Recent advances in fishy odour in aquatic fish products,from formation to control

Aquatic products are one of the most important foods with plenty of high-quality protein, unsaturated fatty acids (EPA, DHA), a variety of minerals and other essential nutrients. However, the bad smell of fish, such as fishy smell and earthy smell, restricts its production and consumption. The main fishy odour substances from freshwater fish and marine fish are different. The geosmin and 2-methylisobomeol are the main compounds in freshwater fish, and aldehydes, alcohols and ketones are found in most marine fish. The odour compounds can come from environment like water, feed and alga, enzymolysis and oxidative reactions of protein and lipid. Thus, it is necessary to remove or inhibit odour by managing farming environment like improving water quality, using physical method like adding some substance to cover the bad smell and using some chemical or biological method to prevent enzymolysis or oxidation. Therefore, knowing the composition of fishy substances and understanding their production pathways will play an important role in suppressing fishy substances and improving the competitiveness of consumer production. Besides, it could provide new ideas for innovative deodorising methods.     

人体手部气味的鉴别研究

运用SPME-GC/MS法对5位个体的手部人体气味进行采样分析,通过比较气味样品中共有成分的相对含量的差异和样品中的非共有成分的不同,结合使用夹角余弦法对来自于5位个体的手部人体气味样品进行鉴别,样品都得到有效地区分。     

生物脱臭技术发展趋势

对当前国内外脱臭方法进行了综述,由于生物处理恶臭物质已成为当今恶臭处理研究的主流,因此,重点叙述了各种生物处理方法、以及提高生物肿臭效率的途径,同时还介绍了一些析研究成果。     

Warning Odor of the North American Porcupine(Erethizon dorsatum)

Volatile compounds in the lipid coating of the lower-back quills of the North American porcupine,Erethizon dorsatum, were collected using headspace trapping on Tenax and analyzed by gas chromatography–mass spectrometry (GC-MS), GC with organoleptic detection, and GC with a chiral stationary phase. Over 50 components were isolated, primarily oxygenated aliphatics, lactones, and isoprenoids. The most abundant constituent was tetradecyl acetate, which does not contribute significantly to the odor of the quill lipids. GC with a wide-bore capillary column and a human nose as detector was used to determine the retention time of the peak with the characteristic porcupine odor. Comparison of this organoleptic chromatogram with those obtained with a flame ionization detector and GC-MS showed the compound to be a -decalactone. The racemic mixture of this optically active substance does not possess the unique odor. Resolution of the enantiomers of -decalactone by GC with a chiral cyclodextrin phase shows that the isomer possessing the characteristic porcupine odor is the(R)--decalactone. We suggest the biological function of this compound is to serve as a warning odor, which, in conjunction with an initial quill strike, produces a conditioned aversion in potential predators.     

Chromatographic analysis of species specific odor profiles inMastomys natalensis andM. coucha (Rodentia: Muridae)

Whole-body volatiles from males of the cryptic multimammate mouse speciesMastomys natalensis andM. coucha were analyzed by dynamic solvent effect sampling and capillary gas chromatography. One compound, 3-nonene-2-one, was always present, sometimes as the major component, in volatiles fromM. coucha and absent, or present only at low levels, in volatiles fromM. natalensis. The mean ±SD of the 3-nonen-2-one peak area forM. coucha was 8599 ±9630 and forM. natalensis 148 ±486. Chromatographic analysis was more reliable in identifying a male's species than were a female's in a two-choice olfactorium.     

