Illegal synthetic dyes in spices: a Singapore case study.

Some synthetic dyes are fraudulently added into spices to appeal visually to consumers. Food regulations in several countries, including the United States, Australia, Japan and the European Union, strictly prohibit the use of unauthorised synthetic dyes in food. Nevertheless, illegal practices persist, where spices contaminated with potentially carcinogenic dyes have been documented, posing potential health risks to consumers. In the present study, 14 synthetic dyes were investigated through liquid chromatography/tandem mass spectrometry in 252 commercially available spices in the Singapore market. In 18 out of these (7.1%) at least 1 illegal dye was detected at concentrations ranging from 0.010 to 114 mg/kg. Besides potential health risks, presence of these adulterants also reflects the economic motivations behind their fraudulent use. Findings in the present study further emphasise the need for increased public awareness, stricter enforcement, and continuous monitoring of illegal synthetic dyes in spices to ensure Singapore's food safety.

The detection, characterization, and quantification of dominant degradation products of nisin A and Z in selected dairy products by liquid chromatography-high-resolution mass spectrometry technique.

Nisin, a bacteriocin produced through fermentation using bacterium Lactococcus lactis, has several commercial variants such as nisin A and nisin Z. Nisin serves as a natural preservative with antimicrobial properties in various food products, including dairy and beverages, for extending product shelf life. The efficacy and safety of nisin A as a bacteriocin has been well characterized. However, there is limited evidence regarding the efficacy, stability, and safety of nisin Z as a food preservative, as it has not undergone comprehensive regulatory reviews. In this work, we studied the stability of nisin A and Z in a selection of yogurt drinks and found nisin to be unstable, particularly in fruit-flavored yogurt drinks. Both nisin A and Z could experience significant degradation leading to the nisin parent ion peaks dropping below detectable level before the product's expiry date. Compared with nisin A, the formation of oxidized metabolite nisin Z+O appeared to be the predominant reaction for nisin Z. These findings highlight the need for further scientific research to understand the behavior of nisin Z under different application conditions, which is crucial for assessing the efficacy and safety of nisin Z under these conditions. One potential application of this knowledge is to optimize the formulation of yogurt-based drinks to stabilize nisin Z and sustain its biopreservative function throughout the product's shelf life. Additionally, the current study shows that for the testing of the presence of nisin A or nisin Z, it is imperative to cover both the parent and the main degradant(s) of nisin. This is especially true for nisin Z, for which the regulatory approval status may vary in different markets. As such, the confirmative identification of nisin Z and its key metabolites in commercial products would be essential.

Determination of ethoxyquin by ultra-high performance liquid chromatography with tandem mass spectrometry and a Singapore survey of ethoxyquin residues in eggs, egg products and poultry.

In this study, an advanced ultra-high performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) method was developed for quantifying ethoxyquin (EQ). The approach employed a distinctive antioxidant added extraction step designed to prevent ethoxyquin decomposition and maintain analytical precision. This method effectively determines residue levels of EQ in eggs, processed egg products, poultry muscle, salmon, and liquid milk. The method was shown to have a limit of quantitation (LOQ) for eggs, milk, salmon, and chicken muscle of 1.5 µg/kg, 1.9 µg/kg, 2.1 µg/kg, and 1.2 µg/kg, respectively. The recoveries of EQ ranged from 79.2% to 107.6%, with a relative standard deviation (RSD) below 8.4%. A surveillance study for the presence of EQ in different types of eggs and poultry muscle available in Singapore was conducted and a total of 140 samples were tested. EQ residues in all samples were found to be below the U.S. Food and Drug Administration (FDA) MRLs of 500 µg/kg. Some samples of salted and preserved eggs from China were detected with higher concentration of EQ.

Determination and Characterization of Gold Nanoparticles in Liquor Using Asymmetric Flow Field-Flow Fractionation Hyphenated with Inductively Coupled Plasma Mass Spectrometry.

The EU has approved the usage of gold as a food additive (E175) and it has been applied in numerous foods for coloring and decoration purposes. Different from the general assumption that edible gold is mainly present in the form of flakes or external coating in foods, this work demonstrated that gold nanoparticles (Au NPs) can be released from gold flakes and extracted under optimized conditions. To support future risk assessment associated with the exposure of Au NPs to human health, an effective approach was established in this study for both size characterization and mass determination of Au NPs released in a commercial gold-containing liquor using Asymmetric Flow Field-flow Fractionation (AF4) hyphenated with Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Our results showed that no Au NPs were detected in the original liquor product and only after ultrasonication for several minutes did Au NPs occur in the ultrasound-treated liquor. Particularly, Au NPs released in the liquor can be well extracted after 100-fold enrichment of gold flakes and the subsequent ultrasonication for 25 min. Size characterization of Au NPs was conducted by AF4-ICP-MS under calibration with Au NP standards. The gold particle sizes detected ranged from 8.3-398.0 nm and the dominant size of the released Au NPs was around 123.7 nm in the processed liquor. The mass concentration of gold particles determined in the liquor sample with gold flakes concentrated and subsequently sonicated was 48.1 µg L-1 by pre-channel calibration and the overall detection recoveries ranged over 82-95%. For the comparison control samples without ultrasonication, there was no detection of Au NPs. The established method was demonstrated to be useful for monitoring Au NPs in liquor and is possibly applied to other similar foodstuffs.

