Liquid Milk Samples Research Articles

Fast preconcentration of Pb(II) and Cu(II) in liquid milk by syringe solid-phase extraction using alginate and PVA biopolymer loaded with activated carbon.

The simultaneous preconcentration and determination of Pb(II) and Cu(II) was afforded by a Syringe Solid Phase Extraction (SSPE) technique, which was developed and described for the first time, exploiting the alginate/carbon/PVA (ACP) sorbent as a support material. Imperative experimental factors were appraised in detail: pH 5.0 for Pb(II) and 4.0 for Cu(II), 75 mg of ACP mass, 4 sample cycles, 9 eluent cycles for Pb(II), 8 eluent cycles for Cu(II), and 1 mol L-1 of HNO3 as the eluent were found to be the optimal conditions for the devised procedure. The preconcentration factors were found to be 100 for both Pb(II) and Cu(II). These optimal conditions closely align with those obtained from the Box-Behnken Design (BBD) optimization. The results confirmed that ACP as the adsorbent could be reused up to 8 times. The LOD values calculated for Pb(II) and Cu(II) were 9.34 and 7.17 μg L-1, respectively. The calculated RSDs were less than 3.3%. The validated recoveries by ERM-BD151 (standard reference sample) were acquired at 97.6% for Pb(II) and 98.9% for Cu(II). The approach designed for the preconcentration of analytes in liquid milk samples proved successful.

Assessment of Cadmium and Mercury Contamination of Milk and Dairy Products in Vietnam

Background: Milk and dairy products are nutritious and can play a significant role in a healthy diet. The safety of milk decreases with increase in concentration of Cadmium (Cd) and Mercury (Hg). The aim is to evaluate the status of Cd and Hg contamination regarding milk and dairy products in some provinces and cities of Vietnam. Methods: 367 samples of liquid milk, yogurt, cheese, milk cake and milk powder were collected in six large cities and provinces of Vietnam, then Cd and Hg levels were quantitatively analyzed. Samples were digested before analysis to remove organic compounds, and the heavy metal concentrations were determined by atomic absorption spectrophotometry. Results: The average concentrations of Cd and Hg in liquid milk were 64.55 and 29.99 ppb; in yogurt, 49.09 and 24.72 ppb; in cheese, 115.81 and 33.75 ppb; in milk cake, 84.44 and 18.08 ppb; and in milk powder, 61.78 and 43.21 ppb, respectively. Conclusion: Hg concentrations in 19.3% of liquid milk, 9.49% of yogurt, 14.29% of cheese, 9.09% of milk cake, and 22% of milk powder were higher than the maximum permitted levels according to national regulations. In contrast, Cd concentrations of all the samples were less than the maximum permitted levels so as not to affect the health of consumers of milk and dairy products produced and processed in Vietnam.

Microplastics in the commercially available branded milk in Bangladesh: An emerging threat for human health

Microplastics (MPs) are polymer-based particles commonly found in diverse foods that pose serious human health impacts throughout the food chain. Assessment of MPs in different food products is a prime measure to combat MP-related food contamination. Therefore, this study first investigated the identification, characterization, and potential risks of MPs in the commercially available milk brands (19 dry powders and 06 liquid brands) in Bangladesh. The presence of MPs in milk samples was 279.47 ± 134.26 particles/kg and 182.27 ± 55.13 particles/L for powder and liquid milk, respectively, with a significant variety. Study findings displayed miscellaneous colors, fiber shapes (powder=78 %; liquid=81 %), > 0.1 mm sizes (powder=69 %; liquid=65 %), and polyethylene (powder=48 %; liquid=44 %) dominating MPs categories. The pollution load index indicated significant pollution due to the high abundance of MPs. Further, other risk-evaluating indices including contamination factor and Nemerow pollution index represent moderate to high MP-induced pollution for both milk samples. Low to moderate polymeric risks are exhibited by powder and liquid milk samples. Children could be exposed to 3.43 times higher MPs than adults through daily oral ingestion, which has significant health effects. This study found that powder milk was the most severely MPs induced risk than liquid milk. Consequently, this study finding established a reference point for MP contamination in milk, so special attention must be taken during production, storage, and packaging stages to reduce MP contamination.