污水厂恶臭控制技术进展

对污水厂恶臭的控制可分为主动控制和被动控制，通常的物理、化学和生物除臭技术多属于被动控制。评述了常用的恶臭控制技术，尤其是南方某污水厂早期的生物除臭试点工程和后来的中试研究结果，总结了当前生物法的研究方向。介绍了恶臭主动控制技术及国外的新进展，提出恶臭控制的根本在于主动控制，通过改进处理工艺，达到同步去除有机物和抑制恶臭气体生成的目的。     

Effect of equilibrium oil extraction on the chemical composition and sensory quality of soy flour and concentrates

Previous studies have shown that ambient-temperature equilibrium, hexane extraction of soy flour yielded the same amount of oil as was extracted from soy flakes by conventional high-temperature processing. The oil obtained at ambient temperatures contained less phospholipid than commercial crude oils obtained by traditional processing. In this study, chemical composition, flavor and odor of soy flour obtained after oil extraction by the equilibrium procedure were evaluated before and after toasting. Results were compared with those obtained for commercial untoasted food-grade soy flakes. Chemical and sensory analyses were performed on soy protein concentrates (SPC) prepared from defatted flour, defatted toasted flour and commercial defatted white food-grade flakes. SPC were made by acid and ethanol-extraction methods. Ethanol extraction of soy flour produced SPC with similar protein, lipid and sensory qualities to those obtained from commercial flakes. Acid extraction produced SPC with more lipid than was obtained by ethanol extraction. Toasted soy flour and flakes had similar sensory properties, as did the SPC prepared from them.     

The effect of short-range host odor stimuli on host fruit finding and feeding behavior of plum curculio adults (Coleoptera: Curculionidae)

In laboratory assays, we investigated responses of female plum curculios (PCs),Conotrachelus nenuphar (Herbst), to host and nonhost fruit or leaf odor when PCs were crawling on experimental tree branchlets or twigs. In choice tests where test specimens were hung from the ends of a wooden crosspiece, PCs made significantly more visits to host plum fruit than to plum leaves, nonhost tomato fruit, wax models of plum fruit, or blanks (wire). In similar tests, PCs made significantly more visits to plum leaves compared to nonhost maple leaves or to blanks. PCs in test chambers that contained host or nonhost odor were significantly more prone to feed on wax plum models in the presence of odor from host fruit or host leaves compared to odor from nonhost fruit or leaves or a water blank. In choice tests offering alternating cluster types on an apple branchlet, PCs visited leaf clusters bearing a host apple fruit more than leaf clusters without a fruit. In tests to assay the distance at which PCs can detect an individual host fruit, PCs crawled from the central stem of an apple branchlet onto a side stem significantly more often when an apple fruit on a side stem was hung 2 cm from the central stem compared to 4 or 8 cm away. Our combined results suggest that PCs use host fruit odor to locate host fruit at close range.     

Attraction of Mature Ceratitis capitata Females to 2-Heptanone, A Component of Coffee Fruit Odor

In indoor laboratory-cage and outdoor field-cage assays, we evaluated the attraction of released, protein-fed, mature Mediterranean fruit fly females to six volatile compounds emitted by attractive crushed ripe coffee fruit: 3-methyl-1-butanal, decanal, 3-methyl-1-butanol, 2-(Z)-pentenol, 2-(E)-hexenol, and 2-heptanone. Previous tests in a wind tunnel indicated that each of these six compounds was more attractive than clean air to females. In laboratory cage assays, none of the compounds elicited a response significantly greater than that to water. In field-cage assays, 2 or 4 l of 2-heptanone in 5 ml of water (but none of the other compounds at 2 or 4 l in 5 ml of water) consistently attracted protein-fed medflies at significant levels that averaged about five times greater than attraction to water alone, although about 40% less than attraction to odor of coffee fruit extract. All types of mature protein-fed females tested (laboratory-cultured virgin, laboratory-cultured mated, wild mated) in field-cage assays responded similarly to 2-heptanone, whereas same-age (9- to 11-day-old) protein-deprived females did not respond significantly to 2-heptanone. Response of protein-fed females to 2-heptanone increased progressively with increasing dose (1, 2, 4, or 8 l in 5 ml of water). Addition of 2 l of 2-heptanone or 2 l of any of the other compounds tested to 5 ml of water extract of coffee fruit did not enhance attractiveness of the extract. Relative to response to water, protein-fed females consistently exhibited a significant positive response to odor of coffee fruit extract but no significant response to odor of Nulure (a proteinaceous food attractant). Together, our findings suggest that mature protein-fed females were responding to 2-heptanone as though it were an oviposition-site stimulus rather than a feeding-site stimulus.