Dehydration of gluten matrix as a result of dietary fibre addition – A study on model flour with application of FT-IR spectroscopy

Nowadays, consumers demand dietary fibre-enriched products of appropriate taste, texture, smell and appearance. Unfortunately, addition of the dietary fibre supplements to bread significantly reduces its quality which is connected with changes in the structure of gluten proteins. Structural changes as well as changes in the water state of gluten matrix induced by eight dietary fibres were observed by using Fourier transform infrared spectroscopy. To facilitate this the difference spectra were calculated by subtraction of the control (gluten only) infrared spectrum from the spectra of gluten-fibre mixtures. The presence of positive bands at ca. 1597 and 1235 cm⁻¹ indicated aggregation of gluten proteins into hydrogen bonded β-sheets. These β-sheets can be formed by other β-sheets, antiparallel-β-sheets, β-turns and/or α-helices. The aggregation is probably induced by partial dehydration of gluten matrix due to competition for water molecules between gluten proteins and fibre polysaccharides. This assumption is confirmed by the presence of the negative band at 3237 cm⁻¹ and decrease in the intensity of the band at 3051 cm⁻¹. These bands are assigned to the weak and strong H-bonds in the gluten matrix, respectively. The results indicated that both weak and strong H-bonds are necessary to dough formation of adequate rheological properties.     

Assessing the Genetic Diversity in the International Cocoa Genebank,Trinidad (ICG,T) using Isozyme Electrophoresis and RAPD

Random amplified polymorphic DNA (RAPD) and isozyme electrophoresis (IE) techniques were used to estimate the level of genetic diversity in a sample of cacao germplasm existing at the International Cocoa Genebank, Trinidad. Twenty-six cocoa populations represented by 459 cocoa genotypes were analysed using IE and 22 populations represented by 353 cocoa genotypes were analysed using RAPD. Despite few differences in the classification of the populations, both techniques revealed three major groups: the indigenous trees, the cultivated Trinitario and the cultivated trees from Ecuador. Two-thirds of the partitioned diversity were found within populations and one-third between the populations, with both techniques.     

Allelic Size Standards and Reference Genotypes to Unify International Cocoa (Theobroma cacao L.) Microsatellite Data

Standardisation of microsatellite allele profiles between laboratories is of fundamental importance to the transferability of genetic fingerprint data and the identification of clonal individuals held at multiple sites. Here we describe two methods of standardisation applied to the microsatellite fingerprinting of 429 Theobroma cacao L. trees representing 345 accessions held in the worlds largest Cocoa Intermediate Quarantine facility: the use of a partial allelic ladder through the production of 46 cloned and sequenced allelic standards (AJ748464 to AJ48509), and the use of standard genotypes selected to display a diverse allelic range. Until now a lack of accurate and transferable identification information has impeded efforts to genetically improve the cocoa crop. To address this need, a global initiative to fingerprint all international cocoa germplasm collections using a common set of 15 microsatellite markers is in progress. Data reported here have been deposited with the International Cocoa Germplasm Database and form the basis of a searchable resource for clonal identification. To our knowledge, this is the first quarantine facility to be completely genotyped using microsatellite markers for the purpose of quality control and clonal identification. Implications of the results for retrospective tracking of labelling errors are briefly explored.     

Nitrogen Use Efficiency in Cacao Genotypes

Cacao (Theobroma cacao L) is mostly grown on soils with low natural fertility. On such soils nitrogen (N) is one of the most yield limiting nutrients for cacao. Information is lacking on N use efficiency in cacao. A greenhouse experiment was conducted to evaluate growth response and N use efficiency by two cacao genotypes. The genotypes used were TSH-565 and ICS-9 and N rates adapted were 0, 120, 240, 360, and 480 mg N /pot. In both genotypes, increasing levels of applied N improved growth (stem girth, dry weight of shoot and roots and shoot/root ratio), and concentration and uptake of N. Genotypes differed significantly for stem girth and ICS -9 produced greater stem girth compared with TSH-565. Nitrogen uptake had a linear relationship with root dry weight of the two genotypes. In both genotypes, increasing levels of applied N overall increased N-uptake efficiency (NEFF = N concentration in shoot x shoot/root), but decreased N-use efficiency by shoot and roots (NUE = g dry matter of shoot or root/mg N) and N-use efficiency of carbohydrate (NUEC = mg of total carbohydrates in shoot/mg of N in shoot). Both genotypes responded differently to applied N, despite the existence of close genetic relatedness between them. The method used here appears to be suitable method for identification of cacao genotypes that are efficient in uptake and utilization of N.     

