A study of dynamics of bitter acids and xanthohumol in hop pellets during storage

ArticleEight varieties of hop pellets were analyzed for the contents of α - acids, ß - acids and xanthohumol according to the EBC 7.7 analytical method. The pellets were extracted with acidified mixture methanol - diethylether and analyzed using HPLC with a diode - array detector and a Nova - Pak column C 18 . Four series of analyses were performed: immediately after the unpacking of the pellets and then after five, seven and nine months of storage at 4 °C. According to the first ser i es of analyses, the contents were assayed as following (α - acids, ß - acids, xanthohumol resp., all in weight % in pellets): Galaxy (13.4, 8.0, 0.74), Citra (11.1, 3.0, 0.48), Tradition (8.2, 8.0, 0.58), Cascade (4.5, 5.2, 0.25), Northern Brewer (4.0, 2.9, 0. 37), Sládek (3.5, 4.0, 0.48), Saaz (2.0, 3.4, 0.24), and Triskel (1.7, 3.6, 0.18). According to these results, variety Galaxy was found as the richest in all three parameters. After nine months of storage at 4 °C, the weight loss of α - acids ranged from 4.1 % (Citra and Triskel) to 66.4% (Galaxy). The losses of β - acids and xanthohumol were less distinctive (from zero to 31.3% and 25.7%, resp.) and indicated good long storage possibilities of these compounds at convenient conditions (darkness, low temperature, elimination of direct influence of oxygen)

Influence of diaphragm configuration on DC diaphragm discharge breakdown in electrolyte solution

International audienc

Reflotation of Coal Slurries from OKD company, Mine Lazy

The goal of the work is a verification of selective flotation on the black coal slurries sampled from slurry ponds of Mine Lazy, OKD company. Reflotation was realized with 6 collectors: Flotakol NX, Flotalex Ekofol 440, Montanol, MP 125 and AF 2. The technology of main flotation was applied. The variance analysis was used for the selectivity evaluation of particular collectors, whereby both the yield and flotation concentrate quality were tested. The goal of the flotation experiments was to achieve the flotation concentrate quality under 10% of ash. From the results follows that by using basic flotation it is possible (with the slurry samples) to reach the marketable coal concentrates with the ash content under 10% by Flotalex collector application

Propriedades mecânicas e morfologia de blendas de polipropileno com Tpes Morphology and mechanical properties of polypropylenes/Tpes blends

Blendas de polipropileno e elastômeros termoplásticos (TPEs), estireno-b-butadieno-b-estireno (SBS) e estireno-b-etileno-co-butileno-b-estireno(SEBS) foram preparadas com o objetivo de avaliar a influência do tipo e da concentração do elastômero nas propriedades mecânicas e na morfologia das blendas. Foram utilizados dois tipos de polipropileno, um homopolímero de propileno (PP-H) e um copolímero randômico de propileno-etileno (PP-R), sendo avaliado também o efeito das características da matriz termoplástica. O elastômero termoplástico aumentou a resistência ao impacto do PP, e a variação da rigidez das blendas foi dependente somente da quantidade de TPE adicionada, sendo estas comparativamente mais rígidas que aquelas com igual teor de elastômero convencional, tipo EPDM e EPR. A blenda com melhor balanço rigidez-impacto foi aquela de PP-R com 10% de SEBS. As blendas do copolímero de propileno-etileno com os TPEs apresentaram maior deformação do que aquelas com o homopolímero, devido à natureza menos cristalina da matriz do copolímero de propileno. As blendas tanto do homo quanto do copolímero de propileno com SEBS ficaram mais homogêneas em função da maior afinidade do bloco central poliolefínico EB (etileno-co-butileno) do primeiro com a região amorfa da matriz, sendo esta mais significativa no PP-R.<br>Blends of polypropylene and thermoplastic elastomers (TPEs) of styrene-butadiene-styrene (SBS) and styrene-ethylene-co-butene-styrene (SEBS) triblock copolymers were prepared to evaluate the effect of the elastomer and its concentration on the material properties. For this purpose, a polypropylene homopolymer (PP-H) and a propylene-ethylene random copolymer (PP-R) were used to evaluate the matrix effect on the tensile properties and morphology of the blends. The addition of TPEs to PP promotes increase on impact resistance and the PP-R/SEBS 10%wt blend showed the best balance in stiffness-impact resistance. The morphology of binary blends was similar to elastomeric domains dispersed into the PP matrix and changed as the TPE type and concentration varied. The size of SEBS domains was more homogeneous than the SBS' in both PP matrices due to the high affinity between the polyolefinic EB (ethylene-butene) middle block of the SEBS with the PP amorphous fraction