Timothy J. Herrman

Microwave plasma-atomic emission spectroscopy as a tool for the determination of copper, iron, manganese and zinc in animal feed and fertilizer.

Quantitative analysis of elements in agricultural products like animal feed and fertilizers by a new instrument using microwave plasma-atomic emission spectroscopy (MP-AES) technology was demonstrated in this work. Hot plate and microwave digestion were used to digest the sample matrices and the consequent digests were subject to atomic absorption spectroscopy (AA), inductive coupled plasma optical emission spectroscopy (ICP-OES) and MP-AES analysis. The detection limit, accuracy and dynamic range for each instrument, were compared and matrix effects were evaluated with respect to the fertilizer and feed materials. The new MP-AES platform can offer comparable or better performance compared to AA and/or ICP-OES with respect to routine analysis for a regulatory program.

Feasibility of surface-enhanced Raman spectroscopy for rapid detection of aflatoxins in maize.

Rapid and sensitive surface-enhanced Raman spectroscopy (SERS) for aflatoxin detection was employed for development of the models to classify and quantify aflatoxin levels in maize at concentrations of 0 to 1,206 μg/kg. Highly effective SERS substrate (Ag nanosphere) was prepared and mixed with a sample extract for SERS measurement. Strong Raman bands associated with aflatoxins and changes in maize kernels induced by aflatoxin contamination were observed in different SERS spectroscopic regions. The k-nearest neighbors (KNN) classification model yielded high classification accuracy and lower prediction error with no misclassification of contaminated samples as aflatoxin negative. The multiple linear regression (MLR) models showed a higher predictive accuracy with stronger correlation coefficients (r = 0.939-0.967) and a higher sensitivity with lower limits of detection (13-36 μg/kg) and quantitation (44-121 μg/kg) over other quantification models. Paired sample t test exhibited no statistically significant difference between the reference values and the predicted values of SERS in most chemometric models. The proposed SERS method would be a more effective and efficient analytical tool with a higher accuracy and lower constraints for aflatoxin analysis in maize compared to other existing spectroscopic methods and conventional Raman spectroscopy.

Effect and interaction of crop management factors on the glycoalkaloid concentration of potato tubers

SummaryPotato tuber glycoalkaloid content was measured in response to nitrogen fertilizer rate, storage temperature, length of storage period and cultivar. Cvs Gemchip, Norchip and Russet Burbank were grown with applied nitrogen fertilizer rates of 0, 168 or 336 kg/ha and then stored at either 4.4 or 10°C. Total glycoalkaloid content was determined one month before harvest, at harvest, after three months of storage and after nine months of storage. Higher rates of nitrogen, higher storage temperature and a period of storage all resulted in significantly (P<0.05) higher concentration of glycoalkaloids. The cv Norchip had higher glycoalkaloids than cvs Gemchip or Russet Burbank. Only the storage period had more influence than the environment (difference between years). Significant (P<0.05) two-way interactions were detected for year x cultivar, year x nitrogen, storage period x cultivar and nitrogen x cultivar. Most interactions were due to the unique responses of cultivars.

Quality response of twelve hard red winter wheat cultivars to foliar disease across four locations in central Kansas

ABSTRACT Twelve hard red winter wheat cultivars were grown at four locations in central Kansas to evaluate the role of foliar fungal diseases on wheat end-use quality in 1995. Disease was allowed to develop naturally on control plots and was controlled partially on plots treated with a systemic fungicide. After harvest, wheat samples were evaluated for the impact of the disease complex (leaf rust, tan spot, speckled leaf blotch) on physical grain quality, grain protein, milling properties, flour absorption, and peak mixing time. Data were analyzed using a mixed model to account for random (location and block) and fixed (cultivar and fungicide) effects. Location significantly influenced quality characteristics except kernel size and peak mixing time. The magnitudes of variation among random effects on all quality characteristics were larger for location than for the interactions between location × cultivar and location × fungicide. The fixed effects portion of the analysis revealed that the cultivar × fung...

CHIPPING PERFORMANCE OF THREE PROCESSING POTATO CULTIVARS DURING LONG-TERM STORAGE AT TWO TEMPERATURE REGIMES

Three potato cultivars (Russet Burbank, Norchip, and Gemchip) grown with nitrogen applied at three rates were stored at two temperature regimes (Treatment 1: 13 months at 10 CTreatment 2: 1 month at 10 C; followed by a 1 C decrease per week until tubers were 4 C; followed by 6 months at 4 C; followed by a 1 C increase per week until tubers were 10 C; followed by 3 months at 10 C). Tuber chemical components and potato chip appearance were measured at harvest and after 3, 6, 9, 11, 12, and 13 months; these measurements were performed within 24 hours of the time potatoes were removed from storage. Sugar responses (tuber glucose, fructose, sucrose) and potato chip appearance were affected by cultivar over time in both years and storage temperatures. Russet Burbank tubers displayed a significantly higher glucose forming potential and produced darker appearing chips, regardless of storage temperature or time in storage, compared to Norchip and Gemchip. Potatoes receiving a cold-storage treatment contained less sugar and produced lighter appearing chips after 12 months storage compared to tubers stored at a constant 10 C for 12 months. The linear association between tuber chemical components and potato chip appearance varied with storage temperature.

