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The present study aimed to investigate coffee flavour perception and release as function of serving temperature to support standardisation in the specialty coffee branch. The coffee cultivar Bourbon Caturra was evaluated at six serving temperatures ranging from 31°C to 62°C. Coffee samples were analysed by dynamic headspace sampling gas chromatography-mass spectrometry and descriptive analyses using sip-and-spit tasting. The release of volatiles followed mostly the van't Hoff principle and was exuberated at temperatures above 40°C. Aliphatic ketones, alkylpyrazines, some furans and pyridines increased most notably at temperatures ⩾50°C. The changes in volatile release profiles could explain some of the sensory differences observed. The flavour notes of 'sour', 'tobacco' and 'sweet' were mostly associated with the coffees served at 31-44°C, whereas coffees served between 50°C and 62°C exhibited stronger 'overall intensity', 'roasted' flavour and 'bitter' notes.

Soy protein isolates were fermented by three commercial Lactobacillus helveticus strains for a maximum of seven days to investigate the resulting proteolysis. The proteolytic activity of the most active strain (LH88) was further analyzed (LC-MS/MS and GC-MS) and it was shown that the β-conglycinin α subunit 1, β-conglycinin α' subunit, glycinin G1, and 2S albumin were specifically degraded. Peptigram analysis and visualization of the crystal structure showed that the hydrolysis sites of β-conglycinin α subunit, α' subunit, and the glycinin G1 were located on the surface of the molecule or at the mobile disordered region, hence being highly accessible for the proteinase of LH88. The proteins were partially further degraded to free amino acids, and subsequently catabolized to volatile compounds. However, most of the proteins remained native, even after seven days of fermentation, thus additional modification of protein structure or adjustment of fermentation conditions are required for effective generation of flavor compounds.

The influence of fermentation temperatures (8°C, 16°C, and 32°C) and yeast levels (2%, 4%, and 6% of the flour) on the formation of volatile compounds in the crust of whole meal wheat bread was investigated. The fermentation times were regulated to optimum bread height for each treatment. The volatile compounds were extracted by dynamic headspace extraction and analyzed by gas chromatography-mass spectrometry. The results were evaluated using multivariate data analysis and ANOVA. In all crust samples 28 volatile compounds out of 58 compounds were identified and the other 30 compounds were tentatively identified. Higher fermentation temperatures promoted the formation of Maillard reaction products 3-methyl-1-butanol, pyrazine, 2-ethylpyrazine, 2-ethyl-3-methylpyrazine, 2-vinylpyrazine, 3-hydroxy-2-butanone, 3-(methylsulfanyl)-propanal, and 5-methyl-2-furancarboxaldehyde whereas at lower temperature (8°C) the formation of 2- and 3-methylbutanal was favored. Higher levels of yeast promoted the formation of 3-methyl-1-butanol, 2-methyl-1-propanol and 3-(methylsulfanyl)-propanal, whereas hexanal was promoted in the crust fermented with lower yeast level.

Analysis of volatile compounds was performed on 81 wheat varieties and landraces, grown under controlled greenhouse conditions, in order to investigate the possibility of differentiating wheat varieties according to their volatile compound profiles. Volatile compounds from wheat samples were extracted by dynamic headspace extraction and analysed by gas chromatography-mass spectrometry. Seventy-two volatile compounds were identified in the wheat samples. Multivariate analysis of the data showed a large diversity in volatile profiles between samples. Differences occurred between samples from Austria compared to British, French and Danish varieties. Landraces were distinguishable from modern varieties and they were characterised by higher averaged peak areas for esters, alcohols, and some furans. Modern varieties were characterised by higher averaged peak areas for terpenes, pyrazines and straight-chained aldehydes. Differences in volatile profiles are demonstrated between wheat samples for the first time, based on variety. These results are significant to plant breeders and commercial users of wheat.

Marama bean ( Tylosema esculentum ) is an underutilised legume indigenous to the Kalahari Desert region of southern Africa. The bean has high lipid content and hence is a potential source for production of edible oil. The headspace volatile composition of freshly pressed marama bean oil was explored and the oil was further studied during 7 months of storage under different light and temperature conditions. The oxidative stability of the oil was examined by measuring peroxide value, vitamin E content and FT-IR spectra. Additionally, the headspace volatile composition of the oil was investigated during storage by use of dynamic headspace GC–MS. The results showed that marama oil is highly stable and has good natural antioxidant properties; enzymatic lipid oxidation does not take place in marama oil. Light has a greater effect on the lipid oxidation than has temperature, and hence marama oil should preferably be stored in darkness and rather at 25 °C than 35 °C. Under these conditions, the marama oil has a shelf life of at least 7 months.

During storage for up to 52 weeks, under mildly accelerated conditions (22 °C, atmospheric air), potato flakes (1% lipid, dried to aw=0.4) were found to undergo oxidative changes as indicated by a slight decrease in headspace oxygen. The headspace concentration of hydrocarbons (ethane and pentane) steadily increased during storage, and the increase was reduced with added antioxidants. For a product without added antioxidants, three short-chain aldehydes increased slightly, but other secondary oxidation products did not change significantly (including thiobarbituric acid reactive substances). Long chain aldehydes (identified by GC–MS) were abundant in fresh products, but decreased during storage. The level of free radicals, as a marker of early events in oxidation and measured directly by electron spin resonance spectroscopy (ESR), increased significantly during the first 2 weeks of storage, followed by a marked decrease for the period of 2–22 weeks of storage to reach a steady state level. Throughout the period of storage, ESR spectrometry was able to rank products protected by natural antioxidant extracts according to increasing level of free radicals: Unprotected>Coffee>Green tea, Grape skin>Rosemary. Hydrocarbons evolved according to a similar pattern and it can be concluded that ESR spectrometry provides a method for detecting early stages of oxidation in this type of low fat dried products.

Aromas of raw and boiled potatoes were compared using a mild extraction technique, ensuring preservation of the very labile composition of potato aroma during analysis. The extracts were evaluated by GC–MS and GC-sniffing using a panel of four judges. A total of 29 compounds were identified by GC–MS in raw potatoes and 25 in boiled. Twenty compounds were found in both raw and boiled potatoes, but most often in very different concentrations. During GC-sniffing, 33 odours were detected in boiled, and 27 in raw potatoes. Eight odours corresponded to compounds identified by GC–MS. Another four odours could be tentatively identified. It is concluded that the change in aroma during boiling of potatoes depends on compounds from lipid oxidation as well as compounds from other types of reactions, for instance the Strecker-degradation.

The aroma of freshly made and stored reconstituted orange juice was analyzed by GC– MS and GC–FID. The importance of the individual compounds was evaluated by calculation of aroma values. For comparison, the same samples were evaluated by a GC-sniffing technique called GC Odour Profiling, using a panel of five assessors. Both methods showed that there were significant differences between freshly made and stored juice, but the two methods did not always show the same compounds/odours to be important. On the other hand, many similarities were seen, as ethyl butanoate, β -pinene, limonene, octanal and linalool were shown to be important by both methods. In conclusion, both methods proved to be useful for identifying important aroma compounds in orange juice and for discrimination between fresh and stored juice.