Hop cone

Dolde,/. umbel, (of hops) cone, strobile. dolden blumig, bliitig, a. umbelliferous, dolieren, v.t. Leather) pare, shave. 

Ships that carried beer tended to be less affected than those that carried water and spirits. Presumably, the beer contained some vitamin C, possibly from the habit of dry hopping , i.e. adding a few hop cones to each barrel. Eventually, it was found that lemon or lime juice every day could prevent scurvy. The admiralty waited fifty years before they applied the discovery and then insisted that all British ships carried lime juice. 

The amount of seed in the hop cone will depend on the method of cultivation practised. On the Continent of Europe, the planting of male hops is... 

Hops are dried on the kiln to a moisture level of about 6 % but it is quite difficult in practice to determine when this is reached, and the experience of the oast man is important. The moisture remaining in the bed of hops is unevenly distributed within the load it is concentrated in the top layer and within the hop cone it is largely in the strig. Hops from the kiln are also very hygroscopic and all these factors make sampling for conventional moisture analysis difficult. 

Natural hop cones, normally dried and pressed, are a bulky product which only contains 5-15 % of active principles. Thus, any process of concentration will reduce handling, transport, and storage costs. Mechanical concentration is used to produce hop powders and pellets while solvent extraction is used to manufacture hop extracts. In addition, the essential oil may be separated by steam distillation. 

Hop powders and pellets deteriorate on storage in the same manner as hop cones [20]. Comminution increases the surface area and the risk of aerial oxidation but the reduced volume allows packaging under an inert atmosphere and/or a partial vacuum. Deterioration in cold store (0-4°C) is less than at ambient temperature (10-30°C) but the loss of a-acid at ambient temperature is considerably less than that experienced by baled hops of the same variety [25,26]. The replacement of whole hops in the copper by powder... 

Some of the bound keto groups may be reduced by pyridine nucleotide-dependent dehydrogenases (C 2.1, see the formation of 6-methylsalicylic acid, D 3.3.1), and some of the activated CHg-groups may be alkylated by S-adenosyl-L-meth-ionine (C 3.3, see the biosynthesis of tetracyclines, D 3.3.7), or may be substituted by dimethylaUyl pyrophosphate (D 6), see the formulas of lupulone and humulone, the bitter principles of hop cones used in brewing beer (F 1). 

Lindsay RF, Priest FG (1975) Decarboxylation of substituted cinnamic acids by enterobacteria the influence on beer flavour. J Appl Bacteriol 39 181-187 Steinhaus M, Schieberle P (2000) Comparison of the most odor-active compounds in Ifesh and dried hop cones (Humulus lupulus L. variety spalter select) based on GC-olfactometry and odor dilution techniques. J Agric Food Chem 48 1776-1783... 

Jerkovic V, Collin S (2007) Occurrence of resveratrol and piceid in American and European hop cones. J Agric Eood Chem 55 8754—8758... 

In addition to hop cones, which are prone to quality loss even under proper storage conditions, processed products from hops are acceptable and utilized. 

Wort boiling with hops or hop products is done in a brew kettle (hop kettle) in which the initial and subsequent worts from the lautering step are collected. Addition of hops is adjusted according to the type and quality of beer desired. The quantity (in hop cones/hectoliter) for fight lager beer is 130-150 g for Dortmund-type beer, 180-220 g for Pilsener beer, 250-400 g for dark Munich beer, 130-170 g and for malt beer and dark bock beer, 50-90 g. The critical factor is the content of bitter substances in the hops selected. The utilization of the bitter substances (a-acids) is only 30-35%. 

The primary aromatic substances in beer are derived from raw materials (barley or hops) that confer the beer s typical odour and taste. Bitter acids of hops have a bitter taste (see Section 8.3.5.1.3), but hop cones also contain 0.3-1% m/m of terpenoids (60-80% of hop essential oil), which have a considerable influence on the smell of beer. The main components of aromatic hop oils are sesquiterpenic hydrocarbons in which a-humulene, P-caryophyllene and famesene dominate. The major monoter-penic hydrocarbon is myrcene. For example, the essential oil content of fine aromatic varieties, such as Saaz, is 0.8% m/m, of which 23% is myrcene, 20.5% a-humulene, 14% famesene 6% and P-caryophyUene. Significant components of the hop aroma in beer are mainly isomeric terpenoid monoepoxides resulting from autoxidation and diepoxides of a-humulene and fS-caryophyUene, but also other terpenoids. Important components of hops odour are also various alcohols (such as geraniol and hnalool), esters (ethyl 2-methylpropanoate, methyl 2-methylbutanoate, propyl 2-methylbutanoate and esters of terpenic alcohols, such as geranyl isobutanoate), hydrocarbons, aldehydes and ketones formed by oxidation of fatty acids, such as (3E,5Z)-undeca-l,3,5-triene, (Z)-hex-3-enal, nonanal, (Z)-octa-l,5-dien-3-one, their epoxides, such as ( )-4,5-epoxydec-2-enal and sulfur compounds. Other important components of hops are so-called polyphenols (condensed tannins) that influence the beer s taste and have antioxidant effects. Less important compounds are waxes and other hpids. Hop products, such as powder, pellets and extracts (by extraction with carbon... 

The basic humulone homologues (8-265) are cohumulone and adhumulone and minority components are prehumulone and posthumulone. Analogously, the main lupulone homologues (8-266) are colupulone, adlupulone, prelupulone and postlupu-lone. These acids are bitter only by name, but in fact they have an indifferent taste and are almost insoluble in water and have pronounced bacteriostatic activity. The approximate composition of these two groups of bitter acids in different hop varieties is shown in Table 8.43. Their content is about 25% of the dry weight of the hop cones. 

In addition to bitter substances, hop cones contain a number of monoterpenes and sesquiterpenes (0.5 3%) that carry their own characteristic aroma. Some non-volatile components present in the hop, such as polyphenols (3-6%), contribute to a full mouth feel during beer tasting. Important non-volatQe components of hop cones are also prenylated flavonoids that show oestrogenic and anti-carcinogenic effects. 

Chalcones, dihydrochalcones and aurones are not particularly important components of plant food materials, but they occur as notable pigments of flowers of many ornamental plants, such as the common snapdragon Antirrhinum spp., Scrophulariaceae) (Asteraceae), cosmos Cosmos spp.) and dahlia Dahlia spp.) from the Asteraceae family. Chalcones are also pigments of legume seeds (9-99) and woods. Prenylated chalcones are found in hop cones (10-98). 

Prenylated isoflavones are related to prenylated flavonoids (chal-cones and flavanones or dihydroflavones) located in mature female cones of hops Humulus lupulus, Cannabinaceae), which exhibit oestrogenic and anticarcinogenic effects. Their amount depends on the weather conditions and the hops variety. The most common compound is a chalcone xanthohumol (10-98), which does not exhibit oestrogenic activity. Its content in hop cones is around 1%. Xanthohumol is accompanied by the flavanone isoxanthohumol, which arises from xanthohumol by conversion in an acidic media during heating. Isoxanthohumol is therefore the main prenylated flavonoid in beer. At concentrations of about 10 to 100 times lower. 

Steinhaus P., Schieberle P. Comparison of the most odor-active compounds in fresh and dried hop cones Humulus lupulus L. variety... 

The evolution of the hop bitter acids during ripening of the hops has been studied in detail (63). The formation of the hop bitter acids starts already in the very early stages of the growth of the hop cone. It appears that the various hop alpha acids are produced at different rates. The percentage of cohumulone in unripe hops is much lower than normal (64), but near the end of the ripening period the ratios become more or less constant for a given hop variety. 

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