Various sized Box and heap fermentations and solar dryer trial pdf

1 CARD 013VIE/05 FERMENTATION AND DRYING TRIAL Can Tho University, 18-23/4/06 Trial Title: Various sized Box and heap fermentations and solar dryer trial Introduction Prior to this trial, fermentation boxes, of varying sizes and a solar drier were constructed at Can Tho University. Fermentations, as described in the materials and methods, were conducted and the drier tested under the prevailing weather conditions in Can Tho. The main aim of the trials was to acquaint CTU staff with the methods employed in conducting fermentation and drying trials as well as dry bean analysis and to note whether fermentation parameters were comparable to those encountered in other countries. Materials and methods In Can Tho Province, there is only one substantial cocoa farmer and he does not grow enough cocoa for CTU to be able to purchase sufficient beans to conduct this trial. Beans were therefore purchased from Ben Tre province as described. Pods were weighed prior to breaking and wet beans recovered weighed post pod breaking. With this first fermentation and drying trial conducted at CTU, during April 2006, an attempt was made to conduct experimentation on a number of fermentation parameters during the one trial. These factors included: • Size and surface to volume ratio (SVR) of fermenting mass: Surface to volume ratio is important in that it affects the rate of air penetration into a fermenting mass. It’s affected by factors such as the mass of beans and shape of the fermenting mass This was attempted using the following treatments: Treatment 1 (T1): Box fermentation of 100kg wet bean. SVR was 12.86 sq M / cu M of beans. Treatment 2 (T2): Box fermentation 50kg wet beans. SVR was 16.6 sq M/ cu M wet beans. Treatment 3 (T3): Box fermentation 25kg wet beans SVR was 20.56 sq M / cu M wet beans. Treatment 3a (T3a): Replication of T3 Treatment 4 (T4): Box fermentation of 10kg wet beans. SVR was 30 sq M / cu M wet beans. Treatment 5 (T5): Conical heaped shaped fermentation of 25kg wet beans laid on floor lined with banana leaves and sides covered with banana leaves. SVR was 33 sq M / cu M wet beans. This method is typically employed in West African cocoa fermentations. All box fermentations were lined with banana leaves to standardise this aspect. • Length of pod storage: The beans obtained were from three different farmers in one village in Ben Tre province. The local practice is to harvest pods and store them until sufficient pods have been collected, over successive harvest, to conduct a fermentation. Fresh beans, in sufficient quantities, could not be obtained. The length of pod storage varied from one farmer to the next but an estimate of an average of seven days pod storage was made. Because of the difficulty of obtaining fresh pods in Ben Tre, it was decided to transfer future pod storage trials to WASI. • Aeration / Turning regime. Each treatment had a turning regime of one turn on the second day of a fermentation, thereby standardizing this parameter. All boxes and the heap fermentation were covered, bottom, sides and top, with banana leaves thereby standardizing this factor. The main variable in aeration was therefore the surface to volume ratio which is a function of size and shape of the fermenting mass. • Length of fermentation time: This parameter was varied by taking sub-samples for drying on days 5 and 6. A sample fermented for 5 days before solar drying would be labelled Sun Dried Fermented (SDF5). As they were all placed on the one dryer, their drying time was standardized. These fermentation treatments x length of fermentation time then led to the production of 10 dried bean samples, e.g. T1SDF5, T1SDF6 and so on from the 5 fermentation treatments. 2 Illustration 1: Box fermentation at Can Tho. Temperatures were measured simply by taking a reading with a thermometer from the center of the mass on a once daily basis. Physical and chemical analyses of samples taken during fermentations were conducted as per the project laboratory manual. Results and Discussion The first thing noted during this initial trial was that fermentations failed to take off in all treatments except treatment 5 (heap fermentation). This was an extremely unusual occurrence and may be due to the fact that these were the first fermentations conducted at Can Tho University. It is considered that, because the beans were broken on a large concreted area, there was probably an absence of fruit flies which are the usual major source of inoculum. The second major source of an inoculum is usually the bottom and sides of boxes, from previous fermentations. As these boxes were new, an accumulation of microbial flora, from previous fermentations would not be present. Because of this problem, only results from treatment 5 are presented and discussed in detail. Temperatures of fermentations Temperature of Fermentations 30 32 34 36 38 40 42 44 46 0123456 Day of Fermentation Temperature o C T1 T2 T3a T3b T4 T5 Figure 1: Temperature profiles during fermentation Figure one demonstrates that a satisfactory elevation in temperature only occurred with treatment 5. The next highest was T1 which reached 39 o C and this is not considered sufficient for proper flavour development. A reason that the heap