Browsing by Author "Van de Walle, D."

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Applicability of the melanger for chocolate refining and Stephan mixer for conching as small-scale alternative chocolate production techniques
(Journal of Food Engineering, 2019-02) Hinneh, M.; Van de Walle, D.; Haeck, J.; Abotsi, E.E.; De Winne, A.; Saputro, A.D.; Messens, K.; Van Durme, J.; Afoakwa, E.O.; De Cooman, L.; Dewettinck, K.
Conventional dark chocolate production methods that are applied in the industry consist of several steps, which require equipment with big investment costs. There are however few cost-effective alternatives suggested for small-scale production. Meanwhile, knowledge on these alternative equipment/techniques are insufficient to promote miniature production of high quality chocolates, either for research purposes in an industrial context, or for producers in developing countries, where the cost of investing in conventional equipment seems to be an impediment. The aim of this study was two-fold; first, to assess the feasibility of utilizing the ECGC-12SLTA CocoaTown melanger as an alternative to the conventional 3-roll refiner at different settings and fat content. Thereafter, one optimal setting was selected for each equipment for further investigation on the impact of the refining on some quality attributes of the final dark chocolate (70% cocoa). Secondly, the Stephan mixer; being used to mimick a conching-like process, was assessed with respect to two processing factors; the dry conching temperature (60 °C, 80 °C) and the duration of vacuum pump connection (0, 30, 60 min). The latter was to facilitate adequate moisture removal. The melanger proved to be a suitable alternative to the 3-roll refiner, provided that refining was carried out at moderate/high (ca. 40%) fat content, as is often the case for “high-percentage-cocoa” chocolates. Refining for 180 min with the mini drum at 40% resulted in D (v,0.9) significantly (p < 0.05) lower than when the 3-roll refiner was used. Nonetheless, a comparative advantage of the latter would be its short throughput time (5–10 min). Due to a resultant linear speed gradient of the chocolate mass due to the cylindrical roller stones, a more efficient refining was achieved with the mini drum than with the big drum. More so, refining in excess fat (40%) may have contributed to a more efficient coating of the newly created hydrophilic sugar surfaces, thus, limiting the possibility for moisture-induced agglomeration as may have been the case for the recipe with 27% fat. In spite of trivial difference in moisture content, chocolates manufactured following melanger and 3-roll refining showed significant (p < 0.05) differences in terms of particle size, flow parameters and color. For chocolates that were conched with the Stephan mixer, the vacuum duration had a significant (p < 0.05) impact on moisture content and D (v,0.9). Also, an impact of all factors and their interaction on the Casson yield values of the chocolates was observed. However, these factors proved to be less important in dictating the final viscosities of the chocolates. Among others, it is suggested that the influence of the high fat content of the chocolates may have played a more important role. Although all chocolates exhibited less thixotropic behavior, a direct proportional relationship between the particle surface area and thixotropy was observed. Finally, the interaction effect of both factors also significantly (p < 0.05) influenced the color of the chocolates.
Assessing the influence of pod storage on sugar and free amino acid profiles and the implications on some Maillard reaction related flavor volatiles in Forastero cocoa beans
(Elsevier Ltd, 2018) Hinneh, M.; Semanhyia, E.; Van de Walle, D.; De Winne, A.; Tzompa-Sosa, D.A.; Scalone, G.L.L.; De Meulenaer, B.; Messens, K.; Van Durme, J.; Afoakwa, E.O.; De Cooman, L.; Dewettinck, K.
The practice of pod storage (PS) has been applied in many cocoa producing countries, especially by Ghanaian farmers over the years. However, the study of PS has not received much attention, hence, until now, its potential impact on specific flavor precursor development and implications on the flavor of cocoa beans still remains uncovered. The study was therefore aimed at exploring this possibility through physico-chemical and flavor precursor analyses, carried out on equally fermented and dried pod stored (0, 3 and 7 days) Ghanaian cocoa beans. Flavor analysis was also conducted on equally roasted pod stored cocoa beans. Through visual assessment of the pods, pulp and beans, the compelling impact of PS on fermentation index (FI) and nib acidity could be demonstrated by the various biochemical and physical changes such as respiration, moisture reduction, and cellular degradation, occurring during the process. Whereas the entire reaction of sugar degradation may be deemed complex, a clear relationship between the FI, nib acidity and the glucose content was observed. Also, PS was found to increase with marginal increase in total reducing sugars (glucose and fructose). Although the concentration of free amino acids was directly proportional to the duration of PS, within the framework of this study, a significant difference (p <.05) was only observed in the case of extended duration (7 days). Overall, 7 PS seemed to have enhanced the formation of more volatiles. This was followed by 0 PS and finally 3 PS. Suggestively, these findings could provide some indications in explaining the typical flavor profiles of the Ghanaian cocoa beans, considering the fact that 87.8% of Ghanaian farmers adhere to this practice. Meanwhile, for the chocolate industry, the surging demand for cocoa/chocolate products exhibiting unique flavors, could be partly addressed by adopting PS as a tool for varietizing the flavor capacity of “bulk” cocoa through the expression or suppression of specific flavor precursors in the raw material on the farm level, which comes with almost no additional cost. © 2018 Elsevier Ltd
Comparing flavor profiles of dark chocolates refined with melanger and conched with Stephan mixer in various alternative chocolate production techniques
(European Food Research and Technology, 2019-01) Hinneh, M.; Van de Walle, D.; Tzompa-Sosa, D.A.; Haeck, J.; Abotsi, E.E.; De Winne, A.; Messens, K.; Van Durme, J.; Afoakwa, E.O.; De Cooman, L.; Dewettinck, K.