Detection, Identification and Size Distribution of Silver Nanoparticles (AgNPs) in Milk and Migration Study for Breast Milk Storage Bags.

The engineered silver nanoparticles (AgNPs) have been widely used in various food contact materials (FCMs) based on their antibacterial properties. This widespread use of nanosilver has, however, increased the risk of exposure of AgNPs to human due to their migration from FCMs causing a potential hazard present in foods. Therefore, it is important to establish a reliable and practical method for the detection of AgNPs in food matrices to support risk assessment on AgNPs exposure. Taking the examples of milk and AgNPs-containing breast milk storage bags, this study established an approach for size characterization and quantification of AgNPs in milk and evaluated the relevant silver migration, based on enzymatic digestion and the analysis by asymmetric flow field-flow fractionation (AF4) hyphenated with inductively coupled plasma mass spectrometry (ICP-MS) and single particle inductively coupled plasma mass spectrometry (SP-ICP-MS). No migration of AgNPs was found from breast milk storage bags under various simulated storage conditions as well as extreme scenarios. The suitability and reliability of this method were also validated by the determination of multiple parameters, including accuracy, repeatability, limit of detection (LOD), limit of quantification (LOQ), and recovery, for AF4-ICP-MS and SP-ICP-MS, respectively, with good and overall acceptable evaluation results obtained for all. The established and validated approach was demonstrated to be suitable for the characterization and quantitation of AgNPs in milk as well as the analysis of their migration from breast milk storage bags.

Separation and size characterization of highly polydisperse titanium dioxide nanoparticles (E171) in powdered beverages by using Asymmetric Flow Field-Flow Fractionation hyphenated with Multi-Angle Light Scattering and Inductively Coupled Plasma Mass Spectrometry.

The application of titanium dioxide as E171 food additive has become an issue of debate due to numerous reports that titanium dioxide nanoparticles (TiO2 NPs) inside the products may pose risks to human health. However, there is still a lack of an official standardized methodology for the detection and size characterization of TiO2 particles in foods containing E171. In this study, a method was presented for size characterization of TiO2 particles with various independent verifications in coffee creamer and instant drink powders, using Asymmetric Flow Field-Flow Fractionation hyphenated with Multi-Angle Light Scattering and Inductively Coupled Plasma Mass Spectrometry (AF4-MALS-ICP-MS). TiO2 particles from these products were well extracted, followed by their optimized AF4 separation using anionic surfactant Sodium Dodecyl Sulfate (SDS) (0.05%, pH 9) and mixed surfactant NovaChem (0.2%), respectively. Size determination of TiO2 NPs was conducted based on AF4 calibration with polystyrene nanospheres and verification with TiO2 NPs standard suspension of 100 nm under two different AF4 conditions. The TiO2 particle sizes detected ranged from 24.4 - 544.3 nm for coffee creamer and 27.7 - 574.3 nm for instant drink powders, with the TiO2 NPs detection recoveries of 75% and 92%, respectively. Hydrodynamic diameters from AF4 size calibration could be independently validated by the gyration diameters from online MALS measurement. The established approach was demonstrated to be reliable and pragmatic for size profiling of highly polydisperse TiO2 particles and thus useful for monitoring E171 in similar foodstuffs.

An effective approach for size characterization and mass quantification of silica nanoparticles in coffee creamer by AF4-ICP-MS.

Silicon dioxide (SiO2) has been used as a food additive (E551) for decades. However, some safety concerns have been raised recently due to the detection of silica nanoparticles (SiO2 NPs) in a variety of foodstuffs and their unknown long-term health risk to humans. In order for risk assessment to be conducted, it is essential to establish a reliable, valid, and pragmatic method for analysis of SiO2 NPs in foods for estimation of exposure. This paper presents an effective approach for both size characterization and mass quantification of SiO2 NPs in commercial high-fat coffee creamer using asymmetric flow field-flow fractionation (AF4) coupled to inductively coupled plasma mass spectrometry (ICP-MS). SiO2 NPs from coffee creamer were well extracted after cleanup with hexane in a two-phase (hexane vs. water) aqueous environment. Size determination of SiO2 NPs was performed by on-line AF4-ICP-MS based on calibration with monodispersed standards. The dominant primary size of SiO2 NPs in the studied sample was 36.5 nm. The mass percentages of SiO2 NPs (vs. total SiO2) were 18.6% for the dominant primary nano-silica particles by prechannel calibration and 35.7% for total SiO2 NPs (≤ 100 nm) by postchannel calibration, with recoveries of 89-96% for the former and 75% for the latter. The established approach was demonstrated to be efficient and practical for routine analysis of polydispersed SiO2 NPs with wide nano-size distribution in coffee creamer. This method may be extended to monitor the presence of SiO2 NPs in other similar complex food matrices. Graphical abstract.