Evaluation of a Bacillus stearothermophilus tube test as a screening tool for anticoccidial residues in poultry

A Bacillus stearothermophilus var. calidolactis C953 tube test was evaluated for its ability in detecting the residue of selected anticoccidial drugs in poultry, specically sulfamethazine, furazolidone, and amprolium. Various concentrations of each drug were injected into chicken liver and kidney tissues and these tissues were tested to determine the drug detection limits for each drug. The detection limit was defined as the drug concentration at which 95% of the test results were interpreted as positive. The limits of detection in liver tissue were 0.35 µg/ml for furazolidone, 0.70 µg/ml for sulfamethazine and 7.80 µg/ml for amprolium. In kidney tissues, they were 0.30 µg/ml for furazolidone, 0.54 µg/ml for sulfamethazine, and 7.6 µg/ml for amprolium. It was concluded that this tube test could be used to screen for the residue of these three drugs in poultry.     

Residence Time Distribution and Barrel Fill in Pet Food Twin‐Screw Extrusion Cooking

The residence time distribution and barrel fill of pet food in a twinscrew extruder was determined under conditions of a constant ratio of feed rate to screw speed. Specific feeding load was held constant at 0.16 kg/hr/ rpm while feed rate ranges were 24–56 kg/hr and screw speed ranges were 150–350 rpm. The residence time rapidly decreased as feed rate and screw speed increased. The spread of the residence time distribution (RTD) was smaller at higher feed rates and screw speed, however analysis of the normalized RTD indicated greater mixing. The barrel fill was constant at ≈50% throughout the range of experimental conditions.     

Classification of cassava into ‘bitter’ and ‘cool’ in Malawi: From farmers' perception to characterisation by molecular markers

Cassava roots, a major food in Africa, contain cyanogenic glucosides that may cause toxic effects. Malawian women farmers considered fields of seemingly similar cassava plants to be mixes of both ‘cool’ and ‘bitter’ cultivars. They regard roots from ‘cool’ cultivars as non-toxic. Roots of ‘bitter’ were considered to require extensive traditional processing done by women to be safe for consumption. But curiously, these women farmers preferred ‘bitter’ cultivars since toxicity confers protection against theft, which was a serious threat to the food security of their families. We studied how well these farmers comprehend the effects of genetic variations in cassava when dealing with cyanogenesis in this complex system. Using molecular markers we show that most plants farmers identified as belonging to a particular named cultivar had a genotype typical of that cultivar. Farmers' ethno-classification into ‘cool’ and ‘bitter’ cultivars corresponded to a genetic sub-division of the typical genotypes of the most common cultivars, with four-fold higher cyanogenic glucoside levels in the bitter cultivars. Examining morphology, farmers distinguished genotypes better than did the investigators when using a standard botanical key. Undoubtedly, these women farmers grasp sufficiently the genetic diversity of cassava with regard to cyanogenesis to simultaneously benefit from it and avoid its dangers. Consequently, acyanogenic cassava – the breeding of which is an announced good of some cassava genetic improvement programmes – is not a priority to these farmers. Advances in molecular genetics can help improve food supply in Africa by rapid micropropagation, marker assisted breeding and introduction of transgenic varieties, but can also help to elucidate tropical small-scale farmers' needs and skills. This revised version was published online in August 2006 with corrections to the Cover Date.     

Stability of isoflavones during extrusion processing of corn/soy mixture

The influence of extrusion processing in the presence of corn on the quantity and quality of genistein, daidzein, and their respective beta-glucoside, acetyl glucoside, and malonyl glucoside derivatives was evaluated. Products of 100% soy (textured) and a blend of 20% soy protein concentrate (SPC) and 80% corn meal (direct-expanded) were extruded, with evaluations before and after extrusion. In addition, a 3 x (3 x 3) split-plot factorial experiment investigated the influence of barrel temperature (110, 130, 150 degrees C), moisture content (22, 24, 26%), and relative residence time (1, 0.8, 0.6) on extruder response and isoflavone profile. The extrusion barrel temperature had the most influence on isoflavone profile, especially decarboxylation of the malonyl beta-glucoside, followed by the moisture content. The amount of extractable isoflavones decreased after extrusion for both the SPC and SPC/corn meal blend when extracted with 80% aqueous methanol but remained approximately the same when first hydrated with water before extraction. However, initially hydrating with water produced enzymatic glycolysis in the unextruded samples, increasing the aglycons dramatically.     

