Niacin contents of cereal-milling products in food-composition databases need to be updated

The niacin content of cereal raw materials reported in food-composition databases often differs considerably. One major reason for this discrepancy is the analytical method used for its measurement is that a significant part of the niacin in cereals exists in bound form. In this study, we compared the niacin content of some representative cereal raw materials analysed with a sensitive and validated ultra-high performance liquid chromatography-fluorescence method against the values found in five national food-composition databases. We used established extraction methods that are assumed to liberate niacin available for absorption (acid hydrolysis mimicking human digestion) or total niacin (strong acid-alkaline hydrolysis). The niacin content (mg/100 g dry weight) obtained with acid hydrolysis ranged from a low level in corn flour (0.26), white wheat flour (0.45) and oat flakes (0.48), to a higher level in wholegrain flours (rye: 0.79, barley: 0.99, wheat: 0.88), wheat bran (2.7) and wheat germ (2.7). The niacin content with the acid-alkaline hydrolysis, however, was 1.9-11-fold the value measured after extraction with acid hydrolysis. In general, the niacin content found in the databases is closer to the results obtained after the acid-alkaline extraction, suggesting that the niacin values reported in the databases may not reflect actual bioaccessible niacin but total niacin.Peer reviewe

Influence of long term nitrogen limitation on lipid, protein and pigment production of Euglena gracilis in photoheterotrophic cultures

Nitrogen limitation is considered a good strategy for enhancement of algal lipid production while conversely N repletion has been shown to result in biomass rich in proteins. In this study, the influence of long-term N limitation on Euglena gracilis fatty acid (FA), protein, chlorophyll a, and carotenoid concentrations was studied in N limited cultures. Biomass composition was analyzed from three-time points from N starved late stationary phase cultures, exposed to three different initial N concentrations in the growth medium. Total lipid content increased under N limitation in ageing cultures, but the low N content and prolonged cultivation time resulted in the formation of a high proportion of saturated FAs. Furthermore, growth as well as the production of proteins, chlorophyll a and carotenoids were enhanced in higher N concentrations and metabolism of these cellular components stayed stable during the stationary growth phase. Our findings showed that a higher N availability and a shorter cultivation time is a good strategy for efficient E. gracilis biomass production, regardless of whether the produced biomass is intended for maximal recovery of polyunsaturated FAs, proteins, or photosynthetic pigments. Additionally, we showed an increase of neoxanthin, beta-carotene, and diadinoxanthin as a response to higher N availability.Peer reviewe

Ultra-high performance liquid chromatographic and mass spectrometric analysis of active vitamin B12 in cells of Propionibacterium and fermented cereal matrices

A sensitive and selective method is needed to analyse in situ produced vitamin B12 in plant-based materials, potential new dietary sources of vitamin B12. A UHPLC/UV method was developed and validated for the determination of human active vitamin B12 in cell extracts of Propionibacterium freudenreichii subsp. shermanii and after immunoaffinity purification in extracts of cereal matrices fermented by P. freudenreichii. An Acquity HSS T3 C18 column resulted in a baseline separation, a calibration curve of excellent linearity and a low limit of detection (0.075 ng/5 μL injection). As confirmed by UHPLC–MS, the active vitamin B12 could be separated from pseudovitamin B12. The recovery of vitamin B12 from purified spiked cereal matrices was good (>90%; RSD < 5%). A nutritionally relevant amount of active vitamin B12 was produced by P. freudenreichii in cereal malt matrices (up to 1.9 μg/100 g) in 24 h at 28 °C.Peer reviewe

Elintarvikekemia ja -analytiikka

vokyliopistopaino.helsinki.fi, puh. (09) 7010 2363, E-mail: [email protected]. Yksikön huom.: EK

EuroFIR guidelines for assessment of methods of analysis: GAMA

Food Chemistry-Volume 193: 10th International Food Data Conference (IFDC): Joining nutrition, agriculture and food safety through food compositionAnalytical methodology is a key factor in food composition databases and specific criteria, at the component level, is needed for comparison of analytical data from different sources. The aim of this work is to describe how EuroFIR guidelines for assessment of methods of analysis are created and made available to users. Comprehensive information for macronutrients, vitamins, minerals and trace elements addressing all aspects of analytical procedures was obtained from international standards, and scientific literature. Documentation was compiled in a confluence wiki format provided for each component: background information, description of reference methods of analysis and critical steps, available reference materials, proficiency testing schemes, other analytical methods and relevant references. The information for each nutrient was collated, edited and presented with hypertext links to additional pages where more detailed information can be accessed using full text searches. The wiki format is a useful tool for preparing information and disseminating to users.The work was supported by the EuroFIR Network of Excellence (FOOD-CT-2005-513944), funded under the EU 6th Framework Food Quality and Safety Programme, and its follow-up project EuroFIR Nexus (FP7-CSA-CA-265967), funded under the EU 7th Framework Communications Systems Architecture-Coordination Action Programme.info:eu-repo/semantics/publishedVersio