Developments on the Bioactive Compounds and Food Uses of the Tubers: Colocasia esculenta (L) Schott (Taro) and Xanthosoma sagittifolium (L) Schott (Tannia)

Two varieties of Cocoyam Colocasia esculenta (L) Schott (Taro) and Xanthosoma sagittifolium (L) Schott (Tannia) are experiencing renewed interest not only in Africa but also in the rest of the world. They are considered to be cheaper sources of carbohydrates than cereals or other bulbous crops because of their high calorie yield per hectare, low production costs, and relatively low susceptibility to insect and pest infestation. In addition to their nutritional benefits, they contain bioactive compounds such as polyphenols, proteins, mucilage, polysaccharides, lipids and anti-polyphenol antioxidants. These bioactive compounds have been shown to provide consumers with health benefits such as anti-cancer, anti-inflammatory, antioxidant and dyslipemic properties. Interestingly, you don't need to consume the raw tubers or leaves to get these numerous health benefits, as the different parts of the plants which are nutrient-dense, have been used in various food applications such as flour, chips, poi, syrup, weaning foods for babies, local delicacies, and starch production. These products compete favourably with products from other root and tuber crops. Therefore, this article describes various value-added products made from Cocoyam that can be consumed to reap the numerous health benefits associated with consuming Cocoyam.

​Quality Characters of Tannia [Xanthosoma sagittifolium (L.). Schott] as Affected by Tillage, Planting Methods, Plant Nutrition and Application of Soil Conditioners

Background: Tannia is one of the six most important root and tuber crops grown world-wide. Tannia possess good keeping quality compared to other vegetables. The tubers are considered more nutritious than colocasia and potato. But the crop is still under-exploited compared to other tuber crops. Hence the study was undertaken to identify the effect of tillage and nutrition on quality characters of tannia. Methods: A field experiment was conducted at College of Agriculture, Vellayani, Kerala during 2014-15 to study the effect of organic nutrition on quality characters of tannia. The design used was split plot design with four replications. The treatments consisted of tillage and planting methods as main plot treatments (L1- conventional tillage followed by pit system, L2- conventional tillage followed by mound system, L3- deep tillage followed by pit system and L4- deep tillage followed by mound system). The sub plot treatments were combinations of soil conditioners (S1- control, S2- coir pith, S3- rice husk) and two nutrition systems (N1- integrated nutrient management (INM) and N2- organic nutrition). Result: Results of the experiment revealed that the quality characters of tannia was improved by deep tillage to a depth of 30 cm followed by pit system of planting, application of coir pith as soil conditioner @ 500 g plant-1 and organic nutrition (FYM @37.5 t ha-1 + wood ash @ 2 t ha-1).

Study of the effect of process parameters on the yield of fermentable sugar from red cocoyam (Xanthosoma sagittifolium) peels via acid and enzyme hydrolysis

The aim of this work is to study the acid and enzymatic hydrolysis of cocoyam peels using HCl, H2S04 acids and cellulase enzyme. The cellulase was secreted from Aspergillus Niger (A. niger) fungi. The proximate analysis of the substrate showed that cocoyam peel is a lignocellulosic biomass with a cellulose composition of 48%. The effect of the process parameters (time, temperature, acid concentration and pH) on the yield of glucose in acid and enzymatic hydrolysis of the cocoyam peel was respectively investigated. Maximum glucose yield of 44.5% was obtained after 3 days of enzymatic hydrolysis at 30°C and pH 5. The HCl acid hydrolysis showed a maximum glucose yield of 27.3% at 70°C, 5% HCl after 180 minutes. The glucose yield in H2S04 hydrolysis was relatively lower than that of the HCl with a maximum yield of 26.5% at 70°C, 5% H2SO4 after 180 minutes. In addition to, the functional groups present in the glucose synthesized from cocoyam ground peels and the standard glucose were evaluated using Fourier Transformed Infrared (FTIR). The FTIR results showed similarities in the functional groups present in both sugars. Cocoyam peel can be used for the production of glucose and further fermentative process to produce ethanol.

