Albacore tuna : a quality guide for off-the-dock purchasers [1995]

Revised March 1995. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the Sea Grant Catalog: http://seagrant.oregonstate.edu/publication

Smoking Fish at Home Safely

Important guide to safe preparation and storage of smoked fish. Easy for beginners and a good review of proper techniques for some of the "old pros." 4 pages

Direct injection gas chromatography of volatiles from fishery products

The use of gas chromatography for the separation, comparison, and subsequent identification of flavor volatiles from food products has proven highly successful in recent years. The development of various techniques for the concentration of the volatiles before gas chromatographic analysis has greatly extended the use of this important analytical tool. The injection of vapors directly into the chromatograph without prior concentration is the simplest method and has been used successfully on many food products. However, the use of this technique on the volatiles of fishery products has met with limited success. The complexity and nature of the flavor compounds found in fishery products have required the use of highly sensitive instruments and columns with very efficient separation power. The purpose of this investigation was to develop a method for the separation and comparison of volatiles from fishery products by this direct vapor injection technique. Preliminary investigations showed that a nine foot column of diisodecyl phthalate on 80/100 mesh, methanoic KOH treated, celite 545, operated isothermally at 35°C, would give satisfactory separation of one to three ml samples of volatiles from heated fishery products. The technique was not, however, sensitive enough to allow direct sampling of cold products unless they were highly spoiled or autoxidized. This investigation showed that direct vapor injection, using the column and conditions described, will show differences between size and number of peaks in heated fresh, oxidized, and spoiled fishery products. Several peaks in autoxidizing menhaden oil were shown to increase with hours of oxidation and a peak with the same retention time as trimethylamine was observed in the chromatograms of spoiled fish. The direct injection technique did not show large differences between fresh dover sole, rockfish, oysters, or beef. Tentative identification of various peaks from the chromatograms of oxidized salmon oil was attempted by comparison of retention data to known compounds and by functional group analysis by the method of Hoff and Feit (34). In this manner the possible existance of C₁ to C₇ alkanals, 2-hexen-1-al, methane, heptane, ethanol, butanol, and acetone was shown. The methods of tentative identification used were preliminary in nature and confirming tests would be necessary before positive identifications could be made. A comparison of chromatograms from fish, oysters, beef, and fish oils showed that several similar peaks appear in every case. These peaks were found at retention times of 0.71, 0.87, 1.42, 2.21, 2.83, 3.62, 5.20, and 5.51 minutes

Perceptions of wood in rivers and challenges for stream restoration in the United States

This article reports a study of the public perception of large wood in rivers and streams in the United States. Large wood is an element of freshwater aquatic ecosystems that has attracted much scientific interest in recent years because of its value in biological and geomorphological processes. At the heart of the issue is the nature of the relationship between scientific recognition of the ecological and geomorphological benefits of wood in rivers, management practices utilizing wood for river remediation progress, and public perceptions of in-channel wood. Surveys of students' perceptions of riverscapes with and without large wood in the states of Colorado, Connecticut, Georgia, Illinois, Iowa, Missouri, Oregon, and Texas suggest that many individuals in the United States adhere to traditionally negative views of wood. Except for students in Oregon, most respondents considered photographs of riverscapes with wood to be less aesthetically pleasing and needing more improvement than rivers without wood. Analysis of reasons given for improvement needs suggest that Oregon students are concerned with improving channels without wood for fauna habitat, whereas respondents elsewhere focused on the need for cleaning wood-rich channels for flood risk management. These results underscore the importance of public education to increase awareness of the geomorphological and ecological significance of wood in stream systems. This awareness should foster more positive attitudes toward wood. An integrated program of research, education, and policy is advocated to bridge the gap between scientific knowledge and public perception for effective management and restoration of river systems with wood