Optimisation of the determination of thiamin, 2-(1-hydroxyethyl)thiamin, and riboflavin in food samples by use of HPLC

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.

Thiamin (Vitamin B1) - A scoping review for Nordic Nutrition Recommendations 2023

Only a few studies have explored relationships between thiamine intake and function, and a few studies have examined the effects of supplements on various clinical or biochemical outcomes. None of these studies, however, makes a useful contribution to understanding requirements in healthy populations. The requirement of thiamine relates to energy and carbohydrate intake. Clinical signs of deficiency have been observed at intakes below 0.5 mg/day, which corresponds to 0.05 mg/MJ. In other studies, thiamine excretion in the urine and normalisation of enzyme activity were normalised at intakes of 0.07-0.08 mg/MJ. The lower limit of intake thus estimates at 0.05 mg/MJ. It has not been possible to set a safe upper intake level for thiamine due to a lack of data. Studies on pregnant and lactating women indicate a higher requirement as assessed by biochemical parameters. A few studies indicate that thiamine utilisation is impaired among elderly subjects.

RP-HPLC Separation and 1H NMR Identification of a Yellow Fluorescent Compound-Riboflavin (Vitamin B2)-Produced by the Yeast Hyphopichia wangnamkhiaoensis

The yeast Hyphopichia wangnamkhiaoensis excretes a brilliant yellow fluorescent compound into its growth culture. In this study, we isolated and identified this compound using reverse-phase high-performance liquid chromatography-diode array detector (RP-HPLC-DAD) as well as 1H NMR and UV-Vis spectroscopy. Two of the three RP-HPLC-DAD methods used successfully separated the fluorescent compound and involved (1) a double separation step with isocratic flow elution, first on a C18 column and later on a cyano column, and (2) a separation with a linear gradient elution on a phenyl column. The wavelengths of maximum absorption of the fluorescent compound-containing HPLC fractions (~224, 268, 372, and 446 nm) are in good agreement with those exhibited by flavins. The 1H NMR spectra revealed methyl (δ 2.30 and 2.40) and aromatic proton (δ 7.79 and 7.77) signals of riboflavin. The 1H NMR spectra of the samples spiked with riboflavin confirmed that the brilliant yellow fluorescent compound is riboflavin. The maximum excitation and emission wavelengths of the fluorescent compound were 448 and 528 nm, respectively, which are identical to those of riboflavin.

Weissella cibaria riboflavin-overproducing and dextran-producing strains useful for the development of functional bread

This work describes a method for deriving riboflavin overproducing strains of Weissella cibaria by exposing three strains (BAL3C-5, BAL3C-7, and BAL3C-22) isolated from dough to increasing concentrations of roseoflavin. By this procedure, we selected one mutant overproducing strain from each parental strain (BAL3C-5 B2, BAL3C-7 B2, and BAL3C-22 B2, respectively). Quantification of dextran and riboflavin produced by the parental and mutant strains in a defined medium lacking riboflavin and polysaccharides confirmed that riboflavin was only overproduced by the mutant strains, whereas dextran production was similar in both mutant and parental strains. The molecular basis of the riboflavin overproduction by the mutants was determined by nucleotide sequencing of their rib operons, which encode the enzymes of the riboflavin biosynthetic pathway. We detected a unique mutation in each of the overproducing strains. These mutations, which map in the sensor domain (aptamer) of a regulatory element (the so-called FMN riboswitch) present in the 5’ untranslated region of the rib operon mRNA, appear to be responsible for the riboflavin-overproducing phenotype of the BAL3C-5 B2, BAL3C-7 B2, and BAL3C-22 B2 mutant strains. Furthermore, the molecular basis of dextran production by the six W. cibaria strains has been characterized by (i) the sequencing of their dsr genes encoding dextransucrases, which synthesize dextran using sucrose as substrate, and (ii) the detection of active Dsr proteins by zymograms. Finally, the parental and mutant strains were analyzed for in situ production of riboflavin and dextran during experimental bread making. The results indicate that the mutant strains were able to produce experimental wheat breads biofortified with both riboflavin and dextran and, therefore, may be useful for the manufacture of functional commercial breads.

