Evaluation of ED-XRF for the detection of inorganic adulterants in turmeric, paprika and oregano.

Herbs and spices are known to be prone to food fraud and accurate analytical tools are needed to detect adulterants. Amongst the potential adulteration, dilution with bulking agents has regularly been reported, especially with inorganic materials such as talc or brick powder. Energy Dispersive X-Ray Fluorescence (ED-XRF) spectrometry is a well-established non-destructive analytical technique for qualitative and quantitative elemental analysis of a wide variety of samples. ED-XRF was here evaluated for the detection of inorganic adulterants in turmeric, paprika and oregano, which were selected as representative for the herbs & spices food category. Magnesium, silicon, and calcium were identified as elements to detect talc, soapstone, brick/clay powder, and chalk inorganic adulterants. ED-XRF successfully detected adulterated samples when spiked down to 5% (w/w) in the selected herbs and spices. With its ease-of-use and speed, ED-XRF is well adapted for the monitoring of inorganic adulteration of herbs and spices along the supply chain.

Detection and characterization of small-sized microplastics (≥ 5 µm) in milk products.

Microplastics (MPs) have gained a high degree of public interest since they are associated with the global release of plastics into the environment. Various studies have confirmed the presence of MPs throughout the food chain. However, information on the ingestion of MPs via the consumption of many commonly consumed foods like dairy products are scarce due to the lack of studies investigating the "contamination" of this food group by MPs. This lack of occurrence data is mainly due to the absence of robust analytical methods capable of reliably quantifying MPs with size < 20 µm in foods. In this work, a new methodology was developed to accurately determine and characterize MPs in milk-based products using micro-Raman (µRaman) technology, entailing combined enzymatic and chemical digestion steps. This is the first time that the presence of relatively low amounts of small-sized MP (≥ 5 µm) have been reported in raw milk collected at farm just after the milking machine and in some processed commercial liquid and powdered cow's milk products.

Longitudinal Changes of Mineral Concentrations in Preterm and Term Human Milk from Lactating Swiss Women.

An adequate mineral supply to preterm infants is essential for normal growth and development. This study aimed to compare the mineral contents of human milk (HM) from healthy mothers of preterm (28-32 weeks) and full term (>37 weeks) infants. Samples were collected weekly for eight weeks for the term group (n = 34) and, biweekly up to 16 weeks for the preterm group (n = 27). Iron, zinc, selenium, copper, iodine, calcium, magnesium, phosphorus, potassium, and sodium were quantitatively analyzed by Inductively Coupled Plasma-Mass Spectrometry. The mineral contents of both HM showed parallel compositional changes over the period of lactation, with occasional significant differences when compared at the same postpartum age. However, when the comparisons were performed at an equivalent postmenstrual age, preterm HM contained less zinc and copper from week 39 to 48 (p < 0.002) and less selenium from week 39 to 44 (p < 0.002) than term HM. This translates into ranges of differences (min-max) of 53% to 78%, 30% to 72%, and 11% to 33% lower for zinc, copper, and selenium, respectively. These data provide comprehensive information on the temporal changes of ten minerals in preterm HM and may help to increase the accuracy of the mineral fortification of milk for preterm consumption.

Validation of a dilute and shoot method for quantification of 12 elements by inductively coupled plasma tandem mass spectrometry in human milk and in cow milk preparations.

Nutritional information about human milk is essential as early human growth and development have been closely linked to the status and requirements of several macro- and micro-elements. However, methods addressing whole mineral profiling in human milk have been scarce due in part to their technical complexities to accurately and simultaneously measure the concentration of micro- and macro-trace elements in low volume of human milk. In the present study, a single laboratory validation has been performed using a "dilute and shoot" approach for the quantification of sodium (Na), magnesium (Mg), phosphorus (P), potassium (K), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), selenium (Se), molybdenum (Mo) and iodine (I), in both human milk and milk preparations. Performances in terms of limits of detection and quantification, of repeatability, reproducibility and trueness have been assessed and verified using various reference or certified materials. For certified human milk sample (NIST 1953), recoveries obtained for reference or spiked values are ranged from 93% to 108% (except for Mn at 151%). This robust method using new technology ICP-MS/MS without high pressure digestion is adapted to both routinely and rapidly analyze human milk micro-sample (i.e. less than 250 µL) in the frame of clinical trials but also to be extended to the mineral profiling of milk preparations like infant formula and adult nutritionals.