Effect of extrusion on isoflavone content and antiproliferative bioactivity of soy/corn mixtures

The present studies were conducted to determine changes in the quantities of select isoflavones and in the bioactivity (ability to inhibit proliferation of human breast cancer cell lines) of extracts from blends of soy protein and cornmeal during extrusion processing. The extrusion of samples resulted in an average 24% decrease in the concentration of total isoflavones for all samples. Although the amounts of specific genistein-derived and daidzein-derived forms changed following extrusion, the content of the aglycones genistein and daidzein per g sample generally did not change. The extrusion of samples generally resulted in decreased antiproliferative action toward breast cancer cells, although antiproliferative activity was not eliminated. Therefore, extrusion of soy protein/cornmeal-containing foods are likely to retain a considerable portion of their isoflavone content and some of the health benefits associated with soy.     

Nitrogen Contribution of Peanut Residue to Cotton in a Conservation Tillage System

ABSTRACT

Leguminous crops, particularly winter annuals, have been utilized in conservation systems to partially meet nitrogen (N) requirements of succeeding summer cash crops. Previous research also highlights the benefits of utilizing summer annual legumes in rotation with non-leguminous crops. This study assessed the N contribution of peanut (Arachis hypogaea L.) residues to a subsequent cotton (Gossypium hirsitum L.) crop in a conservation system on a Dothan sandy loam (fine-loamy, kaolinitic, thermic Plinthic Kandiudults) at Headland, AL during the 2003–2005 growing seasons. Treatments were arranged in a split plot design, with main plots of peanut residue retained or removed from the soil surface, and subplots as N application rates (0, 34, 67, and 101 kg ha^{? 1}) applied in fall and spring. Peanut residue did not influence seed cotton yields, leaf N concentrations, or plant N uptake for either growth stage or year of the experiment. There was a trend for peanut residue to increase whole plant biomass measured at the first square in two of three years. Seed cotton yields and plant parameters measured at the first square and mid-bloom responded favorably to spring N applications, but the recommended 101 kg N ha^{? 1} did not maximize yields. The results from this study indicate that peanut residue does not contribute significant amounts of N to a succeeding cotton crop, however, retaining residue on the soil surface provides other benefits to soils in the southeastern U.S.     

Identification and quantitation of volatile compounds in two heated model compounds, trilinolein and linoleic acid esterified propoxylated glycerol

Static headspace (HS) and capillary gas chromatography/infrared spectroscopy-mass spectrometry (GC/IR-MS) were used to collect, separate, identify, and quantitate the oxidative and thermal decomposition products in two heated model compounds, linoleic acid esterified propoxylated glycerol (EPG-08 linoleate) and trilinoleylglycerol, both without added antioxidants. Approximately 4 L of EPG-08 linoleate or trilinoleylglycerol was heated in a deep-fat fryer at 192 +/- 8 degrees C for 12 h each day until the oil sample contained > or =20% polymeric material, which occurred after 24 h of heating. The major volatile compounds both in heated EPG-08 linoleate and in heated trilinoleylglycerol were pentane, hexanal, 2-heptenal, 1-octen-3-ol, 2-pentylfuran, 2-octenal, and 2, 4-decadienal. The identified volatile compounds from heated EPG-08 linoleate are those generally expected from the oxidative and thermal decomposition of fats and oils containing linoleic acid, except acetoxyacetone (1-acetoxy-2-propanone). Acetoxyacetone was found at 2.1, 3, and 2.4 ppm in the unheated, 12 h heated, and 24 h heated samples, respectively.     

The effect of genotype,location and season on cassava starch extraction

When cassava is harvested too early, it often leads to reduction in yield, while delayed harvest leads to development of woody and fibrous tuberous roots, and reduction in starch content. The optimum harvest time is not known. The objectives of this study were to determine the effect of genotype, location and season on starch extraction in order to find an optimum harvest regime for cassava, and to find the best parameter for monitoring starch levels in cassava tuberous roots. Results showed that genotypic effect was large for starch weight, starch extraction rate on fresh weight basis, and root dry matter content. This suggested that high starch weights could be realised by selection of suitable varieties for starch extraction. It was found that cassava harvesting and starch extractions should be done between October and November since the highest starch extraction rates were achieved during that period, and drying of the extracted starch using the open air method was fast and convenient. The results also suggested that starch levels can efficiently be monitored using starch extraction rate on fresh root weight basis. Starch content on fresh root basis and root dry matter content can also be used to determine the optimum time to harvest cassava for starch extraction but were inferior to starch extraction on fresh root weight basis.