Collaborative study: Quantification of total folate in food using an efficient single-enzyme extraction combined with LC-MS/MS

Untargeted Screening Based on UHPLC-HRMS of Total Folates Produced by Lactic Acid Bacteria in Fermented Milk and During Yogurt Shelf Life

Folate deficiency is a widespread nutritional issue, and biofortifying dairy products through lactic acid bacteria (LAB) is a promising strategy to enhance natural folate levels. This study aimed to develop a reliable method for selecting Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus strains with enhanced folate production for use as functional starter cultures. Initially, a traditional microbiological assay (MA) was used to measure folate production in 36 LAB strains isolated from fermented milks. Due to MA's limitations, an untargeted and semi-quantitative method combining ultra-high-performance liquid chromatography (UHPLC) with high-resolution mass spectrometry (HRMS) was developed for a more comprehensive folate screening. The MA showed higher folate production in S. thermophilus strains (309-639 µg/L) compared to L. delbrueckii subsp. bulgaricus (up to 48 µg/L). Subsequently, nine selected LAB strains were further analyzed using the UHPLC-HRMS approach, which enabled the identification and semi-quantification of six folate metabolites, namely dihydrofolate, tetrahydrofolate (THF), 10-formyl-THF, 5,10-methenyl-THF, 5,10-methylene-THF, and 5-methyl-THF. Lab-scale yogurt production using the top-performing strains, as identified through the HRMS method, demonstrated an increase in folate content over a 14-day shelf life. These findings revealed the potential of UHPLC-HRMS as a high-throughput alternative method for folates detection, offering a promising tool for screening folate-enhanced LAB strains for biofortification.

Limitations of current analytical reference methods to determine vitamins in foods: Challenges to support regulatory compliance and nutritional composition data

Foods are analysed for their vitamin content to support the verification of regulatory compliance or to generate food composition data. Many international reference methods for the analysis of vitamins in foods originate from the 1990s. Advances in nutrition science and analytical technology and the continuing evolution of statutory regulations necessitate the need of new or supplementary regulatory standards. We have evaluated recent developments in these areas and conclude that most current international reference methods are no longer fit-for-purpose to accurately determine vitamin content in foods and food supplements. We have made recommendations to consider new and/or updated reference methods and regulatory standards for the analysis of vitamins A, D, E, K, B1, B2, B3, B5, B6, B7, B9, B12, C and carotenoids in foods and food supplements. This area of nutrients may benefit from globally harmonised definitions specifying what compounds to include or exclude for analysis, and applicable bioactivity factors.

Strategic Priorities of the Scientific Plan of the European Research Infrastructure METROFOOD-RI for Promoting Metrology in Food and Nutrition

The pan-European distributed Research Infrastructure for Promoting Metrology in Food and Nutrition (METROFOOD-RI) has evolved in the frame of the European Strategy Forum on Research Infrastructures (ESFRI) to promote high-quality metrology services across the food chain. The METROFOOD-RI comprises physical facilities and electronic facilities. The former includes Reference Material plants and analytical laboratories (the ‘Metro’ side) and also experimental fields/farms, processing/storage plants and kitchen-labs (the ‘Food’ side). The RI is currently prepared to apply for receiving the European Research Infrastructure Consortium (ERIC) legal status and is organised to fulfil the requirements for operation at the national, European Union (EU) and international level. In this view, the METROFOOD-RI partners have recently reviewed the scientific plan and elaborated strategic priorities on key thematic areas of research in the food and nutrition domain to which they have expertise to contribute to meet global societal challenges and face unexpected emergencies. The present review summarises the methodology and main outcomes of the research study that helped to identify the key thematic areas from a metrological standpoint, to articulate critical and emerging issues and demands and to structure how the integrated facilities of the RI can operate in the first five years of operation as ERIC.

Identification of the prepared foods promising for dietary folate intake in Beijing, China

The aim of the present study was to analyze folate content and composition in foods consumed daily by Chinese people. The concentration of seven folate derivatives in sixty-four selected foods was determined by a liquid-chromatography tandem-mass spectrometry method. The total folate levels ranged from 0.28 to 129 µg/100 g fresh weight, with an average of 21.18 μg/100 g. The highest folate content was found in boiled egg yolk and waxy corn (>120 µg/100 g), abundant folate levels in cooked vegetables such as hot pepper, spinach, soybean sprout, stem lettuce, coriander, and broccoli (44-72 µg/100 g), and lowest in Coca Cola (0.28 µg/100 g). 5-Methyl-tetrahydrofolate was the major folate derivative in various foods, accounting for 72% of the total folates on average, with the highest being 90% in egg yolk. These data will enable estimation of the daily folate intake and allow dietary recommendations to improve folate status in humans.