Physiological deterioration of cassava roots

Rapid post-harvest physiological deterioration of cassava roots (Manihot esculenta Crantz) appears to be due essentially to wound responses, comparable to those observed in other plant storage organs. The wound responses observed include: increased activity of phenylalanine ammonia lyase, an enzyme associated with phenol biosynthesis; increased activity of peroxidase and polyphenol oxidase; formation of phenols/polyphenols including leucoanthocyanidins, catechins, sco-poletin and condensed tannins, and often the formation of a wound periderm. In cassava, the responses did not remain localised at wound surfaces in roots when held at low storage humidity but spread through the roots causing a discolouration of the vascular tissue and storage parenchyma. Roots stored at high humidity showed a more typical wound response with localised production of phenols and periderm formation.     

Pretreatment of cassava stems and peelings by thermohydrolysis to enhance hydrolysis yield of cellulose in bioethanol production process

The potential of wastes obtained from the cultivation of Manihot esculenta Crantz as raw material for bioethanol production was studied. The objective was to determine the optimal conditions of hemicellulose thermohydrolysis of cassava stems and peelings and evaluate their impact on the enzymatic hydrolysis yield of cellulose. An experimental design was conducted to model the influence of factors on the pentose, reducing sugar and phenolic compound contents. Residues obtained from the optimal pretreatment conditions were hydrolysed with cellulase (filter paper activity 40 FPU/g). The hydrolysates from pretreatment and enzymatic hydrolysis were fermented respectively using Rhyzopus spp. and Sacharomyces cerevisiae. The yield of enzymatic hydrolysis obtained under the optimal conditions were respectively 73.1% and 86.6% for stems and peelings resulting in an increase of 39.84% and 55.40% respectively as compared to the non-treated substrates. The ethanol concentrations obtained after fermentation of enzymatic hydrolysates were 1.3 and 1.2 g/L respectively for the stem and peeling hydrolysates. The pentose and phenolic compound concentrations obtained from the multi-response optimization were 10.2 g/L; 0.8 g/L and 10.1 g/L; 1.3 g/L respectively for stems and peelings. The hydrolysates of stems and peelings under these optimal conditions respectively gave ethanol concentrations of 5.27 g/100 g for cassava stems and 2.6 g/100 g for cassava peelings.     

Characterization and productivity of cassava waste and its use as an energy source

This study sought to quantify and characterize cassava waste as fuel. The wastes from three cultivars were collected to study and were divided into three distinct parts of the cassava plant: seed stem, thick stalks, and thin stalks. Physical and chemical analyzes were carried out to determine the elemental composition of the waste: volatile matter; fixed carbon; ash; moisture; lignin; cellulose; hemicellulose; ash composition and higher heating value were determined. We conducted a thermogravimetric analysis in oxidizing and inert atmospheres to study the behavior of the waste as fuel. The root productivity obtained ranged from 7.7 to 13.0 t ha⁻¹ yr⁻¹ on a dry basis (db), and the ratio between waste and roots varied from 0.36 to 0.91. The physical and chemical properties of cassava waste are analogous to those of woody biomass regarding the elemental composition, the higher heating value, and thermogravimetric analysis. Ash content varied from 2.5% to 3.5%, reaching around 6.0% in samples unwashed. Approximately 60% of the ashes are alkali oxides, especially P₂O₅, K₂O, and CaO, which have low melting points. The alkali index calculated suggests that there is a strong tendency that the combustion process leads to ash fouling and the formation of ash deposits.     

Enzymatic modifications of pea protein and its application in protein-cassava and corn starch gels

The interactions between starch and proteins during processing influence pasting and rheological properties of starch and produce modifications on starch gel structure. Enzymatic modifications have been proposed for overcoming the limitations of using proteins as food ingredients. This work aimed to study the impact of native and enzymatically modified pea proteins on the properties of protein-starch (from cassava or corn) gels. Pea protein isolate (PPI) was incubated with endopeptidase (AL) or microbial transglutaminase (TG). Pasting profile, rheological behaviour and water retention capacity of protein-starch gels were analyzed. Protein (native and enzymatically modified) incorporation increased the viscosity of both corn and cassava starches during gel preparation. However, the hydrolyzed protein reduced drastically the increment of viscosity of protein-starch gels. The addition of PPI led to corn starch network that shifted from an elastic-like nature to a more viscous-like, whereas the opposite effect was observed in cassava gel network. TG- and AL-treated proteins led to a decrease of both G′ and G″ moduli of protein-starch gels, and AL-treated proteins showed the highest decrease on these parameters. Hydrolyzed proteins also favoured the syneresis of the protein-corn starch gel, whereas crosslinked proteins tended to reduce it. Enzymatic modifications of pea proteins affected significantly pasting and rheological properties of protein-starch gels.     

聚硅硫酸铁铝的制备及絮凝法处理酒精废液

以硅酸钠、硫酸亚铁和硫酸铝为原料制备聚硅硫酸铁铝絮凝剂(PSFA)。考察了Al3+/Fe2+、(Al3++ Fe2+)/SiO2、反应温度、反应时间等因素对制备的聚硅硫酸铁铝处理酒精废液的絮凝性能的影响。通过正交实验确定了制备PSFA絮凝剂的最佳反应条件：n(Al3+)/n(Fe2+)＝4/1、n(Al3+ + Fe2+)/n(SiO2)=2/1、反应温度60 ℃、Al3+反应时间1.5 h,Fe2+反应时间1.0 h。通过正交实验确定了最佳絮凝条件：絮凝剂PSFA投加量为5 mL/L水样,水样温度为55 ℃,水样pH=11,该条件下浊度去除率在94％以上。同时,用酚醛泡沫作载体,对固定化聚硅硫酸铁铝絮凝剂进行研究探索。     

修饰预糊化木薯淀粉性能研究

介绍了经化学修饰后再进行预糊化制备得到的修饰预糊化木薯淀粉的性能，并与国产预糊化木薯淀粉和泰国泰花牌预糊化木薯淀粉的性能进行了比较。结果表明：修饰预糊化木薯淀粉的性能达到且超过泰国泰花牌预糊化木薯淀粉的性能，远远优于国产预糊化木薯淀粉。     

Influence of microbiological and chemical quality of traditional starter made from cassava on “attiéké” produced from four cassava varieties

Attiéké is a steamed fermented cassava semolina and food now included in many African countries habits. Non-control of production factors is an important constraint causing manufacturing defaults. Moreover, toxic varieties are used in fermented foods.The aim of this study was to characterize and optimize microbiological, physicochemical and biochemical qualities of attiéké Ebrié. The analyses were performed on traditional inoculum and 4 cassava varieties.The lactic fermentation of cassava dough had positive impact on microbiological and chemical qualities of prepared attiéké that showed slight acidity (pH = 4.6), high starch (80–90 g/l00 g) and low cyanide contents (2.79–5.00 mg/kg). Therefore, sweet varieties are suitable for preparing attiéké.