Studies on the Free Sugars of the Barley Grain V. Comparison of Sugars and Fructosans With Those of Other Cereals

Abstract

MACLEOD AND PREECEI CEREAL SUGARS AND FRUCTOSANS[J. Inst. Brew.period of time. From this it could be in ferred that 8-resin is not the sole product of changes occurring in a-soft resin; this is what might be expected in view of the known properties of humulone and of the fact that a-soft resin is a mixture. The results of the present experiments do not, in fact, permit the reaching of any definite conclusions concerning the genesis of 8-resin for, as yet, there is no information concerning the storage changes undergone by lupulone and by other constituents of the p-portion of the soft resin. One noteworthy feature of the data shown in Table III is the relatively considerable increase in the y-resin (hard resin) content of the three hops between the fourth and sixth months of storage. This increase apparently bears little or no direct relation either to changes in the total soft resin or in a-soft resin during this interval of time. The source or sources of these increments of y-resin cannot be deduced from the present analytical data. SummaryThe 8-resin of hops partially inhibits 1.precipitation of the lead compound of a-soft resin.2. A method has been devised for estima tion of S-resin.3. Three hops examined at the age of 3 months contained, respectively, 0»66, 0-71 and 0-63% of 8-resin; at six months the corresponding values were estimated to be 1-36, 0-92 and M8%.4. The 8-resin contents of a selection of seven hops kept in cold store were found at 18 months to range from 1-10 to 3-75%. Duplicate quantities of these same hops stored for 18 months in warehouse gave figures between the limits 1'63 and 4-04%. In all seven cases, warehouse storage was more conducive to accumulation of 8-resin than was cold storage.5. Three very old hops (10, 12 and 12 years) were found to contain 2»46, 2*71 and 2-96%, respectively, of 8-resin.6. The experimental data do not permit conclusions to be reached concerning the source of the S-resin formed during storage. Ripe intact grains of rye, wheat and barley are rich in fructosan and in glucodifructose, oats may contain moderate amounts of these carbohydrates, but maize contains neither. Fructosan content runs parallel with the content of water-soluble gum-like pentosans, so that the amounts of each decrease in the order: rye, wheat, barley, oats, maize. Moreover, the fructosan-rich and pentosan-rich cereals are those which contain abundant j3-amylase in the raw grain* Taxonomic relationships of these aspects of parallel distribution of apparently unrelated materials are dis cussed, and it is suggested that the composition of the ripe grain depends on the degree of development along particular paths reached at the stage adjudged to repre sent ripeness, development differing to a major extent from one cereal to another and to a minor extent between samples of the same cereal, but depending also in some measure on post-harvest changes* Cereal adjuncts used for brewing contribute types and amounts of carbohydrates which depend on the nature of the raw cereal and on whether whole grain...

Relationships Between Fructans Content and Barley Malt Quality

“…Early work by other authors also suggested that fructans together with sucrose and raffinose are being used as substrate during respiration in the initial stages of germination before hydrolysis of starch begins (MacLeod et al 1953;MacLeod and Preece 1954). This idea is supported by the findings of other authors (Harris and MacWilliam 1954).…”

“…Some authors suggested that if this is the case, genotypes/varieties with high fructan and glucose concentrations may germinate more efficiently and thus malt more readily (Harris and MacWilliam 1954;Smith and Morgan 1980). These studies have shown that there is considerable variation in the acid soluble β-glucan, fructans and free sugar content of some barley varieties (MacLeod et al 1953;MacLeod and Preece 1954;Smith and Morgan 1980;Cozzolino et al 2014a, b Fructans content (% w/w) Apparent aƩenuaƟon limit (%) R 2 = 0.03 RMSE = 3.42 …”

Variation in the Biochemical Composition of Acid Extracts From Barleys of Contrasting Malting Quality

“…These results provide evidence for enhanced con centrations of fructosan in better malting varieties. The role of fructosan in barley is not clear;10 detailed studies of isolated cell walls have been made on material inactivated with 80 per cent ethanol18 which dissolves fructosans of intermediate complexity, [14][15][16][17][18] and results in preparations free from fructose. 13 However, although fructosans of high molecular weight do occur in barley," it is more likely that fructosans have a metabolic rather than structural significance; MacLeod et al suggest" that fructosans, together with sucrose and raffinose, fuel respiration in the initial stages of germination before hydrolysis of starch begins.…”

Water‐soluble Carbohydrates of Seeds of the Gramineae

“…When the yield of polysaccharide was sufficiently large, fractionation by means of ammonium sulphate was carried out. In the hands of Preece and Mackenzie (1952) this technique has proved outstandingly useful for separating pure ^-glucosan from crude water-soluble polysaccharides of barley and oats, and, since a survey of cereal grains (MacLeod and Preece, 1954) had shown a remarkable variation in the content of this particular carbohydrate, it was felt that the presence or absence of this p-glucosan might prove a point of some significance.…”

“…However, a general survey of the water-soluble carbohydrates of common cereal grains (MacLeod and Preece, 1954) has shown that considerable differences are possible both in the relative quantities present and in the chemical constitution of certain carbohydrate fractions. It seemed of interest, therefore, to extend this work from the cereals to include a representative series of seeds of wild grasses, so as to establish the range of composition possible within a complete natural family; even if the results of such a survey shed no light on taxonomic problems, they should be at least of some general biochemical interest.…”