Sustainable synthesis of fluorescent polymer carbon dots@PVA for sensitive chlortetracycline detection.

Antibiotic residues persist in the environment and represent serious health hazards; thus, it is important to develop sensitive and effective detection techniques. This paper presents a bio-inspired way to make water-soluble fluorescent polymer carbon dots (PCDs@PVA) by heating biomass precursors and polyvinyl alcohol (PVA) together. For example, the synthesized PCDs@PVA are very stable with enhanced emission intensity. This property was observed in a wide range of environmental conditions, including those with changing temperatures, pH levels, UV light, and ionic strength. PCDs@PVA detected the antibiotic chlortetracycline (CTCs) with great selectivity against structurally related compounds and a low detection limit of 20 nM, demonstrating outstanding sensitivity and specificity. We confirmed the sensor's practical application through real sample analysis, yielding recovery rates of 98%-99% in samples of milk, honey, and river water. The synthesized PCDs@PVA fluorescence sensor was successfully used for CTCs detection in real samples.

[Determination of five veterinary drug residues in milk by ultra-high performance liquid chromatography-quadrupole/electrostatic field orbitrap mass spectrometry based on modified chitosan membrane purification].

Milk is an important consumer product with high nutritional value. The presence of veterinary drug residues in milk owing to the indiscriminate use of veterinary drugs may affect consumer health. In the mass spectrometric analysis of trace compounds, chromatographic co-eluting components easily interfere with the mass spectral signals obtained, affecting the accuracy of qualitative and quantitative analyses. Matrix purification is a promising method to reduce the matrix effect. Chitosan is a natural biopolymer with numerous active functional groups such as amino, acetyl, and hydroxyl groups; these groups can adsorb lipids through hydrophobic and electrostatic interactions. Chitosan also has the advantages of low production cost, stable chemical properties, and convenient modification. Novel chitosan-based materials are promising candidates for lipid purification. In this study, a chitosan membrane was modified with trimethoxyoctadecylsilane (C18-CSM). C18-CSM was prepared through one-step hydrolysis and used as a dispersive solid phase extraction (DSPE) adsorbent to purify the matrix during milk pretreatment. We combined C18-CSM with ultra-high performance liquid chromatography-quadrupole/electrostatic field orbitrap mass spectrometry (UHPLC-Q/Exactive Orbitrap MS) to develop an effective method for the extraction and determination of ofloxacin, enrofloxacin, ciprofloxacin, diazepam, and metronidazole in milk. C18-CSM was characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, and water contact angle testing. The results indicated that the material has a rough surface and uniformly dense cross-section. The water contact angle of C18-CSM was 104°, indicating its good hydrophobicity. The pretreatment conditions (extraction solvent, dosage of NaCl, extraction frequency, and dosage of C18-CSM) that influenced the recoveries of the five veterinary drugs were investigated in detail. The optimal conditions were established as follows: 5% formic acid in acetonitrile, 1 g NaCl, extraction 1 time, 20 mg C18-CSM. Separation was performed on a Hypersil GOLD VANQUISH column (100 mm×2.1 mm, 1.9 µm). The mobile phase consisted of 0.1% formic acid aqueous solution and 0.1% formic acid in acetonitrile, and was flowed at a rate of 0.3 mL/min. The sample injection volume was 1 µL, and the column temperature was maintained at 25 ℃. Mass spectrometric analysis was performed in positive electrospray ionization mode. To verify the necessity of the purification material, the matrix effect was investigated using the matrix-matched standard curve method. The use of C18-CSM reduced the matrix effects of the five necessity drugs from the range of -22%-8.8% to the range of -13%-3.6%, indicating that C18-CSM is a highly efficient DSPE material. Under optimal conditions, the developed method showed good linearities within the range of 0.5-100 µg/L, with correlation coefficients (r2)≥0.9970. The limits of detection(LODs) and quantification (LOQs) were 0.2 µg/L and 0.5 µg/L, respectively. To assess the accuracy and precision of the method, we prepared milk samples with three spiked levels (low, medium, and high). The recoveries of the five veterinary drugs were ranged from 79.5% to 115%, and the intra-day and inter-day relative standard deviations were 7.0%-13% (n=6) and 1.3%-11% (n=3), respectively. This study provides a simple, accurate, and reliable method for the rapid and simultaneous determination of the five veterinary drug residues in milk.

