Detlef Passern's research while affiliated with Technische Universität Braunschweig and other places

Publications (6)

Article
Cocoa fermentations in Ghana and Trinidad as well as anaerobic fermentation-like incubations of fresh cocoa beans in Germany were carried out under controlled conditions. Samples of beans were taken during the course of these treatments and determinations were made as to acidification (pH, acetic acid content), proteolysis (free α-amino nitrogen, p...
Article
Investigations of proteolysis during anaerobic cocoa seed incubation have been extended by disc and SDS-gel electrophoretic protein analysis. Two protein bands (2.6 × 104 and 4.4 × 104 Dalton) were found to be vacuolar storage proteins, which accumulated during seed ripening (90 to 160 days after pollination) and which were specifically utilised du...
Article
Proteolysis in cocoa seeds was studied by fermentation-like anaerobic incubation to determine whether post-mortem proteolysis depends only on temperature and acidity. In acetone dry powder incubation, autolytic release of α-amino nitrogen is optimal at pH 4.0-4.5 and is higher at 55°C than at 45°C. Proteolysis increases with acidification. However,...
Article
Characteristic post-mortem changes in subcellular structures are described which are caused by the penetration of acetic acid during incubation of cocoa seeds in aqueous media. In the storage cells lipid is agglomerated and separates from hydrophilic portions in proportion to the acetic acid concentration and pH. This effect is less pronounced at 5...
Article
During anaerobic incubation in citric acid/NaOH (35 mmol; pH 5.5) at 40°C the fresh weight of ripe cocoa seeds (without testae) increases considerably (17–27% within 40 h) by water absorption. This is similar to water uptake during germination at 25–30°C. At 50°C in the same medium, weight increase (3.5–7.3% within 40 h) as well as net water uptake...
Article
Chemical reactions in cocoa seeds during fermentation and roasting may depend on post-mortem structural changes in the mesophyll cells. Aeration, temperature and acetic acid concentration vary considerably during commercial fermentation. Light and electron microscopic studies of seeds after artificial fermentations give evidence that the kind and t...

Citations

... Durante la fermentación, la pulpa sufre fermentación alcohólica, acética y láctica, provocando la muerte del embrión debido a la generación de calor, producción y migración de ácidos orgánicos y alcohol hacia la parte interior de los granos de cacao, provocando incremento de tamaño de los granos (hinchazón) y cambios en las membranas celulares que facilitan el movimiento libre de enzimas y sustratos dentro del grano(Afoakwa, 2016a;Amoa-Awua, 2015). En condiciones anaeróbicas, los microorganismos producen ácido acético y etanol, lo cual inhibe la germinación de los granos de cacao y contribuye con cambios estructurales dentro del grano, tales como la remoción de los compartimentos que almacenan a las enzimas y los sustratos y movimientos de componentes citoplasmáticos a través de los cotiledones de cacao(Afoakwa, 2016a), lo cual ocurre a una temperatura aproximada de 50 o C(Biehl, Quesnel, Passern, y Sagemann, 1982). En el inicio de la fermentación existe un metabolismo anaeróbico de los azúcares. ...
... In recent years, there has been an increased interest in exploring methods for controlled cocoa fermentation. Fermentation using a submerged artificial fermentation system based on Biehl & Passern (1982) was built to bring up new perspectives on cocoa fermentation under controlled environmental conditions (Voigt et al., 1994a). The effect of acetic acid on beans during fermentation increases the amount of free amino acid content compared to traditional methods Pasau, 2013). ...
... The health properties of cocoa and cocoa products are not solely dependent on their polyphenol contents, but also contributed to by other components such as methylxanthines (caffeine and theobromine), peptides, and minerals. (Biehl et al., 1982). Cocoa beans contain four types of proteins, namely albumins, globulins, prolamin, and glutelin. ...
... This phenomenon inhibits the entry of water into protein storage vacuoles and decreases its solubility before the entry of acids. At 50 C the proteins are insoluble and less accessible to proteolytic enzymes (because they are coated by lipids) when the pH is reduced before the water enters the vacuoles that contain them Biehl, Passern, and Passern 1977). ...
... The increase in fat content in advanced fermentation stages may be attributed to the combined action of acidity and temperature during fermentation, which resulted from the modification of lipid bonds (Servent et al., 2018). Similar finding was noted on 18 observations (0 h, 48 h, and 144 h fermentation) conducted by Biehl et al. (1982), showing a strong negative correlation (R 2 = 0.937) between fat and protein during fermentation. Aside from establishing that fermentation also reduces bioactive compounds such as polyphenols and anthocyanins (Dang and Nguyen, 2019;Zyzelewicz et al., 2014), this study revealed the negative and positive effects of fermentation days on the proximate composition. ...
... Chocolate aroma components consist of volatile compounds which are mainly formed from amine and carboxyl groups. The last two compounds are the result of peptide and carbohydrate reforms that take place during the fermentation process (Biehl et al., 1985) The candidate compounds for forming a distinctive chocolate aroma consist of hydrophobic amino acids, hydrophilic peptides, and reducing sugars (Voi et al, 1994). The Maillard reaction which takes place intensely during the roasting of cocoa beans produces volatile compounds consisting of alcohol groups of ether, furan, thiazole, pyrone, acid, ester, aldehyde, imine, amine, oxazole, pyrazine, and pyrrole. ...