Teresa Sánchez

Comparison of pasting and gel stabilities of waxy and normal starches from potato, maize, and rice with those of a novel waxy cassava starch under thermal, chemical, and mechanical stress.

Functional properties of normal and waxy starches from maize, rice, potato, and cassava as well as the modified waxy maize starch COLFLO 67 were compared. The main objective of this study is to position the recently discovered spontaneous mutation for amylose-free cassava starch in relation to the other starches with well-known characteristics. Paste clarity, wavelength of maximum absorption (lambda(max)), pasting properties, swelling power, solubility, and dispersed volume fraction measurements and gel stability (acid and alkaline resistance, shear, refrigeration, and freeze/thaw stability) were evaluated in the different types and sources of starch included in this study. lambda(max) in the waxy cassava starch was reduced considerably in comparison with that of normal cassava starch (535 vs 592 nm). RVA peak viscosity of waxy cassava starch was larger than in normal cassava starch (1119 vs 937 cP) and assumed a position intermediate between the waxy potato and maize starches. Acid, alkaline, and shear stability of waxy cassava starch were similar to normal cassava except for alkaline pH, at which it showed a low effect. Gels from normal root and tuber starches after refrigeration and freeze/thaw had lower syneresis than cereal starches. Gels from waxy starches (except for potato) did not present any syneresis after 5 weeks of storage at 4 degrees C. Waxy cassava starch was the only one not showing any syneresis after 5 weeks of storage at -20 degrees C. Natural waxy cassava starch is, therefore, a promising ingredient to formulate refrigerated or frozen food.

Differentiation between Cooking Bananas and Dessert Bananas. 1. Morphological and Compositional Characterization of Cultivated Colombian Musaceae (Musa sp.) in Relation to Consumer Preferences

The morphological, physical, and chemical characteristics of 23 unripe cultivated varieties of Colombian Musaceae were assessed. Fresh pulp dry matter helped to discriminate the following consumption subgroups: FHIA dessert hybrids (hydes: 24.6%) < dessert bananas (des: 29.4%) < nonplantain cooking bananas (cook: 32.0%) < FHIA cooking hybrids (hycook: 34.2%) < plantains (pl: 41.1%). Banana flour starch content on dry basis (db) varied from 74.2 to 88.2% among the varieties, with: pl: 86.5% > cook and hycook: 84% > des: 81.9% > hydes: 79.7% (p <or= 0.01). Flour pH varied in the range 4.8 to 6.2, with the highest pH for the plantain subgroup (5.6), which also had lower titratable acidity than those of the cooking banana and FHIA groups with 7.9, 13.6, and 15.6 mEq H(+)/100 g db, respectively (p <or= 0.05). pl and hycook presented the highest glucose and fructose contents at 0.8% and 1.5% (p <or= 0.05). No significant differences were observed between the groups in proteins (3.2%), total soluble sugars (1.7%), and crude fibers (3%). pl had lower ash, calcium, and magnesium contents (2.7%; 8.4 and 90.7 mg/100 g db) than des (3.2%; 9.3 and 117.9 mg/100 g db) and hydes (3.9%; 23.7 and 125 mg/100 g db) (p <or= 0.05). pl and des had significantly lower peel percentages (38%) than the other subgroups (42-45%). The principal components analysis (PCA) highlights the strong relationship between some of the varietal characteristics and the consumption pattern, which is especially marked for the plantain subgroup in relation to stakeholder and the consumer preferences.

Development of waxy cassava with different biological and physico-chemical characteristics of starches for industrial applications

The quality of cassava starch, an important trait in cassava breeding programs, determines its applications in various industries. For example, development of waxy (having a low level of amylose) cassava is in demand. Amylose is synthesized by granule‐bound starch synthase I (GBSSI) in plants, and therefore, down‐regulation of GBSSI expression in cassava might lead to reduced amylose content. We produced 63 transgenic cassava plant lines that express hair‐pin dsRNAs homologous to the cassava GBSSI conserved region under the control of the vascular‐specific promoter p54/1.0 from cassava (p54/1.0::GBSSI‐RNAi) or cauliflower mosaic virus (CaMV) 35S (35S::GBSSI‐RNAi). After the screening storage roots and starch granules from field‐grown plants with iodine staining, the waxy phenotype was discovered: p54/1.0::GBSSI‐RNAi line A8 and 35S::GBSSI‐RNAi lines B9, B10, and B23. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis showed that there was no detectable GBSSI protein in the starch granules of plants with the waxy phenotype. Further, the amylose content of transgenic starches was significantly reduced (<5%) compared with the level in starch granules from the wild‐type (about 25%). The inner structure of the waxy starch granules differed from that of the untransformed ones, as revealed by transmission electron microscopy analysis as well as morphological changes in the iodine–starch complex. Endothermic enthalpy was reduced in waxy cassava starches, according to differential scanning calorimeter analysis. Except B9, all waxy starches displayed the A‐type X‐ray diffraction pattern. Amylogram patterns of the waxy cassava starches were analyzed using a rapid viscosity analyzer and found to have increased values for clarity, peak viscosity, gel breakdown, and swelling index. Setback, consistency, and solubility were notably reduced. Therefore, waxy cassava with novel starch in its storage roots was produced using the biotechnological approach, promoting its industrial utilization. Biotechnol. Bioeng. 2011; 108:1925–1935.

