Starch Retrogradation in Cassava Flour From Cooked Parenchyma

Process-Induced Modifications on Quality Attributes of Cassava (Manihot esculenta Crantz) Flour

Cassava flour (CF) is a suitable representative and one of the easiest shelf-stable food products of the edible portion of the highly perishable cassava root (Manihot esculenta Crantz). The quality and type of CF are dependent on processing variables. Broadly categorized into fermented and unfermented CF, unfermented CF is white, odorless, and bland, while fermented CF has a sour flavor accompanied by its characteristic odor. The use of fermented CF as a composite is limited because of their off-odors. Modifications in CF processing have given rise to prefixes such as: modified, unmodified, gelatinized, fortified, native, roasted, malted, wet, and dry. Consumed alone, mostly in reconstituted dough form with soups, CF may also serve as a composite in the processing of various flour-based food products. Fermenting with microorganisms such as Rhizopus oryzae and Saccharomyces cerevisiae results in a significant increase in the protein content and a decrease in the cyanide content of CF. However, there are concerns regarding its safety for consumption. Pre-gelatinized CF has potential for the textural and structural improvement of bakery products. The average particle size of the CF also influences its functional properties and, subsequently, the quality of its products. Cassava flour is best stored at ambient temperature. Standardizing the processing of CF is a challenge because it is mostly processed in artisanal units. Furthermore, each variety of the root best suits a particular application. Therefore, understanding the influence of processing variables on the characteristics of CF may improve the utilization of CF locally and globally.

Comparing Characteristics of Root, Flour and Starch of Biofortified Yellow-Flesh and White-Flesh Cassava Variants, and Sustainability Considerations: A Review

Cassava is a significant food security and industrial crop, contributing as food, feed and industrial biomass in Africa, Asia and South America. Breeding efforts have led to the development of cassava variants having desirable traits such as increased root, flour, and starch yield, reduced toxicity, reduced pest/disease susceptibility and improved nutrient contents. Prominent among those breeding efforts is the development of colored-flesh cassava variants, especially biofortified yellow-fleshed ones, with increased pro-vitamin A carotenoids, compared to the white-flesh variants. The concept of sustainability in adoption of biofortified yellow-flesh cassava and its products cannot be fully grasped without some detailed information on its properties and how these variants compare to those of the white-flesh cassava. Flour and starch are highly profitable food products derived from cassava. Cassava roots can be visually distinguished based on flesh color and other physical properties, just as their flours and starches can be differentiated by their macro- and micro-properties. The few subtle differences that exist between cassava variants are identified and exploited by consumers and industry. Although white-flesh variants are still widely cultivated, value addition offered by biofortified yellow-flesh variants may strengthen acceptance and widespread cultivation among farmers, and, possibly, cultivation of biofortified yellow-flesh variants may outpace that of white-flesh variants in the future. This review compares properties of cassava root, flour, and starch from white-flesh and biofortified yellow-flesh variants. It also states the factors affecting the chemical, functional, and physicochemical properties; relationships between the physicochemical and functional properties; effects of processing on the nutritional properties; and practical considerations for sustaining adoption of the biofortified yellow-flesh cassava.

Evaluation of black tea polyphenol extract against the retrogradation of starches from various plant sources

The effects of black tea polyphenol extract (BTPE) on the retrogradation of starches from different plant sources were studied using differential scanning calorimetry (DSC) and X-ray diffraction (XRD). DSC analysis shows that the gelatinization temperature of maize starch and starches from different rice varieties increased with increasing BTPE level. After storage at 4 °C, BTPE at a concentration of 15% markedly retarded the retrogradation of maize starch and starches from different rice varieties. Native maize starch and starches from different rice varieties showed typical A-type X-ray diffraction patterns, while native potato starch showed a typical B-type X-ray diffraction pattern. Adding BTPE significantly affected the crystalline region and intensities of X-ray diffraction peaks of maize and rice starch granules. It is concluded that adding BTPE markedly inhibits the retrogradation of maize starch and starches from different rice varieties, but has no significant influence on the gelatinization and retrogradation characteristics of potato starch.

Preparation of chitosan oligomers COS and their effect on the retrogradation of intermediate amylose rice starch

Chitosan oligomers (COS) were obtained by enzymatic hydrolysis and H2O2 oxidative treatment, and then separated into different fractions using ultra-filtration membranes. Each COSM fraction prepared using enzymatic hydrolysis retained its structure, especially the reduced end residue (-NH2 group), and had a peak for molecular weight. On the other hand, each COSH fraction prepared by oxidative treatment had partly damaged -NH2 groups and two peaks for molecular weight. These results indicate that the same COS fractions prepared by the two methods differ in their amino groups and in their molecular weights, though they can both pass through the same size ultra-filtration membrane. The effect of COS on the retrogradation of intermediate amylose rice starch (IA-RS) was also investigated. The 5 k < COSM < 10 k fraction had the best anti-retrogradation ability; the retrogradation ratio of IA-RS with this fraction was reduced by 14.5%, compared to the control, and its relative crystallinity was only 59.69%. 10 k < COSM < 30 k fraction was second best, while the COSM < 5 k fraction had no effect. Therefore, the molecular size of COS determined its anti-retrogradation capability. All COSH fractions from oxidative treatment had no effect on the retrogradation.