Determination of 11 nutrients in liquid milk by ultra-performance liquid chromatography-tandem mass spectrometry

To establish an ultra-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS) method for simultaneous determination of 11 nutritional components(thiamine, riboflavin, nicotinamide, nicotinic acid, pantothenic acid, pyridoxine, pyridoxal, pyridoxamine, biotin, choline, L-carnitine) in liquid milk. Milk samples were shaken with 20 mmol/L ammonium formate solution and heated in a water bath at 100 ℃ for 30 min, then incubated with papain and acid phosphatase at 45 ℃ for 16 h, the lower liquid was collected after centrifugation for analysis. UPLC separation was performed on an ACQUITY~(TM) HSS T3(3.0 mm×150 mm, 1.8 μm) column, 2 mmol/L ammonium formate(containing 0.1% formic acid) solution and acetonitrile(containing 0.1% formic acid) were used as mobile phase. Quantitative detection was performed by internal standard method. 11 nutritional components can be effectively separated and detected in 12 min, and the linear correlation coefficients(R~2) were all above 0.995. The limits of detection(LODs) were between 0.05 and 0.50 μg/L, and the limits of quantification(LOQs) were between 0.20 and 1.25 μg/L. The recovery rates of three-level addition were 85.6%-119.3%, and the precision RSDs were between 3.68% and 7.82%(n=6). Based on the detection of 60 liquid milk samples from 5 different animals, it was found that the contents of 11 nutrients in liquid milk from different milk sources were significantly different, but pyridoxine could not be detected. The method can quantitatively detect 11 water-soluble nutrients, including free and bound forms, by effective enzymolysis. It is sensitive, reproducible and can meet the needs of quantitative detection.

Evaluation of essential and trace metals/metalloids distribution and probable human health risk implications from branded liquid and powder milks available in Dhaka City, Bangladesh.

The processed forms of milk, branded liquid, and power milk available in Dhaka city, the capital of Bangladesh, were investigated for essential and trace metal/metalloids regarding nutritional and human health risk aspects. For this, the potential nutritional contribution, estimated daily intake (EDI) and non-carcinogenic risk for six different life stages with male and female categories, as well as the carcinogenic risk for children and adults of both genders, were addressed. In total, 46 branded liquid and powder milk samples were considered for this analysis employing atomic absorption spectroscopy. The concentration of essential elements showed the trends of K > Ca > Na > Mg > Fe > Zn > Mn > Cu and K > Ca > Na > Mg > Fe > Cu > Mn > Zn for liquid and powder milk samples, respectively, but the potentially hazardous one showed the same trends (Cr > Pb > Hg > As > Cd) for both items. Except for Cr, Hg, and Fe, the elemental compositions of both milk categories differed considerably (< 0.05). Compared to the threshold values for milk samples (liquid and powder), Fe (19% and 27%), Mn (100% and 63%), Cu (0% and 23%), Zn (94% and 0%), Pb (25% and 13%), and Cr (0% and 3%) showed above the permissible limits. The nutrient input was the highest for Ca (27.2% and 18.7%), followed by Mg, K, and Na. The EDI of studied elements was within the daily permissible limit in both the milk category (except age group (≤ 3) and the female category). The non-carcinogenic risk assessment showed that the age groups ≤ 3 for liquid milk and ≤ 3 and 3 < X ≤ 14 with female categories for powder milk exceeded the threshold level (> 1) in the case of Cr, Cd, As, Zn, and Mn. The probable carcinogenic risks indicated an unacceptable risk level (< 1.00E-04) for the ingestion of Cr through powder milk samples for children in male and female categories. Finally, it believes that green cow farming practices and green milk processing technology, as well as continuous monitoring of toxic metals, can limit the ultimate risk worldwide.

Solid phase extraction of Aflatoxin M1 in milk samples by graphene oxide-poly-L-lysine nanocomposite followed by HPLC

ABSTRACT An efficient, novel and green Graphene Oxide-Poly-L-Lysine (GO-PLL) adsorbent was successfully synthesised and used for solid-phase extraction of aflatoxin M1 (AFM1) in liquid milk samples followed by high performance liquid chromatography (HPLC) equipped with fluorescence detector (FLD). The synthesised adsorbent was characterised by Fourier Transform Infrared Spectrophotometry (FT-IR), Field Emission Scanning Electron Microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDX) and X-Ray diffraction (XRD) analysis. Different parameters affecting the recovery percentage of AFM1 including pH of sample solution, amounts of adsorbent, contact time and desorbent solution (types and volume) were completely investigated and optimised. It was found that, with an enrichment factor of 15.2, the calibration curve is linear in the range of 0.05–4.00 ng ml−1 AFM1 and the limit of detection (LOD) and limit of quantification (LOQ) values were 0.019 and 0.063 ng mL−1, respectively. The relative standard deviations (RSDs) ranged from 4.5% to 5.7% and 4.2% to 6.7% for intra-day and inter-day variations, respectively. Finally, the proposed solid-phase extraction method was successfully applied for determination of trace levels of AFM1 in different milk samples.