Prediction of carotenoids, cyanide and dry matter contents in fresh cassava root using NIRS and Hunter color techniques

Efforts are currently underway to improve carotenoids content in cassava roots through conventional breeding as a strategy to reduce vitamin A deficiency. However, only few samples can be quantified each day for total carotenoids (TCC) and β-carotene (TBC) contents, limiting the gains from breeding. A database with >3000 samples was used to evaluate the potential of NIRS and chromameter devices to predict root quality traits. Maximum TTC and TBC were up to 25.5 and 16.6 μg/g (fresh weight basis), respectively. NIRS predictions were highly satisfactory for dry matter content (DMC, R(2): 0.96), TCC (R(2): 0.92) and TBC (R(2): 0.93). NIRS could also distinguish roots with high or low cyanogenic potential (R(2): 0.86). Hunter color parameters could also be used for predictions, but with lower accuracy than NIRS. NIRS or chromameter improve selection protocols, allowing faster gains from breeding. Results also demonstrate that TBC and DMC can be improved simultaneously (required for the adoption of biofortified cassava).

Differentiation between Cooking Bananas and Dessert Bananas. 2. Thermal and Functional Characterization of Cultivated Colombian Musaceae (Musa sp.)

The starch and flour thermal and functional characteristics of 23 cultivated varieties of bananas in Colombia were assessed. Onset temperature for gelatinization of starches measured by differential scanning calorimetry (DSC) varied from 59.7 to 67.8 degrees C, thereby significantly differentiating dessert bananas (63.2 degrees C) from nonplantain cooking bananas (65.7 degrees C) from FHIA hybrids (66.6 degrees C) and plantains (67.1 degrees C). FHIA hybrids are significantly discriminated from dessert banana landraces but not from the cooking group. The starch amylose contents varied from 15.4 to 24.9%; most dessert banana starch amylose contents were below 19%, whereas in cooking banana starches the contents were over 21%. Flour functional properties were assessed by Rapid ViscoAnalyser (RVA) using silver nitrate as alpha-amylase inhibitor. The flour pasting temperature was relevant to differentiate dessert bananas (69.5 degrees C) from FHIA dessert hybrids and nonplantain cooking bananas (72.8 degrees C) from cooking hybrids and plantains (75.8 degrees C). Among other criteria, the cooking ability also helped to differentiate dessert bananas and FHIA hybrids from cooking bananas. A close relation between cultivar genotypes and uses with the thermal and pasting properties were revealed.

Molecular and supra-molecular structure of waxy starches developed from cassava (Manihot esculenta Crantz)

The aim of this work was to characterize the amylopectin of low amylose content cassava starches obtained from transgenesis comparatively with a natural waxy cassava starch (WXN) discovered recently in CIAT (International Center for Tropical Agriculture). Macromolecular features, starch granule morphology, crystallinity and thermal properties of these starches were determined. M¯(w) of amylopectin from the transgenic varieties are lower than WXN. Branched and debranched chain distributions analyses revealed slight differences in the branching degree and structure of these amylopectins, principally on DP 6-9 and DP>37. For the first time, a deep structural characterization of a series of transgenic lines of waxy cassava was carried out and the link between structural features and the mutated gene expression approached. The transgenesis allows to silenced partially or totally the GBSSI, without changing deeply the starch granule ultrastructure and allows to produce clones with similar amylopectin as parental cassava clone.

Combined effect of fermentation, sun-drying and genotype on breadmaking ability of sour cassava starch.

