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    Sensory and affective response to chocolate differing in cocoa content: A TDS and facial electromyography approach.
    (Elsevier B.V., 2023-08-08) Wagner J; Wilkin JD; Szymkowiak A; Grigor J
    Existing research has offered insight into facial activities and their associations with hedonic liking during the consumption of basic food samples and suggests facial changes during consumption are linked to the hedonic evaluation of tastes and, thus related to the taster's perception rather than the tastes themselves. This study tests whether, during the consumption of commercially available dark chocolate, a complex food product, which can be high in bitterness but expectedly so, how facial activities are linked to the bitterness levels and the hedonic liking of the samples. To do this we carried out two studies with untrained consumers, the first of which captured temporally dynamic sensory perception during the consumption of dark chocolate samples of 36% and 85% cocoa content, using the Temporal Dominance of Sensations (TDS) approach. The second study captured facial EMG over the corrugator and zygomaticus muscles during the consumption of dark chocolate samples (36%, 70%, and 85% cocoa). Specifically, the aim of this research was to investigate whether corrugator activity had a greater association with bitterness perception, linked to cocoa, or hedonic evaluation. Capturing the dynamic sensory profile of chocolate samples allowed an investigation into the time points most evident of sensory variation related to the bitterness and sweetness of the taste, allowing insight into whether facial activities also deviated during this time. These data offer evidence to suggest that corrugator was associated with hedonic evaluation during consumption of the samples, with the most liked samples (being those with 70% and 36% cocoa) eliciting similar corrugator activities and less activity than the least liked 85% cocoa content sample; however, there was also evidence to suggest a significant variation in participants' corrugator activity during the period of oral processing when bitterness was most evident in the 85% cocoa sample and sweetness was most evident in the 36% cocoa sample (i.e., the time when bitterness and sweetness were most divergent) Further investigation showed a variation in facial activities elicited during consumption of the 36% cocoa sample based on whether individuals were part of the group who favoured the 85% cocoa sample or the group favouring the 36% cocoa sample. The findings, therefore, suggest facial EMG, specifically over the corrugator, appears to be related to the hedonic evaluation of a complex food product and not the taste itself. Furthermore, being aware of the time points where sensory variations are most apparent between samples can allow for targeted investigation into facial EMG and its ability to distinguish food samples.
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    Genetic studies of Phytophthora on Theobroma cacao from East New Britain and Bougainville (Papua New Guinea) : a thesis presented in partial fulfilment of the requirements for the degree of Master of AgriScience (Horticulture) at Massey University, Palmerston North, New Zealand
    (Massey University, 2016) Butubu, James
    DNA was extracted from 14 Phytophthora isolates from Theobroma cacao plants (SG2 hybrids, hybrid derived clones and Trinitario varieties) collected from New Britain and Bougainville in Papua New Guinea (PNG). A fragment of the mitochondrial genome cytochrome b (cytb) region was amplified from these DNAs using the polymerase chain reaction (PCR) and compared to cytochrome b sequences from Phytophthora palmivora and other Phytophthora (two isolates previously isolated from cocoa lesions and two P. palmivora isolates obtained from culture collection-Australia). All isolates were identical in their cytb gene sequence and similar to P. palmivora. Additionally, we sequenced the mitochondrial genomes of four isolates from PNG. The syntenic arrangement of genes in one complete assembly was compared with other published mitochondrial genomes. The sequences of four mitochondrial genes (COII, nad2, rps10 and SecY) from the four PNG isolates were aligned with orthologues from accessions of P. palmivora and other Phytophthora species available in the NCBI Genbank reference database. A concatenated data matrix was produced with 2,295 homologous sequence positions. 34 accessions of Phytophthora (including 14 P. palmivora) were used to construct a maximum likelihood tree of phylogenetic relationships. This reconstruction recovered all 10 major clades of Phytophthora previously reported. In this phylogenetic reconstruction, the four PNG isolates were clearly identifiable as P. palmivora and these were closely related to the Clade 4 Phytophthora species P. megakarya and P. quercetora. Of the genes analysed, COII showed greatest variability, resolving P. palmivora into three sub groups. COII was sequenced in all P. palmivora isolates from PNG and used to reconstruct an ML tree. The phylogenetic analyses suggested a potential origin for the PNG strain of P. palmivora in Samoa. Syntenic comparisons of P. palmivora and other clade 4 species identified a potential target for developing a Loop Mediated Amplification (LAMP) assay for P. palmivora near the atpH gene region. DNA amplification primers were designed for this region using PrimerExplorer, V4, Eiken Chemical CO.Ltd) and validated against available DNAs for Clade 4 and other Phytophthora species.
