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1.
Food Chem ; 346: 128975, 2021 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-33429296

RESUMEN

As bisphenol A (BPA) is harmful to human health, it is of great significance to develop a new method for BPA detection. Herein, we designed a BPA biosensor by integrating an amplifying DNA circuit with Mg2+-dependent DNAzyme into the sensing system. The BPA-aptamer binding activated a DNA circuit for signal amplification based on toehold-mediated strand displacement. A catalytic Mg2+-dependent DNAzyme was formed through synergistically DNA hybridization, which can cleave the dual-labeled substrate DNA into two segments. The separation of the fluorophore and quencher produces a high fluorescence response for BPA detection. This biosensor exhibited a superior sensitivity with a detection limit of 50 fM. The method is selective and robust, which can work even in milk samples with satisfactory accuracy. The biosensor analytical results were also verified by liquid chromatography coupled with mass spectrometry (LC-MS) and no obvious difference existed between the two methods.


Asunto(s)
Compuestos de Bencidrilo/análisis , Técnicas Biosensibles/métodos , ADN Catalítico/química , Leche/química , Fenoles/análisis , Animales , ADN/química , ADN/metabolismo , ADN Catalítico/metabolismo , Colorantes Fluorescentes/química , Límite de Detección , Magnesio/química , Técnicas de Amplificación de Ácido Nucleico , Hibridación de Ácido Nucleico , Espectrometría de Fluorescencia
2.
Food Chem ; 346: 128961, 2021 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-33454576

RESUMEN

OBJECTIVE: To assess the levels of heavy metals and their antagonists in dairy products available in the markets of São Luís, northeastern Brazil. METHODS: Chemical analysis of the heavy metals copper(Cu), lead(Pb), mercury(Hg), and nickel(Ni) and their antagonists iron(Fe), zinc(Zn), calcium(Ca), selenium(Se), and cobalt(Co) contained in dairy products using inductively coupled plasma optical emission spectrometry (ICP-OES). RESULTS: The main heavy metal observed in dairy products were Hg; Pb; Se and Ni. A significant negative correlation was observed between the concentrations of Cu and Fe (rho = -0.634, p = 0.001), Cu and Zn (rho = -0.794, p = 0.000) in whole milk. A non-significant positive correlation was observed between Pb and Ca (rho = 0.387, p = 0.056), and Hg and Se (rho = 0.055, p = 0.795). CONCLUSIONS: Dairy product brands available in the markets of São Luís could be considered a source of heavy metal contamination (Hg, Pb, Se, Cu, Ni) with weak correlations with their antagonists.


Asunto(s)
Metales Pesados/análisis , Leche/química , Espectrofotometría/métodos , Animales , Brasil , Niño , Cobre/análisis , Productos Lácteos/análisis , Humanos , Mercurio/análisis , Níquel/análisis , Medición de Riesgo , Espectrofotometría/instrumentación , Zinc/análisis
3.
Food Chem ; 346: 128893, 2021 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-33387835

RESUMEN

The excessive use of tetracyclines (TCs), a bacteriostaticantibiotic, in food products, has led to the accumulation of TCs residues in the human body, affecting human health seriously. Therefore, the development of a highly sensitive method to detect TCs in food is of utmost importance. This study reports a novel sensing strategy using aptamer-induced fluorescence fluctuation of graphene quantum dots (GQDs) and palladium nanoparticles (Pd NPs) for the rapid and label-free detection of tetracycline with a limit of detection of 45 ng.mL-1. A novel single-step synthesis of positively charged Pd NPs and one-step green synthesis of GQDs directly from graphite has been developed. The proposed strategy provides an efficient way to detect low traces of TCs and a new technique for the development of aptamer-based sensors.


