Hop beta acids: Properties, significance and utilization.

Krofta, Karel; Mikyška, Alexandr

doi:10.18832/kp2014010

Cited by 6 publications

(3 citation statements)

References 54 publications

(89 reference statements)

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“…Beta-acids are known to deliver a 9-fold lower bitterness aspect to beer compared to alpha-acids [ 21 ]. However, they are very prone to oxidation reactions if exposed to oxygen [ 22 ], and this leads to the formation of eight degradation products, with hulupones as the major product. Hulupones provide a short, lingering, fine bitterness, similar to that of iso-alpha-acids but with less intensity.…”

Section: Resultsmentioning

confidence: 99%

The Stability of Hop (Humulus lupulus L.) Resins during Long-Period Storage

Rutnik

Ocvirk

Košir

2023

Plants

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The stability of alpha-acids, beta-acids and hop storage index (HSI) values under different conditions (aerobic/anaerobic, 4 °C/room temperature) was studied in a two-year trial. Six different varieties (Celeia, Aurora, Bobek, Styrian Gold, Savinjski Golding and Styrian Wolf) were used in the form of cones and pellets. Alpha- and beta-acids were determined by HPLC and HSI by spectrophotometry. Anaerobic conditions at 4 °C were best for alpha-acids, beta-acids and HSI values; however, 10–35% of the alpha-acids were still lost after two years. The decline was greater (63–99%) under aerobic conditions and at room temperature. Alpha-/beta-acid ratios increased in hop cones and decreased in hop pellets, whereas HSI values increased in all storage conditions. Overall, the performance was better for pellets than for hop cones. Storage conditions, storage form and hop variety had significant effects on the stability of hop resins.

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Section: Resultsmentioning

confidence: 99%

The Stability of Hop (Humulus lupulus L.) Resins during Long-Period Storage

Rutnik

Ocvirk

Košir

2023

Plants

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“…β-Acids cannot be isomerized due to their structural differences (they do not contain a tertiary alcohol group in the aromatic nucleus). Also their solubility in wort is lower and their antimicrobial effects are not as signifi cant as those of α-acids (Krofta and Mikyška, 2014;Vrisekoop et al, 2012). α-Acids are isomerized to iso-α-acids during wort boiling.…”

Section: The Resistance Of Bacillus Bacteria To Bitter Hop Substancesmentioning

confidence: 99%

“…β-hořké kyseliny nemohou v důsledku strukturní odlišnosti isomerovat (neobsahují terciární alkoholovou skupinu v aromatickém jádru). Jejich rozpustnost v mladině je nižší a jejich antimikrobiální účinky nejsou ve srovnání s α--hořkými kyselinami tak významné (Krofta a Mikyška, 2014;Vrisekoop et al, 2012). α-hořké kyseliny v průběhu chmelovaru isomerují na iso-α-hořké kyseliny, které jsou v mladině více rozpustné a mají vyšší antimikrobiální účinky.…”

Section: Rezistence Bakterií Bacillus K Hořkým Chmelovým Látkámunclassified

Brewing Microbiology - Bacteria of the Genera Bacillus, Brevibacillus and Paenibacillus and Cultivation Methods for their Detection - Part 1

Brožová¹,

Kubizniaková²,

Matoulková³

2018

Kvasny Prum

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Bacteria of the genus Bacillus are often detected in brewing operations, but they rank among less hazardous contaminants. They are not able to survive in the vegetative form in beer and spoil it. Spores of Bacillus bacteria are present especially in malt and grain adjuncts. They are able to survive wort boiling, however in the following phases they are not able to germinate because of their sensitivity to bitter hop substances and low pH of fermenting wort and fi nished beer. We provide here an overview of basic morphological and physiological properties of these bacteria and describe their importance in brewing process. Particular attention is given to species B. cereus and B. licheniformis for which has been proved the presence of the horA gene, which is associated with resistence of lactic acid bacteria to hop substances. Species Brevibacillus brevis and Paenibacillus macerans, which were previously included in the genus Bacillus, are also described.Brožová, M., Kubizniaková, P., Matoulková, D., 2018: Mikrobiologie pivovarské výroby -bakterie rodů Bacillus, Brevibacillus a Paenibacillus a kultivační metody pro jejich detekci -1. část. Kvasny Prum., 64(2): 50-57Bakterie rodu Bacillus jsou v pivovarských provozech často detekovány, řadí se však mezi méně rizikové kontaminanty. Ve vegetativní formě nejsou schopné přežívat v pivu a nekazí ho. Spory bakterií Bacillus jsou přítomny zejména ve sladu a obilných náhražkách sladu, přežijí chmelovar, ale v navazujících fázích výroby piva nevyklíčí -jsou citlivé na hořké chmelové látky a nízké pH kvasící mladiny a hotového piva. V publikaci jsou popsány základní morfologické a fysiologické vlastnosti těchto bakterií, je zde popsán jejich význam v procesu výroby piva. Zvláštní pozornost je věnována druhům B. cereus a B. licheniformis, u kterých byla prokázána přítomnost genu horA, který je spojován s rezistencí bakterií mléčného kvašení k chmelovým látkám. Publikace se dále věnuje druhům Brevibacillus brevis a Paenibacillus macerans, které byly dříve řazeny do rodu Bacillus. (meat, vegetables, milk, cereals). Due to their frequent occurrence in nature and thermoresistant spores, they enter the brewing operation mostly with raw materials (water, malt, hop). Bacillus bacteria are able to survive mashing and wort boiling, therefore they can also be found in fi nished beer (Back, 2005;Vaughan et al., 2005). However, in most species their following growth in beer is inhibited by bitter hop products and acid pH (Back, 2005;Basařová et al., 2010). Generally, they are not considered hazardous brewing contaminants, due to their inability to grow in beer, nor after adaptation to outer conditions, and the fact that they do not affect biological stability of fi nished beer. Undesirable is the ability of some bacilli to reduce nitrates to nitrites that may cause the formation of N-nitrosamines in beer (Back, 2005;Bokulich and Bamforth, 2013;Briggs et al., 2004). Keywords ■ 2 GENERAL CHARACTERISTICS OF GENUS BACILLUSBacteria of the genus Bacillus are aerobic or facultative anaerobic,...

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Biopreservation of beer: Potential and constraints

Kordialik‐Bogacka¹

2022

Biotechnology Advances

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Hop beta acids: Properties, significance and utilization.

Cited by 6 publications

References 54 publications

The Stability of Hop (Humulus lupulus L.) Resins during Long-Period Storage

The Stability of Hop (Humulus lupulus L.) Resins during Long-Period Storage

Brewing Microbiology - Bacteria of the Genera Bacillus, Brevibacillus and Paenibacillus and Cultivation Methods for their Detection - Part 1

Biopreservation of beer: Potential and constraints

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