fermentation proceeded satisfactorily is that inoculum may have been obtained from the 3 banana leaves used to line the bottom and sides of the fermenting mass. Also, with the highest surface to volume ratio of all treatments, this may have increased aeration and therefore, accelerated the fermentation. Titrable acidity of whole beans during fermentations. TA Whole beans 0 0.5 1 1.5 2 2.5 3 3.5 4 0123456 Day of fermentation TA (mls 0.1N NaOH/g T1 T2 T3a T3b T4 T5 Figure 2: Titrable acidity of whole beans during fermentation Figure 2 demonstrates again that only treatment 5 fermented properly. Titrable acidity (TA) tends to climb during a fermentation due to the production of acetic and lactic acids by bacterial species. This has only happened in this treatment. For this reason and the temperature profiles, treatment 5 is therefore the only fermentation which will be discussed in detail further on. pH bean component Treatment 5 3 3.5 4 4.5 5 5.5 6 6.5 7 0123456 Day of fermentation pH Whole bean Kernel Pulp Figure 3: pH of bean components of T5 during fermentation Figure 3 demonstrates the pH of bean components during the treatment 5 fermentation. Results are similar to the averages of 10 commercial fermentations in Papua New Guinea (Figure 4). This indicates that the method of not using fermenting boxes, but rather simple heap fermentations is a viable option for farmers in Vietnam. It not only makes the fermentation simpler to conduct but also negates the need for expenditure on fermentation boxes. 4 pH of bean componnets in typical PNG fermentation 3 3.5 4 4.5 5 5.5 6 6.5 0123456 Day of Fermentation pH Whole beans Kernel Pulp Figure 4. Typical pH values (Average of 10 ferments) of bean components during fermentations in PNG TA bean components in T5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 0123456 Day of fermentation Titrable acidity 0.1N NaOH/g Whole bean Kernel Pulp Figure 5: Titrable acidity levels in bean components during fermentation of treatment 5 5 TA bean components in PNG fermentations 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 0123456 Day of fermentation Titrable acidity 0.1N NaOH/g Whole bean Kernel Pulp Figure 6: Typical Titrable Acidity of bean components during fermentations (Average of 10) in Papua New Guinea Figure 5 shows the titrable acidity levels of the various bean components during the treatment 5 fermentation. Again values are similar to those of the averages of 10 commercial fermentations in Papua New Guinea (PNG) shown in figure 6. This again indicates the viability of fermentations of this type in Vietnam. First Drying Trial (D1) at Can Tho University (CTU) Introduction A 3M x 3M drying bed sized dryer was constructed at Can Tho University (CTU) during the first visit of the Australian counterpart in April 2006. The drying trial was conducted in tandem with the fermentation trial (F1) and is therefore presented in this single document. As previously stated, For any given product, drying rate is going to be influenced by a combination of weather and dryer design based factors including; temperature, relative humidity/ rainfall, wind/air velocity, exposure of product surface and solar radiation. The dryer design is intended to enhance all of the above factors during its operation. Materials and methods Beans were taken from day 5 and day 6 of the fermentation and placed in separate heaps (approx 2 kg wet bean each) on the dryer. At the end of the fermentation i.e. 6 days all of the fermenting boxes contents were mixed and placed on the dryer to note the rate of drying of a larger mass of cocoa. The mass of this bulked sample was 220kg wet beans. Temperature and relative humidity levels, both ambient and within the dryer, were taken using a data logger purchased for the project. Individual samples, from the dryer, were taken from each fermentation treatment sample and the bulk mixture on a daily basis. Tests of moisture pH, titrable acidity (TA) were conducted on these samples as per standard methods of the laboratory manual. 6 Illustration 2: Large scale solar drier (3M x 3M drying bed) at Can Tho University. Results and Discussion Rates of drying and changes in moisture, pH and TA are presented in the following figures 7, 9 & 10. The conditions inside the dryer compared to ambient are presented in figure 8. Moisture % of T5SDF6 & Bulk sample 0 10 20 30 40 50 60 01234 Day of drying % moisture whole beans T5 SDF6 Bulk Sample 220kg Figure 7. Drying rate of cocoa in the solar dryer The results presented in figure 7 indicate a rapid rate of drying, with levels of 6-7% moisture being obtained by day 4. The treatment 5 sample was approximately 2kg. The bulked sample of 220kg, as could be expected, dried more slowly but was still commercially dry by day 4. These drying rates compare favourably with standard practices which can take 10-12 days to achiever 7-8% moisture. The weather during this drying period was fairly dry, with little rainfall. Results are therefore not indicative of what drying rates would be like in an extended wet period. 