Changes in Diacetyl and Amino Acid Concentration during the Fermentation of Dry-Hopped Beer: A Look at Twelve <i>Saccharomyces</i> Species and Strains

Bruner, James; Marcus, Andrew; Fox, Glen

doi:10.1080/03610470.2022.2078946

Cited by 3 publications

(4 citation statements)

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“…Centennial hops have approximately 0.5% (of total mass) of lysine. 110 Huell Mellon variety had 1.1%, and Spahir, Hersbrucker, Hercules, and Amarillo varied between 0.5− 0.8%. Proline content varied from 2.2 to 7.9%.…”

Section: Proteins and Amino Acids In Beer Matrixmentioning

confidence: 98%

“…Crude protein content in hops varies from 13 to 20%, from which the amino acid fraction comes to 10%. , Depending on the variety, the lysine content may vary. Centennial hops have approximately 0.5% (of total mass) of lysine . Huell Mellon variety had 1.1%, and Spahir, Hersbrucker, Hercules, and Amarillo varied between 0.5–0.8%.…”

Section: Proteins and Amino Acids In Beer Matrixmentioning

confidence: 99%

“…To further enhance the aroma, a process of dry hopping, or adding hops into the fermenter during fermentation, or to add hops immediately after fermentation is used . For each of these additions of hops, more amino acids would be added . However, bitter compounds from hops like iso-α-acids and their derivatives like humulinone interact with LTP and protein Z, resulting in complexes which positively impact foam stability and lacing.…”

Section: Proteins and Amino Acids In Beer Matrixmentioning

confidence: 99%

“…122 For each of these additions of hops, more amino acids would be added. 110 However, bitter compounds from hops like iso-α-acids and their derivatives like humulinone interact with LTP and protein Z, resulting in complexes which positively impact foam stability and lacing. Humulinone has several sites from which can bind to protein Z, including Asn-37, Ser-292, Lys-290, and Pro-395, and it can be introduced to beer through dry hopping, which results in a decrease in soluble protein content or free amino nitrogen content.…”

Section: Proteins and Amino Acids In Beer Matrixmentioning

confidence: 99%

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A Review of N-Heterocycles: Mousy Off-Flavor in Sour Beer

Martusevice,

Li,

Hengel

et al. 2024

J. Agric. Food Chem.

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Beer has over 600 flavor compounds and creates a positive tasting experience with acceptable sensory properties, which are essential for the best consumer experience. Spontaneous and mixed-culture fermentation beers, generally classified as sour beers, are gaining popularity compared to typical lager or ale styles, which have dominated in the USA for the last few decades. Unique and acceptable flavor compounds characterize sour beers, but some unfavorable aspects appear in conjunction. One such unfavorable flavor is called "mousy". This description is usually labeled as an unpleasant odor, identifying spoilage of fermented food and beverages. It is related as having the odor of mouse urine, cereal, corn tortilla chips, or freshly baked sour bread. The main compounds responsible for it are N-heterocyclic compounds: 2-acetyltetrahydropyridine, 2-acetyl-1-pyrroline, and 2-ethyltetrahydropyridine. The most common beverages associated with mousy off-flavor are identified in wines, sour beers, other grainbased beverages, and kombucha, which may contain heterofermentative lactic acid bacteria, acetic acid bacteria, and/or yeast/fungus cultures. In particular, the fungal species Brettanomyces bruxellensis are associated with mousy-off flavor occurrence in fermented beverages matrices. However, many factors for N-heterocycle formation are not well-understood. Currently, the research and development of mixed-cultured beer and non/low alcohol beverages (NABLAB) has increased to obtain the highest quality, sensory, functionality, and most notably safety standards, and also to meet consumers' demand for a balanced sourness in these beverages. This paper introduces mousy off-flavor expression in beers and beverages, which occurs in spontaneous or mixed-culture fermentations, with a focus on sour beers due to common inconsistency aspects in fermentation. We discuss and suggest possible pathways of mousy off-flavor development in the beer matrix, which also apply to other fermented beverages, including non/low alcohol drinks, e.g., kombucha and low/nonalcohol beers. Some precautions and modifications may prevent the occurrence of these off-flavor compounds in the beverage matrix: improving raw material quality, adjusting brewing processes, and using specific strains of yeast and bacteria that are less likely to produce the off-flavor. Conceivably, it is clear that spontaneous and mixed culture fermentation is gaining popularity in industrial, craft, and home brewing. The review discusses important elements to identify and understand metabolic pathways, following the prevention of spoilage targeted to off-flavor compounds development in beers and NABLABs.

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Section: Proteins and Amino Acids In Beer Matrixmentioning

confidence: 98%