PhD Thesis

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Subject: search.filters.subject.Cocoa

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    Process optimisation and quality evaluation of cocoa based chocolates
    (Department of Community Science, College of Horticulture,Vellanikkara, 2019) Shahanas, E; Seeja Thomachan Panjikkaran
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    Genetic analysis of inbreds, inbred crosses and hybrids of Cocoa (Theobroma cacao L.)
    (Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara, 2019) Vijayakumar Narayanapur, B; Suma, B
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    Standardisation of technology for value addition of cocoa(theobroma cacao L.)
    (Department of Processing Technology,College of Horticulture, Vellanikkara, 2005) Sunilkumar, K; Pushpalatha, P B
    Cocoa is the sole source for chocolate and its manufacture continued to be the monopoly of multinational companies. Even though, cocoa is mainly grown in small-holder sector, the growers are forced to sell their produce at a price decided by the multinational companies. The growers are facing acute problem due to ineffective procurement system of the companies and the unrealistic price offered by them. In this context, development of viable technologies for small-scale processing and value addition of cocoa will help a long way to safe guard the interest of farmers (Amma et al., 2004). Hence the present study was taken up with the objectives of standardization of primary and secondary processing of cocoa for small scale unit and the development of an Instant Chocolate Beverage Powder (ICBP) and studying its suitability for preparation of value added products. The primary processing technology for cocoa was standardised in terms of fermentation, drying and storage of cured beans. Pod storage for four days was found to produce quality beans during the major (April- May) as well as minor (Sept- Oct.) harvest seasons of cocoa. The application of pectinase (0.01per cent) enhanced the effectiveness of fermentation as reported by Bhumibhamon and Jinda (1997). The quality analysis of sun dried and oven dried beans revealed the superiority of sun dried beans over the other. The most desirable pH (5.82-5.84) of the beans was achieved in sun dried samples. The effectiveness of fermentation and drying as judged by the cut test (Wood and Lass, 1985) revealed the superiority of selected fermentation and drying treatments. Packaging and storing the beans in jute bag with double lining of polythene was found to retain quality of beans to an acceptable level upto ten months during both the seasons. The secondary processing of cocoa (alkalisation, roasting and grinding) was standardised for small scale units. Alkalising the cured beans with one per cent Sodium carbonate for four hours was found beneficial. The chocolate prepared using alkalised beans was ranked superior with respect to pH and sensory attributes. Grading the beans based on size before roasting is to be done to get good quality powder and butter. Large sized beans (1.2 g) gave better quality powder compared to that of small and medium sized beans. The quality of beans roasted in shallow pans was superior compared to that roasted in small scale roaster. The ideal duration for grinding the roasted beans was identified as four to six hours when a table top grinder of two litre capacity (suitable for small scale unit) was used. A value added product viz., ICBP was developed adopting the technology of spray and cabinet drying. The ideal inlet/ outlet temperature for production of quality ICBP was standardized as 190/900 C for spray drying and the feed composition formulated with 14 per cent cocoa, 63 per cent milk solids and 23 per cent additives produced the best quality ICBP. The quality of the spray dried powder was better than that of cabinet dried samples. In addition to the suitability for preparation of beverage, the ICBP was found useful as a base material for preparation of chocolate, shake and pudding.
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    Endophytic microorganism mediated systemic resistance in cocoa against phytophthora palmivora (Butler) Butler.