Asunto(s)
Aptámeros de Nucleótidos/química , Técnicas Biosensibles/métodos , Grafito/química , Leche/química , Paladio/química , Puntos Cuánticos/química , Tetraciclina/análisis , Animales , Colorantes Fluorescentes/química , Humanos , Límite de Detección , Nanopartículas del Metal/química , Tetraciclina/química
4.
J Chromatogr A ; 1638: 461898, 2021 Feb 08.
Artículo en Inglés | MEDLINE | ID: mdl-33486221

RESUMEN

A 4-layer sandwiched device (4LSD) well suited for coupling to online ion chromatography (IC) systems was described and simultaneously performed target anion enrichment, matrix removal and sample injection within seconds. The basic assembly consisted of an extraction solution channel, a sample solution channel and two electrolyte channels. Cation-exchange resin (CER) was utilized to support the solution chamber, increase electrical conductivity and improve pressure resistance to achieve compatibility with a peristaltic pump. Filter placement ensured loop circulation of the 4LSD and prevented resin leakage. The 4LSD showed comparable performance to that of conventional solid-phase extraction (SPE) pretreatment in terms of matrix interference removal while enabling automation. The applied current, sample/extraction solution flow rate ratio, and initial concentration were discussed and optimized. Controllable 1-40-fold enrichment can be ensured. The migration phenomenon of different anions was discussed. F-, Cl-, NO2-, Br-, NO3-, SO42- and ClO4- exhibited satisfactory linear detection ranges within 2.5-1000 µg·L-1, and the calculated limits of detection (LODs) in milk formula were within the 0.097-0.79 mg·kg-1 range. The 4LSD was successfully applied to the determination of anions in milk formula with good spiked recoveries ranging between 92.54% and 107.2%, except for the NO2- recovery. The relative standard deviations (RSDs) ranged from 0.69% to 8.29%.


Asunto(s)
Cromatografía/métodos , Conductividad Eléctrica , Electroquímica/instrumentación , Electroquímica/métodos , Animales , Aniones/análisis , Automatización , Resinas de Intercambio de Catión , Límite de Detección , Leche/química , Reproducibilidad de los Resultados , Extracción en Fase Sólida
5.
Food Chem ; 339: 128059, 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-33152864

RESUMEN

A colorimetric aptasensing strategy for detection of kanamycin was designed based on aptamer biorecognition and signal amplification assisted by nicking enzyme. The aptamer of kanamycin was designed to be contained in the metastable state hairpin DNA. The target DNA as recycling DNA was located in the loop of hairpin DNA. The presence of kanamycin stimulates the continuous actions, including specific recognition of the aptamer to kanamycin, the hybridization between target DNA and signal probe, the cleavage function of nicking enzyme. The actions induced accumulation of numerous free short sequences modified by platinum nanoparticles (PtNPs), which can catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB)-H2O2 to produce a colorimetric response. The aptasensor exhibited good selectivity and sensitivity for kanamycin in milk with a detection limit as low as 0.2 pg·mL-1. In addition, the proposed assay is potentially to be extended for other antibiotics detection in foods by adapting the corresponding aptamer sequence.


Asunto(s)
Aptámeros de Nucleótidos/metabolismo , Técnicas Biosensibles/métodos , Colorimetría/métodos , Desoxirribonucleasa I/metabolismo , Secuencias Invertidas Repetidas , Kanamicina/análisis , Leche/química , Animales , Aptámeros de Nucleótidos/química , Aptámeros de Nucleótidos/genética , Bencidinas/química , Sondas de ADN/química , Contaminación de Alimentos/análisis , Peróxido de Hidrógeno/química , Kanamicina/metabolismo , Límite de Detección , Nanopartículas del Metal/química , Hibridación de Ácido Nucleico , Platino (Metal)/química
6.
Food Chem ; 339: 128079, 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-33152872

RESUMEN

In this work, an efficient method for the determination of ß-agonists and fluoroquinolones was established, based on a mixed-mode sorbent of magnetic sulfonated covalent organic framework composites. By coupling with HPLC-MS/MS, the main factors that affect the extraction procedure were optimized. Under the optimal conditions, the proposed HPLC-MS/MS method was successfully utilized for the extraction of ß-agonists and fluoroquinolones in milk and pork meat samples. The method showed good linearities (R2 ≥ 0.9916), and low LOQs of 0.1-0.2 ng g-1 for ß-agonists and fluoroquinolones. The adsorption mechanism was investigated with the assistance of quantum chemistry calculation method, and it is worth noting that the sorbent relied mainly on the multiple adsorption mechanisms, including π-π stacking, hydrophobic, electrostatic attraction and hydrogen-bonding interactions. This work not only provides a simple method for the preparation of a mixed-mode sorbent, but also a routine analysis strategy for monitoring the illegal use of ß-agonists and fluoroquinolones.


