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--- theobroma_cacao_l [2019/09/12 08:27]
andreas
+++ theobroma_cacao_l [2020/12/06 09:43] (aktuell)
andreas
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 [Identification of the key aroma compounds in cocoa powder based on molecular sensory correlations., Frauendorfer, Felix, Schieberle, Peter,  Journal of agricultural and food chemistry, Vol.54(15) 2006, 5521-5529] [[http://worldcocoafoundation.org/wp-content/files_mf/frauendorfer2006.pdf]]
-"Cocoa beans (Theobroma cacao) are the major raw material for chocolate production and fermentation of the beans is essential for the development of chocolate flavor precursors. In this study, a novel approach was used to determine the role of yeasts in cocoa fermentation and their contribution to chocolate quality. Cocoa bean fermentations were conducted with the addition of 200 ppm Natamycin to inhibit the growth of yeasts, and the resultant microbial ecology and metabolism, bean chemistry and chocolate quality were compared with those of normal (control) fermentations. The yeasts Hanseniaspora guilliermondii, Pichia kudriavzevii and Kluyveromyces marxianus, the lactic acid bacteria Lactobacillus plantarum and Lactobacillus fermentum and the acetic acid bacteria Acetobacter pasteurianus and Gluconobacter frateurii were the major species found in the control fermentation. In fermentations with the presence of Natamycin, the same bacterial species grew but yeast growth was inhibited. Physical and chemical analyses showed that beans fermented without yeasts had increased shell content, lower production of ethanol, higher alcohols and esters throughout fermentation and lesser presence of pyrazines in the roasted product. Quality tests revealed that beans fermented without yeasts were purplish-violet in color and not fully brown, and chocolate prepared from these beans tasted more acid and lacked characteristic chocolate flavor. Beans fermented with yeast growth were fully brown in color and gave chocolate with typical characters which were clearly preferred by sensory panels. Our findings demonstrate that yeast growth and activity were essential for cocoa bean fermentation and the development of chocolate characteristics." \\
+Character impact compounds of the volatile fraction of three commercial cocoa powders (Bensdorp, Krüger, Sarotti) isolated using thin-layer high-vacuum distillation (TLHVD) of Soxhlet extracts were: Acetic acid (vinegar), propanoic acid (mouldy), 2-methyl propanoic acid (rancid), phenylacetaldehyde (flowery), 2/3-methyl butanoic acid (sweaty), dehydromevalonic acid lactone (condesed milk, sour), 2-pyrrolidinone (popcorn), pyrrole-2-carboxaldehyde (nut), (R)-(−)-pantolactone (caramel, coconut), furaneol (caramel), massoia lactone (coconut), dihydroxymaltol (caramel), 4-methyl-5-(2-hydroxyethyl)thiazol (peanut), two solerol isomers (red fruit, jam, green notes), vanillin (vanilla) and phenylacetic acid (sweet, flowery). These 17 compounds were detected at the sniff port of the GC-O after a 1:100 dilution. The aroma extract contained acetoin and several alkylated pyrazines e.g. \\
+[Krings, Ulrich, et al. "Thin-layer high-vacuum distillation to isolate volatile flavour compounds of cocoa powder." European Food Research and Technology 223.5 (2006): 675-681]
+"Cocoa beans (Theobroma cacao) are the major raw material for chocolate production and fermentation of the beans is essential for the development of chocolate flavor precursors. In this study, a novel approach was used to determine the role of yeasts in cocoa fermentation and their contribution to chocolate quality... Quality tests revealed that beans fermented without yeasts were purplish-violet in color and not fully brown, and chocolate prepared from these beans tasted more acid and lacked characteristic chocolate flavor. Beans fermented with yeast growth were fully brown in color and gave chocolate with typical characters which were clearly preferred by sensory panels. Our findings demonstrate that yeast growth and activity were essential for cocoa bean fermentation and the development of chocolate characteristics." \\
 [Yeasts are essential for cocoa bean fermentation. Van Thi Thuy Ho, Jian Zhao, Graham Fleet, International Journal of Food Microbiology, Vol.174, 2014, 72-87]
+"In contrast to cocoa from Ecuador, the Chontalpa cocoa shows an intense and distinctive fingerprint of alkyl   pyrazines (2,3,5-trimethyl, 2,6 -dimethyl, 2,3-dimethyl, 2-ethyl-3,5-dimethyl, 2-ethyl-5(6)-methyl, and 3,5-diethyl-2-methyl pyrazine) and linear esters (e.g., ethyl pentanoate, ethyl hexanoate, ethyl octanoate, and ethyl  decanoate). In addition, Chontalpa is characterized by a distinctive signature of some key aroma compounds, including acetic acid (sour), phenyl acetaldehyde (honey-like), 2-phenyl ethanol (flowery),  phenyl propanoid derivates (benzaldehyde and benzyl alcohol), 3-methyl butanal (malty), and butanoic acid (sweaty). On the other hand, the Ecuador aroma signature results from 2-heptanol (citrusy), 3-methyl butanoic acid(rancid), and dimethyl trisulfide (sulfurous)." \\
+[Magagna, Federico, et al. "Advanced fingerprinting of high-quality cocoa: Challenges in transferring methods from thermal to differential-flow modulated comprehensive two dimensional gas chromatography." Journal of Chromatography A 1536 (2018): 122-136] [[https://aperto.unito.it/retrieve/handle/2318/1644892/351315/Manuscript%20OA_4aperto.pdf]]
 **Chocolate** is a sweet food preparation of Theobroma cacao seeds.
@@ Zeile 33: / Zeile 39: @@
 "A number of compounds have been identified by gas chromatography-olfactometry (GC-O) as key odorant compounds in dark chocolate. 2-Methylpropanal, 3-methylpropanal and 2-methylbutanal have been related to chocolate odors while trimethylpyrazine, 2,5-dimethylpyrazine and acetylpyrrole have been attributed cocoa odors. Methylpyrazine, 2,3-dimethylpyrazine, 2-ethyl-6-methylpyrazine and benzaldehyde added a hazelnut/almond note to the aroma profile of chocolate; ethylpyrazine, 3-ethyl-2,5-dimethylpyrazine and tetramethylpyrazine a roasty note." \\
 [Evaluation of solid-phase micro-extraction coupled to gas chromatography-mass spectrometry for the headspace analysis of volatile compounds in cocoa products. Ducki, S., Miralles-Garcia, J., Zumbé, A., Tornero, A., Storey, D. M., Talanta, Vol.74(5), 2008, 1166-1174]
+"The specific cocoa aroma arises from complex biochemical and chemical reactions during the postharvest processing of raw beans, and from many influences of the cocoa genotype, chemical make‐up of raw seeds, environmental conditions, farming practices, processing, and manufacturing stages. There has been much research on cocoa flavor components. However, the relationships between all chemical components that are likely to play a role in cocoa flavor, their sensory properties, and the sources and mechanisms of flavor formation are not fully understood." \\
+[Aprotosoaie, Ana Clara, Simon Vlad Luca, and Anca Miron. "Flavor chemistry of cocoa and cocoa products—an overview." Comprehensive Reviews in Food Science and Food Safety 15.1 (2016): 73-91] [[https://onlinelibrary.wiley.com/doi/full/10.1111/1541-4337.12180]]
 {{:theobroma_cacao.jpg}} \\

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