Green Grass

Lakes, rivers, swamps, and marshes - common in temperate areas - contribute little to the diversity of natural products. Abundant dull-green grass and dull-colored fish and moUusks characterize lakes and rivers, in contrasts with the vivid colors of tropical fish and seaweeds. Haplosclerid sponges are occasionally abundant in freshwater, but their secondary metabolism is limited to demospongic acids (Dembisky 1994), in contrast with the variety of metabolites from marine sponges in the same order. Where not for cyanobacteria (which are as rich of unusual metabolites as the marine strains), tropical amphibians, and aquatic fimgi, freshwater ecosystems would have passed unnoticed in this book. 

F in beer Green grass, fruity, sour/ F /medicinal... 

Z)-3-Hexen-l-ol 67, 82, 55 Fresh, green grass-like, leafy 70... 

Kenong, Xia, and I stop to look around the field. The even stands of tall green grass-like leaves wave slightly in the wind, as if they were friends welcoming us to a feast. For farmers, such a sight is welcome, because it means many plants that will yield abundant grain. 

Grassy Aromatic characteristic of freshly mown green grass. Fresh cut green grass, hexanal... 

Cows eat fresh, green grass that contains carotene, but they do not metabolize the carotene entirely, and so it ends up in their milk. Butter made from this milk is therefore yellow. In the winter the silage cows eat does not contain carotene because it readily undergoes air oxidation, and the butter made at that time is white. For some time an azo dye called Butter Yellow was added to winter butter to give it the accustomed color, but the dye was found to be a carcinogen. Now winter butter is colored with synthetic carotene, as is all margarine. 

Six-carbon volatile alcohols and aldehydes have been found in all freshwater fish surveyed (23-24). However, these compounds have not been found in either salmon residing in saltwater (unpublished data) or in oysters (26). Hexanal has been found in modestly fresh (5-6 days old) saltwater fish (24), but its formation may be the result of autoxldation rather than via enzyme-mediated reactions. Thus, data for the occurrence of hexanal in freshly harvested saltwater fish remains to be developed. Hexanal and (E)-2-hexenal contribute coarse, green-plant-like, aldehydic aroma notes to freshly harvested finfish where their aroma dominates the overall odors within seconds after the death of the fish. (Z)-3-Hexen-l-ol contributes a clean, green-grass-like aroma note. Hexanal always occurs in substantially greater abundance than 1-hexanol in fish. 

Unexplained odors (smell of bitter almonds, peach kernels, newly mown hay, or green grass)... 

This is not to say that milk has no colored substances. It does. Milk contains riboflavin, or vitamin B2, an important enzyme cofactor that has a greenish-yellow hue. Riboflavin is water soluble, so its color is easiest to see in the whey that forms when the liquid portion of milk is separated from the solids, as it is in cheese making. The fat globules in milk have a yellow tinge due to carotenoids, such as beta-carotene, which come from the diet of the milk source. Beta-carotene has nutritional importance because it is a precursor to vitamin A. Summer cow s milk is yellower that winter cow s milk because of what the cows have been eating — fresh green grass has more beta-carotene than hay does. 

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