7 Temp. & RH in Drier & Ambient 0 20 40 60 80 100 120 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 Time of Day Temp oC & RH% Temp in Drier RH in Drier Temp ambient RH ambient Figure 8. Conditions of temperature and relative humidity in dryer compared to ambient. Figure 8 demonstrates the much higher temperatures within the dryer compared to ambient. Temperatures of over 60 o C on the drying bed were obtained between 11AM and 1PM. During the night, temperatures were always well above ambient and this is important as beans can re-hydrate if temperatures are not kept elevated. Similarly Relative humidity (RH) levels are much lower inside the dryer than at ambient and this will also result in an improved drying rate. pH of cocoa during drying 4 4.2 4.4 4.6 4.8 5 5.2 5.4 5.6 012345 Day of Drying pH whole beans T5 SDF5 T5 SDF6 Figure 9: pH of treatment 5 cocoa samples, taken on days 5 & 6 of fermentation, during drying 8 Titrable Acidity during drying 1.5 2 2.5 3 3.5 4 012345 Day of Drying Titrable acidity (mls 0.1N NaOH/g T5 SDF5 T5 SDF6 Figure 10: Titrable acidity of treatment 5 cocoa samples, taken on days 5 & 6 of fermentation, during drying pH and TA levels are presented in figures 9 and 10. Both pH and TA do play a role in flavour, with high chocolate notes usually being associated with a low acid cocoa. T5 is the only fermentation which proceeded properly so only its values should be considered. T5 SDF5 had a pH value of 5.48 and SDF6, 5.01 at the end of drying and this indicates cocoa with similar pH values to West African cocoa which usually has a pH of 5.0- 5.2. Most Pacific and SEA cocoas have pH values around 4.6-4.8 and are regarded as too acidic to be a substitute for West African cocoas. Cocoa Sample pH Acetic % Lactic % Citric% Oxalic% F1T5SDF5 5.48 NA NA NA NA F1T5SDF6 5.0 NA NA NA NA Ghana 5.35 0.27 0.060 0.64 0.60 Malaysian 4.48 0.72 0.420 0.59 0.42 Can Tho (Mr. Vinh) 4.97 0.40 0.127 0.45 0.45 Ben Tre (Mrs. Suong) 5.08 0.28 0.394 0.48 0.39 WASI (VDL03) NA 0.34 0.352 0.60 0.61 WASI (VDL05) NA 0.52 0.128 0.61 0.63 Table 1. pH and organic acid levels of cocoa from the fermentation trial compared to some commercial Vietnamese samples and Ghana and Malaysian samples. * NA not available Table 1 results indicate that the samples of commercial Vietnamese cocoa are intermediate between Ghana and Malaysian cocoas as far as acidity and organic acid levels are concerned. The fermentation trial T5 samples were quite similar to Ghana cocoa. Fermentation for 5 days (T5SDF5) was less acidic than 6 day fermented cocoa (T5SDF6). The organic acids were not performed on the fermentation trial samples as the training at QDPI&F occurred later in August 2006. Summary This initial trial had the aims of: (1) establishing minimum sizes of fermentation e.g. 10kg box, (2) the suitability of heap fermentations, (3) an effect of length of fermentation time i.e. 5 as opposed to 6 day fermentations and (4) the efficiency of the solar dryer. 9 Because fermentations did not proceed properly, apart from treatment 5, no conclusion could be drawn regarding fermentation of 10kg quantities. The heap fermentation, covered with banana leaves, did proceed correctly and indicates this type of fermentation can be recommended. This is the standard type of fermentation conducted in West African countries. The Australian counterpart had noted in previous work in PNG, that a 25kg heap fermentation was the best fermentation method tested in that country for producing a West African type cocoa. This recommendation will be made in extension materials to be produced. The pH values obtained in T5 dry beans was very similar to the West African standard. A heap fermentation also has the advantage that there are no costs involved for box construction. Results obtained indicated the high efficiency of the solar dryer design. However it is noted that this trial was conducted in weather conditions which were dry. Results for the dryer in wetter conditions will be presented in further reports of trials conducted at Can Tho University. 1 Second Fermentation (F2) and Drying Trial at Can Tho University May-June 2006: Introduction: After the first fermentation trial, in which fermentations did not proceed properly in 4 of the 5 treatments, it was decided to repeat some of the fermentations in the hope of obtaining better fermentations and to establish whether the 10kg box fermentations could be successfully conducted in Vietnam. Two replicates each of T2 (50kg box) and T4 (10Kg box) were conducted at CTU in May-June 2006. Fermentations did proceed better than the first attempt but temperatures of both treatments did not reach a satisfactory level. Treatments were named as they were in the first trial and identified as replicates of those treatments. With drying of the cocoa, a second dryer of 2M x 2M drying bed dimensions was constructed. This is the size that would approximate that recommended for smallholder farmers. Samples were taken at the end of a six day fermentation period for each treatment and divided into samples for drying on the large scale and small-scale dryers. Materials and methods Beans were purchased from Ben Tre province as described. Pods were weighed prior to breaking and wet beans recovered weighed post pod breaking. This gave a wet bean / pod recovery rate, an important factor in commercial considerations. Temperatures were measured simply by taking a reading with a thermometer from the center of the mass on a once daily basis. Physical and chemical analyses of samples taken during fermentations were conducted as per the project laboratory manual. Results and Discussion Fermentations: Temperature of Fermentation 25 27 29 31 33 35 37 39 41 43 45 0123456 Day of fermentation Temperature o C F2T2R2 F2T2R3 F2T4R2 F2T4R3 Figure 1: Temperature profiles during fermentation Figure one demonstrates that satisfactory elevations in temperature still did not occur, although temperatures reached were higher than in the first fermentation trial (F1). This is possibly due to inoculum on the sides of boxes being left over from the first fermentation trial. The highest temperature reached was 43 o C in treatment [...]