Olfactory and quantitative analysis of aroma compounds in elder flower (Sambucus nigra L.) drink processed from five cultivars

Fresh elder flowers (Sambucus nigra L.) were extracted with an aqueous solution containing sucrose, peeled lemon slices, tartaric acid, and sodium benzoate to make elder flower syrup. Aroma compounds emitted from the elder flower syrup were collected by the dynamic headspace technique and analyzed by GC-FID and GC-MS. A total of 59 compounds were identified, 18 of which have not previously been detected in elder flower products. The concentrations of the identified volatiles were measured in five elder cultivars, Allesoe, Donau, Sambu, Sampo, and Samyl, and significant differences were detected among cultivars in the concentration levels of 48 compounds. The odor of the volatiles was evaluated by the GC-sniffing technique. cis-Rose oxide, nerol oxide, hotrienol, and nonanal contributed to the characteristic elder flower odor, whereas linalool, alpha-terpineol, 4-methyl-3-penten-2-one, and (Z)-beta-ocimene contributed with floral notes. Fruity odors were associated with pentanal, heptanal, and beta-damascenone. Fresh and grassy odors were primarily correlated with hexanal, hexanol, and (Z)-3-hexenol.     

Fluorescence of raw cane sugars evaluated by chemometrics

In a fluorescence study of raw cane sugar samples, two-way and three-way chemometric methods have been used to extract information about the individual fluorophores in the sugar from fluorescence excitation-emission landscapes. A sample set of 47 raw sugar samples representing a varied selection was analyzed, and three individual fluorophores with (275, 350) nm, (340, 420) nm, and (390, 460) nm as their approximate excitation and emission maxima were found. The spectral profiles of the fluorophores were estimated with the three-way decomposition model PARAFAC. Two-way principal component analysis (PCA) of unfolded fluorescence landscapes confirmed the PARAFAC results and showed patterns of samples related to time of storage. Partial least squares (PLS) calibration models of color at 420 nm had a high model error due to the very high color range of the raw sugars, but variable selection performed on the fluorescence data revealed that all three fluorophores were correlated to color. The (275, 350) nm fluorophore is considered as a color precursor to the color developed on storage and the (340, 420) nm and (390, 460) nm fluorophores show colorant polymer characteristics.     

Reacidification Effects on Water Chemistry and Plankton in a Limed Lake in Sweden

Water chemistry and plankton has been monitored in three Lakes in Tyresta National park SE of Stockholm since 1977. Liming operations started in Lake Långsjön and Lake Trehörningen in 1978 and were repeated every 3–5 years, while Lake Årsjön is an unlimed reference Lake. During 1991–1999, the annual pH median in Lake Långsjön and Lake Årsjön ranged between 6.6–7.1 and 5.2–5.8, respectively, and the composition of phyto- and zooplankton in these lakes did not change markedly. After a final treatment in 1991, the liming of Lake Trehörningen was terminated intentionally. As a result, pH decreased from an annual median 7.1 in 1991, to 6.1 in 1999 (5.8 in 1998). Total organic carbon (TOC) did not change markedly during this period, while the levels of calcium decreased. Metals, known to be influenced by acidification, especially cadmium, manganese and aluminium (Al), increased. The labile-inorganic forms of Al also reached higher levels, especially in 1998. Following the decreasing pH, the total number of phytoplankton taxa decreased by ca 40%. Among zooplankton, the cladocerans Holopedium gibberum, Diaphanosoma brachyurum and Daphnia longispina, common during the limed period, became rare.     

Nitrous oxide emission from a soil under permanent grass: Seasonal and diurnal fluctuations as influenced by manuring and fertilization

The emission of nitrous oxide (N₂O) from soil under grass was measured, following applications of cow slurry and NH₄NO₃ fertilizer. The N₂O-flux from untreated soil averaged 0.58 mg Nm^?2 day^?1 through April to August. Application of slurry at the end of April and at the middle of July caused increases in the daily N₂O-flux of up to 40-fold, compared to untreated grass. Applications of NH₄NO₃ increased the N₂O-flux up to 5 times during the same period. The N₂O-flux often showed marked diurnal fluctuations. These fluctuations are not solely associated with change in temperature, but may also be related to grass root activity and to photosynthesis.     

Vertical distribution of brown trout (Salmo Trutta) and perch (Perca Fluviatilis) in an acidified lake

Brown trout (Salmo trutta) and perch (Perca fluviatilis) had different vertical distributions throughout the year in the acidified lake Gjerstadvann. During summer, the brown trout lived in the 0 to 16 m depth interval, whereas the perch lived in the 0 to 8 m interval. In Gjerstadvann, the thermocline lies at 8 to 10 m depth. The epilimnion pH was usually > 5.6, and the thermocline pH was about 5.2. Brown trout and perch in Gjerstadvann, thus experienced different chemical environment during summer-stratification. Two rivers, one of them acidified, the other circum-neutral, were the most important spawning areas for the Gjerstadvann brown trout. Brown trout parr in the acidified river migrated to the lake and matured at younger ages than the brown trout spawning in the non-acidic river. The brown trout stocks were juvenilized because of low survival rate of adult fish (S = 0.15 to 0.19). The short life span was probably dus to low pH and elevated Al. The perch in Gjerstadvann showed fluctuating year class strength but the survival rate of adult perch (S = 0.57) did not seem to be affected by acidification during this investigation. This may due to its vertical distribution during summer.     