Complete Chloroplast Genome Sequences of Three Aroideae Species (Araceae): Lights into Selective Pressure, Marker Development and Phylogenetic Relationships

Background : Colocasia gigantea, Caladium bicolor and Xanthosoma sagittifolium are three worldwide famous ornamental and/or vegetable plants in the Araceae family, these species in the subfamily Aroideae are taxonomically perplexing due to shared interspecific morphological traits and variation.Result : This study, for the first time ever, assembled and analyzed complete chloroplast genomes of C. gigantea, C. bicolor and X. sagittifolium with genome sizes of 165,906 bp, 153,149 bp and 165,169 bp in length, respectively. The genomes were composed of conserved quadripartite circular structures with a total of 131 annotated genes, including 8 rRNA, 37 tRNA and 86 protein-coding genes. A comparison within Aroideae showed seven protein-coding genes (accD, ndhF, ndhK, rbcL, rpoC1, rpoC2 and matK) linked to environmental adaptation. Phylogenetic analysis confirmed a close relationship of C. gigantea with C. esculenta and S. colocasiifolia, and the C. bicolor with X. sagittifolium. Furthermore, three DNA barcodes (atpH-atpI + psaC-ndhE, atpH-atpI + trnS-trnG, atpH-atpI + psaC-ndhE + trnS-trnG) harbored highly variable regions to distinguish species in Aroideae subfamily.Conclusion : These results would be beneficial for species identification, phylogenetic relationship, genetic diversity, and potential of germplasm resources in Aroideae.

Physicochemical Characterization of Resistant Starch Type-III (RS3) Obtained by Autoclaving Malanga (Xanthosoma sagittifolium) Flour and Corn Starch

The feasibility of obtaining resistant starch type III (RS3) from malanga flour (Xanthosoma sagittifolium), as an unconventional source of starch, was evaluated using the hydrothermal treatment of autoclaving. The physicochemical characterization of RS3 made from malanga flour was carried out through the evaluation of the chemical composition, color attributes, and thermal properties. In addition, the contents of the total starch, available starch, resistant starch, and retrograded resistant starch were determined by in vitro enzymatic tests. A commercial corn starch sample was used to produce RS3 and utilized to compare all of the analyses. The results showed that native malanga flour behaved differently in most of the evaluations performed, compared to the commercial corn starch. These results could be explained by the presence of minor components that could interfere with the physicochemical and functional properties of the flour; however, the RS3 samples obtained from malanga flour and corn starch were similar in their thermal and morphological features, which may be related to their similarities in the content and molecular weight of amylose, in both of the samples. Furthermore, the yields for obtaining the autoclaved powders from corn starch and malanga flour were similar (≈89%), which showed that the malanga flour is an attractive raw material for obtaining RS3 with adequate yields, to be considered in the subsequent research.

Efeito de sistemas e condições de secagem sobre o consumo específico de energia e os compostos bioativos da taioba (Xanthosoma sagittifolium Schott)

No trabalho de pesquisa laboratorial, com secagem de taioba (Xanthosoma sagittifolium Schott) em diferentes temperaturas, em dois sistemas de secagem, secador convencional com aquecimento resistivo (50, 60, 70 e 80 ºC) e um protótipo de controlador higroscópico baseado em tecnologia de bomba de calor (25, 30, 35 e 40 ºC), foram determinados e avaliados a taxa específica de remoção de água (SMER) e a concentração dos compostos bioativos: compostos fenólicos, vitamina C e clorofila total. O secador com bomba de calor proporcionou menor degradação dos compostos bioativos, principalmente, vitamina C. No secador convencional a menor degradação de vitamina C foi de 80,6% a 60 ºC, enquanto na bomba de calor, a maior degradação foi de 70,3% na temperatura de 40 ºC. A SMER aumentou com a elevação da temperatura de secagem. Os valores da SMER variaram entre 3,465 e 8,551 kg de água/kWh para bomba de calor e, entre 6,221 e 16,956 kg de água/kWh para o secador convencional. A SMER da bomba de calor a 40 ºC foi maior que a SMER do secador convencional operando a 50 ºC.