Influence of technological processing on apple aroma analysed by high resolution gas chromatography–mass spectrometry and on-line gas chromatography-combustion/pyrolysis-isotope ratio mass spectrometry

Extracts obtained by simultaneous distillation extraction (SDE) from industrial raw materials, namely single strength apple juices, and concentrates and aromas made thereof (each n = 31, from one production line; origin Poland, Germany, Turkey, Romania and China), as well as commercially available juices (n = 27), were analysed by standard controlled capillary gas chromatography–mass spectrometry (HRGC–MS). During the technological processing from juice to the aroma, no qualitative changes in the apple aroma profile were observed. Major constituents of the juices and aromas under study were found to be 1-hexanol (juice, 0.06–5.9 mg/l; aroma, 47–685 mg/l), 1-butanol (juice, 0.1–4.7 mg/l; aroma, 17–370 mg/l); E-2-hexenol (juice, 0.01–3.4 mg/l; aroma, 12–300 mg/l); E-2-hexenal (juice, 0–3.0 mg/l; aroma 0–470 mg/l), and butyl acetate (juice, 0–1.7 mg/l; aroma, 0–165 mg/l). By far the major component of the apple juice concentrates under study was furfural (2.4–56 mg/kg). The observed occurrence of 3-methyl-1-butanol (juice, 0.01–2.1 mg/l; aroma, 1.5–134 mg/l) and, in part, its acetate (juice, 0–0.3 mg/l; aroma, 0–3.3 mg/l), both known not to be genuine apple constituents, was obviously caused by fermentative effects in the course of industrial juice production. In addition, on-line capillary gas chromatography–isotope ratio mass spectrometry was used in the combustion (C) and the pyrolysis (P) modes (HRGC–C/P–IRMS) for the determination of δ¹³C_V-PDB and δ²H_V-SMOW values of selected apple flavour constituents to check potential isotope discrimination during distillative aroma production. As shown by means of the representative examples of E-2-hexenal, 1-hexanol and E-2-hexenol, their δ²H_V-SMOW values were slightly depleted. However, authenticity assessment by stable IRMS will not be influenced by this effect.     

Authenticity assessment of 2- and 3-methylbutanol using enantioselective and/or 13C/12C isotope ratio analysis

Enantioselective gas chromatography and/or ¹³C/¹²C isotope ratio analysis are suitable tools for the authenticity assessment of the fusel alcohols, 2- and 3-methylbutanol (1 and 2, respectively). The chiral compound, 1 is biosynthesised almost completely as the (S)-enantiomer, regardless of which carbohydrate source is used for fermentation. The type of CO₂ fixation and some plant-specific influences were of prime importance to the ¹³C/¹²C isotope ratios of the starting materials in alcoholic fermentation, and the δ¹³C values of 1 and 2 differed significantly. In general, the δ¹³C values of 2 were about 4–5ö lower than those of 1 produced via the same fermentation process. ¹³C/¹²C isotope ratio analysis results can be used to determine between fusel alcohols produced from different sources, and provides a new and valuable method of authenticity assessment.     

Using <Superscript>1</Superscript>H and <Superscript>13</Superscript>C NMR techniques and artificial neural networks to detect the adulteration of olive oil with hazelnut oil

The lack of any official analytical method to detect the adulteration of olive oil with a low percentage of hazelnut oil is explained by the similarities in the chemical compositions of both kinds of oils. To counter this problem, an artificial neural network based on ¹H-NMR and ¹³C-NMR data has been developed to detect olive oil adulteration, and the results from this ANN are presented here. A training set consisting of hazelnut oils, pure olive oils, and olive oils blended with 2–20% hazelnut oils was used to design and train a multilayer perceptron with 100% correct classifications. This mathematical model was also validated using an external validation set of blend samples (3–15%) and genuine samples. The detection limit of the model was around 8%.     