Sprouts Use as Functional Foods. Optimization of Germination of Wheat (Triticum aestivum L.), Alfalfa (Medicago sativa L.), and Radish (Raphanus sativus L.) Seeds Based on Their Nutritional Content Evolution

Wheat, alfalfa, and radish sprouts are well-renowned for their high nutritional content. However, their optimal imbibition and germination durations are rarely considered in the literature. In this study, reduced imbibition times of 3 h, 10 h, and 4 h were demonstrated for the wheat, alfalfa, and radish seeds, respectively. The evolution of their crude fat, proteins, polyphenols, antioxidant activity, and vitamins were investigated over 7 days of germination. The crude fat and protein loads of these sprouts slightly varied during germination, whereas the phenolic compounds and antioxidant activity maxed out at day 7, 5, and 6 for the wheat, alfalfa, and radish sprouts, respectively, with significant levels of catechin. The vitamins highly increased, showing noteworthy yet different peaks of growth depending on the seed and the vitamin analyzed. Interestingly, alfalfa and radish sprouts, taken at their optimal germination day, would decidedly contribute to meet our Recommended Daily Allowances (RDAs) of vitamins E, A, and B6. Overall, for a greater nutritional content and a potential use of these sprouts as nutraceutical ingredients, our results suggested to leave the wheat, alfalfa, and radish seeds to germinate only over 7, 4, and 6 days, respectively, after which their nutritional quality tended to decrease.

Selection of Riboflavin Overproducing Strains of Lactic Acid Bacteria and Riboflavin Direct Quantification by Fluorescence

Riboflavin (vitamin B₂) is a vitamin of the B group involved in essential biological pathways, including redox reactions and the electron transport chain. Some lactic acid bacteria (LAB) can synthesize riboflavin and this capability is strain-dependent. In the last years, a growing interest has focused on the selection of riboflavin-overproducing food-grade LAB for the vitamin biofortification of fermented foods, as well as for the formulation of innovative functional products.In this chapter we report fast and inexpensive techniques in order to (1) screen LAB isolates able to produce riboflavin from different matrices, (2) select spontaneous roseoflavin-resistant riboflavin overproducing strains, and (3) quantify vitamin B₂ in culture media by fluorescence detection.These protocols could be useful to select new overproducing strains and/or species from different ecological niches, as well as to optimize the conditions for vitamin bioproduction.

Vitamin B2 concentration in cow milk: Quantification by a new UHPLC method and prediction by visible and near-infrared spectral analysis

Until now, there are few information on vitamin B₂ concentration variability in milk. In this study, a novel analytical method to quantify total vitamin B₂ in milk was developed and applied on 676 samples. In parallel, spectral analysis (colorimetry and near infrared spectroscopy) were performed to develop prediction models of vitamin B₂ concentration in milk. The analytical method includes an acid and enzymatic extraction followed by vitamin B₂ quantification by Ultra High Performance Liquid Chromatography coupled with fluorimetry. Samples analysis showed a wide range of concentration from 0.78 to 4.58 mg/L with a mean of 2.09 ± 0.48 mg/L. Two prediction models based on colorimetric analysis allow estimation of vitamin B₂ concentration in milk. Thus, this work shows an analytical method and, for the first time, a prediction method to enable enhancement of researches on vitamin B₂ content of milk and its variation factors.

Fermentation of Cauliflower and White Beans with Lactobacillus plantarum - Impact on Levels of Riboflavin, Folate, Vitamin B12, and Amino Acid Composition

As diets change in response to ethical, environmental, and health concerns surrounding meat consumption, fermentation has potential to improve the taste and nutritional qualities of plant-based foods. In this study, cauliflower, white beans, and a 50:50 cauliflower-white bean mixture were fermented using different strains of Lactobacillus plantarum. In all treatments containing cauliflower, the pH was reduced to <4 after 18 h, while treatments containing only white beans had an average pH of 4.8 after 18 h. Following fermentation, the riboflavin, folate, and vitamin B12 content of the cauliflower-white bean mixture was measured, and compared against that of an unfermented control. The riboflavin and folate content of the mixture increased significantly after fermentation. Relative to control samples, riboflavin increased by 76-113%, to 91.6 ± 0.6 μg/100 g fresh weight, and folate increased by 32-60%, to 58.8 ± 2.0 μg/100 g fresh weight. For one bacterial strain, L. plantarum 299, a significant 66% increase in vitamin B12 was observed, although the final amount (0.048 ± 0.013 μg/100 g fresh weight) was only a small fraction of recommended daily intake. Measurements of amino acid composition in the mixture revealed small increases in alanine, glycine, histidine, isoleucine, leucine, and valine in the fermented sample compared to the unfermented control.