Asunto(s)
Agonistas Adrenérgicos beta/análisis , Fluoroquinolonas/análisis , Análisis de los Alimentos/métodos , Imanes/química , Estructuras Metalorgánicas/síntesis química , Extracción en Fase Sólida/métodos , Ácidos Sulfónicos/química , Agonistas Adrenérgicos beta/química , Agonistas Adrenérgicos beta/aislamiento & purificación , Adsorción , Animales , Técnicas de Química Sintética , Fluoroquinolonas/química , Fluoroquinolonas/aislamiento & purificación , Contaminación de Alimentos/análisis , Carne/análisis , Estructuras Metalorgánicas/química , Leche/química , Porcinos , Factores de Tiempo
7.
Chemosphere ; 262: 128351, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-33182113

RESUMEN

The transfer of POPs in food of animal origin has been studied by a meta-analysis of 28 peer-reviewed articles using transfer rate (TR) for milk and eggs and bioconcentration factors (BCF) for eligible tissues after establishing an adapted methodology. TRs of the most toxic PCDD/Fs into milk were generally elevated and even higher into eggs. BCFs in excreting adult animals varied widely between studies complicating to hierarchize tissues or congeners, even if liver and fat seemed to bioconcentrate more than lean tissues. Short time studies have clearly shown low BCFs contrarily to field studies showing the highest BCFs. The BCFs of PCDD/Fs in growing animals were higher in liver than in fat or muscle. In contrast to easily bioconcentrating hexachlorinated congeners, octa- and heptachlorinated congeners barely bioconcentrate. PCB transfer into milk and eggs was systematically high for very lipophilic congeners. Highly ortho-chlorinated PCBs were transferred >50% into milk and eggs and even >70% for congeners 123 and 167 into eggs. BCFs of the most toxic PCBs 126 and 169 were significantly higher than for less toxic congeners. BCFs seem generally low in PBDEs except congeners 47, 153 and 154. DDT and its metabolites showed high bioconcentration. Differences between tissues appeared but were masked by a study effect. In addition to some methodologic recommendations, this analysis showed the high transfer of POPs into eggs, milk and liver when animals were exposed justifying a strong monitoring in areas with POP exposure.


Asunto(s)
Contaminantes Ambientales/análisis , Contaminación de Alimentos/análisis , Animales , Dibenzofuranos/análisis , Dibenzofuranos Policlorados/análisis , Huevos/análisis , Monitoreo del Ambiente , Cadena Alimentaria , Éteres Difenilos Halogenados/análisis , Ganado , Leche/química , Bifenilos Policlorados/análisis , Dibenzodioxinas Policloradas/análisis
8.
Sci Total Environ ; 754: 142029, 2021 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-33254863

RESUMEN

Agriculture, and livestock production in particular, is criticized for being a contributor to global environmental change, including emissions of greenhouse gases (GHG). Methane (CH4) from grazing ruminants accounts for most of livestock's carbon footprint because a large share of them are reared under suboptimal grazing conditions, usually resulting in both low herbage intake and animal performance. Consequently, the CH4 quota attributed to animal maintenance is spread across few or no animal outputs, increasing the CH4 intensity [g CH4/kg live weight (LW) gain or g CH4/kg milk yield]. In this review, the generalized idea relating tropical pastures with low quality and intrinsically higher CH4 intensity is challenged by showing evidence that emissions from animals grazing tropical pastures can equal those of temperate grasses. We demonstrate the medium-to-high mitigation potential of some grazing management strategies to mitigate CH4 emissions from grazing ruminants and stress the predominant role that sward canopy structure (e.g., height) has over animal behavioral responses (e.g., intake rate), daily forage intake and resulting CH4 emissions. From this ecological perspective, we identify a grazing management concept aiming to offer the best sward structure that allows animals to optimize their daily herbage intake, creating opportunities to reduce CH4 intensity. We show the trade-off between animal performance and CH4 intensity, stressing that mitigation is substantial when grazing management is conducted under light-to-moderate intensities and optimize herbage intake and animal performance. We conclude that optimizing LW gain of grazing sheep and cattle to a threshold of 0.14 and 0.7 kg/day, respectively, would dramatically reduce CH4 intensity to approximately 0.2 kg CH4/kg LW gain, as observed in some intensive feeding systems. This could represent a mitigation potential of around 55% for livestock commodities in pasture-based systems. Our results offer new insights to the debate concerning mitigation of environmental impacts of pastoral ecosystems.