Planktonic and Littoral Microcrustaceans as Indices of Recovery in Limed Lakes in SE Norway

A two year study of planktonic and littoral microcrustaceans (Cladocera and Copepoda) from 15 lakes in the southeastern part of Norway, Østfold county, document the recovery of acidified lakes due to liming. Six lakes that where limed about 10 years ago, seven acid and two neutral reference lakes, were sampled twice a year (1998 and 1999). One acid lake was limed in autumn 1998. Qualitative nethaul samples from the deepest part of the lake and from the most frequent habitat in the littoral zone were used. The limed lakes had a species composition which indicates that these lakes are about to recover. Species associated with neutral lakes dominates while acid-tolerant species were rare. The acid-sensitive species, Daphnia longispina and D. cristata, were found in the limed lakes. This study shows the usefulness of a low-cost sampling program where microcrustaceans are used as bioindicators of recovery.     

Monitoring chemical changes of dry-cured Parma ham during processing by surface autofluorescence spectroscopy

Parma hams at various processing stages were investigated by surface autofluorescence spectroscopy. Fluorescence "landscapes" of raw meat and salted (3 months), matured (11 and 12 months), and aged (15 and 18 months) Parma hams were obtained, and a three-dimensional data array (sample x emission x excitation) was used to develop a PARAFAC model including five components, which all exhibited characteristics of pure fluorophores regarding both excitation and emission spectra. The relative amount of each component related strongly to the processing stage, and sample age showed good correlation to fluorescence data (R = 0.98), with a relative error of prediction of approximately 1 month. Fluorescence measurements from samples of either semimembranosus or biceps femoris were used to predict chemical or sensory reference data, yielding good correlation for biceps femoris data, thereby enabling moisture content, sensory and instrumental color, and proteolysis value to be fairly well predicted. Overall, surface autofluorescence of Parma hams proved to hold relevant information, relating to major chemical/physical changes during processing. It is concluded that fluorescence spectroscopy has potential as an innovative method of quality control in dry-cured ham.     

Chemical and sensory quantification of geosmin and 2-methylisoborneol in rainbow trout (Oncorhynchus mykiss) from recirculated aquacultures in relation to concentrations in basin water

Globally, aquaculture systems with water recirculation experience increasing problems with microbial taste and odor compounds (TOCs) such as geosmin and 2-methylisoborneol (MIB). This study investigated the content of geosmin and MIB in water and the flesh of 200 rainbow trouts from eight recirculated aquaculture systems in Denmark. TOC content in the fish flesh was measured by a dynamic headspace extraction method and was evaluated by a sensory panel. The results showed significant correlations between TOC content in water and fish and between chemical analysis and sensory perception. When geosmin exceeded 20 ng/L in the water, 96% of the fish had an intense muddy flavor, but below 10 ng geosmin/L, 18% of the fish (only 3% in special depuration ponds) had an intense muddy flavor. The results indicate that TOC levels <10 ng/L will ensure that a negligible portion of the fish obtains an unpalatable taste and flavor due to TOCs.     

Lysine limitation alters the storage pattern of protein,lipid and glycogen in on‐growing Atlantic salmon

This experiment aimed to test the interaction of lysine limitation with nutrient accretion and muscle carnitine depot in Atlantic salmon. Fish were fed adequate or low‐lysine diets for 3 months. Lysine intake was significantly less (48%) in fish fed the low‐lysine diet as compared with that fed the adequate one. There was no difference in dietary amino acids between treatments, with the exception of lysine. The lower lysine intake was reflected in plasma free lysine being 52% less while the free lysine concentration in the liver and muscle were unaffected. Although there was no significant difference between voluntary feed intakes among treatments, fish fed the low‐lysine diet had reduced growth, protein and energy deposition as compared with fish fed the adequate lysine diet. White trunk muscle contained more glycogen and less protein in fish fed the low‐lysine diet while no difference in lipid was observed. The livers from fish fed the low‐lysine diet contained less glycogen and slightly more fat and protein than the livers from fish fed the adequate lysine diet. Lysine limitation reduced carnitine in the liver without affecting muscle carnitine depot. Thus, low‐lysine diets did not likely affect the fatty acid oxidation capacity. This fact was supported by unaffected fatty acid profiles and lipid classes between treatments during the 3‐month study. In conclusion, lysine limitation does not deplete the muscle carnitine depot during the on‐growing seawater phase of Atlantic salmon, but affects the deposition pattern of nutrients.