I. Honzík

Effect of Storage Duration and Atmosphere on the Content and Price of Hop Alpha Bitter Acids

Abstract The quality of hops is significantly affected by the content of alpha bitter acids. Maintaining it with minimum losses lies within the competence of both the hop grower and processor depending on how they follow the optimum harvest technology, storage conditions, and post-harvest hop processing. That indicator is considerably affected by the hop storage method, i.e. whether the warehouse is air-conditioned or not, as well as the storage duration. The alpha bitter acid content should not be reduced during storage. The objective of this paper is an analysis of the alpha bitter acid content in the Saaz hop variety in a technological sequence of operations starting with drying at the grower and finishing with six-month storing at the processor, with three storage variants: an air-conditioned warehouse, non-conditioned warehouse, and a variant in which the square bale is moved after 60 days from a non-conditioned warehouse into an air-conditioned warehouse. The analysis of samples to identify the alpha bitter acid content was carried out by means of the ASBC Hops-6 and the HPLC EBC 7.7 methods. Practically in all cases the alpha content declines, although if a square bale is placed in an air-conditioned warehouse this decline is the lowest depending on the storage duration. The economic analysis shows a significant profit referring to the price of alpha contained in 1 t of hops stored in an air-conditioned warehouse. At the date of 1/11/2015 this profit was 14 706 CZK, at the date of 4/1/2016 it was 7646 CZK, and at 1/3/2016 the profit was 6587 CZK.

Pneumatic conveying characteristics of seeds in a vertical ascending airstream

Kroulík M., Hůla J., Rybka A., Honzík I. (2016): Pneumatic conveying characteristics of seeds in a vertical ascending airstream. Res. Agr. Eng., 62: 56–63. Pneumatic conveying characteristics were measured in vertical tubes for seeds of selected varieties of cereals, wide-row crops, oil crops, legumes and catch crops. The measured values were used for graphical representation of variation curves for the chosen groups of seeds. The values of the critical air velocity for seeds (velocity of seed lift) were computed. Statistical significance of differences in the mean values of critical velocities of tested seeds was determined. The critical velocity of cereal seeds ranged from 8.03 to 10.54 m/s. Among the crops grown in wide rows the highest critical velocity of seeds was found out in maize (13.29 m/s), the lowest in sunflower seeds (8.38 m/s). In oil crop seeds, the lowest critical velocity was recorded in poppy (4.67 m/s), which was the lowest value of all seed samples of the tested crops. The highest value of the critical velocity was measured in pea seeds (14.85 m/s).