C/C pattern of honey from Turkey and determination of adulteration in commercially available honey samples using EA-IRMS

Honey adulteration particularly by adding cheap sugars such as High Fructose Corn Syrup (HFCS) and cane sugar syrup into natural honey is widespread. This study reports (¹³C/¹²C, ‰) patterns of 31 authentic honey samples obtained from different sources and regions of Turkey as well as 43 commercial honey samples to determine the adulteration using mass spectrometer coupled to elemental analyzer (EA-IRMS). The analyses indicated that the ranges of (¹³C/¹²C, ‰) values of honey and protein fractions of Turkish honey are from −23.30 to −27.58‰ and −24.13 to −26.76‰, respectively. These values for commercial honey samples were determined to range from −11.28 to −25.54‰ and −19.35 to −25.61‰, respectively. The numbers of adulterated commercial honey samples were found to be 10, which corresponds to 23% of the total number of the samples. Diastase activity, HMF content, electrical conductivity and moisture content of honey samples were also determined. Method validation and uncertainty budget calculations were also reported.     

The combination of stable isotope abundance ratios of H,C, N and S with Sr/Sr for geographical origin assignment of orange juices

Within the EU-project “Pure Juice” established stable isotope methods (δ²H, δ¹³C, δ¹⁵N) have been applied and improved in order to determine and verify the geographical origin of orange juices. In addition, new approaches employing analyses of δ³⁴S and ⁸⁷Sr/⁸⁶Sr have been developed and tested. Approximately 150 authentic orange juice samples from several regions in North- and South-America, Africa and Europe have been analysed. A discrimination of orange producing regions, based on the results which ultimately depend on geographical, climatic and lithological differences was successfully performed. Furthermore, we demonstrate that blending of single strength juice by adding concentrate can be revealed by comparing ⁸⁷Sr/⁸⁶Sr of soluble and insoluble components of the juices. We conclude that regional assignment of orange juice samples is most successful when single parameters are combined in a “multi-element approach”.     

Investigating the impact of botanical origin and harvesting period on carbon stable isotope ratio values (13C/12C) and different parameter analysis of Greek unifloral honeys: A chemometric approach for correct botanical discrimination

The aim of this study was to investigate the impact of botanical origin and harvesting period on carbon stable isotope ratio (¹³C/¹²C), colour intensity (CI), radical scavenging activity (%RSA), P and Sn content of Greek unifloral honeys. Thus, twenty‐four honey samples were collected during harvesting periods 2011–2012 and 2012–2013, from four different regions in Greece. ¹³C/¹²C ratios and minerals were determined using isotope ratio mass spectrometry (IRMS) and inductively coupled plasma optical–emission spectroscopy (ICP‐OES), respectively. CI and %RSA were measured using spectrophotometric assays. Results showed that only ¹³C/¹²C values and %RSA were affected by both botanical origin and harvesting period (P < 0.05). Applying then chemometric analyses to the collected data set, honeys were correctly classified according to honey type (correct classification rate 87.5% and 79.2% using the original and cross‐validation method, respectively). The use of different origin parameters has the potential to aid in honey authentication.     

Structural characterization of barley β-glucan extracted using a novel fractionation technique

A barley β-glucan concentrate prepared according to a novel technology was further purified and subjected to detailed structural characterization by NMR spectroscopy. β-Glucan was hydrolysed with β-glucan-4-glucanohydrolase (lichenase). Fractions of hydrolysate were collected using an HPLC-fraction collector. Intact β-glucan and the major fractions collected were subjected to MALDI-TOF–MS and NMR analyses. The two major oligosaccharides produced by lichenase hydrolysis of purified barley β-glucan were identified as β-d-Glc p-(1 → 4)- β-d-Glc p-(1 → 3)-β-d-Glc p and β-d-Glc p-(1 → 4)-β-d-Glc p-(1 → 4)-β-d-Glc p-(1 → 3)-β-d-Glc p based on ¹³C and ¹H NMR data. Spectrums were similar to those documented for barley β-glucan in the literature.