Stefanie Streule

Mrs. Stefanie Streule

orcid

Research Focus & Metrics

Academic Career Length

5Years (2022-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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9 June 2022 in Heliyon
Verified
Journal Article
Open access
SSStefanie Streule
Stefanie Streule
SLSusette Freimüller Leischtfeld
Susette Freimüller Leischtfeld
MGMartina Galler
Martina Galler
Susanne Miescher SchwenningerSusanne Miescher Schwenninger
Susanne Miescher Schwenninger
Cocoa post-harvest practices were monitored on a small-farm scale (ca. 50 kg fresh beans) at five intermediaries from four provinces in Ecuador: (A) in Manabí, (B) and (E) in Los Ríos, (C) in Cotopaxi, (D) in Guayas. Temperature, pH (pulp, cotyledon), cell counts (yeasts, lactic acid bacteria, acetic acid bacteria) were recorded daily, and cut-tests and sensory descriptive analysis evaluated end quality. An overall inconsistency and variability in processing were observed with different fermentation devices (jute/plastic bags, wooden boxes), pre-drying, turning during fermentation, fermentation duration, and different drying processes (temperatures, direct/indirect). Key parameters (maximum temperature, pH cotyledon development) revealed a significant impact of the fermentation device on the post-harvest process and, therefore, on the fermentation development. 67–74 h in jute bags without turning was sufficient to reach well-fermented cocoa beans without moldy off-flavors, whereas 133 h in plastic bags without turning resulted in 3 ± 1% moldy beans and cocoa liquor with moldy off-flavor. Drying at high temperatures (80 ± 10 °C) with direct heat contact resulted in beans roasted to burnt off-flavor. Conclusively, the whole post-harvest process was crucial for well-fermented beans without off-flavor. Plastic bags seemed unsuitable, while jute bags could be an alternative to wooden boxes.

15 May 2024 in Foods
Verified
Journal Article
Open access
PDF file
SSStefanie Streule
Stefanie Streule
Susette Freimüller LeischtfeldSusette Freimüller Leischtfeld
Susette Freimüller Leischtfeld
KCKarin Chatelain
Karin Chatelain
Susanne Miescher SchwenningerSusanne Miescher Schwenninger
Susanne Miescher Schwenninger
The impact of pod storage (PS) and two drying temperatures of fermented cocoa beans was investigated in Ecuador. Therefore, four variations were simultaneously carried out three times at two locations, independently: 0, 3, and 5 days of PS, dried at 60 °C and 0 days of PS, dried at 80 °C. Pod weight during storage, pulp content, pH, temperature, microbial counts, total free amino acids, protein profiles, sugars, organic acids, cut-test, fermentation index, and sensory profiles were analyzed. Minor differences in fermentation dynamics and bean quality were found between variations with and without PS. A rather accelerated fermentation with pod-stored beans was observed (e.g., faster color change, slightly lower pH in cotyledon after 48 h), along with a significantly higher maximal temperature during 24–42 h (43.1 ± 3.2 °C compared to 39.2 ± 2.0 °C without PS). More well-fermented beans were reached with PS (52.3 ± 22.6%) than without (62.7 ± 9.2%). Differences during fermentation were observed between the locations (e.g., pH, acids, sugars), but sensory evaluation indicated that the impact of location was mitigated with PS. Drying at 80 °C showed no adverse effects, as evidenced by the results of the cut-test and fermentation index. However, sensory evaluations revealed significant differences between 80 °C and 60 °C, with the former exhibiting more bitter and astringent cocoa liquor.

19 August 2024 in Foods
Verified
Journal Article
Open access
PDF file
SSStefanie Streule
Stefanie Streule
AAAmandine André
Amandine André
Susette Freimüller LeischtfeldSusette Freimüller Leischtfeld
Susette Freimüller Leischtfeld
KCKarin Chatelain
Karin Chatelain
EGElodie Gillich
Elodie Gillich
Susanne Miescher SchwenningerSusanne Miescher Schwenninger
Susanne Miescher Schwenninger
This study investigated the impact of the depulping of cocoa beans after pod opening, as well as the influences of pod storage (PS) and fermentation time on the fermentation dynamics and the overall quality of beans and liquors made thereof. Twelve variations were conducted in three experimental runs (with/without depulping; 1-/3-day PS; and fermentation times of 3, 4, 5, 6 or 7 days). Fermentation dynamics (e.g., temperature and pH) and the quality of dried beans (e.g., cut-test and fermentation index) and liquors (sensory assessment, quantification of cocoa key-odorants and tastants) were investigated. It was demonstrated that 17–20% of cocoa pulp, relative to the total bean-pulp-mass weight, could be mechanically removed without negatively affecting the bean quality. No significant differences were found in the percentages of well-fermented beans after 5–6 days fermentation with 1-day PS, resulting in 49 ± 9% with, and 48 ± 12% without depulping. There were no significant differences in key tastants present in the liquors; however, significantly less volatile acids and esters were found when liquors were produced from 5–6 day-fermented depulped beans, with 1-day PS, without negatively affecting the sensory profiles. This strategy allows producers to maximize the cacao fruit’s value by integrating part of the pulp into the cocoa value chain.

30 December 2023 in Foods
Verified
Journal Article
Open access
PDF file
SSStefanie Streule
Stefanie Streule
Susette Freimüller LeischtfeldSusette Freimüller Leischtfeld
Susette Freimüller Leischtfeld
MGMartina Galler
Martina Galler
DMDominik Motzer
Dominik Motzer
MPMonja Poulose-Züst
Monja Poulose-Züst
Susanne Miescher SchwenningerSusanne Miescher Schwenninger
Susanne Miescher Schwenninger
In Ecuador, various processes are applied during cocoa post-harvesting. This study, therefore, explored fermentation parameters across two locations with 2–7 independent runs, focusing on temperature, microbial counts, pH during fermentation and drying, and their impact on cocoa bean quality. Factors including fermentation devices (jute bags, plastic bags, and wooden boxes), pre-drying, turning during fermentation, fermentation duration, and drying temperature were investigated. Fermenting in plastic bags without pre-drying or turning and fermenting in jute bags for only 40 ± 2.0 h yielded low maximal fermentation temperatures Tmax (31.1 ± 0.4 °C and 37.6 ± 1.8 °C), leading to bitter, astringent, woody, and earthy cocoa liquor. Longer fermentation (63 ± 6 h) in wooden boxes with turning (Wt) and in jute bags with pre-drying and turning (Jpt) achieved the highest Tmax of 46.5 ± 2.0 °C, and a more acidic cocoa liquor, particularly in Wt (both locations) and Jpt (location E). Therefore, it is recommended to ferment for a minimum duration from day 1 to 4 (63 ± 6 h), whether using plastic bags (with mandatory pre-drying) or jute bags (with or without pre-drying or turning). Furthermore, this study underscores the risks associated with excessively high drying temperatures (up to 95.2 ± 13.7 °C) and specific dryer types, which can falsify cut-tests and introduce unwanted burnt-roasted off-flavors in the cocoa liquor.