Beer traps

Left, from top) Caring for fruit Seep hose laid around strawberries mulohing around newly planted fruit trees pruning to oreate an open-centered gooseberry bush a simple beer trap protecting ripening fruits from wasps. 

ANDERSEN M L, ouTTRUP H and SKIBSTED L H (2000) Potential antioxidants in beer assessed by ESR spin trapping, J Agric Food Chem, 48, 3106-11. 

Another way to trap sings is to place shallow containers filled with beer in the soil with the top of the container level with the soil snrface. Sings will be attracted to the beer and drown. A solntion of 1 pound of sugar and 1 teaspoon of yeast in a gallon of water fermented two or more days works well. This makes nse of both the trap and the bait concept. 

In addition to mating-disruption pheromones, there are a number of naturally occurring, nonpheromonal attractants and repellents. Many are typically used as food additives or in cosmetics or perfumes, and are derived from diverse plant and animal sources. Capsaicin [44], the spicy component of chili peppers, is used in several bird, deer, and rodent repellents. Maple lactone [45], a common food additive and flavoring, is used in traps to attract cockroaches with its stale beer odor. Methyl... 

Most peptides and proteins are water-soluble, and therefore D-PBS or saline can be used as a vehicle. Often, however, limited information is available about the solubility properties of novel small molecules, and the choice of a non-toxic vehicle is more difficult. For example, 200 pi of a 5% ethanol solution is equivalent to one beer in humans and may affect behavior. A solution of 20% cyclodextrin has no known side effects in vivo, but in rare cases, some compounds are trapped in the solution and therefore mice have no exposure to the compound. Some vehicles used for in vitro studies can be toxic in live mice. Some vehicles such as methylcellulose have no side effect when given p.o., but are toxic if administered i.v. Access to information about the pharmacokinetics properties of a test compound can help in the choice of a vehicle. 

Matusiewicz, H. and M. Kopras. 1997. Methods for improving the sensitivity in atom trapping flame atomic absorption spectrometry Analytical scheme for the direct determination of trace elements in beer. J. Anal. At. Spectrom. 12 1287-1291. 

M. L. Andersen, L. H. Skibsted, Electron spin resonance spin trapping identification of radicals formed during aerobic forced ageing of beer, J. Agric. Food Chem., 46... 

Each chamber was infested before treatment with a population of 750 Blattella germanica consisting of 250 nymphs of mixed age, 250 adult males, and 250 adult females. Populations were sampled monthly with monitoring traps made from baby food jars baited with bread soaked in beer. These escape proof jars were placed in the chambers for a period of 24 hours once per month. Trapped cockroaches were counted as male, female, gravid female, adults showing juvenoid effects, large and small nymphs. 

If there are shiny slime trails on the remain-ing leaves, slugs and snails are at work. Sprinkle wood ashes or diatomaceous earth around plants, or trap the pests in shallow pans filled with stale beer and empty traps daily. 

Fruit with holes. Causes Slugs and snails earwigs birds. Silvery trails near holes indicate slugs or snails. Keep these pests out with barriers of copper flashing, dry ashes, or dia-tomaceous earth. After rain renew ashes or diatomaceous earth. Or trap slugs under boards, in overturned clay pots, or in saucers of beer. See page 218 for an illustration of this pest. 

You can make traps from aluminum pie plates or other recycled containers just sink them to the brim in the soil and fill with beer. Or, cut a 1" hole in the side of an empty coffee can about halfway up. Bury the can so the hole is even with the soil surface and pests can enter, then fill the trap half-full with beer. The lid will keep rain away and allow you access to the pests trapped inside. 

Depending upon both the time and equipment available, 2 mL samples of two beers, preferably one domestic and one foreign, will be purged and trapped, and the components separated and detected. These beers will then be set in strong sunlight for at least 1 hour, and the process repeated, particularly if sulfur compounds are of interest. Isoamyl acetate should be used to set full-scale deflection, if the FID is used, and dimethyl sulfide, if the Hall detector is used. 

Figure E45-1. Chromatograms of beer obtained by purge and trap.

The product was previously identified in beer by Andrews (1987) and in human sweat by Polak et al. (1988), and characterized as sunstruck or lightstruck off-flavor. The cause has been attributed to the degradation of bitter isohumulones from hops under the influence of ultraviolet light (Bondeel et al., 1987). By photofragmentation trans-isohumulone liberates a prenyl radical which can trap a thiol radical, producing an undesired flavor for beer. Holscher et al. (1992) have also shown that 3-methyl-2-buten-l-thiol and 3-mercapto-3-methylbutanol are principally formed under pyrolytic conditions in roast model reactions of prenyl alcohol and sulfur-containing amino acids. 

Gerbersmann C., Lobinski R. and Adams F.C. (1995) Determination of volatile sulfur compounds in water samples, beer and coffee with purge and trap GC-microwave-induced plasma atomic emission spectrometry. Anal. Chim. Acta 316, 93-104. 

Figure 7.2 Effects of beer adaptation on morphological featnres of beer-spoilage lactic acid bacteria (LAB). Beer-spoilage Lactobacillus brevis was grown in MRS broth (a) and degassed beer (b). Cells were trapped on a membrane filter and the morphological features of beer-adapted and nonadapted strains were compared using scanning electron microscopy. Bar, 5 pm. Similar tendencies were also observed for beer-adapted Lactobacillus lindneri (data not shown).

Filtration processes may be classified as either depth filtration or surface filtration. Depth filtration relies on a layer of porous media in which suspended particles in the beer are trapped within the media. Examples in brewing include filter aid filtration, sheet filtration and some forms of filter cartridge. Surface filtration normally refers to membrane technology. A thin layer of membrane has pores throughout the structure. This means that it is possible to achieve very exact filtration, perhaps enabling sterilisation, but typically the quantity of suspended beer particles that may be removed is less than for depth filtration. 

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