Identifying labelling and marketing advantages of nutrients in minced beef meat: A case study

In 2006, the European Commission approved nutrition and health claim regulations of foods to stimulate healthier choices. To document how commercial, minced beef meat complied with regulations, meat samples from 72 carcasses were analysed. These samples were a source of niacin (B3), pyridoxine (B6), phosphorus and iron (cow meat only), and a rich source of protein, monounsaturated fat, vitamin B12 and zinc. A potential exists for establishing beef meat as a source of vitamin K, iron and selenium. The meat's nutrient relevance for young women when ingesting 150 g of raw beef mince/day was estimated. Increased levels of riboflavin (B2), pantothenic acid (B5), iron and selenium beyond presently observed, would better support this group's recommended nutrient intake. If the bioactivity of 25-OH-vitamin D3 could be used in calculations, vitamin D3 in the minced meat would add positively to the intake of vitamin D3 that was 49% of the recommended intake.

Real-Time Detection of Riboflavin Production by Lactobacillus plantarum Strains and Tracking of Their Gastrointestinal Survival and Functionality in vitro and in vivo Using mCherry Labeling

Some strains of lactic acid bacteria (LAB) produce riboflavin, a water-soluble vitamin of the B complex, essential for human beings. Here, we have evaluated riboflavin (B2 vitamin) production by five Lactobacillus plantarum strains isolated from chicha, a traditional maize-based fermented alcoholic beverage from north-western Argentina and their isogenic riboflavin-overproducing derivatives previously selected using roseoflavin. A direct fluorescence spectroscopic detection method to quantify riboflavin production in bacterial culture supernatants has been tested. Comparison of the efficiency for riboflavin fluorescence quantification with and without prior HPLC fractionation showed that the developed method is a rapid and easy test for selection of B2 vitamin-producing strains. In addition, it can be used for quantitative detection of the vitamin production in real time during bacterial growth. On the basis of this and previous analyses, the L. plantarum M5MA1-B2 riboflavin overproducer was selected for in vitro and in vivo studies after being fluorescently labeled by transfer of the pRCR12 plasmid, which encodes the mCherry protein. The labeling did not affect negatively the growth, the riboflavin production nor the adhesion of the strain to Caco-2 cells. Thus, L. plantarum M5MA1-B2[pRCR12] was evaluated for its survival under digestive tract stresses in the presence of microbiota in the dynamic multistage BFBL gut model and in a murine model. After exposure to both models, M5MA1-B2[pRCR12] could be recovered and detected by the pink color of the colonies. The results indicated a satisfactory resistance of the strain to gastric and intestinal stress conditions but a low colonization capability observed both in vitro and in vivo. Overall, L. plantarum M5MA1-B2 could be proposed as a probiotic strain for the development of functional foods.

In situ riboflavin fortification of different kefir-like cereal-based beverages using selected Andean LAB strains

Cereal-based functional beverages represent social, economic, and environmental sustainable opportunities to cope with emerging trends in food consumption and global nutrition. Here we report, for the first time, the polyphasic characterization of three cereal-based kefir-like riboflavin-enriched beverages, obtained from oat, maize and barley flours, and their comparison with classical milk-based kefir. The four matrices were successfully fermented with commercial starters: i) milk-kefir and ii) water-kefir, proving the potential of cereal ingredients in the formulation of dairy-like fermented beverages with milk-kefir starter behavior better in these matrices. In the light of their potentiality, seven riboflavin-producing Andean Lactic Acid Bacteria (LAB) were tested for tolerance to food stresses commonly encountered during food fermentation. Moreover, the LAB strains investigated were screened for spontaneous riboflavin overproducing derivatives. Lactobacillus plantarum M5MA1-B2 with outstanding response to stress, was selected to improve riboflavin content in an in situ fortification approach. The combination of L. plantarum M5MA1-B2 riboflavin overproducing strain with milk kefir starter in oat, lead to cover, for one serving of 100 g, 11.4% of Recommended Dietary Allowance (RDA). Besides, addition of L. plantarum M5MA1-B2 improved performance of water kefir in oat and maize matrices. Proton Transfer Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS) analysis provided the on-line Volatile Organic Compounds profiles supporting the best combination of starter, LAB and cereal matrix for novel functional foods development.