施用生物有机肥对可可苗期生长及土壤酶活性的影响

通过温室盆栽试验研究施用不同生物有机肥对可可苗期生长及土壤酶活性的影响.结果表明:施用生物有机肥BIOa和BIOb的处理可可植株干重,总根长、根系直径、根系表面积和根系总体积显著高于对照(单施化肥)及施用牛粪的处理;施用生物有机肥BIOa的处理可可叶片净光合速率、蒸腾速率和叶绿素含量与对照相比分别增加了169％、270％和28％;施用BIOa的处理土壤酸性磷酸酶、脲酶和蔗糖酶活性与对照相比显著提高了98.7％、92.2％和83.2％.综上所述,施用生物有机肥BIO可显著促进可可地上部植株和根系生长,同时也可显著提高相关土壤酶活性.     

The infection process of Moniliophthora perniciosa in cacao

The development of the basidiomycete Moniliophthora perniciosa in resistant and susceptible Theobroma cacao genotypes was analysed. The infection process leading to broom formation in shoot apexes was characterized by studying the kinetics of basidiospore germination, mode of penetration and colonization of the pathogen. Both resistant and susceptible cacao genotypes were inoculated with M. perniciosa and kept in the greenhouse for 90 days, explants were collected, treated for histological studies and meristematic tissues were observed by electron and light microscopy. Variation in the kinetics of germination between the cacao genotypes was detected 4 h after inoculation. The fungal penetration occurred through the star‐shaped trichome base, natural openings on the cuticular surface and stomata. Host responses between genotypes were found to be different. Compared with non‐infected plants, the swelling of all the stem tissues was evident at 60 days after inoculation. In the susceptible genotype, typical symptoms developed and fungal colonization was more intense than in resistant genotypes, which showed little or no fungal colonization. The investigations reported herein provide an important step in understanding the pattern of pre‐ and post‐penetration events of M. perniciosa in cacao genotypes with different levels of resistance to this disease.     

Temporal change in carbon stocks of cocoa–gliricidia agroforests in Central Sulawesi,Indonesia

In a false-time series, the temporal development of cocoa–gliricidia carbon (C) stocks and soil organic carbon (SOC) were investigated in Napu and Palolo Valleys of Central Sulawesi, Indonesia. As a first step, the Functional Branch Analysis (FBA) method was used to develop allometric equations for the above- and below-ground growth of cocoa and gliricidia. FBA resulted in shoot–root ratios of 2.54 and 2.05 for cocoa and gliricidia, respectively. In Napu and Palolo, the trunk diameter and carbon levels per gliricidia tree were always much greater than that of cocoa. The highest aerial carbon levels were attained at year four in Napu (aerial cocoa–gliricidia = 20,745.2 kg C ha⁻¹) and at year five in Palolo (aerial cocoa–gliricidia = 38,857.0 kg C ha⁻¹). After years four or five, however, the reduced stocking density of gliricidia attributed to a loss of aerial C. During the time spans in question, SOC remained fairly stable though slightly decreasing in Napu and slightly increasing in Palolo. The SOC harbored a vastly greater amount of system C (one-half and one-third of SOC in the 0–15 cm stratum in Napu and Palolo, respectively) relative to tree components. Eight years (Napu) or 15 years (Palolo) after conversion of a rainforest to cocoa–gliricidia agroforestry caused an 88% and 87% reduction of aerial C-stocks in Napu and Palolo, respectively.     

Soil quality index for cacao cropping systems

The soil quality index (SQI) for cacao cropping systems was developed to meet the nutritional criteria of the crop, the environmental safety of the cropping sites and the increasing demand for the production and quality of cocoa. Available water function (AWF), root growth function (RGF), mineral nutrition of plants function (MNF) and environmental safety function (ESF) for potentially toxic elements were included in the additive model of SQI for cacao cropping systems. In this study, over 66% of the cacao fields cropping sites were classified as regular SQI with a range of scores between 0.42 and 0.61. The field cropping site with the highest score (0.73) characterized as typic Alitic Red-Yellow Argisol was rated with high SQI. In contrast, the field cropping sites characterized as abrupt Cohesive Dystrophic Red-Yellow Argisol (0.29), typic Dystrophic Haplic Cambisol (0.39), and latosolic Dystrophic Yellow Argisol (0.40) were rated with low SQI. MNF and AWF were the functions that most contributed to the increase or decrease of SQI scores. The SQI adapted expressed the agro-environmental reality of cacao cropping systems of Bahia, Brazil, and this could be a versatile tool to subsidize the adequate soil management of cacao plantations around the world.