Effects of cashew nutshell liquid on milk production and methane emission of dairy cows in a farm condition.

This study aimed to clarify the efficacy of cashew nutshell liquid (CNSL) in methane emissions, milk production, and rumen fermentation of lactating cows in practical conditions. Ten Holstein lactating cows were used in a free-stall barn with a milking robot. Two treatments were arranged as control (no CNSL additive, n = 5) or CNSL addition (10 g/day of CNSL, n = 5) for 21 days after the 7-day preliminary period. A sniffer method was applied to predict daily methane production and methane conversion factor (MCF). In vitro, rumen gas production was also tested using the rumen fluid of individual cows. Daily dry matter intake (DMI), eating time, milk production, and methane production were not affected by the CNSL addition. However, methane production per DMI and MCF were lower (p ≤ 0.01) for the CNSL cows than those for the control cows. Ruminal total volatile fatty acid (VFA) concentration and acetate proportion tended to be lower (p < 0.15) for CNSL cows. A tendency to decrease (p < 0.10) in methane was also observed in the in vitro incubation with the rumen fluid obtained from the CNSL cows compared with those from the control cows. These results suggest that adding CNSL to diets could reduce the methane yield of cows in practical conditions.

Bta-miR-200a Regulates Milk Fat Biosynthesis by Targeting IRS2 to Inhibit the PI3K/Akt Signal Pathway in Bovine Mammary Epithelial Cells.

Milk fat synthesis has garnered significant attention due to its influence on the quality of milk. Recently, an increasing amount of proofs have elucidated that microRNAs (miRNAs) are important post-transcriptional factor involved in regulating gene expression and play a significant role in milk fat synthesis. MiR-200a was differentially expressed in the mammary gland tissue of dairy cows during different lactation periods, which indicated that miR-200a was a candidate miRNA involved in regulating milk fat synthesis. In our research, we investigated the potential function of miR-200a in regulating milk fat biosynthesis in bovine mammary epithelial cells (BMECs). We discovered that miR-200a inhibited cellular triacylglycerol (TAG) synthesis and suppressed lipid droplet formation; at the same time, miR-200a overexpression suppressed the mRNA and protein expression of milk fat metabolism-related genes, such as fatty acid synthase (FASN), peroxisome proliferator-activated receptor gamma (PPARγ), sterol regulatory element-binding protein 1 (SREBP1), CCAAT enhancer binding protein alpha (CEBPα), etc. However, knocking down miR-200a displayed the opposite results. We uncovered that insulin receptor substrate 2 (IRS2) was a candidate target gene of miR-200a through the bioinformatics online program TargetScan. Subsequently, it was confirmed that miR-200a directly targeted the 3'-untranslated region (3'-UTR) of IRS2 via real-time fluorescence quantitative PCR (RT-qPCR), western blot analysis, and dual-luciferase reporter gene assay. Additionally, IRS2 knockdown in BMECs has similar effects to miR-200a overexpression. Our research set up the mechanism by which miR-200a interacted with IRS2 and discovered that miR-200a targeted IRS2 and modulated the activity of the PI3K/Akt signaling pathway, thereby taking part in regulating milk fat synthesis in BMECs. Our research results provided valuable information on the molecular mechanisms for enhancing milk quality from the view of miRNA-mRNA regulatory networks.

Performance and metabolic evaluation in primiparous beef cows under grazing at different breeding ages.

