Prediction of Tortilla Quality Using Multivariate Modeling of Kernel, Flour and Dough Properties

Advances in high-throughput wheat breeding techniques have resulted in the need for rapid, accurate and cost-effective means to predict tortilla making performance for larger numbers of early generation wheat lines. Currently, the most reliable approach is to process tortillas. This approach is laborious, time consuming, expensive and requires large sample size. This study used a multivariate discriminant analysis to predict tortilla quality using kernel, flour and dough properties. A discriminant rule (suitability = diameter > 165mm + day 16 flexibility score >3.0) was used to classify wheat lines for suitability in making good quality tortillas. One hundred eighty seven hard winter wheat (HWW) varieties from Texas were evaluated for kernel (hardness, diameter, and weight), flour (protein content, fractions and composition), dough (compression force, extensibility and stress relaxation from TA-XT2i) and tortilla properties (diameter, rheology and flexibility). The first three principal components explained 58% of variance. Multivariate normal distribution of the data was determined (Shapiro-Wilk p > 0.05). PCA identified significant correlation between stress relaxation force and rollability. Canonical correlation analysis revealed significant correlation between kernel and tortilla properties (p̂ = 0.75), kernel diameter and weight contributed the highest to this correlation. Flour and tortilla properties were highly correlated (p̂ = 0.74). Glutenin to Gliadin ratio (GGratio), IPP and peak time contributed highest to this correlation and can explain > 60% of variability in tortilla texture (force, distance and work to rupture). The second canonical variate of flour properties is a measure of flour protein content and can explain 26% of the variability in tortilla rollability. Dough and tortilla properties were significantly correlated (p̂ = 0.82, 0.68, 0.54, 0.38 and 0.29). Dough stress relaxation force after 25 seconds is negatively correlated with tortilla diameter (r = - 0.73). Kernel hardness, diameter and weight are the best predictors of tortilla texture after 16 days. Glutenin to gliadin ratio and IPP contributed significantly to tortilla texture. This is the first study to identify the contribution of protein content on tortilla rollability score. Dough extensibility can explain 37% of tortilla rollability. Stress relaxation is the best predictor of tortilla diameter. Tortilla quality variation is attributed to kernel, flour, and dough properties. Logistic regression and stepwise variable selection identified an optimum model comprised of kernel hardness, GGratio, dough extensibility and compression force as the most important variables. Cross-validation indicated 83% prediction efficiency for the model. This emphasizes the feasibility and practicality of the model using variables that are easily and quickly measured. This is the first model that can be used to simultaneously predict both tortilla diameter and rollability. It will be a useful tool for the flat bread wheat breeding programs, wheat millers, tortilla processors and wheat marketers in the United States of America

Effects of Variations in High Molecular Weight Glutenin Allele Composition and Resistant Starch on Wheat Flour Tortilla Quality

Tortilla sales are projected to exceed 9.5 billion by 2014. However, currently no wheat cultivars have been identified that possess the intrinsic quality attributes needed for the production of optimum quality tortillas. Tortillas made with refined wheat flour low in dietary fiber (DF) are popular in the United States due to their sensory properties. This study explored the use of wheat lines (WL) possessing variations in high molecular weight glutenin allele sub-units (HMW-GS) for production of tortillas and also investigated the use of corn based resistant starches (RS), type II (RS2) and wheat based RS type IV (RS4) to increase DF in tortillas. Tortillas were made with 0-15 percent RS and 100 percent whole white wheat (WW). Flour protein profiles, dough, and tortilla properties were evaluated to determine the effects of the allelic variations and RS substitution on tortilla quality. Sensory properties of tortillas with RS were determined. Variations in HMW-GS composition significantly affected the protein quality and tortilla properties. Flour from WL possessing allelic combinations (2*, 17+18, 7, 2+12), (1, 17+18, 5+10), (2*, 17, 2+12) and (1, 2*, 17+18, 2+12) had 12.8-13.3 percent protein. These WL had extensible doughs and produced large diameter tortillas with superior (greater than or equal to 3.0) flexibility after 16 days compared to control. However, WL with (17+18 and 5+10) and (2*, 17+7, 5) produced extensible doughs, large, but less flexible, tortillas compared to control. WL with (2*,17+18,5+10) and (1,2*,7+9,5+10) produced smaller diameter tortillas, but with superior flexibility compared to control. RS2, WW, and cross-linked-pre-gelatinized RS4 (FiberRite) produced hard, less-extensible doughs and thinner tortillas compared to control, due to high water absorption. Cross-linked RS4 (Fibersym) dough and tortillas were comparable to control. 15 percent of RS2 and RS4 increase DF in control to 6 and 14 percent respectively, compare to control (2.8 percent DF). WW tortillas were less acceptable than control in appearance, flavor and texture, while tortillas with 15 percent Fibersym had higher overall acceptability than control. RS2 negatively affected dough machinability and tortilla shelf stability. However, 15 percent RS4 improved the DF in refined flour tortillas to meet FDA's "good source of fiber claim," without negatively affecting dough/tortilla quality

Carbofuran and its toxic metabolites provide forensic evidence for furadan exposure in vultures (Gyps africanus) in Kenya.