Asunto(s)
Gases de Efecto Invernadero , Metano , Alimentación Animal/análisis , Animales , Bovinos , Ecosistema , Metano/análisis , Leche/química , Rumiantes , Ovinos
9.
Food Chem ; 339: 127844, 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-32829243

RESUMEN

Fat-filled milk powders (FMP) are inexpensive milk alternatives predominantly exported to developing countries to satisfy growing demands for dairy proteins. Harsh climatic and sanitary conditions, poor border controls and relatively long periods for distribution and storage enhance the inherent vulnerability of FMP to fraud and stability. Rapid, low-cost methods are needed for extensive routine authentication of FMP products. This study investigated, for the first time, the sample integrity and the quality dynamics of 7 Nigerian FMP brands stored for 7 weeks at 40 °C. The prominent melamine and urea absorption peaks were absent, but protein contents were below the permitted limit. The peak absorbance of the OH functional group increased while the tryptophan contents decreased with storage time. Multiclass analyses differentiated the fresh FMP brands from one another, and from those that were aged. Robust interval-PLS predictions obtained for storage time may be excellent indicators of FMP freshness and stability.


Asunto(s)
Embalaje de Alimentos/métodos , Leche/química , Animales , Cromatografía de Gases , Cromatografía Líquida de Alta Presión , Ácidos Grasos/análisis , Microbiología de Alimentos , Análisis de los Mínimos Cuadrados , Leche/microbiología , Nigeria , Polvos/química , Análisis de Componente Principal , Salmonella/aislamiento & purificación , Temperatura , Triazinas/análisis , Urea/análisis
10.
Food Chem ; 339: 127854, 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-32829245

RESUMEN

Gold nanoparticles (AuNPs)-based lateral flow assay (LFA) enables a rapid detection of tetracycline (TET) in food samples but suffers from low sensitivity. Herein, metal-polydopamine framework (MPF), as a label, was employed to load monoclonal antibodies (mAbs) directly as the probe in LFA for highly sensitive sensing of TET. Combining zeolitic imidazolate framework (ZIF-67) and polydopamine (PDA), a stable MPF with large size, well water-dispersible, excellent affinity and optical properties was prepared through a versatile layer-by-layer assembly (LLA) strategy. Under optimized conditions, the biosensor (MPF-LFA) exhibited a great linear relationship in the range of 0.09-6 ng/mL and a detection limit of 0.045 ng/mL for TET detection, which was over 66-fold more sensitive than traditional AuNPs based LFA. Furthermore, the MPF-LFA was successfully applied to the screening of TET in fish, chicken, milk and shrimp samples with satisfied recoveries from 91% to 114%.


Asunto(s)
Antibacterianos/análisis , Análisis de los Alimentos/métodos , Oro/química , Indoles/química , Estructuras Metalorgánicas/química , Polímeros/química , Tetraciclina/análisis , Animales , Técnicas Biosensibles/métodos , Límite de Detección , Nanopartículas del Metal/química , Leche/química , Alimentos Marinos/análisis , Zeolitas/química
11.
Food Chem ; 339: 127857, 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-32866699

RESUMEN

Chloramphenicol (CAP) is a toxic substance for human health, and detection of CAP residues in milk is necessary. However, most of the traditional CAP detection methods including high performance liquid chromatography-tandem mass spectrometry (HPLC-MS) and enzyme-linked immunosorbent assay (ELISA) are time-consuming and complicated. Herein, an automated microfluidics system for CAP detection in milk was developed. The residual CAP of multiple milk samples was quantitatively detected via competitive immunoassay in a single microfluidic chip simultaneously and automatically, and the reliability of the method was confirmed by flow cytometry. Completion of the detection by the system required less than 20 min and the cost for the detection of ten samples was about US$2.5. The limit of detection was 0.05 µg L-1, and the recovery rate of CAP in milk ranged from 91.3% to 105.5%. The microfluidic system developed in this study exhibited considerable potential in the point-of-care testing (POCT) of CAP in milk.