We aimed to evaluate the metabolic and performance differences in primiparous Nellore cows, which became pregnant at 14 or 24-mo old. Thirty-eight cows with 202 ± 5 days of gestation were divided into two treatments according to breeding age: 14 or 24-mo. Cows were evaluated for body weight (BW), body condition score (BCS), carcass characteristics, milk yield, calves's performance, and blood characteristics. The animals were managed in eight paddocks under continuous grazing and evaluated from 90 d before parturition until 240 d after calving. We observed an interaction between breeding age and time (P < 0.01) for cow BW. Both breeding age categories experienced BW loss during parturition, with a concurrent decrease in BCS. However, following their first calving, the BW of 24-mo cows remained stable (P > 0.05), whereas 14-mo cows exhibited a gradual recovery in BW after parturition (P < 0.05). Milk yield was greater in 24-mo animals (P < 0.01), but decreased with increasing milking days (p < 0.05) for both groups. The weight gain calves from the heifers bred at 24-mo was greater (P < 0.01), which reflected in greater BW at weaning. The beta-hydroxybutyrate (ß-OHB) concentration was greater before calving and a marked decrease after parturition (P < 0.05). The 24-mo cows had greater blood ß-OHB (P < 0.01) at prepartum and 30 days after calving. Blood progesterone was greater in 24-mo cows (P > 0.05). Primiparous beef cows that conceive at either 14 or 24-months of age exhibit distinct nutritional requirements and metabolic profiles. Notably, cows that conceive at 24-months of age have the advantage of weaning heavier calves and displaying a more consistent reproductive cycle following their first calving than cows that conceive at 14-months.

Cow-calf contact: a single-herd observational study of AMS yield during the first 100 days in milk.

An increasing number of dairy farmers plan to implement cow-calf contact (CCC) in their herd which necessitates descriptions of the cows` performance in different systems. The aim of the study was to describe (1) Automatic milking system (AMS) milk yield of cows in a CCC system during the first 100 days in milk (DIM) and (2) AMS milk yield before and after cow-calf separation. In a prospective study at a commercial Norwegian dairy farm, we included all calvings from Norwegian Red cows between January 2019 to April 2020. After calving, cow-calf pairs stayed in an individual calving pen during the first 5-6 d before they were moved to the loose housing unit with the remaining herd. Calves had whole-day (24 h/d) and full physical contact to the cows. Cows were milked in an AMS. From 14 individual cows of which one cow calved twice during the study period, we collected daily AMS yields from 15 different lactations, with parities ranging from 1 (n = 6), 2 (n = 5) and 3 (n = 4). Due to the sample size and structure of the data set, we only calculated descriptive statistics from DIM 7-100. All data is shown separately for primiparous and multiparous cows. Mean (± SD) calf age at (fence-line) separation was 52 d ± 14.8 beyond which suckling was prevented. Our data indicates great individual variation in the AMS milk yield. Prior to separation, primiparous cows` AMS yields ranged from 11.0 to 25.9 kg/d while that of multiparous cows ranged from 4.8 to 28.8 kg/d. Once calves were no longer allowed to suckle, the yield increased gradually. During the week after separation, AMS yields ranged from 17.3 to 30.4 kg/d for primiparous cows and 8.7 to 41.8 kg/d for multiparous cows and these yields increased in DIM 93-100 (26.5 to 34.3 and 20.6 to 38.3 kg/d respectively). This study is limited by a low sample size from a single-herd but may provide useful descriptions of AMS milk yield in a whole-day, full contact CCC system during the first 100 days of lactation.

A green, fluorescent probe employing erythrosine-B for tracing the accidental administration of levamisole in milk and plasma samples.

