Jukka K. Kaitaranta

Gas-liqui chromatographic analysis of 2,4-dinitrophenyl-hydrazones of carbonyl compounds

Abstract Fifteen carbonyl compounds that are known to be flavor components have beenanalyzed as their 2,4-dinitrophenylhydrazones by gas-liquid chromatography on a 2% SE-30 column both isothermally at 232° and with a linear temperature program at a rate of 4°/min from 200 to 270° and on a 12% F-60 column at 225°. The detectors employed were a hydrogen flame ionization detector and an electron capture detector. Mixtures of the 2,4-dinitrophenylhydrazones can be successfully resolved on both columns although derivatives of compounds such as propanal, propenal and acetone with equal numbers of carbon atoms overlap. Some of the 2,4-dinitrophenylhydrazones gave rise to double peaks in gas-liquid chromatography owing mainly to the influence of the solvent. Peaks which were only slightly asymmetric were obtained when ethyl acetate was the solvent. The sensitivity was of the order of nanograms when the flame ionization detector was employed and five-hundred times greater when the electron capture detector was employed.

Comparison of the fatty acids in Baltic herring and available plankton feed

Triglycerides and phospholipids dominate in Baltic herring flesh lipids throughout the plankton growth season though at the same time plankton species and their lipids vary considerably. Wax esters and fatty alcohols do not exist in significant amounts in Baltic herring flesh or plankton. Saturated fatty acids exist in equal proportions in herring and plankton lipids whereas monoenoic acids are more dominant in herring and polyunsaturated acids in plankton lipids, respectively. The component alkyl chains are similar in both fish and plankton fatty acids, thus suggesting the planktonic origin. During the period of abundant availability of plankton the changes in the fatty acids of the herring depot fat are related to the changes in the plankton lipid composition.

Fatty acids in the roe lipids of common food fishes

The roe lipid fatty acids of Baltic herring, roach, perch, burbot and rainbow trout were quantitatively studied by capillary-GLC. The composition of roe fatty acids remain fairly stable during the fish maturation. The fatty acid profiles are very similar in various fish roes though differences exist in the relative amounts of individual components. On average perch and burbot have longer chain lengths and higher unsaturation degrees in their roe fatty acids compared to the other species. Variations in the fatty acids can be related to the roe lipid compositions and apparently also to the diet of the parent fish.

Comparison of changes in headspace volatiles of some coffee blends during storage

Abstract Headspace volatiles of commercial blends of Finnish roasted coffee ‘Juhlamokka’, ‘Presidentti’ and ‘Espresso’ were analysed by gas chromatography. The relative proportions of 43 compounds were observed over a 1 year period. The ratios of acetone butanedione , acetone propanal , thiophene propanal , thiophene butanedione , and butanedione/2-methylfuran were, in most cases, useful indicators of storage age (|r|). The relative proportions of acetone, methyl acetate, 2- and 3-methylfuran, 2-butanone, and 2,5-dimethylfuran were higher in the headspace of further roasted ‘Espresso’ blend containing Robusta quality than of the other blends. Only traces of pyridine were found in ‘Juhlamokka’ and ‘Presidentti’, but it was 5–10 times more abundant in ‘Espresso’. The proportions of methanol, 2-methylpropanal, butanedione, 2- and 3-methylbutanal, 2,3-pentanedione, and 2-furaldehyde were lower in ‘Espresso’ than in other coffees. The levels of acetone and 2-methylpropanal were higher in ground coffee than in the respective coffee beans. The proportion of 3-methylbutanal was greater in whole beans than in ground coffee. No marked differences between these two blends could be found.

Headspace of roasted ground coffee as an indicator of storage time

Abstract Volatiles emitted by roasted, ground coffee stored in laminate bags were analysed by a static headspace gas chromatographic-mass spectrometric (GC-MS) procedure. Ratios of several pairs of compounds in the headspace, such as thiophene/butanedione, 2-methylfuran/butanedione, acetone/butanedione, thiophene/propanal, 2-methylfuran/propanal and acetone/propanal increased with storage time. With CO 2 or air in the bags, the model predicted storage time with linear correlation coefficients of 0·96 and 0·99, respectively. The shares of most of the 38 measured compounds in coffee stored at 37°C for 117 days were not dramatically influenced by the presence of oxygen. Carbon disulphide, dimethyl sulphide and dimethyl disulphide disappeared in bags containing air, probably by oxidation.

Lipids and fatty acids in plankton from the finnish coastal waters of the Baltic sea

Abstract 1. 1. In the Finnish coastal waters phytoplanktonic diatoms dominate in early summer, changing to zooplanktonic Rotatoria in June and later to Copepoda. 2. 2. The lipid contents in plankton varied from 0.2 to 2.5% wet weight or from 1.9 to 17.0% dry weight, respectively. 3. 3. Triglycerides and polar lipids together dominated in phytoplankton while polar lipids alone were the major lipid in zooplankton. Exceptionally high proportions of free fatty acids existed in most samples whereas wax esters were detected only as minor components. 4. 4. Over two thirds of the fatty acids in phytoplankton were composed of C 16 acids, whereas palmitic acid together with polyenoic C 20 and C 22 acids dominated in zooplankton. 5. 5. Monoenoic C 20 and C 22 acids, often abundant in copepods, were found only in minor amounts in this study.