DETERMINATION OF LEVEL OF AFLAFLATOXIN IN RAW MILK AND PASTEURIZED MILK SAMPLES

Aflatoxins are toxic compounds produced mainly by different genera of fungi and transferred to milk through contamination which causes life health hazards. The objective of the current study was to govern its existence in different raw and branded liquid milk samples sold in different areas of District Lahore in Pakistan. For this purpose, 80 samples ,40 raw and 40 branded milk samples were obtained during the months of July and August and analyzed to determine the level of AFM1 in milk by using ELISA technique. Typically, the investigative measures go through the subsequent stages: sampling, extraction, determination and quantification. 50% of the samples were positive for Aflatoxin M1, with a range of 49.73-429.61 ppt. Contamination beyond EU permissible limits for raw milk samples was 67.5% with 52.75-429.60 ppt range and 203.42 ppt mean. Samples collected from Shalimar Tehsil were observed more contaminated than others. On the other hand, branded milk contamination beyond EU limit was 30% with range of 49.73-381.04 ppt and 138.53 ppt mean. Consequently, Greater level of AFM1 in raw milk is a communal health risk, but a checking and scrutiny program for Aflatoxin M1 control in milk industry should be established to avert well-being harms.

The exploration of upconversion luminescence nanoprobes for tobramycin detection based on Förster resonance energy transfer

Tobramycin (TOB) is a broad-spectrum aminoglycoside extensively used as veterinary medicine to treat bacterial infections. However, TOB residue in food and environment may cause great threat to human health. Here, we report, for the first time, the upconversion nanoparticles (UCNPs) for TOB detection based on Förster resonance energy transfer (FRET). The upconversion (UC) luminescence from core-shell structured UCNPs was effectively quenched after addition of MnO2 nanosheets due to the efficient energy transfer from the UCNPs to MnO2 nanosheets. When interacting with TOB, the UC luminescence was restored and increased as a result of coupling between TOB and aptamer, with MnO2 nanosheets dropping off the latter one. The UCNPs@SiO2-MnO2 aptasensors for TOB detection have a good selectivity and sensitivity in a linear range of 10–180 ng mL−1 with a limit of detection (LOD) of 3.04 ng mL−1. The sensors were tested for TOB detection in real samples of liquid milk and fishes and the results are very good and satisfactory. These type of aptasensors are promising for practical applications as they have a high sensitivity, selectivity, low LOD, and are autofluorescence-free.

Identification of the animal origin of milk via Laser-Induced Breakdown Spectroscopy

The identification of milk's animal origin is traditionally performed by chemical/biochemical techniques. More recently, modern spectroscopic techniques are emerging as more suitable tools for this task. In the present work, Laser Induced Breakdown Spectroscopy (LIBS) assisted by machine learning is proposed for the identification of milk animal origin (cow, goat, sheep). For that purpose, 1296 raw liquid milk samples, and 683 lyophilized powdered samples, were studied by LIBS, and the corresponding spectra were analyzed by different machine learning algorithms in view of their classification based on the animal origin. Furthermore, to reduce the spectroscopic data volume, few spectral features related to milk's mineral content were selected and used for the classification of the milk samples. In all cases, predictive models were constructed and evaluated, and the corresponding predictive accuracies were calculated using unknown milk samples. The achieved predictive accuracies using the entire LIBS spectra attained values as high as 92.8 and 95.5% for the liquid and lyophilized powder milk samples, respectively, while using only five spectral lines related to the inorganic content of milk (Mg, Ca, Na, and K), classification accuracies up to 87.6 and 92.9% were obtained for the liquid and lyophilized powder milk samples, respectively. The present findings demonstrate the great potential of LIBS for discriminating milk samples based on animal origin.

Measurement of radioactivity levels of liquid milk samples in Kütahya, Turkey

Measurement of radioactivity levels of liquid milk samples in Kütahya, Turkey

Immunogold Labeling of Milk Proteins at Transmission Electron Microscopy.