A simple and sensitive fluorescent probe has been developed and optimized to detect the non-intentional administration of levamisole (LVM). LVM is used as an anthelmintic therapy in cows, and hence, its residues appear in the drained milk until 60 hours after administering the drug. Meanwhile, levamisole is known to be an adulterant to cocaine and could be detected in addicts' plasma samples. Owing to its severe side effects, including agranulocytosis, which is lethal in many cases, detection and quantification of LVM in milk and plasma samples are of utmost importance. Therefore, a sensitive and selective analytical method is required for this purpose. This work develops a highly fluorescent probe obtained through the reaction between LVM and erythrosine-B in an acidic medium, where the produced ion pair complex has been measured at 553 nm after excitation at 528 nm. The proposed method provides linearity over the concentration range of 0.5-2.0 µg mL-1 for LVM, with a corresponding detection and quantitation limit of 0.5 and 0.3 µg mL-1. Full validation was performed, permitting the application of the suggested method to perform simple extraction steps. All the applied procedures followed the guidelines offered by green analytical chemistry, where the Green Analytical Procedure Index (GAPI) assessed the greenness of the proposed tool, and the yielded pictograms proved the eco-friendliness of the offered tool.

A novel dual-model photoelectrochemical/electrochemical sensor based on Z-scheme TiO2 disks/methylene blue for kanamycin detection.

Herein, a new dual-model photoelectrochemical (PEC)/electrochemical (EC) sensor based on Z-scheme titanium dioxide (TiO2) disk/methylene blue (MB) sensibilization for the detection of kanamycin (Kana) was developed. Metal-organic framework-derived porous TiO2 disks were synthesized and exhibited excellent anodic photocurrent under visible light excitation. Subsequently, amino-labeled double-stranded DNA (dsDNA) was introduced into the modified electrode. Photocurrent was enhanced with MB embedded in dsDNA to form Z-scheme TiO2/MB sensibilization. When the target, Kana, was present, it specifically bound to the aptamer in the dsDNA, leading to the disruption of the dsDNA structure and the release of MB. This release of MB and the increase in target spatial resistance resulted in a significant weakening of PEC signal and a decreased oxidation peak current of MB. The PEC sensor successfully detected Kana in the range of 2-1000 pM with an LOD of 0.17 pM. Meanwhile, the EC sensor for Kana detection showed a linear range of 5-500 pM with an LOD of 1.8 pM. Additionally, the sensor exhibited excellent selectivity, reproducibility, stability, and good recoveries when applied to milk and honey samples. As a result, this method has the potential for application in ensuring food safety through the rapid determination of antibiotics in food.

Cryogel with Modular and Clickable Building Blocks: Toward the Ultimate Ideal Macroporous Medium for Bacterial Separation.

The lack of practical platforms for bacterial separation remains a hindrance to the detection of bacteria in complex samples. Herein, a composite cryogel was synthesized by using clickable building blocks and boronic acid for bacterial separation. Macroporous cryogels were synthesized by cryo-gelation polymerization using 2-hydroxyethyl methacrylate and allyl glycidyl ether. The interconnected macroporous architecture enabled high interfering substance tolerance. Nanohybrid nanoparticles were prepared via surface-initiated atom transfer radical polymerization and immobilized onto cryogel by click reaction. Alkyne-tagged boronic acid was conjugated to the composite for specific bacteria binding. The physical and chemical characteristics of the composite cryogel were analyzed systematically. Benefitting from the synergistic, multiple binding sites provided by the silica-assisted polymer, the composite cryogel exhibited excellent affinity toward S. aureus and Salmonella spp. with capacities of 91.6 × 107 CFU/g and 241.3 × 107 CFU/g in 0.01 M PBS (pH 8.0), respectively. Bacterial binding can be tuned by variations in pH and temperature and the addition of monosaccharides. The composite was employed to separate S. aureus and Salmonella spp. from spiked tap water, 40% cow milk, and sea cucumber enzymatic hydrolysate, which resulted in high bacteria separation and demonstrated remarkable potential in bacteria separation from food samples.

Multi-functional nanozyme-based colorimetric, fluorescence dual-mode assay for Salmonella typhimurium detection in milk.

