Preliminary sampling of aflatoxin M1 contamination in raw milk from dairy farms using feed ingredients from Rwanda.

Milk is susceptible to aflatoxin M1 (AFM1) contamination when dairy cattle consume feed contaminated with aflatoxins and is considered as a public health concern. This pilot study assessed the prevalence and amount of total aflatoxin contamination in commercially available dairy feed and the corresponding AFM1 contamination in raw milk from samples collected at farms using local, commercially available dairy feed across Rwanda's five provinces. The inclusion criteria to select dairy farm participants were (1) to have at least two cows and (2) use of commercially prepared dairy feeds. Importantly, the majority of cattle rearing households in Rwanda rely principally on grazing or other freely available feedstock, rather than on commercially prepared feeds. In total, 170 raw milk samples were collected during one sampling period from dairy farms using commercially prepared dairy feeds. In addition, 154 dairy feed samples were collected simultaneously with the milk samples. These farms were previously targeted in a larger study measuring aflatoxin contamination of Rwandan feeds and feed ingredients. The mean AFM1 concentration in these samples was 0.89 ± 1.64 µg/l (median: 0.33 µg/l) with a maximum of 14.5 µg/l. Maize bran was the principal dairy feed ingredient used by farmers in the sampling, representing more than 65% of the total feed samples collected, with mean aflatoxin concentration of 90.5 µg/kg (median 32.3 µg/kg). The authors note that this preliminary sampling is not generalizable across Rwandan milk production and consumption; the limited pilot study presented here was not designed with the robustness necessary for broad-scale generalization. Thus, the data presented should not be broadly applied outside of the context of the study.

Toxigenic mycoflora, aflatoxin and fumonisin contamination of poultry feeds in Ghana.

The study was undertaken to identify the major mycotoxigenic fungi, aflatoxin and fumonisin levels in prepared poultry feeds in Ghana. Three hundred and fifty (350) prepared feed samples were randomly collected from 133 commercial poultry farms, 76 feed processors and eight (8) feed vendors in three major poultry producing regions of Ghana over two seasons. Fungi were isolated using the serial dilution method on potato dextrose agar and identified using standard methods of identification. Total aflatoxin and fumonisin levels were quantified using AgraStrip® Total Aflatoxin and Fumonisin Quantitative test Watex® from RomerLab, USA. Eight (8) different fungi were isolated from the feed samples with isolation frequency as follows: Aspergillus flavus (47%), A. niger (24%), A. fumigatus (17%), A. oryzae (3%), A. tamarii (2%), Penicillium sp. (3%), Colletotrichum sp. (4%) and Rhizopus sp. (0.1%). Feed samples collected during the rainy season recorded higher mean colony counts (3.39 ± 0.29) than that of the dry season (1.10 ± 0.18). Total aflatoxin and fumonisin levels ranged from 0 to 118 ppb with a mean of 57.25 ± 2.55 ppb, and 0.28-15 ppm with a mean of 1.54 ± 0.12 ppm, respectively. The study revealed co-occurrence of aflatoxin and fumonisin in all the feed samples. Significant correlations (r = 0.298, r = 0.694) (p < 0.05) were observed among the aflatoxin and fumonisin levels and the fungi isolated. Seventy-four percent (74%) of all the feed samples exceeded the 15 ppb Ghana Standards Authority threshold, the EU regulatory limit of 20 ppb and the FAO/WHO recommended maximum permissible limit of 30 ppb for poultry feeds. Although fumonisin levels were less than the EU guidance values of 20 ppm for poultry feeds, 20% of the samples were higher than the FAO/WHO maximum tolerable daily intake limit of 2 ppm. Proper handling of prepared feeds and ingredients could prevent or minimize toxigenic fungi contamination and lower the likelihood of mycotoxin development in poultry feeds.

Cytotoxicity assessment of Aflatoxin B1 after high voltage atmospheric cold plasma treatment.

Aflatoxin B1 (AFB1) is a secondary metabolite produced by Aspergillus flavus and A. parasiticus, and is a known carcinogen in humans and animals. High voltage atmospheric cold plasma (HVACP) technology has already shown promise to decontaminate AFB1 in food and feed. This study aimed to investigate the cytotoxicity of AFB1 after HVACP treatment. AFB1 (100 µM) was treated at 85 kV with HVACP for 0, 2, 5, 10, and 20 min. HepG2 cells were exposed to HVACP-treated AFB1 for 72 h and assessed for cell viability, caspase-3 activity, DNA fragmentation, and protein carbonyls for each treatment time. Cell viability, caspase-3 activity, DNA fragmentation levels, and protein carbonyls contents of HepG2 cells exposed to HVACP-treated AFB1 after 20 min was not significantly different compared to non-exposed HepG2 cells (P > 0.05). However, their contents were significantly higher in non-exposed cells compared to the other HVACP treatment times (P < 0.01). Twenty minutes of HVACP treatment for AFB1 significantly reduced AFB1 cytotoxicity and oxidative damage and showed potential as a safe aflatoxin decontamination technology.

