Scientific Opinion on Flavouring Group Evaluation 13Rev1: Furfuryl and furan derivatives with and without additional side‐chain substituents and heteroatoms from chemical group 14

Selection of a Novel DNA Aptamer Specific for 5-Hydroxymethylfurfural Using Capture-SELEX

A capture systematic evolution of ligands by exponential enrichment (Capture-SELEX) was described to discover novel aptamers specific for 5-hydroxymethylfurfural (5-HMF), and a biosensor based on molecular beacon was constructed to detect 5-HMF. The ssDNA library was immobilized to streptavidin (SA) resin to select the specific aptamer. The selection progress was monitored using real-time quantitative PCR (Q-PCR), and the enriched library was sequenced by high-throughput sequencing (HTS). Candidate and mutant aptamers were selected and identified by Isothermal Titration Calorimetry (ITC). The FAM-aptamer and BHQ1-cDNA were designed as the quenching biosensor to detect 5-HMF in milk matrix. After the 18th round selection, the Ct value decreased from 9.09 to 8.79, indicating that the library was enriched. The HTS results indicated that the total sequence numbers for 9th, 13th, 16th, and 18th were 417054, 407987, 307666, and 259867, but the number of sequences for the top 300 sequences was gradually increased from 9th to 18th, and the ClustalX2 analysis showed that there were four families with high homology rate. ITC results indicated that the K_d values of H1 and its mutants H1-8, H1-12, H1-14, and H1-21 were 2.5 μM, 1.8 μM, 1.2 μM, 6.5 μM, and 4.7 μM. The linear range of the quenching biosensor was from 0 μM to 75 μM, and it had a similar linear range in the 0.1% milk matrix. This is the first report to select a novel aptamer specific for 5-HMF and develop quenching biosensor for the rapid detection of 5-HMF in milk matrix.

Comparison of the Effects of 5-Hydroxymethylfurfural in Milk Powder Matrix and Standard Water on Oxidative Stress System of Zebrafish

5-Hydroxymethylfurfural (5-HMF) and furfural (FF) are products of the maillard reaction (MR) in milk powder and their safety is controversial. The concentration changes of 5-HMF and FF after a period of cold storage were determined by high-performance liquid chromatography (HPLC). Then, we compared the toxicity effects of 5-HMF (2, 20, or 200 μM) in milk powder matrix and standard water on the oxidative stress system of zebrafish embryos. The results showed that the concentration of 5-HMF was stable, and the concentration of FF degraded over time. 5-HMF-exposed zebrafish embryos had a LC₅₀ value of 961 μM for 120 h. High-concentration of 5-HMF exposure resulted in developmental toxicity and induced oxidative stress. 5-HMF exposure resulted in low expression of gstr gene at 200 μM in both matrices. Moreover, sod, cat, gstr, and gpxla genes were differentially highly expressed in other groups or showed no significant difference. Residual levels in all groups were well below the exposed dose, with a maximum value of only 0.4‱. These results provided a theoretical basis for understanding the effects of 5-HMF exposure in milk powder matrix on the oxidative stress system and suggested that the presence of 5-HMF in our daily consumption of milk powder does not produce significant toxic effects and need not be overstressed.

Scientific Opinion on Flavouring Group Evaluation 13 Revision 3 (FGE.13Rev3): furfuryl and furan derivatives with and without additional side-chain substituents and heteroatoms from chemical group 14

The Panel on Food additives and Flavourings of the EFSA was requested to update Flavouring Group Evaluation 13 using the Procedure as outlined in Commission Regulation (EC) No 1565/2000, to include an evaluation of the flavouring substances 2-ethyl-5-methylfuran [FL-no: 13.125] and 2-octylfuran [FL-no: 13.162]. FGE.13 revision 3 (FGE.13Rev3) deals with 26 flavourings substances of which 24 have been already evaluated to be of no safety concern. For [FL-no: 13.125] and [FL-no: 13.162], a concern for genotoxicity was raised in FGE.13Rev1. This concern could be ruled out based on new genotoxicity data on supporting substances in FGE.67Rev3. Subsequently, [FL-no: 13.125 and 13.162] were evaluated, through a stepwise approach that integrates intake from current uses, toxicological threshold of concern (TTC), and available data on metabolism and toxicity, along the B-side of the Procedure, making use of a BMDL of 8.51 mg/kg body weight (bw) per day. The Panel derived this BMDL from an oral subchronic toxicity study with the supporting substance 2-pentylfuran [FL-no: 13.059]. Using this BMDL, for [FL-no: 13.125 and 13.162], adequate margins of safety were calculated based on the MSDI approach. The Panel concluded that the 26 candidate substances in FGE.13Rev3 do not give rise to safety concerns at their levels of dietary intake, when estimated on the basis of the MSDI approach. Adequate specifications for the materials of commerce have been provided for all 26 substances. Data on uses and use levels are needed for [FL-no: 13.130]. For 21 flavouring substances [FL-no: 13.011, 13.102, 13.108, 13.113, 13.114, 13.122, 13.125, 13.127, 13.129, 13.132, 13.133, 13.135, 13.136, 13.139, 13.141, 13.143, 13.146, 13.149, 13.162, 13.178 and 13.185], the mTAMDI intake estimates are above the TTC for their structural class and more reliable data on uses and use levels are required to finalise their evaluation.