Asunto(s)
Antibacterianos/análisis , Cloranfenicol/análisis , Microfluídica/métodos , Leche/química , Animales , Automatización , Inmunoensayo , Límite de Detección , Microfluídica/economía , Sistemas de Atención de Punto , Reproducibilidad de los Resultados
12.
Food Chem ; 340: 127923, 2021 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-32889212

RESUMEN

Identification of glycomacropeptide (GMP) and ß-lactoglobulin (ß-lg) present in cheese whey is difficult on SDS-PAGE due to their close proximity during electrophoresis and poor sensitivity of commonly used staining dye 'coomassie brilliant blue' (CBB) towards GMP. A simple method has been developed for the detection of GMP and ß-lg by staining acrylamide gel after tricine SDS-PAGE using cationic 'stains all' dye. After staining and destaining major whey proteins, viz. ɑ-lactalbumin (ɑ-la) and ß-lg appear red while GMP stains blue. The method can be used for the identification of these macromolecules in cheese whey and the detection of adulteration of milk with rennet whey.


Asunto(s)
Caseínas/análisis , Electroforesis en Gel de Poliacrilamida/métodos , Contaminación de Alimentos/análisis , Lactoglobulinas/análisis , Fragmentos de Péptidos/análisis , Animales , Caseínas/química , Quimosina/análisis , Glicina/análogos & derivados , Lactoglobulinas/química , Leche/química , Fragmentos de Péptidos/química , Colorantes de Rosanilina
13.
Food Chem ; 337: 127973, 2021 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-32927224

RESUMEN

To establish the effect of the presence of milk serum proteins on heat-induced changes to lactoferrin, lactoferrin alone, and lactoferrin mixed with either milk serum or ß-lactoglobulin was heated at 65 °C, 70 °C and 75 °C for 30 min. After heating, the effect of milk serum proteins on aggregation of lactoferrin was characterized, after which the effect of such aggregation on digestion and bacteriostatic capacity of lactoferrin were determined. The presence of milk serum proteins accelerated the aggregation of lactoferrin during heating through thiol/disulphide interchange. Lactoferrin also formed disulphide-linked aggregates when it was heated with ß-lactoglobulin. Protein aggregates formed at 75 °C were much more resistant to infant digestion, causing decreased peptide release from lactoferrin. Heating lactoferrin and milk serum proteins together accelerated the loss of bacteriostatic activity upon heating. In conclusion, heat-induced aggregation of lactoferrin with milk serum proteins affected both its digestion and its bacteriostatic activity.


Asunto(s)
Lactoferrina/química , Lactoferrina/farmacocinética , Proteínas de la Leche/química , Animales , Antibacterianos/farmacología , Digestión , Jugo Gástrico , Calor , Humanos , Lactoglobulinas/química , Leche/química , Tamaño de la Partícula , Proteína de Suero de Leche/química
14.
Food Chem ; 338: 128031, 2021 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-32950007

RESUMEN

A comprehensive study on packaging used in commercially available milk products from Spanish markets has been presented. Concentrations of four phthalates, seven parabens and BPA were determined in forty-two milk products. Eleven brands and five types of packaging (metallic aluminium bag, carton, high-density polyethylene, metal pail and polyethylene terephthalate) were included in the study. BPA showed the lowest concentrations (8.3 pg/g f.w.), far below those of phthalates (6431 pg/g f.w.) and parabens (6234 pg/g f.w.). Metallic aluminium bags were the least migrating packaging (considering plasticisers and monomers) followed by HDPE bottles, in the case of phthalates. Parabens showed their highest concentrations for fresh-milk samples. Levels found were far below the specific migration limits established by the EU and the cumulative hazard index was lower than 1, indicating that adverse health effects were not expected. In general, the results found in Spanish samples were lower than those reported in other countries.


Asunto(s)
Leche/química , Plastificantes/análisis , Conservadores Farmacéuticos/análisis , Animales , Compuestos de Bencidrilo/análisis , Humanos , Límite de Detección , Parabenos/análisis , Fenoles/análisis , Ácidos Ftálicos/análisis , España
15.
Sci Total Environ ; 751: 141830, 2021 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-33182002