The influence of genotype and post-harvest treatments on expansion ability of sour cassava starch was investigated using 13 cassava genotypes from Colombia. Starches from cassava grown at 1000 m and 1700 m.a.s.l (3 lowland and 10 highland clones respectively) were modified by fermentation (0 or 30 days) and drying (oven or sun) treatments. RVA average peak viscosity decreased regularly from 952 cP in native starch to 699 cP in fermented and sun-dried starch. Granule size analysis revealed that fermentation hydrolysed lowland and highland granules by exocorrosion and endocorrosion respectively. This result was corroborated by significantly higher RVA breakdown and lower intrinsic viscosity in highland clones, reflecting different sensitivity to fermentation. For the first time, amylose contents ranging from 15.7 to 21.7% were correlated with expansion ability (3.0-8.6 mL/g) of sour cassava starch. Therefore the combination of cassava genotypes (mainly amylose content) and post-harvest treatments is key for expansion ability. Supra-molecular granule structure influenced sensitivity to fermentation.

Toward better understanding of postharvest deterioration: biochemical changes in stored cassava (Manihot esculenta Crantz) roots:

Abstract Food losses can occur during production, postharvest, and processing stages in the supply chain. With the onset of worldwide food shortages, interest in reducing postharvest losses in cassava has been increasing. In this research, the main goal was to evaluate biochemical changes and identify the metabolites involved in the deterioration of cassava roots. We found that high levels of ascorbic acid (AsA), polyphenol oxidase (PPO), dry matter, and proteins are correlated with overall lower rates of deterioration. On the other hand, soluble sugars such as glucose and fructose, as well as organic acids, mainly, succinic acid, seem to be upregulated during storage and may play a role in the deterioration of cassava roots. Cultivar Branco (BRA) was most resilient to postharvest physiological deterioration (PPD), while Oriental (ORI) was the most susceptible. Our findings suggest that PPO, AsA, and proteins may play a distinct role in PPD delay.

Evaluation of the Functional Properties of Promising Dioscorea trifida L. Waxy Starches for Food Innovation

Few natural waxy starches are offered to the industry demand. Therefore, the morphological, physical, and chemical characteristics of “Mapuey” waxy starch were assessed. Amylose contents of starches isolated from Dioscorea trifida L. (“Mapuey”) landraces cultivated in the Amazons of Venezuela were lower ( 8.7%). DSC onset gelatinization temperatures varied from 71.1 to 73.2°C. All starches exhibited B-type patterns, with degrees of crystallinity varying from 28% to 33%. The highest crystallinity was found for the starches exhibiting the highest amylose content. At 90°C, solubility and swelling power varied from 2.3 to 4.3% and 20.9 to 32.8%, respectively. Gel clarity was variable from 20.8 to 62.1%. A 5% starch suspension induced a high RVA peak viscosity between 1667 and 2037 cP. This natural waxy yam resource is a promising ingredient for food industry.

LOCAL Regression Algorithm Improves near Infrared Spectroscopy Predictions When the Target Constituent Evolves in Breeding Populations

The CGIAR Harvest Plus Challenge Program began in the mid-2000s to support the genetic improvement of nutritional quality in various crops, including the carotenoids content of cassava roots. Successful conventional breeding requires a large number of segregating progenies. However, only a few samples can be quantified by high performance liquid chromatography each day for total carotenoids (TCC) and β-carotene (TBC) contents, limiting the gains from breeding. This study describes the usefulness of near infrared (NIR) spectroscopy and the efficiency of a large database coupled to a LOCAL regression algorithm to reach accurate TCC/TBC predictions on fresh cassava roots. The cassava database (6026 samples) was built over six years. TCC values ranged from 0.11 μg g−1 to 29.0 μg g−1, whereas TBC ranged from negligible values up to 20.1 μg g−1. All values were measured and expressed on a fresh weight basis. Between 2009 and 2014 increases in TCC and TBC were 86% and 122%, respectively. A comparison of calibrations using partial least squares (PLS) regression and LOCAL regression was done. The standard error of prediction were 1.82 μg g−1 for TCC and 1.28 μg g−1 for TBC using PLS model and 1.38 μg g−1 and 1.02 μg g−1, respectively, using LOCAL regression. The specificity of the data, with increasing content of the constituent of interest year after year, clearly showed the limitation of the classical partial least squares regression approach. The LOCAL regression algorithm takes advantage of large databases; this study highlighted the efficiency of this concept. NIR spectroscopy coupled to LOCAL regression led to efficient models for breeding programmes aiming at increasing carotenoids content in fresh cassava roots. NIR spectroscopy can also be used to predict other important constituents such as dry matter content and cyanogenic glucosides.