Influence of genotype and processing intensity on the content of nutritionally important substances in barley grain mill products

Selected materials of hulless spring barley, variety AF Cesar and new genetic resources with a reduced proportion of amylose polysaccharide (waxy starch), lines KM 2454, KM 2551 and KM 2975, were grown in 2019 on field in the locality of Zvíkov u Lišova, kept in ecological growing regime. After harvest, samples of grain, groats and pearled fines, prepared by pearling of different intensity on a peeling - hulling machine Ekonos 3, were evaluated according to the content of biologically active components of the grain (beta-glucans, crude protein, starch, and fat). In accordance with the intensity setting on the machine using control flaps, samples of 4 fractions of groats (A, B, C and D) and pearled fines were obtained. With increasing pearling intensity, an increase in the starch content was observed on average in the groats fraction and the content of beta-glucans (hereinafter BG) increased in both fractions (groats and pearled fines), while the content of crude protein (hereinafter CP) decreased. The different intensity of pearling the grain of individual barley materials also led to an increase in the starch and BG content and a decrease in CP, while the differences between the individual genotypes were in most cases statistically significantly different. With a higher intensity of grain flow through the machine, groats with a BG content above 7% were obtained with the high starch content at the same time. Processing of pearled kernels by boiling in water resulted in a significant increase in the BG content of all tested barley materials compared to the values measured in the natural (raw) state. The highest BG content was determined in cooked samples from grain of the KM 2551 line after the third pearling intensity (fraction C = 7.72 ± 0.05%), but the absolute largest difference between natural and cooked groats was found in the sample after the second pearling intensity of the KM 2454 line (by 1.12% BG).