obtained on 96-well plates with standard protocol. The developed approach features an integrated sample enrichment scheme, reduced reagents consumption, multiple channels for parallel processing and no reliance on advanced laboratory instruments, thereby providing potential for a low-cost and easy-to-use immunodetection system.ISSN:0925-400

Nitrogen and Phosphorus Replacement Value of Three Representative Livestock Manures Applied to Summer Maize in the North China Plain

Land application of livestock manure may reduce the use of mineral fertilizers and alleviate the environmental degradation associated with mineral fertilizers application. However, how to optimize utilization of livestock manure value is not well understood and documentation regarding the nitrogen (N) and phosphorus (P) fertilizer replacement values (NFRV and PFRV, respectively) needs further scrutiny. Therefore, three representative livestock manures, i.e., pig, chicken, and cattle manure, were applied at different usages to assess their N and P availability in comparison to reference mineral fertilizers over summer maize growing seasons. The results show that the average NFRVs of pig, chicken, and cattle manures were 41.7–58.4%, 27.5–44.4%, and −3.6–36.1%, respectively, when based on different references (grain yield, total dry matter yield, grain N uptake, total N uptake), at different N application levels. The NFRV increased with the elevated N application rate for cattle manure treatment. In the P trials, livestock manure had a higher PFRV at a low P application level, and the average PFRVs of pig, chicken, and cattle manures were 80.3–164.8%, 77.9–143.7%, and 94.1–168.0%, respectively, at different P application levels. We conclude that livestock manure produced the lowest NFRV and highest PFRV at a low fertilizer application rate; pig manure had the highest N availability; and cattle manure had the highest P availability