Fresh Cassava Roots Research Articles

Production of fungal protein from rasped fresh cassava roots using 200- and 3000-litre fermentors

The results are given of experiments on the nonaseptic, high-temperature production of a fungal biomass from cassava ( Manihot esculenta Crantz). The experiments were conducted at the pilot plant level at CIAT, using the fungus Aspergillus fumigatus I-21A as a second stage in the evaluation of the technology developed and tested previously on a laboratory scale at the University of Guelph. A brief description of the process and a schematic representation of the different steps required at this level are included. The substrate employed was grated fresh cassava roots from several low-cyanide cultivars with a total quantity utilized of approximately 425 kg of cassava per fermentation. The initial concentration of carbohydrates in the culture medium was adjusted to 40 g l −1. The fungus used is characterized by its ability to grow at very low pH (3.5) and reasonably high temperature (45°C), selective growth conditions which appear to obviate the need for sterilization and maintenance of aseptic conditions. The protein yields reported were not as high as obtained in previous small-scale fermentations, with the total crude protein content of the final product averaging < 35% of dry matter. This was partially due to an incomplete utilization of carbohydrates. The quality of the tap water as related to pH of the culture medium might also have had some adverse effect on the growth of the micro-organism. While the protein of the final product was low in sulphur-containing amino acids, particularly methionine, its amino acid profile compared favorably with that of other protein sources. The results obtained to date suggest that single-cell protein (SCP) production from cassava may have potential for practical application in cassava producing areas provided safe operational procedures can be established.

The relationship between methods of making cassava flour and coumarin formation during drying.

The susceptibity of fresh cassava roots to deterioration under tropical conditions has seriously limited its full utilization. The roots are extremely perishable so that a few days after harvest, deterioration may set in, and are consequently rendered unfit for edible purpose1).Several methods have been devised to preserve the roots, but processing into dried cassava chips, or cassava flour is one of the cheapest and most utilized methods of preservation2). Further, it has been noted that cassava flour can be utilized as a good replacement-source for noodle3), bread, cake and some fermented foods4) such as puto. Thus, it has become important to elucidate the factors related to the production of good quality cassava flour. On the other hand, it has been clarified that the bluish fluorescent components, that is, the coumarin derivatives such as scopoletin, esculin and scopolin are formed in cassava tissue, inresponse to artificial or natural injury, or in relation to physiological and microbial deteriorations occurring during storage.5)-8) We assumed that such stress metabolites as the coumarin derivatives might be fbrmed in larger amounts in the cut-injured tissue in the course of drying of thet issue since not only cut-injury but also drying must supply a stress to the living tissue cells, and lesser amounts might be produced when the tissue cells die in a shorter period as in fast drying resulting in cassava flour of better quality. Further, we thought that the TLC assay of the above fluorescent components in cassava flour might be useful to evaluate the food quality of the flour. This paper deals with the relation of various methods of making cassava flour with the intensity of the fluorescent components in the flours.

Storage of Fresh Cassava (Manihot esculenta). II. Simple Storage Techniques

SUMMARYThe development of two simple techniques, box storage and field clamps, which allow curing and storage of fresh cassava roots for 1 and 2 month periods, is described. Consistent and acceptable results have been obtained following storage of roots in boxes packed in moist but not wet sawdust and kept at ambient temperatures. The design of field clamps that maintain internal temperature below 40°C, to allow successful curing and storage, varies in different seasons. Storage life of roots is enhanced by the selection of roots in good condition, and any delay in placing the roots in storage results in poorer out-turns.

Changes in quality of cassava roots during storage

SummaryChanges that occurred during the storage of fresh cassava roots and their effect upon acceptability of the roots both for human consumption as a fresh vegetable and for animal feed purposes are reported. During storage there was a rapid accumulation of total sugars accompanied by a small decline in starch content. In those roots showing internal discolouration and deterioration the percentage of sucrose declined very dramatically. Although roots softened during storage they required a longer cooking time for human consumption. In most cases roots remained of acceptable eating quality over an eight‐week period although none of the stored roots were as good as freshly harvested roots. All stored roots had a sweet flavour and frequently an uneven texture not present in fresh roots. Cassava intake by pigs was lower for stored than for freshly harvested roots: this reduction was more marked for sweet than for bitter varieties which suggests that hydrocyanic acid content is not the only factor limiting consumption, texture and organoleptic changes may also be important. Despite all the changes that occurred during storage the feeding quality of cassava meal in rat feeding trials was not noticeably affected, thus for practical purposes the preparation of cassava meal for diets for domestic animals, notably chicken and pigs, might eliminate the limitations observed in texture and eating quality of stored roots.

Alterações de qualidade da fécula durante o armazenamento das raízes de mandioca

SECCAO DE TECNOLOGIA AGRI­COLA, INSTITUTO AGRONOMICO DE CAMPINAS. SUMMARY Determinations of colour, viscosity, and speed of sedimentation in samples of starch prepared from fresh cassava roots, and also from roots stored during 24, 48, and 72 hours at field condition and also at room temperature were undertaken using several cassava varieties. It has been noted that the stored roots gave progressively worse starch in re­lation to colour and type of sedimentation. Viscosity is also affected, but in a few cases starch quality did not became worse. Changes in starch quality preceded the occurrence of the characteristic blue veins of stored cassava roots. From the observations it is con-clued that storage of cassava roots longer than 24 hours is not advisable.