An empirical evaluation of three vibrational spectroscopic methods for detection of aflatoxins in maize

Three commercially available vibrational spectroscopic techniques, including Raman, Fourier transform near infrared reflectance (FT-NIR), and Fourier transform infrared (FTIR) were evaluated to help users determine the spectroscopic method best suitable for aflatoxin analysis in maize (Zea mays L.) grain based on their relative efficiency and predictive ability. Spectral differences of Raman and FTIR spectra were more marked and pronounced among aflatoxin contamination groups than those of FT-NIR spectra. From the observations and findings in our current and previous studies, Raman and FTIR spectroscopic methods are superior to FT-NIR method in terms of predictive power and model performance for aflatoxin analysis and they are equally effective and accurate in predicting aflatoxin concentration in maize. The present study is considered as the first attempt to assess how spectroscopic techniques with different physical processes can influence and improve accuracy and reliability for rapid screening of aflatoxin contaminated maize samples.

Segregating Hard Red Winter Wheat into Dough Factor Groups Using Single Kernel Measurements and Whole Grain Protein Analysis

ABSTRACT In accordance with the Grain Quality Acts of 1986 and 1990, scientists at Kansas State University are studying the feasibility of implementing a quality-based marketing system for hard red winter (HRW) wheat in the Southern Plains. This research addresses the development of a segregation system that uses the single kernel characterization system and the whole grain near-infrared analyzer to evaluate the milling and baking quality of wheat as a single value called “dough factor”. This single value represents the amount of flour-water dough that can be produced from a given unit of wheat. Samples of HRW wheat (≈100 per location) were collected at five Kansas country elevators during the 1995 and 1996 harvests. After the dough factor was measured for individual samples, the samples were composited into seven dough factor groups to establish binning and segregation strategies and to explore the relationship between wheat quality measurements and dough factor groups. Results showed that dough factor g...

Determination of aflatoxins in animal feeds by liquid chromatography/tandem mass spectrometry with isotope dilution

The objective of the present study is to develop a simple, fast method for detection of aflatoxins in animal feeds. Simultaneous quantitation of four aflatoxins (AFB(1), AFB(2), AFG(1) and AFG(2)) in animal feeds was achieved in a single liquid chromatography/tandem mass spectrometry (LC/MS/MS) run. The solid-phase extraction cleanup step is eliminated with the stable isotope dilution method. Matrix effects were observed and overcome by isotope dilution. The method was tested in a variety of animal feed matrices and proved to be accurate and reliable. Method ruggedness tests resulted in recoveries of 78% to 122% with an intra-day assay precision of 2% to 15% and an inter-day assay precision of 3% to 17%. These results indicate that this method is suitable for quantitation of aflatoxins in animal feeds.

Evaluation of two liquid chromatography/tandem mass spectrometry platforms for quantification of monensin in animal feed and milk.

Monensin is an anticoccidial drug that has been used as an additive in medicated feed. The United States Food and Drug Administration (USFDA) has included monensin in the national surveillance schemes for residues in foodstuff. In this study, two simple, selective and rapid methods were developed to determine monensin content in animal feed and milk. The methods enabled the detection of monensin residues as low as 1 ppb. Moreover, the two methods were used as models to compare two common liquid chromatography/tandem mass spectrometry (LC/MS/MS) platforms; an LC linear ion trap (LC/LIT) and an LC triple quadrupole (LC/QqQ). The two instrument platforms were evaluated for their matrix effect dependence, precision and accuracy. The LC/QqQ presented a lower limit of detection and limit of quantitation (LOD and LOQ) and showed less matrix dependence as compared to the LC/LIT. The LC/QqQ instrument also demonstrated a better intermediate precision. For example, the intermediate precision standard deviation calculated for 27 analyses across three days was 4% and 11% for LC/QqQ and LC/LIT, respectively. Overall, the LC/QqQ represents a better choice for analysis of monensin with respect to LOD, LOQ, matrix interference and precision.

Machine Vision Detection of Bonemeal in Animal Feed Samples

There is growing public concern about contaminants in food and feed products, and reflection-based machine vision systems can be used to develop automated quality control systems. An important risk factor in animal feed products is the presence of prohibited ruminant-derived bonemeal that may contain the BSE (Bovine Spongiform Encephalopathy) prion. Animal feed products are highly complex in composition and texture (i.e., vegetable products, mineral supplements, fish and chicken meal), and current contaminant detection systems rely heavily on laborintensive microscopy. In this study, we developed a training data set comprising 3.65 million hyperspectral profiles of which 1.15 million were from bonemeal samples, 2.31 million from twelve other feed materials, and 0.19 million denoting light green background (bottom of Petri dishes holding feed materials). Hyperspectral profiles in 150 spectral bands between 419 and 892 nm were analyzed. The classification approach was based on a sequence of linear discriminant analyses (LDA) to gradually improve the classification accuracy of hyperspectral profiles (reduce level of false positives), which had been classified as bonemeal in previous LDAs. That is, all hyperspectral profiles classified as bonemeal in an initial LDA (31% of these were false positives) were used as input data in a second LDA with new discriminant functions. Hyperspectral profiles classified as bonemeal in LDA2 (false positives were equivalent to 16%) were used as input data in a third LDA. This approach was repeated twelve times, in which at each step hyperspectral profiles were eliminated if they were classified as feed material (not bonemeal). Four independent feed materials were experimentally contaminated with 0–25% (by weight) bonemeal and used for validation. The analysis presented here provides support for development of an automated machine vision to detect bonemeal contamination around the 1% (by weight) level and therefore constitutes an important initial screening tool in comprehensive, rapid, and practically feasible quality control of feed materials.