RESUMEN

This systematic review presents the potential toxicity of heavy metals such as lead (Pb), mercury (Hg), cadmium (Cd), iron (Fe), nickel (Ni), aluminum (Al), and copper (Cu) in raw cow milk, focusing on their contamination sources and on the assessment of the related human health risk. Multiple keywords such as "raw cow milk, heavy metals, and human health" were used to search in related databases. A total of 60 original articles published since 2010 reporting the levels of these metals in raw cow's milk across the world were reviewed. Data showed that the highest levels of Ni (833 mg/L), Pb (60 mg/L), Cu (36 mg/L) were noticed in raw cow milk collected in area consists of granites and granite gneisses in India, while the highest level of Cd (12 mg/L) was reported in barite mining area in India. Fe values in raw cow milk samples were above the WHO maximum limit (0.37 mg/L) with highest values (37.02 mg/L) recorded in India. The highest Al level was (22.50 mg/L) reported for raw cow's milk collected close to food producing plants region in Turkey. The Target Hazard Quotients (THQ) values of Hg were below 1 suggesting that milk consumers are not at a non-carcinogenic risk except in Faisalabad province (Pakistan) where THQ values = 7.7. For the other heavy metals, the THQ values were >1 for Pb (10 regions out of 70), for Cd (6 regions out of 59), for Ni (3 out of 29), and for Cu (3 out of 54). Exposure to heavy metals is positively associated with diseases developments. Moreover, data actualization and continuous monitoring are necessary and recommended to evaluate heavy metals effects in future studies.


Asunto(s)
Metales Pesados , Leche , Animales , Bovinos , Monitoreo del Ambiente , Femenino , Humanos , India , Metales Pesados/análisis , Metales Pesados/toxicidad , Leche/química , Pakistán , Medición de Riesgo , Turquia
16.
Food Chem ; 334: 127588, 2021 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-32721837

RESUMEN

A mixture of sphingoid bases (SPGs) was prepared from butter serum, a by-product of anhydrous milk fat production. The mixture comprised seven types of SPGs with C16 to C19 alkyl chains. These milk SPGs inhibited the oxidation of fish oil triacylglycerol (TAG) more effectively than did a standard SPG (d18:1) with α-tocopherol. Reaction products were prepared from the combination of d18:0 or d18:1 with acrolein and propanal. Both sets of reaction products showed antioxidant activity toward fish oil TAG. Antioxidant activity of reaction products from d18:0 was stronger than that of reaction products from d18:1, suggesting that the molecule d18:0 may be a significant focus of the difference in antioxidant activity between milk SPGs and d18:1. To use SPGs as food additives in the future, an appropriate source of SPGs will be needed, and butter serum appears to have promise as a source of functional SPGs with strong antioxidant activity.


Asunto(s)
Antioxidantes/química , Aceites de Pescado/química , Leche/química , Esfingolípidos/química , Triglicéridos/química , Acroleína/química , Aldehídos/química , Animales , Aditivos Alimentarios/química , Hidrólisis , Oxidación-Reducción , alfa-Tocoferol/química
17.
Food Chem ; 338: 127820, 2021 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-32827899

RESUMEN

Lactoferrin (LF), a bioactive multifunctional protein of the transferrin family, is found mainly in the secretions of all mammals, especially in milk. In the present study, a hybridoma cell (LF8) secreting IgG against bovine LF was screened, and the purified LF8 mAb showed high specificity and affinity to bovine LF. The linear range of ic-ELISA to detect LF was 9.76 ~ 625 ng/mL, with a limit of detection (LOD) of 0.01 ng/mL. The average recovery of intra- and inter-assay were (104.45 ± 4.12)% and (107.13 ± 4.72)%, respectively. The LOD of colloidal gold- and AuNFs-based strip by naked eye were 9.7 and 2.4 ng/mL, respectively, and the detection time was less than 10 min without any samples pretreatment and expensive equipment. The developed ELISA and lateral flow immunosensors based on specific IgG could be used directly for rapid detection of the bovine LF content in cow milk samples.


Asunto(s)
Inmunoensayo/métodos , Lactoferrina/análisis , Leche/química , Animales , Anticuerpos Monoclonales , Bovinos , Ensayo de Inmunoadsorción Enzimática , Femenino , Oro Coloide , Inmunoensayo/instrumentación , Inmunoglobulina G/inmunología , Lactoferrina/inmunología , Límite de Detección , Nanopartículas del Metal/química , Ratones Endogámicos BALB C , Sensibilidad y Especificidad
18.
Int J Food Microbiol ; 337: 108950, 2021 Jan 16.
Artículo en Inglés | MEDLINE | ID: mdl-33212341

