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Journal of Food Science and Engineering 2013年第5期3卷 235-245页

作者： Emmanuel Ohene Afoakwa john edem kongor Jemmy Felix Takrama Agnes Simpson Budu Henry Mensah-Brown Department of Nutrition and Food Science University of Ghana P.O. Box LG 134 Legon-Accra Ghana Cocoa Research Institute of Ghana P.O. Box 8 New Tafo-Akim Eastern Region Ghana Department of Food Process Engineering University of Ghana LegonoAccra Ghana

Changes in total polyphenols, O-diphenols and anthocyanin concentrations during fermentation and drying of pulp pre-conditioned cocoa （Theobroma cacao） beans were investigated using standard analytical methods. Increasing pod storage, fermentation and drying led to variable reductions in total polyphenols, O-diphenols and anthocyanins content of the beans. The rates of reduction were however more pronounced during fermentation than pod storage and drying. Storage of cocoa pods between 3-7 days with 6 and 7 days of fermentation and drying respectively retained 85%-90% of the total polyphenol and O-diphenols of the cocoa beans. Similarly, anthocyanin content of beans from the 10 days of pod storage decreased by 70% in the sixth day of fermentation. Pod storage decreased the anthocyanin content at all periods of fermentation. These suggest that the post-harvest treatments of pod storage, fermentation and drying all results in variable reductions in polyphenolic content （total polyphenols and O-diphenols） and anthocyanins content of cocoa beans.

关键词： Theobroma cacao pod storage pulp pre-conditioning fermentation drying total polyphenols O-diphenols anthocyanins.

Effects of Fermentation and Drying on the Fermentation Index and Cut Test of Pulp Pre-conditioned Ghanaian Cocoa （Theobroma cacao） Beans

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Journal of Food Science and Engineering 2013年第11期3卷 625-634页

作者： john edem kongor Jemmy Felix Takrama Agnes Simpson Budu Henry Mensah-Brown Emmanuel Ohene Afoakwa Department of Nutrition & Food Science University of Ghana Legon-Accra Ghana Cocoa Research Institute of Ghana New Tafo-Akim Eastern Region Ghana Department of Food Process Engineering University of Ghana Legon-Accra Ghana

Investigations were conducted to establish effects of fermentation and drying on the fermentation index （FI） and cut test of pulp pre-conditioned Ghanaian cocoa beans using a 4 x 3 full factorial experimental design with the principal factors being pod storage （0, 3, 7 and 10 d） and fermentation time （0, 3 and 6 d） to study the changes occurring during the fermentation process. The study also used a 4 x 3 full factorial design with pod storage （0, 3, 7 and 10 d） and drying time （0, 3 and 7 d） being the principal factors investigated to study the changes occurring during the drying process. FI and cut test of the beans were studied during fermentation as well as the drying process. FI of the beans increased significantly with pod storage and fermentation but decreased slightly during drying. FI of the unfermented beans increased slightly from 0.674 for the unstored pods to 0.763 after 10 days of pod storage. The FI of the fermented beans （six days fermentation） also increased from 1.390 for the unstored pods to 1.424 for pods stored for 10 days. It decreased from 1.389 at the start of drying for the unstored pods to 1.105 for pods stored for 10 days at the end of drying （seven days）. FI of all the beans were however, above 1.0 at the end of fermentation and drying for all pod storage treatments. Cut test revealed that storage of pods for 3, 7 and 10 days increased the percentage of brown beans by 66%, 94% and 72%, respectively, by the sixth day of fermentation. Percentage of brown beans decreased to 61%, 76% and 63%, respectively, for pods stored for 3, 7 and 10 d at the end of drying （seven days）. Cocoa pods can be stored for up to 10 days, fermented for six days and dried for seven days with the necessary formation of brown pigments characteristics of well fermented and dried cocoa beans.

关键词： Theobroma cacao pod storage pulp pre-conditioning fermentation drying fermentation index cut test.

The Effect of the Operational Parameters on the Draft Requirement of Ripping in a Sandy Clay Soil

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Open Journal of Optimization 2016年第1期5卷 1-13页

作者： john Ndisya Ayub Gitau Duncan Mbuge Angela Hiuhu Department of Environmental & Biosystems Engineering University of Nairobi Nairobi Kenya

This study set out to investigate the effect of operational parameters (i.e. ripping depth and operational speed) during a ripping operation on the draft requirement during ripping in a sandy-clay soil. Field experiments, laboratory tests and numerical modelling techniques were utilised to observe how the draft force varied with changing values of the operational parameters. The discrete element method in the edem AcademicTM software platform was employed to model the soil en-masse to obtain a virtual experimentation platform on which different treatments combing different settings of the operational parameters were investigated. Statistical methods, including ANOVA, regression analysis and the student t-test were applied to establish the significance of the effect of the operational parameters on the draft requirement;statistical analysis revealed that the draft increased linearly with the ripping depth and operating speed suggesting that they are directly proportional. Lower values of the ripping depth and operating speed were found to give the minimum amount of the draft requirement.

关键词： Draft Requirement Discrete Element Method Numerical Simulation Specific Draft Ripping Depth Operational Speed

Optimization of the Angle of Frog in Mouldboard Tillage Operations in Sandy Clay Soil

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Open Journal of Optimization 2015年第4期4卷 131-140页

作者： Angela Hiuhu Ayub Njoroge Gitau Duncan Onyango Mbuge john Ndisya Mulwa Department of Biosystems Engineering University of Nairobi Nairobi Kenya

This paper investigated the effect of three independent variables including: tillage speed (ranges of below 2.5 m/s and between 2.5 m/s and 5 m/s), tillage depth (range of 10 cm from 0 cm to 30 cm) and frog angle (30° 40°, and 50°) on draught forces. The experimental work was completed with determination of the draught forces using an analytical method (Saunders Equation). Numerical Simulation: Discrete Element Method (DEM) was used to verify the results obtained analytically. The results indicated that tillage depth has a stronger influence on the draught forces as compared to the tillage speed. Minimal draught forces can then be achieved through operating at shallow tillage depth and maintaining a frog angle of 30°. The results showed a variance of ±15.95% to the calculated values supporting DEM as a numerical method capable of predicting draft forces correctly, tillage power optimization and determination of optimal frog angle for the mouldboard plough.

关键词： DEM edem Soil-Cut Interactions Modelling Tillage Draught