ANALYSIS OF NON-FRIABLE RESIDUES REMAINING FROM FRIABILIMETER TREATMENT OF SCOTTISH DISTILLING MALTS

Initially correlation coefficients and regression lines relating non-friable residues of malts after Friabilimeter treatment, to other established parameters of malt analysis, were determined. Thereafter, non-friable residues were further fractionated by sieving. The seven fractions obtained were found to comprise two main groups: a coarse fraction collecting mainly between 2.0 and 2.2 mm., and a fine fraction collecting between 1.4 and 1.7 mm. Variations due to the effects of modification, barley variety, moisture and husk, are discussed. Results suggest that the finer fractions (collecting below 1.7 mm) when expressed as a proportion of total non-friable residue, may provide an improved means of predicting malt quality; while the fraction collecting between 2.00 and 2.2 mm, should be included in measurements estimating the proportion of barley which has failed to malt.     

STUDIES ON BARLEY AND MALT WITH THE RAPID VISCOANALYSER: [III] THE PREDICTION OF MALTING POTENTIAL FROM VISCOGRAMS

Examination of the relationships between extract and viscogram data of malts suggested the measurement of Time to Peak as a cultivar-independent measure of quality potential. This was tested against a large number of samples from the routine assessment programme. Both barleys and malts were examined. Some comparisons with the Falling Number Apparatus are reported. Prediction of malting potential from the differences between viscograms of barleys with and without added enzyme was also assessed. No measurement from the viscogram of barley was sufficiently accurate for predicting malting potential of a population of crossbreds from a breeding programme.     

AMMONIUM PERSULPHATE IN MALTING: CONTROL OF NDMA AND INCREASED YIELD OF MALT EXTRACT

Application of ammonium persulphate to barley just beginning to germinate, allows the production of malts with a low NDMA content, even when high NO, conditions are used during kilning. No other palliative, such as sulphuring, is required. Like bromate, the persulphate reduces root growth and malting loss but, unlike bromate, it does not restrict nitrogen modification. It appears to enhance the effect of gibberellic acid. Use of persulphate, therefore, not only gives a greater yield of malt but can also give more extract from a given weight of malt. It may also facilitate the malting of inferior barley samples.     

GRAIN AND MALT MILLING ENERGIES RELATIVE TO MALTING QUALITY PARAMETERS IN A MUTANT OF cv. TROUBADOUR

The mutant barley genotype TR49 and its parental cultivar Troubadour were grown at 5 sites throughout Spain in 1990. Large differences between sites were observed for a range of grain and malt quality characters. TR49 had very slightly higher milling energy in the grain than Troubadour, but, during the early stages of malting, showed a more rapid loss in milling energy. From the relationship between milling energy and other quality parameters, this was deduced to result from a more efficient and extensive modification of the endosperm cell walls in the mutant genotype.     

THE RELATIONSHIP BETWEEN SOME BARLEY AND GREEN MALT PROPERTIES AND MALT HOT WATER EXTRACT

Further studies have been made on the relationships between malt hot-water extract (HWE) and some barley and green malt characters previously identified as influencing HWE.^17,18 Relationships were found to be relatively consistent between spring and winter barleys and over years, suggesting that these characters play an important fundamental role in determining the HWE attainable under standard malting conditions.     

A NEW MALTING INDEX: PREDICTION OF MALTING QUALITY BY ENDOSPERM HYDRATION

The hydration of barley samples, representing all nine NIAB malting grades, has been measured by determining the levels of a tracer ion using x-ray analysis with a scanning electron microscope. There was a linear relationship between hydration of the ventral endosperm and NIAB malting grade. This relationship was not affected by the total nitrogen level of the barley and can be used as a novel malting index to successfully predict the malting quality of barley on sample sizes too small for micromalting.     

A RAPID TEST FOR THE PREDICTION OF MALTING QUALITY OF BARLEY

A grinding energy method developed for the prediction of the nutritional value of grass was adapted and used to differentiate barleys of good malting quality from those difficult to malt. This is a very rapid test (a few minutes per sample) and could be used as an initial step in screening for malting quality.     