Rapid and high-sensitive Salmonella detection in milk is important for preventing foodborne disease eruption. To overcome the influence of the complex ingredients in milk on the sensitive detection of Salmonella, a dual-signal reporter red fluorescence nanosphere (RNs)-Pt was designed by combining RNs and Pt nanoparticles. After being equipped with antibodies, the immune RNs-Pt (IRNs-Pt) provide an ultra-strong fluorescence signal when excited by UV light. With the assistance of the H2O2/TMB system, a visible color change appeared that was attributed to the strong peroxidase-like catalytic activity derived from Pt nanoparticles. The IRNs-Pt in conjunction with immune magnetic beads can realize that Salmonella typhimurium (S. typhi) was captured, labeled, and separated effectively from untreated reduced-fat pure milk samples. Under the optimal experimental conditions, with the assay, as low as 50 CFU S. typhi can be converted to detectable fluorescence and absorbance signals within 2 h, suggesting the feasibility of practical application of the assay. Meanwhile, dual-signal modes of quantitative detection were realized. For fluorescence signal detection (emission at 615 nm), the linear correlation between signal intensity and the concentration of S. typhi was Y = 83C-3321 (R2 = 0.9941), ranging from 103 to 105 CFU/mL, while for colorimetric detection (absorbamce at 450 nm), the relationship between signal intensity and the concentration of S. typhi was Y = 2.9logC-10.2 (R2 = 0.9875), ranging from 5 × 103 to 105 CFU/mL. For suspect food contamination by foodborne pathogens, this dual-mode signal readout assay is promising for achieving the aim of convenient preliminary screening and accurate quantification simultaneously.

A sensitive aptasensor mediated by gold nanoparticles/metal organic framework lattice for detection of Pb2+ ion in marine products.

Herein, an enzyme-free fluorescent aptasensor was introduced for the ultrasensitive quantification of lead (Pb2+) ion as a hazardous pollutant of the environment and foodstuffs. A nanocomposite of zeolitic imidazolate frameworks-8 and gold nanoparticles (ZIF-8@AuNPs) was utilized as an efficient quencher of the fluorescence intensity of carboxyfluorescein (FAM) signal reporter. The establishment of a hybrid structure between attached aptamer on ZIF-8@AuNPs nanocomposite, and its FAM-tagged complementary (CP) strand decreased the fluorescence response. The preferential binding between the aptamer and Pb2+ released CP strands, which retrieved the fluorescence signal. The aptasensor could assess Pb2+ in the linear concentration range of 1 pM-1 nM with a detection limit (LOD) of 0.24 pM. Besides, it could quantify Pb2+ in various samples, including fish, shrimp, tap water, milk, and serum samples. The developed aptasensor with the superiorities of easiness, cost-effectiveness, easy-to-operate, and rapidness is promising for controlling marine foodstuff safety.

Employing a magnetic chitosan/molybdenum disulfide nanocomposite for efficiently removing polycyclic aromatic hydrocarbons from milk samples.

This study aimed to develop a highly efficient nanocomposite composed of magnetic chitosan/molybdenum disulfide (CS/MoS2/Fe3O4) for the removal of three polycyclic aromatic hydrocarbons (PAHs)-pyrene, anthracene, and phenanthrene. Novelty was introduced through the innovative synthesis procedure and the utilization of magnetic properties for enhanced adsorption capabilities. Additionally, the greenness of chitosan as a sorbent component was emphasized, highlighting its biodegradability and low environmental impact compared to traditional sorbents. Factors influencing PAH adsorption, such as nanocomposite dosage, initial PAH concentration, pH, and contact time, were systematically investigated and optimized. The results revealed that optimal removal efficiencies were attained at an initial PAH concentration of 150 mg/L, a sorbent dose of 0.045 g, pH 6.0, and a contact time of 150 min. The pseudo-second-order kinetic model exhibited superior fitting to the experimental data, indicating an equilibrium time of approximately 150 min. Moreover, the equilibrium adsorption process followed the Freundlich isotherm model, with kf and n values exceeding 7.91 mg/g and 1.20, respectively. Remarkably, the maximum absorption capacities for phenanthrene, anthracene, and pyrene on the sorbent were determined as 217 mg/g, 204 mg/g, and 222 mg/g, respectively. These findings underscore the significant potential of the CS/MoS2/Fe3O4 nanocomposite for efficiently removing PAHs from milk and other dairy products, thereby contributing to improved food safety and public health.