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    An agro-economic approach to the optimal allocation of land to rubber, oil palm & cocoa : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Agricultural Economics at Massey University
    (Massey University, 1990) Guha, Amitabha
    This study details the formulation of a dynamic mathematical programming model for obtaining optimal crop-soil allocation plans for perennial crops. The hypothetical model was built to complement soil survey studies in making land-use recommendations for Malaysian plantations. The intertemporal linear programming model was constructed to solve the problem of allocating Rubber, Oil Palm and Cocoa to various soil types encountered in Malaysia over a three year land allocation period in such a manner so as to maximize the present value of annual after-tax net income over the crops optimal rotation age. The framework also treats alternative goals by requiring basic consumption needs be met, and permits borrowings (upto a prespecified limit) and lendings to cover annual negative and positive annual cash balances respectively. Data input-output coefficients used in model formulation reflect the agro-economic environment in which Malaysian plantations today operate. However, commodity prices forecasted by the FAO for the commodities concerned were used in the valuation of planted assets beyond the three year land allocation model horizon. The results obtained on computation provide detailed planting plans with respect to the amount of a particular soil type that should be allocated to a crop and the year in which the planting(s) should be carried out. In addition, the amount of labour, fertilizer and capital goods required in any of the three years within the horizon is generated, as is the amount of crop produced and sold, AIso, annual income and expenses are automatically allocated to the various tax-brackets in such a manner as to minimize cash lost through taxation. By making multiple optimization runs, the sensitivity of the optimal plan to changes in the various parameters was also examined.
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    The impact of smallholder cocoa production on rural livelihoods : case study in the Solomon Islands : a thesis presented in partial fulfilment of the requirements for the degree of Master of AgriScience at Massey University, Palmerston North, New Zealand
    (Massey University, 2013) Hivu, Dorcas Oroi
    Through its working policy, the Solomon Islands government aimed to increase smallholder production of cash crop products, such as cocoa, through which the country not only earned revenue but farmers also earned income. As such, smallholder farmers in the Solomon Islands have been encouraged to venture into cash crop earning activities. In the last decades, donor agencies have been involved a lot with farmers to increase cash crop production. However, rural households depend largely on subsistence activities for their livelihood. Based on the understanding that a lot of assistance has been given to smallholder farmers throughout the country, both by the government and outside aid agencies, this study seeks to investigate the impact of smallholder cash crop production on rural livelihoods. A qualitative case study approach was utilised in this study. Data was collected through semi-structured interviews with farmers. This study used the Sustainable Livelihood Framework as a guide to investigate the livelihoods at household level. The results show that household’s involvement in cash crop production is facilitated by the church with very limited support from the central government. This study provides an empirical example of how a community integrates cash cropping as part of their livelihood through their own initiatives. Factors which enable households to integrate cash crops as a part of their livelihood include: motivation to participate due to community commitment to the church; access to a trusted market; nature of the crop; and labour availability. Cash cropping, as shown in this study, does not undermine or substitute food production since there is abundant land available. Results also show that cash cropping has significantly improved household income and consequently increase household standard of living. This research found that the benefits of cash cropping are distributed across all households within the community as all households grow crops. Households benefit directly from cash cropping through access to cash. Access to cash opens up opportunities for households and/or individuals to venture into other livelihood activities within the community. This study also found that cash cropping has some negative implications. Access to cash through cash cropping results in a change in cultural expectations towards cash; a change in children’s attitude towards education; decreased participation in communal work; and contributes to reduction in the cultivation of traditional crops with cultural importance to the community. This research suggests that institutions through which rural households have access to and/or benefit from cash cropping should be supported by the government.