THE EFFECT OF INCREASED STEEPING TEMPERATURE ON MALT PROPERTIES

Steeping barley at 30°C instead of 16°C can reduce malting time by 24 hours. The malts produced have normal analytical values but the mashes filter slowly and the malts would be expected to give poor wort separation in a brewery. These run-off problems probably result mainly from starch-protein interactions.     

EVALUATION OF MALT QUALITY

To achieve an effective Quality Assurance in production suitable for computerisation, it is essential to determine the evaluation of the malt quality and to provide it with a simple code. The meaning given to the term ‘malt quality’ must be fully understood so that the relevant weighing factors can be assigned to the various analysis parameters. Thus, the choice of the type of evaluation system is essential for stating the quality of the malt (i.e., the composition of the various analysis parameters) by means of a simple code.     

AN ASSESSMENT OF THE MALTING QUALITY OF A MUTANT OF THE BARLEY CV. TROUBADOUR GROWN UNDER SCOTTISH CONDITIONS

The barley mutant, TR49, selected in Spain for rapid germination, and its parent cultivar Troubadour, were grown in Scotland in 1991 and assessed for a range of grain and malt quality characters. Results suggested that both genotypes had a potential dormancy problem, although TR49 showed a slight but significant improvement over Troubadour. TR49 produced very large grain which did not completely modify during malting, but still showed an advantage over its parent cultivar for all malting parameters assessed.     

USE OF THE HAGBERG FALLING NUMBER APPARATUS TO DETERMINE MALT AND BARLEY QUALITY

The Hagberg Falling Number measurement, widely used in the milling industry for assessing the baking quality of wheat flour, has been modified and used as a rapid mashing technique to assess malt quality. Barley Malt flour is mixed with cold mashing liquor containing 0.1% calcium chloride and 15 mM beta-mercapto-ethanol. The slurry is heated and mixed by the Falling Number apparatus, and the starch is gelatinized. After one minute of heating/mixing the stirring rods are raised and released. As the gelatinized starch is hydrolysed by amylases, the viscosity of the slurry decreases allowing the stirring rods to fall. The time taken for these rods to fall a fixed distance is called the Falling Number. A relationship has been determined between the Falling Number obtained for a malt and the quality of the malt. Poor quality malts had a high Falling Number (e.g. >200s) whilst good malts had a low Falling Number (e.g. <150s). The correlation coefficient between Falling Number and Hot Water Extract (IOB coarse grind) was ?0.89, and between Falling Number and Friability was ?0.96. These good correlations indicate the measurement was influenced by the degree of endosperm modification. Being a mashing technique, however, the Falling Number was also influenced by other factors which influence mashing such as enzyme complement and water binding. This technique has the potential to measure malt quality using a commercial apparatus more rapidly than present malt analyses. No significant relationship could be determined between the Falling Number and the malting quality of barley.     

SOME BARLEY GRAIN AND GREEN MALT PROPERTIES AND THEIR INFLUENCE ON MALT HOT-WATER EXTRACT: II. PROTEIN,PROTEINASE AND MOISTURE

This paper continues the study of variation between varieties in some properties of barley and malt and examines protein-related characters and moisture uptake. Initial rate of moisture uptake was more closely related to enzyme activities than maximum moisture content. Significant varietal variation was found in all characters and this variation was greater than environmental variation with the exception of grain nitrogen concentration. In the endosperm endopeptidase activity was the character most highly correlated with malt hot water extract (HWE). The combined influence of protein- and β-glucan-related characters was investigated and the relative influence of each group of characters on HWE varied in different sections of the grain. In the endosperm the protein- and β-glucan-related characters accounted for 30% and 60% of the variation in HWE respectively.     

A RELATION BETWEEN MALT EXTRACT AND MALTING TIME AND THE TWO-STAGE NATURE OF THE MALTING PROCESS

An equation relating the extract of malt and malting time is established empirically. Application of this relationship to micro- and large-scale maltings reveals the two-stage nature of the malting process. It is suggested that the second, or modification, stage of malting is controlled by a diffusion process.     