The use of alternative equipment for chocolate production is gaining attention in recent times in many countries. This is due to the lower cost of investment and maintenance, multi-functionality, and lower throughput. This study was conducted to investigate the applicability of two of such equipment; melanger and Stephan mixer. In the first set-up, the possibility of refining chocolate with the melanger in comparison with the conventional 3-roll refiner was explored. Whereas in the second set-up, the applicability of the Stephan mixer (aided with a vacuum pump) for a conching-like application was also investigated. From each set-up, 70% dark chocolates produced through various alternative means were then evaluated on the basis of their flavor profiles. Specific groups of volatiles such as aldehydes, ketones, terpenes and terpenoids, showed significant (p < 0.05) differences due to the different refining techniques applied. However, this effect was not reflected in terms of the overall volatile concentrations of these chocolates. For chocolates which were conched with Stephan mixer, the decreasing effect of vacuum duration and its interaction with dry conching temperature on the total volatile concentration also proved significant (p < 0.05). Finally, an agglomerative hierarchical clustering of all chocolates on the basis of their aroma volatiles revealed three distinct clusters. Nonetheless, a 112—member consumer preference testing showed statistically similar (p > 0.05) preference for these representative chocolates from the clusters. These findings stimulate various practical application possibilities for tuning chocolate flavor through alternative processing for both industries and various artisans worldwide.
Constraints for future cocoa production in Ghana
(Agroforestry Systems, 2018-10) Kongor, J.E.; De Steur, H.; Van de Walle, D.; Gellynck, X.; Afoakwa, E.O.; Boeckx, P.; Dewettinck, K.
To address the growing global demand for cocoa, sustainable intensification of its production in West Africa is considered crucial. This paper analyzes the determinants of cocoa productivity and profitability by smallholder farmers in Ghana to provide insights into challenges for future cocoa farming, which will guide the formulation and prioritization of tailored policies to address them. A four-stage sampling technique was used to select a total of 731 cocoa farmers from various districts in all six cocoa growing regions in Ghana. Selected farmers were interviewed using a semi-structured questionnaire. The results show that cocoa productivity and profitability was very low with an average of 234 kg ha−1 and Gh¢ 568 (ca. US$ 150) per ha, respectively. Farm management practices, namely control of capsid and black pod disease, fertilizer application and pruning, significantly (p < 0.05) influenced cocoa productivity. Capsid control and fertilizer application showed the highest impact on productivity. Farm size, however, had a negative impact, which implies that increase in farm size results in decreased smallholder cocoa productivity. Farmers should be encouraged to sustainably intensify farm management through controlling black pod disease and capsids, regular pruning and efficient application of fertilizer rather than focusing on excessive land expansion, which eventually hampers productivity and biodiversity. © 2017, Springer Science+Business Media Dordrecht.
Pod storage with roasting: A tool to diversifying the flavor profiles of dark chocolates produced from ‘bulk’ cocoa beans? (part I: aroma profiling of chocolates)
(Food Research International, 2019-05) Hinneh, M.; Abotsi, E.E.; Van de Walle, D.; Tzompa-Sosa, D.A.; De Winne, A.; Simonis, J.; Messens, K.; Van Durme, J.; Afoakwa, E.O.; De Cooman, L.; Dewettinck, K.
The impact of pod storage (PS) and roasting temperature (RT) on the aroma profiles of dark chocolates were evaluated. Cocoa liquor samples comprised of ten different combinations of PS and RT, whilst keeping the roasting time fixed at 35 min. Additionally, commercial cocoa liquors from renowned origins (Ecuador, Madagascar, Venezuela, Vietnam, Ivory Coast and Ghana) were acquired for comparison. From these, 70% dark chocolates were produced under the same conditions after which they were subjected to headspace solid-phase microextraction-gas chromatography–mass spectrometry (HS-SPME-GC–MS) analysis. Although both PS and RT were found to influence the aroma volatile concentrations, the impact of RT over PS seemed to be greater. An agglomerative hierarchical clustering (AHC) of all chocolates on the basis of their aroma profiles revealed a similar impact as earlier observed, where major clustering of the chocolates was in accordance with the intensity of the roasting process applied. However, within each group, the dissimilarities owing to PS among the chocolates was clearly depicted. Comparatively, chocolates with low (100–120 °C), instead of moderate to high (135–160 °C) RT's, rather showed a low dissimilarity with those from the commercial cocoa liquors of the different origins. Although from the same beans, the diversity of aroma profiles of these chocolates as well as the similitude of some treatments to some chocolates from commercial grade cocoa liquors, unequivocally underscores the possibility for steering diverse distinct flavors from ‘bulk’ cocoa through PS and roasting, with beneficial implications, both from an application and an economic point of view.