Effects of dispersing media on the rheological and tribological properties of basil seed mucilage-based thickened liquids.

The development of thickening powders for the management of dysphagia is imperative due to the rapid growth of aging population and prevalence of the dysphagia. One promising thickening agent that can be used to formulate dysphagia diets is basil seed mucilage (BSM). This work investigates the effects of dispersing media, including water, milk, skim milk, and apple juice, on the rheological and tribological properties of the BSM-thickened liquids. Shear rheology results revealed that the thickening ability of BSM in these media in ascending order is milk < skim milk ≈ apple juice < water. On the other hand, extensional rheology demonstrated that the longest filament breakup time was observed when BSM was dissolved in milk, followed by skim milk, water, and apple juice. Furthermore, tribological measurements showed varying lubrication behavior, depending on the BSM concentration and dispersing media. Dissolution of BSM in apple juice resulted in the most superior lubrication property compared with that in other dispersing media. Overall, this study provides insights on BSM's application as a novel gum-based thickening powder in a range of beverages and emphasizes how important it is for consumers to have clear guidance for the use of BSM in dysphagia management.

Flow properties of single origin chocolates: Effect of product formulation and particle size.

The objective of this research was to evaluate changes in flow behavior of chocolate during chocolate grinding using a stone grinder as affected by chocolate formulation. Three different types of chocolates were evaluated. Two chocolates without milk added (70% chocolate) and two chocolates with milk added and with different amounts of cocoa nibs (30% chocolate and 14% chocolate) were tested. For the 70% chocolates, nibs of two different origins were used; therefore, a total of four samples were evaluated. Chocolates were processed in a stone grinder, and samples were taken as a function of grinding time. For each timepoint, the flow behavior of the samples was measured using a rotational rheometer and fitted to the Casson model. Particle size was measured using a laser scattering instrument. Results showed that yield stress increased linearly while the Casson plastic viscosity decreased exponentially with grinding time (smaller particles). Particle size distribution of the chocolates showed a prominent bimodal distribution for short grinding times (∼9 h) with small (∼15 µm) and large (∼100 µm) particles; with longer grinding time, the population of larger particles decreased. Yield stress values were higher for the 70% chocolate, but they were not very different between the two milk chocolates tested. The Casson plastic viscosity was greatest for the 70% chocolate, followed by the 30% chocolate. The 14% chocolate had the lowest Casson plastic viscosity. Changes of Casson plastic viscosity with particle size were more evident for the dark chocolates compared to the milk ones. These results are helpful to small chocolate producers who need better understanding of how the formulation and grinding of chocolate affect its flow behavior, which will ultimately affect chocolate handling during production.

A novel ratiometric electrochemical sensing platform combined with molecularly imprinted polymer and Fe-MOF-NH2/CNTs-NH2/MXene composite for efficient detection of ofloxacin.

BACKGROUND: Ofloxacin (OFL) is often abused in medicine and animal husbandry, which poses a great threat to human health and ecological environment. Therefore, it is necessary to establish efficient method to detect OFL. Electrochemical sensor has attracted widespread attention due to the advantages of low cost and fast response. However, most electrochemical sensors usually use one response signal to detect the target, which makes it sensitive to the variable background noise in the complex environment, resulting in low robustness and selectivity. The ratio detection mode and employing molecularly imprinted polymer (MIP) are two strategies to solve these problems. RESULTS: A novel molecular imprinting polymer-ratiometric electrochemical sensor (MIP-RECS) based on Fe-MOF-NH2/CNTs-NH2/MXene composite was prepared for the rapid and sensitive detection of OFL. The positively charged Fe-MOF-NH2 and CNTs-NH2 as interlayer spacers were introduced into the negatively charged MXene through a simple electrostatic self-assembly technique, which effectively prevented the agglomeration of MXene and increased the electrocatalytic activity. A glass carbon electrode was modified by the composite and a MIP film was electropolymerized on it using o-phenylenediamine and ß-cyclodextrin as bifunctional monomers and OFL as template. Then a MIP-RECS was designed by adding dopamine (DA) into the electrolyte solution as internal reference, and OFL was quantified by the response current ratio of OFL to DA. The current ratio and the concentration of OFL displayed a satisfying linear relationship in the range of 0.1 µM-100 µM, with a limit of detection (LOD) of 13.2 nM. SIGNIFICANCE: Combining molecular imprinting strategy and ratio strategy, the MIP-RECS has impressive selectivity compared with the non-imprinted polymer-RECS, and has better repeatability and reproducibility than non-ratiometric sensor. The MIP-RECS has high sensitivity and accuracy, which was applied for the detection of OFL in four different brands of milk and was verified by HPLC method with satisfactory results.

