The chemistry of beer flavor instability remains shrouded in mystery, despite decades of extensive research. It is, however, certain that aldehydes play a crucial role because their concentration increase coincides with the appearance and intensity of "aged flavors". Several pathways give rise to a variety of key flavor-active aldehydes during beer production, but it remains unclear as to what extent they develop after bottling. There are indications that aldehydes, formed during beer production, are bound to other compounds, obscuring them from instrumental and sensory detection. Because freshly bottled beer is not in chemical equilibrium, these bound aldehydes might be released over time, causing stale flavor. This review discusses beer aging and the role of aldehydes, focusing on both sensory and chemical aspects. Several aldehyde formation pathways are taken into account, as well as aldehyde binding in and release from imine and bisulfite adducts.
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http://dx.doi.org/10.1021/jf303670z | DOI Listing |
Science
November 2024
CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Universidade do Porto, Vairão, Portugal.
Parrots produce stunning plumage colors through unique pigments called psittacofulvins. However, the mechanism underlying their ability to generate a spectrum of vibrant yellows, reds, and greens remains enigmatic. We uncover a unifying chemical basis for a wide range of parrot plumage colors, which result from the selective deposition of red aldehyde- and yellow carboxyl-containing psittacofulvin molecules in developing feathers.
View Article and Find Full Text PDFFood Chem
February 2025
Department of Food and Nutritional Sciences, University of Reading, RG6 6DZ, UK.. Electronic address:
Control of aroma formation during production of barley malt is critical to provide consistent and high-quality products for the brewing industry. Malt quality can be affected by the inherent variability of raw material and processing conditions, leading to inconsistent and/or undesirable profiles. Dried green malts were cured isothermally at 65, 78 and 90 °C for 8.
View Article and Find Full Text PDFFoods
September 2024
Postgraduate Program in Food Science and Technology, Institute of Technology, Federal University of Pará, Belém 66075-110, Brazil.
Beer is a popular beverage consumed globally, and studies have emphasized the benefits of moderate consumption as well as its sensory effects on consumers. Color is a crucial sensory attribute, being the first aspect a consumer notices when assessing a beer's quality. This review seeks to offer detailed insights into how brewing methods, raw materials, and the chemical diversity of beer influence the production of beer color.
View Article and Find Full Text PDFIndian J Ophthalmol
October 2024
Departments of Vitreo-Retina and Ocular Oncology and Cataract, and Phacorefractive Surgery, Sankara Eye Hospital, Shimoga, Karnataka, India.
Purpose: The main factor that causes cataracts is the increased oxidative stress and imbalance of an antioxidant defense mechanism, which leads to significant changes in the lens microarchitecture. Senile cataract is the most common type of acquired cataracts due to aging.
Methods: We carried out a case-control study in the biochemistry department to examine the antioxidant status (catalase and total antioxidant capacity [TAC]) and lipid peroxidation marker, that is, malondialdehyde (MDA) in human lens epithelial cells (HLECs) of different grades of senile cortical, nuclear, and posterior subcapsular cataracts.
Plant J
October 2024
The Albert Katz Department of Dryland Biotechnologies, French Associates Institute for Agriculture and Biotechnology of Dryland, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Beer Sheva, 8499000, Israel.
Among the three active aldehyde oxidases in Arabidopsis thaliana leaves (AAO1-3), AAO3, which catalyzes the oxidation of abscisic-aldehyde to abscisic-acid, was shown recently to function as a reactive aldehyde detoxifier. Notably, aao2KO mutants exhibited less senescence symptoms and lower aldehyde accumulation, such as acrolein, benzaldehyde, and 4-hydroxyl-2-nonenal (HNE) than in wild-type leaves exposed to UV-C or Rose-Bengal. The effect of AAO2 expression absence on aldehyde detoxification by AAO3 and/or AAO1 was studied by comparing the response of wild-type plants to the response of single-functioning aao1 mutant (aao1S), aao2KO mutants, and single-functioning aao3 mutants (aao3Ss).
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