Probiotic abilities of riboflavin-overproducing Lactobacillus strains: a novel promising application of probiotics

The probiotic potential of Lactobacillus plantarum and Lactobacillus fermentum strains, capable of overproducing riboflavin, was investigated. The riboflavin production was quantified in co-cultures of lactobacilli and human intestinal epithelial cells, and the riboflavin overproduction ability was confirmed. When milk and yogurt were used as carrier matrices, L. plantarum and L. fermentum strains displayed a significant ability to survive through simulated gastrointestinal transit. Adhesion was studied on both biotic and abiotic surfaces. Both strains adhered strongly on Caco-2 cells, negatively influenced the adhesion of Escherichia coli O157:H7, and strongly inhibited the growth of three reference pathogenic microbial strains. Resistance to major antibiotics and potential hemolytic activity were assayed. Overall, this study reveals that these Lactobacillus stains are endowed with promising probiotic properties and thus are candidates for the development of novel functional food which would be both enriched in riboflavin and induce additional health benefits, including a potential in situ riboflavin production, once the microorganisms colonize the host intestine.

Riboflavin-overproducing strains of Lactobacillus fermentum for riboflavin-enriched bread

Lactobacillus fermentum isolated from sourdough was able to produce riboflavin. Spontaneous roseoflavin-resistant mutants were obtained by exposing the wild strain (named L. fermentum PBCC11) to increasing concentrations of roseoflavin. Fifteen spontaneous roseoflavin-resistant mutants were isolated, and the level of vitamin B₂ was quantified by HPLC. Seven mutant strains produced concentrations of vitamin B₂ higher than 1 mg L⁻¹. Interestingly, three mutants were unable to overproduce riboflavin even though they were able to withstand the selective pressure of roseoflavin. Alignment of the rib leader region of PBCC11 and its derivatives showed only point mutations at two neighboring locations of the RFN element. In particular, the highest riboflavin-producing isolates possess an A to G mutation at position 240, while the lowest riboflavin producer carries a T to A substitution at position 236. No mutations were detected in the derivative strains that did not have an overproducing phenotype. The best riboflavin overproducing strain, named L. fermentum PBCC11.5, and its parental strain were used to fortify bread. The effect of two different periods of fermentation on the riboflavin level was compared. Bread produced using the coinoculum yeast and L. fermentum PBCC11.5 led to an approximately twofold increase of final vitamin B₂ content.

The quantitative analysis of thiamin and riboflavin and their respective vitamers in fermented alcoholic beverages

This research aimed to develop a simple and effective method for analyzing thiamin (B(1)), riboflavin (B(2)) and their respective vitamers by high performance liquid chromatography (HPLC) in fermented alcoholic beverages. The method developed here employs a phosphate buffer/methanol gradient elution on a single reverse phase column, coupled with independent fluorescent detection regimes. It also employs a precolumn derivatization to convert thiamin to thiochrome via an alkaline potassium ferricyanide solution. The method described here allowed a spike recovery of better than 97%, with a typical linear detection range (R(2) ≥ 0.9997) between ≤ 5 and ≥ 500 μg/L for all vitamers studied. Lager style beers were found to contain significantly (p < 0.001) less thiamin than other tested styles of beers (lager, 35.7 μg/L; ale, 88.3 μg/L; stout/porters, 104.4 μg/L; wheat beers, 130.7 μg/L), which may be due to the raw material and extensive processing that occurs for this style. There was no statistical difference (p = 0.608) between the riboflavin content of each beer style. Furthermore, wines and ciders contain less thiamin and riboflavin than beer, which is also likely to be due to the base materials used and the differences in processing steps to produce these beverages.