Milk intended for human consumption is subjected to technological treatments to ensure its safety and storage stability. These treatments deeply modify some of its structural and nutritional characteristics. Principal modifications involve proteins that partly adsorb onto the membrane of milk fat globules upon homogenization or whey proteins that undergo denaturation and aggregation during thermal treatments. Transmission electron microscopy is a powerful approach to investigate milk ultrastructure, due to its high-resolution power. Immunogold labeling of β-lactoglobulin and β-casein proteins represents a sophisticated approach to examine their structure and localization following technological processes such as homogenization and UHT treatment. However, liquid milk is a very challenging matrix because of its complex multiphasic nature. To preserve both ultrastructure and antigenicity, and to obtain an efficient labelling in liquid milk samples, some precautions shall be adopted in fixation, embedding, and labeling steps as here reported.

Old dogs, new trick: Classical starch˗sodium iodide reagent as the chromogenic substrate of peroxidase-like nanozymes

2, 2′-azinobis-3-ethylbenzthiazoline-6-sulfonate (ABTS), 3, 3′, 5, 5′-tetramethylbenzidine (TMB), o-phenylenediamine (OPD) are typical chromogenic substrates to evaluate the activity of peroxidase-like nanozymes. However, these substrates are toxic, unstable, and the coloration reactions are slow. Herein, the classical starch-sodium iodide reagent was utilized as the chromogenic substrate to evaluate peroxidase-like activity of nanozymes. Starch-sodium iodine is less toxic, more stable and faster color reaction than ABTS, TMB and OPD. Under the catalysis of peroxidase-like nanozymes such as Mo5N6 nanosheets, graphene oxide nanosheets, Fe3O4 nanoparticles, CeO2 nanoparticles, iodide ion (I–) is oxidized by H2O2 to produce blue color complex (starch-I2). Taking Mo5N6 nanosheets as the peroxidase-like nanozyme, the color reaction completed within 5 min at room temperature (25 ºC), and the chromogenic substrate remained stable within 30 days. The maximum reaction rate (Vmax) using starch-sodium iodine as the chromogenic substrate was more than 100-fold higher than that of TMB. Based on this, a sensitive colorimetric sensor and facile portable agarose gel test kits were proposed and applied for the detection of H2O2 residue in liquid milk samples with fast response.

High and stable surface-enhanced Raman spectroscopy activity of h-BN nanosheet/Au1Ag3 nanoalloy hybrid membrane for melamine determination

In this work, a hexagonal boron nitride (h-BN)/AuAg nanoalloy hybrids (NAHs) was synthesized to fabricate h-BN/Au1Ag3 membrane as a solid surface-enhanced Raman spectroscopy (SERS) substrate for sensitive SERS detection of melamine. The AuAg nanoalloys were in situ grown on h-BN by chemical reduction method, and the Au/Ag molar ratio was tuned to achieve optimal SERS performance. After the SERS performance of h-BN/AuAg NAHs with different Au/Ag ratios was analyzed, h-BN/Au1Ag3 NAHs were chosen for SERS analysis. The h-BN/Au1Ag3 membrane can be obtained through simple filtration of h-BN/Au1Ag3 NAHs on chromatographic paper. As expected, the solid SERS substrates of h-BN/Au1Ag3 membrane were uniform and demonstrated good selectivity, repeatability and reproducibility for SERS detection of melamine. The results demonstrate that h-BN/Au1Ag3 membrane exhibited high SERS activity for 4-mercaptobenzoic acid (4-MBA) with limit of detection (LOD) at 1.0 ng L−1, and its analytical enhancement factor (AEF) reached 3.6 × 108. The possible enhancement mechanism, including electromagnetic mechanisms (EM) and chemical mechanisms (CM) were illustrated by finite-difference time-domain (FDTD) and density functional theory (DFT) simulations in detail, respectively. The concentration of melamine in the 0.05–5.0 mg L−1 range showed good linear relationship (R2 = 0.9940) with SERS intensity with LOD of 0.01 mg L−1. Finally, the recoveries of melamine in liquid milk samples are 87.7–105.7% with relative standard deviations (RSDs) in range of 0.6–2.6%, providing precise safety evaluation of melamine in milk samples.