Pod storage with roasting: A tool to diversifying the flavor profiles of dark chocolates produced from ‘bulk’ cocoa beans? (Part II: Quality and sensory profiling of chocolates)
(Food Research International, 2020-02-20) Hinneh, M.; Abotsi, E.E.; Van de Walle, D.; Tzompa-Sosa, D.A.; De Winne, A.; Simonis, J.; Messens, K.; Durme, J.V.; Afoakwa, E.O.; De Cooman, L.; Dewettinck, K.
The impact of pod storage (PS) and roasting temperature (RT) on the quality parameters and the sensory profiles of dark chocolates were evaluated. Dark chocolates (70%) from ten liquors of different PS and RT combinations as well as six liquors of different origins (Ecuador, Ghana, Ivory Coast, Madagascar, Venezuela and Vietnam) with variable genetic groups were produced under identical conditions and compared. To a greater extent, the range of chocolate quality attributes underscored the generally minimal effects of PS, RT and origin of liquor on the processing conditions. Although with a few exceptions, generally, chocolate acidity (pH and TA) decreased with increasing PS and vice versa in the case of RT. Furthermore, results from a balanced incomplete block design (BIBD) involving a 16-member expert panel also revealed the impact of the applied treatments (PS and RT) on the final flavor profiles of the chocolates irrespective of the origin or genetic groups of the cocoa beans. The same was confirmed when instrumental aroma results were correlated with the sensory data using partial least squares (PLS) regression models. Thus, this study demonstrates the possibility of creating diverse flavor profiles (even towards ‘fine’ flavor) from ‘bulk’ cocoa beans through an optimized combination of PS and RT. The findings are therefore expected to challenge the status-quo, especially in the way ‘bulk’ cocoa is currently processed and consequently priced, thereby, possibly fostering a win-win situation between cocoa producers and industries.
Tuning the aroma profiles of FORASTERO cocoa liquors by varying pod storage and bean roasting temperature
(Food Research International, 2019) Hinneh, M.; Van de Walle, D.; Tzompa-Sosa, D.A.; De Winne, A.; Termote, S.; Messens, K.; Van Durme, J.; Afoakwa, E.O.; De Cooman, L.; Dewettinck, K.
The unique impact of roasting conditions on the aroma quality of cocoa beans has been demonstrated in many studies. However, information on the additional impact of pod storage (PS) and its combined effect with roasting temperature (RT) is unknown. Hence, this study sought to elucidate the collective contribution of these post-harvest/process parameters on the aroma profiles of cocoa liquors produced from Forastero cocoa beans. The beans had been subjected to different treatments following a 3 × 4 full factorial experiment, consisting of PS (0, 3, 7 days) and RT (100, 120, 140, 160 °C). Statistical analysis of the results from HS-SPME-GC–MS revealed significant (p < .05) impact of both PS and RT as well as their interaction effects on the ten groups of volatiles (acids, alcohols, esters, terpenes, aldehydes, ketones, pyrazines, furans, pyrroles and others) and their overall aroma concentration. An exception was however noted for aldehydes, where the total concentration was only significantly (p < .05) influenced by the individual effects of PS and RT. A subsequent clustering of the liquors, first on the basis of all identified volatiles, then, on the basis of the odor-active volatiles, also revealed similar pattern where liquors with high RT's possessed more volatiles with higher concentrations and vice versa. More so, it seemed that no or very minimal PS treatment was necessary for preserving more aromatic volatiles with typically fruity, floral or spicy flavor notes, whereas, for liquors with volatiles exhibiting more cocoa, chocolate, nutty and roasted flavor notes, prolonged PS (> 3 days) treatment was required. These findings are expected to challenge the status-quo, specifically in the conventional ways through which the aroma potential of ‘bulk’ cocoa may be steered. On the one hand, the idea of manipulating PS treatment and roasting conditions may indeed consolidate the possibility of creating diverse and/or distinct aroma profiles from the same ‘bulk’ cocoa beans, whereas, on the other hand, it raises the question whether the Ghanaian cocoa beans - being described as ‘bulk’ cocoa - could be a consequence of prolonged pod storage treatment. © 2019 Elsevier Ltd