A Cost-Effective and Sensitive Method for the Determination of Lincomycin in Foods of Animal Origin Using High-Performance Liquid Chromatography.

BACKGROUND: Lincomycin (LIN) is extensively used for treating diseases in livestock and promoting growth in food animal farming, and it is frequently found in both the environment and in food products. Currently, most of the methods for detecting lincomycin either lack sensitivity and precision or require the use of costly equipment such as mass spectrometers. RESULT: In this study, we developed a reliable high-performance liquid chromatography-ultraviolet detection (HPLC-UVD) method and used it to detect LIN residue in 11 types of matrices (pig liver and muscle; chicken kidney and liver; cow fat, liver and milk; goat muscle, liver and milk; and eggs) for the first time. The tissue homogenates and liquid samples were extracted via liquid-liquid extraction, and subsequently purified and enriched via sorbent and solid phase extraction (SPE). After nitrogen drying, the products were derivatized with p-toluene sulfonyl isocyanic acid (PTSI) (100 µL) for 30 min at room temperature. Finally, the derivatized products were analyzed by HPLC at 227 nm. Under the optimized conditions, the method displayed impressive performance and demonstrated its reliability and practicability, with a limit of detection (LOD) and quantification (LOQ) of LIN in each matrix of 25-40 µg/kg and 40-60 µg/kg, respectively. The recovery ranged from 71.11% to 98.30%. CONCLUSIONS: The results showed that this method had great selectivity, high sensitivity, satisfactory recovery and cost-effectiveness-fulfilling the criteria in drug residue and actual detection requirements-and proved to have broad applicability in the field of detecting LIN in animal-derived foods.

Children's Iodine Intake from Dairy Products and Related Factors: A Cross-Sectional Study in Two Provinces of China.

Dairy products are a significant source of iodine, and their contribution to iodine intake must be evaluated regularly. However, there is a lack of data on iodine intake from dairy products in China. Through a cross-sectional study, we determined the iodine content of dairy products in the Chinese diet and estimated iodine intake among Chinese children. Intake records for 30 consecutive days were used to investigate the consumption of dairy products by 2009 children from Yunnan and Liaoning Provinces. The iodine contents of 266 dairy products with high intake frequency were determined using inductively coupled plasma-mass spectrometry (ICP-MS). We then calculated the iodine intake and contribution of dairy products and explored the related factors of dairy iodine intake through a generalized linear mixed model. Ultra-high-temperature (UHT) sterilized milk accounted for 78.7% of the total dairy products, with an iodine content of 23.0 µg/100 g. The dairy product intake rate of children in China was 83.6%, with an average daily intake of 143.1 g. The median iodine intake from milk and dairy was 26.8 µg/d, 41.5% of the estimated average recommendation (EAR) for younger children and 31.8% of the EAR for older children. The daily milk iodine intake of children in Yunnan Province was 9.448 µg/day lower than that of children in Liaoning Province (p < 0.001), and the daily iodine intake of children in rural areas was 17.958 µg/day lower than that of children in urban areas (p < 0.001). Chinese dairy products were rich in iodine, and the content of iodine was intermediate to that reported in Europe and the USA. However, children's daily intake of milk iodine was lower than that of children in other developed countries due to the lower daily intake of dairy products, especially those in rural areas.