RESUMEN

Foodborne pathogens such as Salmonella can endure dry environments of milk powders for extended periods due to the increased adaptability at a low water activity (aw) and proliferate when powders are hydrated. This study compared the survivability and the thermal resistance of a 5-serovar Salmonella cocktail in dry and hydrated nonfat dry milk (NFDM) and whole milk powder (WMP) stored for 180 days at ambient temperature (~20 °C). This study was designed as two factorial (storage days and milk powder type) randomized complete block design with three replications as blocks. The milk powders were spray inoculated with 5-serovar Salmonella cocktail and dried back to the original pre-inoculation aw. The D-values of Salmonella in inoculated NFDM and WMP were determined periodically (every 30 days, starting from day one). The milk powders were also individually hydrated on each analysis day to determine D- and z-values of Salmonella in hydrated powders. The D-values were determined using thermal-death-time disks and hot-water baths at 80, 85 and 90 °C for milk powders, and 59, 62 and 65 °C for hydrated powders. The D- and z-values of Salmonella at specific temperatures within dry or hydrated powders during the storage period were compared at P ≤ 0.05 using two-way ANOVA and Tukey's Test. The D-values of Salmonella in WMP on day 1 were 18.9, 9.9 and 4.4 min at 80, 85 and 90 °C, respectively, which increased to 29.4, 13.6 and 6.5 min at 80, 85 and 90 °C, respectively, on day 180. Whereas, D-values of Salmonella in NFDM on day 1 were 17.9, 9.2 and 4.4 min at 80, 85 and 90 °C, respectively, and stayed similar during the storage. The D-values of Salmonella in milk powder remained similar throughout the storage once hydrated. The overall z-value of Salmonella in NFDM and WMP was 16.3 °C, whereas in hydrated NFDM and WMP, the overall z-value was 6.4 °C.


Asunto(s)
Almacenamiento de Alimentos , Alimentos en Conserva/microbiología , Leche/microbiología , Salmonella/fisiología , Agua/análisis , Animales , Microbiología de Alimentos , Calor , Viabilidad Microbiana , Leche/química , Polvos , Agua/metabolismo
19.
Food Chem ; 337: 127994, 2021 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-32919273

RESUMEN

Bovine derived chymosin in rennet cannot coagulate camel milk (CAM). The study aimed at producing cheese curd from CAM using a recombinant camel chymosin. Pasteurized CAM was prepared for curdling using a recombinant camel chymosin (50 IMCU/ kg). CAM (pH 6.65) contained 2.83% Fat, 3.34% proteins and 9.11% non-fat solids. Physicochemical properties of soft cheese from cultured CAM were 51.89%, 15.62%, 20.21% and 2.47% for moisture, protein, fat and ash, respectively. Cultured CAM afforded higher cheese yield (8.75%) than non-cultured CAM (3.34%). CAM cheese whey had 48.94% and 76.80% of the fat and proteins, respectively, of their corresponding concentrations in CAM. The study is the first report on soft cheeses from CAM (cultured and non-cultured) using a recombinant camel chymosin, with reference to whey constituents. CAM cheese and whey could be added-value products.


Asunto(s)
Queso , Quimosina/química , Animales , Camelus/metabolismo , Manipulación de Alimentos , Leche/química , Proteínas de la Leche/análisis , Proteínas Recombinantes/química , Suero Lácteo/química , Proteína de Suero de Leche/análisis
20.
Food Chem ; 337: 127946, 2021 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-32927223

RESUMEN

The counterfeit use of reconstituted milk to simulate fresh milk in some countries is largely driven by profiteering; hence, establishing a robust market-surveillance method is an important objective. In this study, an untargeted metabolomics approach that uses ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) was established to discover biomarkers that can be used to classify UHT and reconstituted milk. Furthermore, 36 positive- and 24 negative-ionization mode features were selected as candidate markers to establish a UPLC-tandem mass spectrometry (UPLC-MS/MS) multiple reaction monitoring (MRM) method. The support vector machine (SVM) method was used to process the responses of the selected potential markers, and 100% classifiability was observed. The marker metabolites could be divided into three categories by hierarchical clustering analysis: peptides, lipids, and nucleic acids. The results suggest that the untargeted-to-MRM metabolomics method is an effective tool for distinguishing between UHT and reconstituted milk.


Asunto(s)
Biomarcadores/análisis , Metabolómica/métodos , Leche/química , Espectrometría de Masas en Tándem/métodos , Animales , Cromatografía Líquida de Alta Presión/métodos , Calor
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