Impact of various storage conditions on enzymatic activity, biomass components and conversion to ethanol yields from sorghum biomass used as a bioenergy crop.

With increased mandates for biofuel production in the US, ethanol production from lignocellulosic substrates is burgeoning, highlighting the need for thorough examination of the biofuel production supply chain. This research focused on the impact storage has on biomass, particularly photoperiod-sensitive sorghum biomass. Biomass quality parameters were monitored and included biomass components, cellulose, hemicellulose and lignin, along with extra-cellular enzymatic activity (EEA) responsible for cellulose and hemicellulose degradation and conversion to ethanol yields. Analyses revealed dramatic decreases in uncovered treatments, specifically reduced dry matter content from 88% to 59.9%, cellulose content from 35.3% to 25%, hemicellulose content from 23.7% to 16.0% and ethanol production of 0.20 to 0.02gL(-1) after 6months storage along with almost double EEA activities. In contrast, biomass components, EEA and ethanol yields remained relatively stable in covered treatments, indicating covering of biomass during storage is essential for optimal substrate retention and ethanol yields.

The effect of process variables during drying on the physical and chemical characteristics of corn dried distillers grains with solubles (DDGS)--plant scale experiments.

Corn dried distillers grains with solubles (DDGS) are highly valued as an animal feed for its nutrient content. The amount of wet distillers grains (WDG) and condensed distillers solubles (CDS) blended together during drying affects nutritive value and physical characteristics of DDGS. Effect of changing the ratio of WDG and CDS, and recycled DDGS during drying on particle size, particle size distribution, particle and bulk densities, color, chemical composition, and amino acid content was studied. Moisture content and particle size of DDGS decreased with decreasing amount of CDS added. About 80% of the particles were within a narrow size range (<1500 microm). Bulk density and tapped density of samples produced with different CDS content ranged from 420.5 to 458.1 and 498.8 to 544.3 kg/m(3), respectively. True density decreased with reduction in CDS added. As the CDS content reduced, DDGS became lighter in color. Insoluble fiber contents (protein and insoluble fiber) and amino acids increased while fat, total soluble sugars and glycerol decreased as the CDS content added to WDG reduced. The correlation coefficient of individual chemical components with CDS was above 0.90. Results from this study will be helpful in predicting the physical and nutritive property changes due to variable ratios of blending CDS to WDG during the drying process.

Effect of viscoelastic relaxation on moisture transport in foods. Part I: solution of general transport equation.

Within the framework of continuum mechanics, Singh et al. developed an integro-differential equation, which applies to both Darcian (Fickian) and non-Darcian (non-Fickian) modes of fluid transport in swelling biological systems. A dimensionless form of the equation was obtained and transformed from moving Eulerian to the stationary Lagrangian coordinates. Here a solution scheme for the transport equation is developed to predict moisture transport and viscoelastic stresses in spheroidal biopolymeric materials. The equation was solved numerically and results used for predicting drying and sorption curves, moisture profiles, and viscoelastic stresses in soybeans. The Lagrangian solution was obtained by assembling together several schemes: the finite element method was used to discretize the equation in space; non-linearity was addressed using the Newton-Raphson method; the Volterra term was handled via a time integration scheme of Patlashenko et al. and the Galerkin rule was used to solve the time-differential term. The solution obtained in Lagrangian coordinates was transformed back to the Eulerian coordinates. In part II of this sequence we present the numerical results.

Effect of viscoelastic relaxation on moisture transport in foods. Part II: sorption and drying of soybeans.

The general fluid transport equation presented in Part-I of this paper is used for predicting moisture transport and viscoelastic stresses during sorption and drying of soybeans. Predicted drying curves were validated using experimental data obtained from literature (average absolute difference 6-13%). For drying temperatures used in the soybean processing industry (70-93 degrees C), smooth moisture profiles were obtained, which indicated Fickian (Darcian) transport. As the drying temperature approached the glass transition temperature (25 degrees C at 10% moisture content), the moisture profiles became sharper, which indicated non-Fickian (non-Darcian) transport. The viscoelastic stress profiles clearly exhibited the role of the force terms during imbibition and drying. Increase in drying temperature tends to decrease the stress relaxation function but reduction in moisture content during drying tends to increase it. The increase in stress due to the reduction in moisture content below 10% was not compensated by an increase in drying temperature. Drying of soybeans below 10% moisture content should be avoided in the industry because this will lead to thicker flakes that reduce the amount of oil recovery. During imbibition of soybeans, a high magnitude of stresses was obtained in the rubbery regions, which may cause critical regions prone to fissuring. The role of glass transition on stress development and critical region development was clearly observed during drying and imbibition of soybeans.