    (Department of Plant Pathology, College of Horticulture, Vellanikkara, 2011) Sainamole Kurian, P; Koshy, Abraham
    The study on ‘Endophytic microorganism mediated systemic resistance in cocoa against Phytophthora palmivora (Butler) Butler’ was carried out during 2005-2010. The pathogen causing pod rot of cocoa was isolated from infected pods, and its pathogenicity established. Based on cultural and morphological characters, it was identified as Phytophthora palmivora (Butler) Butler. Endophytes were isolated from samples of feeder roots, tender shoots, leaves and pods of cocoa collected from various locations of major cocoa growing areas of the state. The population of endophytic microflora varied among different locations and parts of the plant, and in general, the population was more in roots. Bacteria and fluorescent pseudomonads were more abundant than filamentous fungi and yeasts. Out of the 325 endophytic isolates comprising of 116 bacteria, 153 fluorescent pseudomonads, 34 yeasts and 22 fungi, 82 were found exerting antagonism towards the pathogen. These antagonistic endophytes were further evaluated in in vitro by dual culture and by inoculation on detached cocoa pods, and leaves. It was found that, 25 isolates were more efficient antagonists. These included endophytic isolates of 12 fluorescent pseudomonads, nine bacteria and four fungi. The 25 efficient endophytic antagonists were evaluated for growth promoting ability in cocoa seedlings. It was observed that eight isolates had a profound effect on growth promotion. Hence, these were selected as potential endophytes and were subjected to various tests to study the attributes underlying their antagonistic and growth promoting effects. The potential endophytes consisted of isolates of two bacteria, five fluorescent pseudomonads and one fungus. These eight potential endophytes along with two reference cultures were evaluated in in vitro for various attributes, which underlay their beneficial effects. It was found that, isolates EB-35, EB-40, and EF-81 produced more ammonia. Phosphate soulubilizing ability was maximum for EB-35. The isolates EB-35, EB-40 and EB-65 produced high quantity of IAA. High score for antagonistic index was obtained by EB-31 and EB-35. Vigour index of coca seedlings was also high for EB-31 and EB-35. The plant growth promoting index worked out based on aforementioned attributes was high for five isolates viz., EB-31, EB-35, EB-40, EB-65 and EF-81, which were selected as promising endophytes and were subjected to further studies and in vivo evaluation. The promising endophytes were found to produce volatile and non-volatile inhibitory metabolites against the pathogen. Maximum inhibition through volatile production was with EB-35 and EB-31. While through non-volatiles, the maximum inhibition was by EB-35 and EB-40. Of the four promising bacterial endophytes, three emitted fluorescence under UV light and EB-31 and EB-65 produced more siderophores under iron limiting condition. A pot culture experiment was conducted to study the induction of systemic resistance and suppression of Phytophthora infection in cocoa seedlings by the promising endophytes. Here also, endophytic isolates effected growth promotion in cocoa seedlings and reduction in infection. Induction of systemic resistance was studied by assay of defense related compounds and enzymes. In general, the study revealed more accumulation of phenols and proteins in treated seedlings. Higher activity of PO, PPO, and β-1,3-glucanase was also noticed. Native PAGE analysis revealed six isoforms of PO and seven of PPO. More isoforms were present in endophyte treated plants. Promising endophytes were evaluated for efficiency in reducing Phytophthora pod rot in field in comparison with two reference cultures and chemicals. During the first phase of experiment, viz., after first spraying, maximum reduction in disease was observed in EB-65 and EF-81. Whereas, after second spraying least incidence was in EB-31. After two weeks of third spraying, minimum disease was observed in Pf1 and EB-35. However, the isolate EB-31 was the most efficient one which recorded the least disease incidence during most of the period under observation especially when the disease was at its peak. Based on cultural, morphological and biochemical characters coupled with results of molecular characterization, the promising bacterial endophytes were identified as Pseudomonas putida (EB-31), Bacillus subtilis (EB-35), P. plecoglossicida (EB-40) and P. aeruginosa (EB-65). The isolate EF-81 was identified as Penicillium minioluteum. In the radiotracer experiment, it was found that EB-35 and EB-65 entered the cocoa seedlings when applied on leaves and also inside the pods on application on the intact surface.