Assessment of Aflatoxin M1 Contamination in Egyptian Milk and Cheese تقييم تلوث اللبن والجبن في السوق المصري بالأفلاتوکسين M1

A screening survey of the presence of aflatoxin M1 (AFM1) was carried out on 170 samples of Egyptian dairy products. Selected samples included raw buffalo or cow milk, pasteurized milk, UHT milk, fermented milk, soft cheese, hard cheese, and processed cheese were analyzed by competitive ELISA technique. Out of 60 liquid milk and fermented milk samples analyzed, 12 samples (20%) were found to be contaminated with AFM1, at levels ranging from 10.12 to 86.54 ng/kg. Eight from the positive samples (66.6%) failed to reach the acceptable level of the European Commission Regulation (50 ng/kg). Buffalo’s milk is safe regarding AFM1 contamination since all the buffalo milk samples were consistently negative. AFM1 was found in 22 samples (36.67%) of out 60 cheese samples at concentrations between 25.12 to 253.04 ng/kg. The highest mean value of AFM1, 231.39 ng/kg, was found in Ras cheese (hard type) samples followed by the processed cheeses with 114.76 ng/kg. Kariesh cheeses displayed the lowest levels, 53.32 ng/kg. Cheeses made from cow’s milk showed higher AFM1 positive samples, while cheeses made from buffalo’s milk tested were consistently negative. Regarding the cheese ripening age, out of 50 cow milk cheese samples, 26 were found to be positive to AFM1. The highest positive incidence was noted in long-term ripened hard cheeses (70%), while the lowest in fresh unripened cheeses (40%). It is highly recommended from the results that milk and cheese products have to be controlled periodically for AFM1 contamination.

Levels of Perfluorinated Compounds in Liquid Milk Products in Korea

This study was carried out to monitor the level of 17 perfluorinated compounds (PFCs) present in liquid milk products sold on the Korean market. The liquid milk samples were extracted via liquid-liquid extraction and analyzed by LC-MS/MS. Excellent linearity over the calibration range (r2>0.99), and the limit of quantification of perfluorooctane sulfonate (PFOS) was 0.021 ng/g, and perfluorotetradecanoic acid (PFOA) was 0.057 ng/g. The accuracy was in the range of 72.5-115.3%, and the precision was under 20%. The preprocessing method for this experiment is considered appropriate for analysis of milk samples. The proposed analytical method was applied for the determination of PFCs in 98 liquid milk product samples, and the average content of total PFCs was 0.6576 ng/mL. PFOA and PFOS were detected in most samples, and their levels were less than 0.1 ng/mL, which was lower than those in other studies.

A novel composite of conductive metal organic framework and molecularly imprinted poly (ionic liquid) for highly sensitive electrochemical detection of bisphenol A

A novel composite of conductive metal organic framework and molecularly imprinted poly (ionic liquid) (CMOF-MIPIL) was prepared for highly sensitive detection of bisphenol A (BPA). Ni-based CMOFs with various organic ligands, i.e., 2,3,6,7,10,11-hexaiminotriphenylene, hexa-aminobenzene, and 2,3,6,7,10,11-hexahydroxytriphenylene were synthesized. The electrochemical properties of the obtained Ni-based CMOFs were investigated. The results demonstrated that Ni3(HITP)2 had the highest conductivity and largest effective surface area. CMOF-MIPIL was then prepared with Ni3(HITP)2 as supporter, BPA as template, and ILs as monomer and cross-linker. Under optimal conditions, CMOF-MIPIL sensor exhibited a linear range of BPA detection from 0.005 to 5.0 μM. The detection limit was 4.0 nM. Compared with MIPIL, Ni3(HITP)2, and CMOF-NIPIL-based sensors, the performance of this sensor for BPA detection was superior due to the excellent conductivity and the presence of specific recognition sites. In addition, CMOF-MIPIL sensor had excellent selectivity for BPA. The proposed assay was used for detection of BPA in environmental water samples, plastic bottle and fresh liquid milk samples with success.

Survey of Aflatoxin M1 in Commercial Liquid Milk Products in China

The objective of this study was to investigate the occurrence of aflatoxin M1 (AFM1) in Chinese liquid milk products. A total of 190 liquid milk samples, including 168 ultrahigh-temperature-treated milk samples and 22 pasteurized milk (PM) samples, were collected in August 2019. A screening assay with the Charm rapid test kit and a confirmation method with high-performance liquid chromatography were used for AFM1 analysis. Nine (4.74%) samples were screened positive, of which 5 (2.11%) samples were confirmed with concentration levels of 0.022 to 0.049 μg/kg. The AFM1 levels confirmed were all below the maximum residue levels set by China, the European Union, the United States, and the Codex Alimentarius Commission. The detection rate of AFM1 in domestic milk samples was 3.39%, while no AFM1 was detected in samples of imported milk. The prevalences of AFM1 detected in three groups of brands were as follows: group I, the major brands of China, 2.70%; group II, the local city domestic brands, 4.55%; and group III, the brands imported into China, 0. The detection rate of AFM1 was significantly higher in PM samples (9.09%) than in ultrahigh-temperature-treated samples (1.19%) (P < 0.05). Although the residue level of AFM1 did not exceed the maximum residue levels in any of the samples, the higher detection rate in local Chinese brands, especially in PM samples, deserves the attention of the Chinese government and consumers.