USE OF THE FRIABILIMETER TO ASSESS HOMOGENEITY OF MALT

A method has been developed for assessing the homogeneity of a sample of malt using the Friabilimeter. Material retained by the Friabilimeter sieve is further fractionated using a sieve with slits 2·2mm wide by 23mm long, as recommended by the EBC for assessing corn size. Material composed of unmodified grains and large pieces of endosperm is collected from the sieve and weighed. This gives a rapid and reproducible estimate of the proportion of unmodified material in the sample. The technique readily detects small quantities of unmodified grain added to a sample of malt. Staining half corns with Calcofluor gives similar scores for homogeneity but with poorer reproducibility and the technique is much slower. Staining with methylene blue gives much lower figures for homogeneity and is also slower and less reproducible than the Friabilimeter method.     

STUDIES ON THE MALTING POTENTIAL OF BARLEY AND MALT WITH THE FALLING NUMBER APPARATUS

The Falling Number Apparatus was investigated as a possible technique for the identification of barleys and malts with high malting potential. The FN method was not as accurate or as rapid as that based on Pearling Resistance. The effect of increasing times of malting on the Falling Times of malts was also investigated to determine whether the progress of malting could be monitored, as was the effect of different cultivars. Testing under conditions inhibitory to amylolytic activity was found necessary to give useful results. Some comparisons with the Rapid Visco Analyser (RVA) are presented.     

APPLICATION OF A COMMERCIAL ENZYME PREPARATION IN THE BARLEY MALTING PROCESS

This paper presents data on barley micromalting with addition of the CELLUCLAST enzyme complex. This is a commercial, multicarbohydrase with distinct β-glucanase and proteinase activities. The enzyme was added to steeping and germination phases, in different quantities (0.05%; 0.75% and 0.1% of initial barley). The enzyme was added to different malting phases: to the 2nd and 3rd steep water, at the beginning of germination on the 1st day by spraying, on the 2nd day of germination and in combination of addition to 3rd steeping water and in germination start (50% of total quantity of each). CELLUCLAST enzyme had a significant effect on reduction of wort viscosity, extract difference, wort filterability and protein breakdown, depending on the quantity of added enzyme and the malting phase to which it was added. There was no negative effect on other malt quality parameters. The best values of cytolytic breakdown parameters (viscosity, extract difference, filtration rate) were obtained with addition of 0.075% of CELLUCLAST, on the first day of germination.     

EFFECT OF STORAGE TIME ON THE MALTING QUALITY OF SOME BARLEY VARIETIES

Changes in the malting quality of some barley varieties were monitored at monthly intervals from harvest All the varieties were found to improve after storage for up to one year. Varieties with poorer malting grades improved at a faster rate than good varieties, although ranking consistent with malting grade was maintained.     

A COMPARISON OF SOME RAPID SCREENING TESTS FOR MALTING QUALITY

A series of rapid tests which have been proposed for the assessment of barley malting quality have been compared. The most accurate prediction of hot water extract was obtained by a multiple regression involving α-Amylase, Total Nitrogen and Grinding Resistance.     

EXPRESSION OF EXTRACT OF DISTILLING MALTS ON A PERCENTAGE BASIS: CHANGES IN RELATIONAL FACTORS FOLLOWING THE 1979 REVISION OF THE IOB METHOD OF EXTRACT DETERMINATION

The derivation of the factor linking excess gravity with % soluble extract and also the factor relating the expression of hot water extract by either % soluble extract or litre degrees/kg is described. The effect of the 1979 revision to the temperature of the specific gravity determination on these factors is highlighted and a modified value for each is advanced.     

THE EFFECT OF CULTIVAR MIXTURES ON MALTING QUALITY IN WINTER BARLEY

A range of winter barley cultivars was grown, either as pure stands or as components of mixtures, in a trial in 1995–96. For malting quality characters, mean values of mixtures did not differ from mean values of the appropriate monocultures, except for decreases in homogeneity, as determined by a fluorescence test of cell wall modification. When disease pressure was modified by fungicide, hot water extract was not significantly altered, although this may have been due to the restriction of malting to grain retained by a 2.5 mm sieve. One mixture, comprised of three related winter malting cultivars, gave higher hot water extracts than its components, as pure stands, with no adverse effects on homogeneity. This was not simply attributable to lower grain nitrogen content .