Cocoa Yield Research Articles

Production of cocoa butter‐like fat from interesterification of vegetable oils

Cocoa butter‐like fat was prepared from completely hydrogenated cottonseed and olive oils by enzymatic interesterification. The optimum reaction time to produce the major‐component of cocoa butter, 1(3)‐palmitoyl‐3(1)‐stearoyl‐2‐monoolein (POS), was 4 hr. The cocoa butter‐like fat was isolated from the reaction mixture by two filtration steps. The yield of cocoa butter‐like fat was 19%, based on the weight of the original oils. Chromatographic analysis of the product by reversephase high‐performance liquid chromatography (HPLC) has shown it contains triglyceride components similar to those of cocoa butter, but that it has slightly more diglycerides. The melting point of this product, as measured by a differential scanning calorimeter, is 39°C, which compares well to the 36°C melting point of natural cocoa butter.

Effect of cocoa pod borer, Conopomorpha cramerella, on cocoa yield and quality in Sabah, Malaysia

Cocoa pod borer ( Conopomorpha cramerella) is a pest of cocoa in South-East Asia. It first appeared in Sabah, Malaysia, in 1980, but at that time there was no quantitative information on the damage it could cause. This paper describes the derivation of a damage relationship relating yield loss to pest attack level. When < 60% of harvested cocoa pods show internal attack, yield loss is < 5%, but with 90% of pods attacked yield loss is about 40%. When bean extraction from attacked pods is by hand, the major component of yield loss is loss of bean number, rather than reduced size of extracted beans, and the quality of the extracted beans is not impaired. Using scoops to remove beans from damaged pods reduces the overall yield loss, but is likely to result in reduced quality of the dry beans. The damage relationship is used to estimate losses in two commercial fields over a 3-year period (1982–1984). Annual yield losses ranged from 22 to 54%. Losses for the whole estate were estimated from estate records, and for the same years ranged from 42 to 49%.

Effect of Foliar Application of Potassium on Cocoa Yield

SummaryTwo years’ trials were conducted at three places in Western Nigeria to examine the effect of foliar application of potassium during drought on cocoa yield components. Foliar application of potassium chloride to mature Amelonado trees caused apparent increases in wet bean weight, dry bean weight, husk weight and pod weight, but only the effect on dry bean weight at two sites was statistically significant.

Improving Precision of Cocoa Progeny Trials Using Calibrator Trees

SUMMARYIn nine breeding trials with cocoa in Ghana the experimental trees were interplanted with temporary trees of a standard variety as ‘calibrators’. The calibrators were removed after 2–2½ years before there was strong competition with the permanent trees. Trunk diameters of the calibrators were used as covariates in analyses of trunk size and yield of dry cocoa up to 7 years after planting, giving reductions in standard errors of differences between progenies of up to 25% in analyses of size and 15% in analyses of yield.

The effects of cocoa swollen‐shoot virus on the growth and yield of Amelonado and Amazon cocoa (Theobroma cacao) in Ghana

SUMMARYThe virulent strain A of cocoa swollen‐shoot virus (CSSV) severely decreased the growth and yield of Amelonado cocoa (Theobroma cacao) trees kept free of capsids (Distantiella theobroma and Sahlbergella singularis) and the dieback fungus (Calonectria rigidiuscula) in Ghana. Fifteen per cent of graft‐inoculated Amelonado trees showed symptoms within 4 months, and 48, 80 and 100% within 6, 12 and 20 months, respectively. Infected trees, whether shaded or unshaded, began to decline 6 months after infection, and deteriorated rapidly during the next 27 months by which time 16 % had died and most others were moribund; fertilizer applications had no significant effect on the rate at which infected trees deteriorated. Yields of pods and dry cocoa were greatly reduced 2 yr after infection and were very low after 3 yr; yields were significantly reduced by virus infection but there were no significant further effects of applying fertilizer. These results confirm that CSSV strain A alone is very damaging and often eventually lethal to Amelonado trees in Ghana, and indicate that the conflicting results obtained previously in Ghana and Nigeria were probably due to differences in the virulence of the CSSV strains tested.In contrast, the virus had much less effect on cocoa trees of the Amazon type; only 3% of graft‐inoculated Amazon trees showed symptoms within 4 months, and 43, 84 and 97% after 1, 2 and 3 yr, respectively. Slight deterioration of tree canopies was first detected c. 15 months after infection and, although it continued slowly during the next 21 months, the decline was much less severe than that of Amelonado trees. Yields of both unshaded and shaded trees were apparently reduced by virus infection, but yield losses were much smaller than those of Amelonado trees. These results support the present objectives of controlling the spread of CSSV in Ghana by roguing infected trees, and selecting cultivars with greater tolerance to infection for future use.

Effects of Rainfall on Yield of Cocoa in Ghana

SummaryEffects of rainfall on yield of cocoa from a large-scale experiment has been investigated at 10 and 12 sites, over seven years, in the Eastern and Ashanti regions of Ghana. There was a positive association between yield and rainfall at certain times of year, but a negative association at other times. Variation due to the regression of yield on monthly rainfall varied up to 23 per cent, while a maximum variation of 31 per cent accounted for the regression of yield on the total rainfall of February to April in the Eastern region.

Effects of Ground Covers and Fertilizers on Establishment and Yield of Cocoa on Clear-Felled Land in Ghana

SUMMARYAn experiment is described on the establishment of cocoa on clear-felled land, using various ground covers on which 22 NP:KMg factorial treatments were later superimposed. Growth of cocoa was improved in mulched and clean-weeded plots and the unshaded trees began bearing two years after planting, which is exceptionally early for young cocoa in Ghana. In the third year responses to NP fertilizer were obtained and in the following year yields were very high, up to 2170 pounds dry cocoa per acre. This was partly responsible for K deficiency, particularly in plots without mulch and KMg, which led to declining yields especially on the NP plots. Significant increases were thence obtained from the KMg fertilized plots. Mulching at the rates used in this experiment is too expensive and uneconomic, but K fertilizer applied at rates higher than the present rate of 75 lb K2O/acre/annum may be needed on Ghanaian forest soils if they are clear-felled for growing unshaded cocoa.