... kg box fermentation was a suitable option for Vietnamese farmers with only a few trees and testing the efficiency of a small-scale dryer for extension purposes Due to a lack of proper progression of the fermentations, no conclusion could be drawn regarding 10kg box fermentations The trial did however demonstrate similar efficiencies of the 9sqM and 4sqM bed sized dryers 5 Third Fermentation (F3) and. .. Materials and methods Beans were purchased from Ben Tre province as described in previous trials Results and Discussion The effect of heaping beans overnight on drying rates: A 100kg fermentation was conducted and samples taken for drying on days 3, 4 and 5 of the fermentation Samples taken for drying were then divided in two, with one being left continually spread on the dryer and the other heaped overnight,... Fermentation (F4) and Drying Trial at Can Tho University, April 2007: Introduction: In the previous fermentation and drying trial (F3), little difference was noted in the drying times of beans heaped overnight (H) and those left flat (F) on the drier However this trial was conducted during wet weather and the drying times for both treatments were seven days It was therefore decided to repeat the trial in drier... values and the reason for this is not immediately apparent Titrable acidity levels tended to increase with drying time and this could be assumed to be caused by a concentration of the nonvolatile lactic and citric acids in beans during moisture loss 5 Effect of fermentation time and heaping of beans during drying on dry bean characteristics Table 1 Effect of length of fermentation time and heaping... in the first trial The first 50kg box fermentation showed the highest levels of titrable acidity as it did with temperature profiles Although there was an improvement in fermentation parameters over the first trial conducted at CTU, three of the four fermentations did not reach satisfactory temperature levels and the fermentations are not discussed in any further detail Second Drying Trial (D2) at... Materials and methods Pods were purchased from Ben Tre province and transported to Can Tho University as described in previous trials Due to problems with fermentations proceeding properly, as noted in the first three trials, temperature was the only parameter measured during the fermentation Results and Discussion A 50kg box fermentation was conducted and samples taken for drying, by the four treatments given,... rate of moisture loss and there is a need to try the heaping procedure during the day, when drying rates are maximal Effect of heaping beans on drier on and washing on Kernel/Pulp Ratio 6.5 6 Kernel/Pulp Ratio 5.5 5 UH 4.5 UF WH 4 WF 3.5 3 2.5 2 0 1 2 3 4 5 6 7 Days of Drying Figure 3: Effect of heaping beans overnight and wash procedure on kernel/pulp ratio 2 The practice of heaping beans overnight... Rates of drying and changes in pH and TA are presented in the following figures 4, 5 & 6 Average Moisture % drying beans 70 60 Moisture % 50 50kg Large drier 40 50 kg Small drier 30 10kg Large drier 10kg Small drier 20 10 0 0 1 2 3 4 5 6 Day of drying Figure 4 Drying rate of cocoa in the solar dryer 3 The results presented in figure 4 indicate similar drying rates for the large and smaller dryer The weather... cocoa into the water and therefore a less acidic cocoa It has been reported in trials outside Vietnam that it results in cocoa of higher flavour scores and reduced shell content This led to four treatments being conducted: 1 2 3 4 Unwashed beans, heaped overnight (UH) Unwashed beans left flat on drier (UF) Washed beans heaped overnight (WH) Washed beans left flat on drier (WF) Materials and methods Pods... demonstrate that heaping of beans overnight did not have any effect of slowing down the rate of drying Reasons for this are not immediately apparent but may be due to the fact that the trial was conducted in wet weather For both heaped and un-heaped treatments, the drying time was seven days as opposed to the 45 days encountered earlier in the year It therefore may be necessary to repeat this trial in the . FERMENTATION AND DRYING TRIAL Can Tho University, 18-23/4/06 Trial Title: Various sized Box and heap fermentations and solar dryer trial Introduction Prior to this trial, fermentation boxes,. suitability of heap fermentations, (3) an effect of length of fermentation time i.e. 5 as opposed to 6 day fermentations and (4) the efficiency of the solar dryer. 9 Because fermentations. progression of the fermentations, no conclusion could be drawn regarding 10kg box fermentations. The trial did however demonstrate similar efficiencies of the 9sqM and 4sqM bed sized dryers. 1 Third