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    Genetic analysis of certain clones,hybrids and inbreds in cocoa
    (Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 1998) Rose Mary Francies; Achamma Oommen
    Genetic studies in cocoa (Theobroma cacao L.) using various population viz., clones, biclonal crosses, biclonal pair crosses and inbreds were undertaken in College of Horticulture, Kerala Agricultural University, Thrissur, during 1994-97. The study assessed variability, association of yield attributes and relative importance of these attributes for yield variation using multiple regression and path analysis. Selection indices, inbreeding depression and limits to genetic diversity for heterosis were also worked out. Wide spectrum of variability existed in the populations studied. The highest variability was observed in yield of dry beans/tree and precocity of bearing (pods/tree - 5 years from planting), whereas, traits pod width and bean width showed low variability. Clones GI 10.2, S 27.16, GI 14.17 of Clonal base population, hybrids H'8 (GI 5.9 x GII 23.3), H2 (M 13.12 x GI 5.9) of Series IV biclonal crosses and hybrids H4 (M 16.9 x GII 19:5), H3 (M 16.9 x GII 20.4) of Series 11 biclonal crosses, exhibited superior yield - performance. Yield however, recorded only moderate heritability and therefore moderate expected genetic advance. Strong correlation was observed for yield with pod weight, dry weight/bean and efficiency index but not with precocity of bearing, chlorophyll contents and net photosynthesis rate. Multiple regression and path analysis revealed the importance of dry weight/bean, bean size and efficiency index in determining the yield in cocoa. High correlation exhibited by many traits was due to indirect effects. Selection index for yield, based on the above traits viz., dry weight/bean, bean length, bean thickness and efficiency index recorded a relative efficiency of 150.35 per cent over direct selection. Inbreeding depression was observed for growth traits. The rate of depression was more in the second inbred generation as compared to that in the first inbred generation. Number of hybrids exhibiting relative heterosis in desirable direction ranged from one (eg. pod width, bean length and thickness) to seventeen (number of beans/pod). Considerable genetic divergence among clonal genotypes was evident. Results indicated that the chances for occurrence of a high frequency of heterotic crosses and high values of heterosis are more, when the parental divergence is moderate.
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    Standardisation of in vitro techniques for rooting,hardening and micrografting in cocoa (Theobroma cacao L.)
    (Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 1997) Bindu, M R; Mallika, V K
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    Effect of weather on cocoa and improvement of bean size through seasonal crop orientation
    (Department of Agronomy, College of Horticulture, Vellanikkara, 1997) Prameela, K P; Vikraman Nair, R
    With an objective of understanding the probable reasons for seasonal fluctuations in flowering and fruiting and also to orient the cocoa crop to a season favourable for bean size, a four year investigation was carried out at the College of Horticulture, Vellanikkara during 1993-96. The influence of weather variables on flowering was studied by correlating weekly flower production with weather parameters of previous one to twelve weeks. This was done using plants with and without fruit load. Flower production was also correlated with increase in fruit load of previous one to twelve weeks. The possible effects of soil moisture deficit and surplus on flowering was also studied. The influence of weather on fruiting was studied by correlating monthly pod yield with weather variables of previous one to seven months. The influence of fruit load on fruiting was also studied by correlating monthly pod yield with increase in fruit load of previous one to seven months. For crop orientation study two sets of plants were used, one as control and the other as treatment. The plants used as control were retained as such without disturbing pods. In the other set, defloration was done excepting during the period from April to July. The results revealed that maximum temperature and bright sunshine hours were positively correlated with flower production while rainfall, relative humidity and number of rainy days were negatively' correlated. However, summer rains had positive effect. Fruit load had negative influence on flowering. For pod production the seasonal difference was much pronounced. During monsoon season a comparatively dry condition with high temperature and low relative humidity caused high pod production after five to six months, while in a non-monsoon period production was favoured by high humidity and high rainfall. Pod load affected flower and fruit production adversely. Models were developed to predict flower and fruit production from weather variables and pod load. The crop orientation study showed that the crop could be oriented to the favourable season of October-November without affecting the total annual yield. However, during years of heavy incessant rains the practice may fail.