Stability and expression of K-ras mimotopes in freeze-dried recombinant Lactococcus lactis NZ3900-fermented milk powder during storage in vacuum packaging.

AIMS: This study aims to evaluate the storage stability of the freeze-dried recombinant Lactococcus lactis NZ3900-fermented milk powder expressing K-ras (Kristen rat sarcoma viral oncogene homolog) mimotopes targeting colorectal cancer in vacuum packaging. METHODS AND RESULTS: The freeze-dried L. lactis-fermented milk powder stored in 4-ply retortable polypropylene (RCPP)-polyamide (PA)-aluminium (AL)-polyethylene terephthalate (PET) and aluminium polyethylene (ALPE) was evaluated throughout 49 days of accelerated storage (38°C and 90% relative humidity). The fermented milk powder stored in 4-ply packaging remained above 6 log10 CFU g-1 viability, displayed lower moisture content (6.1%), higher flowability (43° angle of repose), water solubility (62%), and survivability of L. lactis after simulated gastric and intestinal digestion (>82%) than ALPE packaging after 42 days of accelerated storage. K-ras mimotope expression was detected intracellularly and extracellularly in the freeze-dried L. lactis-fermented milk powder upon storage. CONCLUSIONS: This suggests that fermented milk powder is a suitable food carrier for this live oral vaccine.

The Aggregated and Micellar Forms of ß-Casein Purified from Donkey and Bovine Milk Present Potential as Carriers for Bioactive Nutritional Compounds.

In recent years, there has been a growing interest in the pure casein fraction of milk protein, particularly ß-casein due to its physicochemical properties as well as its bio- and techno-functional properties. The utilization of self-assembled ß-caseins from bovine origin as nanocarriers for the delivery of nutraceutical compounds or drugs has increased dramatically. Concerning ß-caseins from other milk sources, the use of hypoallergenic donkey ß-caseins as a potential delivery vehicle for nutraceutical hydrophobic compounds is beginning to generate interest. The present review deals with casein micelles models, bovine and donkey ß-casein molecular structures, as well as their physical-chemical properties that account for their exploitation in nutraceutics and pharmaceutics. This review work suggests the possibility of developing delivery systems for hydrophobic bioactive compounds using ß-casein purified from hypoallergenic donkey milk, highlighting the potential of this protein as an innovative and promising vehicle for enhancing the enrichment and bioavailability of various bioactive substances in food products.

A ratiometric SERS aptasensor based on catalytic hairpin self-assembly mediated cyclic signal amplification strategy for the reliable determination of E. coli O157:H7.

A ratiometric SERS aptasensor based on catalytic hairpin self-assembly (CHA) mediated cyclic signal amplification strategy was developed for the rapid and reliable determination of Escherichia coli O157:H7. The recognition probe was synthesized by modifying magnetic beads with blocked aptamers, and the SERS probe was constructed by functionalizing gold nanoparticles (Au NPs) with hairpin structured DNA and 4-mercaptobenzonitrile (4-MBN). The recognition probe captured E. coli O157:H7 specifically and released the blocker DNA, which activated the CHA reaction on the SERS probe and turned on the SERS signal of 6-carboxyl-x-rhodamine (ROX). Meanwhile, 4-MBN was used as an internal reference to calibrate the matrix interference. Thus, sensitive and reliable determination and quantification of E. coli O157:H7 was established using the ratio of the SERS signal intensities of ROX to 4-MBN. This aptasensor enabled detection of 2.44 × 102 CFU/mL of E. coli O157:H7 in approximately 3 h without pre-culture and DNA extraction. In addition, good reliability and excellent reproducibility were observed for the determination of E. coli O157:H7 in spiked water and milk samples. This study offered a new solution for the design of rapid, sensitive, and reliable SERS aptasensors.