Improvement of AOAC Official Method 984.27 for the determination of nine nutritional elements in food products by Inductively coupled plasma-atomic emission spectroscopy after microwave digestion: single-laboratory validation and ring trial.

A single-laboratory validation (SLV) and a ring trial (RT) were undertaken to determine nine nutritional elements in food products by inductively coupled plasma-atomic emission spectroscopy in order to improve and update AOAC Official Method 984.27. The improvements involved optimized microwave digestion, selected analytical lines, internal standardization, and ion buffering. Simultaneous determination of nine elements (calcium, copper, iron, potassium, magnesium, manganese, sodium, phosphorus, and zinc) was made in food products. Sample digestion was performed through wet digestion of food samples by microwave technology with either closed or open vessel systems. Validation was performed to characterize the method for selectivity, sensitivity, linearity, accuracy, precision, recovery, ruggedness, and uncertainty. The robustness and efficiency of this method was proved through a successful internal RT using experienced food industry laboratories. Performance characteristics are reported for 13 certified and in-house reference materials, populating the AOAC triangle food sectors, which fulfilled AOAC criteria and recommendations for accuracy (trueness, recovery, and z-scores) and precision (repeatability and reproducibility RSD and HorRat values) regarding SLV and RT. This multielemental method is cost-efficient, time-saving, accurate, and fit-for-purpose according to ISO 17025 Norm and AOAC acceptability criteria, and is proposed as an improved version of AOAC Official Method 984.27 for fortified food products, including infant formula.

Comparison of ion-selective electrode and inductively coupled plasma-mass spectrometry to determine iodine in milk-based nutritional products.

The performances of 2 official methods for iodine analysis based on inductively coupled plasma-mass spectrometry (ICP-MS) and the ion-selective electrode (ISE) method were compared for milk-based products. The aim of the study was to determine the performance characteristics of both methods to check the labeled concentration of iodine. Good precision was found for both methods with highest relative standard deviation of repeatability (RSD(r)) at 2.3 and 2.7% for ISE and ICP-MS, respectively. Intermediate reproducibility (RSD(iR)), single laboratory within 6 different days, was also good with the highest values at 7.3 and 8% by ISE and ICP-MS, respectively. Measurement uncertainty was estimated based on the RSD(iR) data, and it was concluded that both methods were capable of determining iodine concentrations within an uncertainty below +/- 20%. The accuracy of the methods was determined by analyzing certified reference materials, in-house proficiency test samples, and commercial products. Both methods returned similar results when applied on freshly opened samples. In samples that had been opened and kept exposed to air during storage, ISE returned lower iodine concentrations than ICP-MS. In commercial samples, the linear regression between both methods was ISE = 0.95 x ICP-MS -0.060 for freshly opened samples and ISE = 0.85 x ICP-MS + 0.069 for samples exposed to air. The tendency of ISE to return lower results than ICP-MS is explained by the fact that ISE is sensitive to iodide but does not measure iodine that may be bound organically to the matrix. This seems to be more pronounced in samples that were stored longer. Because in most countries iodine is labeled as total iodine, acceptance of an international standard based on the ICP-MS technique which takes all forms of iodine into account, is recommended. This would help to avoid any potential dispute on the accuracy of labeled iodine concentrations in finished products.

ED-XRF as a tool for rapid minerals control in milk-based products.

An ED-XRF method for the rapid determination of a series of analytes (phosphorus, sulfur, chlorine, potassium, calcium, iron, zinc) in milk-based products has been developed and validated. The investigated samples were commercial products obtained from various parts of the world. Reference values measured by inductively-coupled plasma-optical emission spectroscopy and by potentiometry for chloride were used to calibrate the ED-XRF. Calibrations were established with 30 samples, and validation was made using a second set of 30 samples. An evaluation of this alternative method was done by comparison with data from the reference methods. Pellets of 4 g were prepared under 2 tons of pressure. For each sample, 3 pellets were prepared and analyzed. Limits of quantification and repeatabilities were evaluated for the described analytes.