A novel UHPLC method for determining the degree of coffee roasting by analysis of furans.

The aim of this study was to develop a multi-analyte UHPLC method for furans and to apply it to commercial coffee samples as well as commercial roasting trials. Furans, as rising time-temperature indicators (TTIs), promised to be an alternative to unsatisfactory roasting temperature measurements. Consequently, a UHPLC-UV method for the determination of 5-hydroxymethyl-2-furfural (HMF), 5-hydroxymethyl-2-furoic acid (HMFA), 2-furfural (F), 5-methylfurfural (MF), 2-furyl methyl ketone (FMC), 2-furoic acid (FA), and for 3-caffeoylquinic acid (3-CQA) was developed and validated. Commercial roasted coffee beans contained 77.7-322 mg/kg HMF, 73.3-158 mg/kg HMFA, 109-200 mg/kg 2-F, 157-209 mg/kg MF, 12.3-32.8 mg/kg FMC, and 137-205 mg/kg FA. Roasting trial samples showed strong rising HMF contents (max.: Arabica: 769 mg/kg, Robusta: 364 mg/kg) followed by a distinct decline. Only MF and FA appeared as steady rising TTIs in the roasting process in Arabica and Robusta beans. 3-CQA fitted well as a decreasing TTI as expected.

High-throughput quantitation of bovine milk proteins and discrimination of commercial milk types by external cavity-quantum cascade laser spectroscopy and chemometrics.

Analysis of bovine milk proteins is crucial in many food and non-food industrial applications, nevertheless labour-intensive wet-chemical, low-throughput methods are still routinely used. In this work, external cavity-quantum cascade laser (EC-QCL) mid-infrared spectroscopy is employed as a rapid method for protein analysis of commercial bovine milk. Combined analysis of the amide I and II bands enabled quantitation of individual proteins (casein, ß-lactoglobulin, α-lactalbumin) and total protein content. IR spectra of spiked and diluted milk samples were employed for calibration of the target analytes in the presence of a complex matrix by partial least squares (PLS) regression modelling. A sample set of different milk types (pasteurized; differently processed extended shelf life, ESL; ultra-high temperature, UHT) was analysed, and results agreed well with reference methods. Quantitation of temperature sensitive proteins enables detailed distinction between milk types experiencing different heat loads during processing, and discrimination between diverse bovine milk types is successfully demonstrated.

Determination of vitamin B12 in four edible insect species by immunoaffinity and ultra-high performance liquid chromatography.

Insects are rich in major nutrients, such as protein and fat. Recently, minor nutrients like vitamins have become the subjects of interest in insects. Hence, this study reports on the development and validation of a method for the determination of vitamin B12 in mealworm (Tenebrio molitor larvae), cricket (Gryllus assimilis), grasshopper (Locusta migratoria) and cockroach (Shelfordella lateralis), using an ultra-high performance liquid chromatography approach with preliminary immunoaffinity chromatography sample preparation. The method was validated regarding linearity, specificity, accuracy and precision, as well as limits of detection/quantification, and was found to be satisfactory for the desired application. Found levels of vitamin B12 were 1.08 µg/100 g for mealworm, 2.88 µg/100 g for cricket, 0.84 µg/100 g for grasshopper, and 13.2 µg/100 g dry weight for cockroach, representing the first validated report on the content of vitamin B12 in edible insects. Observed interferences are likely caused by the presence of pseudovitamin B12.

Determination of the native forms of vitamin B1 in bovine milk using a fast and simplified UHPLC method.

The aim of this study was to develop a high-throughput UHPLC method for the determination vitamin B1 active compounds; thiamin, thiamin monophosphate and thiamin diphosphate in bovine milk. In order to sustain the native vitamin B1 phosphorus esters, sample preparation is crucial. Various acids as well as commonly used enzymes and their enzyme mixtures were compared. Method accuracy was confirmed using certified reference material as well as comparison with the corresponding CEN method, and was found to be satisfactory. Studied milk samples showed significant amounts of thiamin monophosphate, which can make up to 53.9% of the total vitamin B1 content in commercial milk, and up to 78% in raw milk. Moreover, a tremendous variation of the total content of vitamin B1 was observed between single cows, which ranged from 0.24mg/L up to 0.54mg/L of total vitamin B1.