Multi-Target Analysis and Suspect Screening of Xenobiotics in Milk by UHPLC-HRMS/MS

The development of suspect or non-target screening methods to detect xenobiotics in biological fluids is essential to properly understand the exposome and assess its adverse health effects on humans. In order to fulfil that aim, the biomonitorization of human fluids is compulsory. However, these methods are not yet extensively developed, especially for polar organic xenobiotics in biofluids such as milk, as most works are only focused on certain analytes of interest. In this work, a multi-target analysis method to determine 245 diverse xenobiotics in milk by means of Ultra High Performance Liquid Chromatography (UHPLC)-qOrbitrap was developed. Under optimal conditions, liquid milk samples were extracted with acetonitrile in the presence of anhydrous Na2SO4 and NaCl, and the extracts were cleaned-up by protein precipitation at low temperature and Captiva Non-Drip (ND)—Lipids filters. The optimized method was validated at two concentration-levels (10 ng/g and 40 ng/g) obtaining satisfactory figures of merit for more than 200 compounds. The validated multi-target method was applied to several milk samples, including commercial and breast milk, provided by 4 healthy volunteers. Moreover, the method was extended to perform suspect analysis of more than 17,000 xenobiotics. All in all, several diverse xenobiotics were detected, highlighting food additives (benzothiazole) or phytoestrogens (genistein and genistin) in commercial milk samples, and stimulants (caffeine), plasticizers (phthalates), UV filters (benzophenone), or pharmaceuticals (orlistat) in breast milk samples.

Aflatoxin M1 in pasteurized and UHT milk marked in Morocco

Milk plays an essential role in a balanced diet for human health. Mycotoxins are among the most toxic compounds found in milk of lactating cows. The purpose of this work was to assess aflatoxin M1 (AFM1) levels in 67 liquid milk samples (46 pasteurized and 21 UHT) randomly collected during 2019 from supermarkets and dairy shops in four Moroccan cities (Casablanca (n = 27), El Jadida (n = 10), Fez (n = 18) and Meknès (n = 12)). AFM1 was determined in milk by liquid chromatography (LC) after immunoaffinity column (IAC) cleanup. Analytical results indicated that out of the 67 analyzed samples, 9 (13.4%) were considered as positively contaminated, while 58 samples (86.6%) had AFM1 under the detection limit. For positive samples, AFM1 levels ranged between 10 and 77 ng/L, with an overall average value of 4.46 ± 14.09 ng/L. It has to be underlined that only one pasteurized milk sample contained AFM1 at concentration (77 ng/L) that exceeded the Moroccan maximum regulatory limit of 50 ng/L, while 100% of milk samples were below the limit of 500 ng/kg set by Codex Alimentarius standards. Based on the contamination levels found in this study and milk consumption data in the country, the estimated exposure level of Moroccan adults to AFM1 from milk was estimated at 0.88 ng/person/day (0.0125 ng/kg b.w./day). This exposure level is considered higher than the dietary intakes estimated by JECFA for the Middle Eastern and the African diets.

Classification of different liquid milk by near-infrared spectroscopy and ensemble modeling

Dairy products are necessary components of a healthy diet for human and nowadays, liquid milk become very popular because of its convenience. The identification of a brand of liquid milk is of importance. In this study, near-infrared (NIR) spectroscopy is used for rapid and objective classification of different brands of liquid milk. Chemometric methods including extreme learning machine (ELM) and its ensemble version (EELM) are investigated and compared. A dataset containing 144 samples from 6 brands are collected for experiment. A model-independent filter algorithm, i.e., relief-based feature selection, was used for variable reduction. Principal component analysis (PCA) is used as a tool of exploratory analysis for visualizing the difference among liquid milk samples of different brands. All samples were divided into three subsets, i.e., the training set, validation set and test set, for constructing, optimizing and testing the model, respectively. The model developed by the EELM procedure achieved 100% of classification accuracy, indicating that NIR spectroscopy combined with variable reduction and the EELM algorithm is feasible for classifying the brands of liquid milk.