Forensic analysis of carbofuran residues in weathered tissue samples for evidence of Furadan exposure in vultures (Gps africanus) by HPLC gave concentration (mg/Kg dry tissue weight) ranges of bdl - 0.07 (carbofuran), bdl - 0.499 (3-ketocarbofuran) and 0.013-0.147 (3-hydroxycarbofuran) in beaks, bdl-0.65 (carbofuran), 0.024-0.190 (3-ketocarbofuran) and 0.017-0.098 (3-hydroxycarbofuran) in feet, 0.179-0.219 (3-ketocarbofuran) and 0.081-0.093 (3-hydroxycarbofuran) in crop content, 0.078-0.082 (3-ketocarbofuran) and 0.091-0.101 (3-hydroxycarbofuran) in muscle of a laced carcass and 0.006-0.014 (carbofuran), 0.590-1.010 (3-ketocarbofuran) and 0.095-0.135 (3-hydroxycarbofuran) in soil sampled from a poisoning site. These compounds were confirmed by GC-MS. The results showed that HPLC combined with GC-MS is suitable for forensic analysis of carbofuran residues in bird tissue samples and that forensic investigation should include its two toxic metabolites, 3-hydroxycarbofuran and 3-ketocarbofuran

Carbofuran use and abuse in Kenya: Residues in soils, plants, water courses and the African white-backed vultures (<em>Gyps africanus</em>) found dead.

The increasing number of incidences of alleged wildlife poisoning with Furadan in Kenya has sparked off a strong lobby fronted by wildlife conservationists against Furadan use in the country and prompted this study. The worst-case scenario was in 2004 in Athi River, where a massive number of 187 African white-backed vultures (Gyps africanus) and hyenas were found dead at a spo where poisoning was suspected to have occurred through a Furadan-laced camel carcass bait. This study was initiated by the Peregrine Fund&mdash;Africa Project, and the objective was to provide evidence for Furadan exposure, its misuse and involvement in vulture poisoning and potential impact on areas near two wildlife conservancies in two most affected districts. The study found evidence for ready availability of Furadan 5G in local veterinary retail shops and its illegal misuse by pastoralists and farmers against wildlife to protect their animals and crops. Analysis of soil, water and plants taken from the farms and water sources by high-perfomance liquid chromatography (HPLC) and gas liquid chromatography&ndash;mass spectrometry (GC&ndash;MS found residues of carbofuran, 3-hydroxycarbofuran and 3-ketocarbofuran, indicating that Furadan was used extensively in farming causing residual environmental distribution and contamination and posing risks to small birds and mammals. Forensic analysis of residues in beaks, feet and crop content of the dead vultures as well as in a laced camel carcass bait and soil samples from one site of poisoning also showed carbofuran and its two metabolites supporting allegations of Furadan involvement in wildlife poisoning and high-mortality cases of African whitebacked vultures (Gyps africanus) in Kenya

Soil and water contamination with carbofuran residues in agricultural farmlands in Kenya following the application of the technical formulation Furadan.

This study was undertaken to determine the concentrations of carbofuran residues in water, soil and plant samples from selected sites in the farmlands in Kenya and to demonstrate the impact of Furadan use on the local environment. Soil, water and plant samples obtained from agricultural farmlands where the technical formulation Furadan has been used extensively showed high environmental contamination with concentrations of carbofuran and its two toxic metabolites 3-hydroxycarbofuran and 3-ketocarbofuran, separately, ranging from 0.010-1.009 mg/kg of dry surface soil, 0.005-0.495 mg/L in water samples from two rivers flowing through the farms and bdl-2.301 mg/L in water samples from ponds and dams located close to the farms. Maize plant samples contained these residues in concentrations ranging from 0.04-1.328 mg/kg of dry plant tissue. The significantly high concentration levels of carbofuran and its metabolites, 3-ketocarbofuran and 3-hydroxycarbofuran, found in various matrices demonstrate that Furadan was used extensively in the two areas and that there was environmental distribution and exposure of residues in water which posed risks when used for domestic purposes or as drinking water for animals in two wildlife conservancies where the dams and ponds are located. Surface soil contamination was also high and posed risks through run-off into the dams and rivers as well as through secondary exposure to small birds and mammals