A RAPID SMALL SCALE METHOD FOR THE DETERMINATION OF MALT EXTRACT

Barley yield and malt quality affected by fall and spring planting under rainfed conditions

Background

As a result of the changing climate characteristics, it is necessary to reevaluate the planting time for crop plants. The aim of the present study was to determine the quality characteristics of malting barley cultivars in fall and spring plantings.

Methods

Sixteen malting barley cultivars were used. Two fall-planted and two spring-planted trials were conducted in two consecutive years. The field trials were carried out in a randomized complete block design with four replications in Tokat province of Turkey under rainfed conditions.

Results

Grain yields varied between 4.38 and 5.71 t/ha in fall-planted trials and between 3.12 and 4.89 t/ha in spring-planted trials. Malt extracts were between 77.0% and 78.0% kg in fall-planted trials and between 73.9% and 76.9% in spring-planted trials. Alpha amylase activities ranged from 77.9 to 81.4 Ceralpha unit (CU)/g in fall-planted trials and from 80.8 to 100.9 CU/g in spring-planted trials. Diastatic power ranged from 194.5 to 331.1 Windisch-Kolbach unit (°WK) in fall-planted trials and from 129.0 to 259.8 °WK in spring-planted trials. GGE biplot analysis indicated that winter barley cultivar Durusu and facultative barley cultivar Ince-04 were the best with consistent grain yields while Ince-04 was the best with stable malt extract across the trials. In scatter plot graphics, winter barley cultivars Durusu, Aydanhanim, Yildiz and facultative Ince-04 had superior performance in fall-plantings for grain yield and malt extract. In spring planting, facultative Ince-04 had higher performance than those of other cultivars. In spring plantings, facultative or winter barley cultivars that do not have strong vernalization requirement had better yield and malt quality. Appropriate planting time and cultivars can allow a better use of available water in malt barley production under rainfed conditions. Lastly, instead of evaluating the grain yield or malt quality alone, it would be best to evaluate the target product (malt extract percentage) obtained from a particular region, process, or production methodology.

A novel approach to monitor the hydrolysis of barley (Hordeum vulgare L) malt: a chemometrics approach

Malting barley is a process that has been profusely studied and is known to be influenced by several physical and biochemical properties of the grain. In particular, the amount of material that can be extracted from the malt (malt extract) is an important measure of brewing performance and end quality. The objectives of this study were (a) to compare the time course of hydrolysis of different malting barley (Hordeum vulgare L) varieties and (b) to evaluate the usefulness of mid-infrared (MIR) spectroscopy as high-throughput method to monitor malt hydrolysis. Differences in the pattern of hydrolysis were observed between the malt samples analyzed where samples from the same variety that have similar hot water extract (HWE) values tend to have the same pattern of hydrolysis. Principal component score plots based on the MIR spectra showed similar results. Partial least-squares discriminate analysis (PLS-DA) was used to classify malt samples according to their corresponding variety and time course of hydrolysis. The coefficient of determination (R(2)) and the standard error of cross validation (SECV) obtained for the prediction of variety and time course of hydrolysis were 0.67 (1.01) and 0.38 (19.90), respectively. These differences might be the result of the different composition in sugars between the barley varieties analyzed after malting, measured as wort density and not observed when only the HWE value at the end point is reported. This method offers the possibility to measure several parameters in malt simultaneously, reducing the time of analysis as well as requiring minimal sample preparation.