Aflatoxins and ochratoxin A contamination in rice,corn and corn products from Punjab,Pakistan

In present study, a total of 275 retail cereal samples including rice, corn and corn products was analyzed for the presence of aflatoxins and ochratoxin A (OTA) using HPLC equipped with a fluorescence detector. The data has shown that 38 out of 68 samples of rice, 37/105 of corn and 43/102 samples of corn products have been found contaminated with AFs, average level of AFB₁ and total AFs, 8.23 and 19.54, 7.90 and 12.08, and 5.47 and 7.85 μg/kg, respectively. Furthermore, 34, 28 and 26 numbers of rice, corn and corn product samples were found to be contaminated with OTA with an average level of 12.94, 5.29 and 3.69 μg/kg, respectively. The samples of rice, corn and corn products found above the permissible European Union (EU) limit for AFB₁ and total AFs were 18, 13 and 14 and 28, 14 and 20%, respectively; however, the samples of rice, corn and corn products above the EU limit were 40, 14 and 15%, respectively.     

Variation in vitamin E level and aflatoxins contamination in different rice varieties

In the present study, a total of 380 samples of 5 rice varieties were investigated for the presence of aflatoxins (AFs) and tocopherols (Vitamin E) using HPLC, equipped with a fluorescence detector. The data revealed that super basmati rice has the highest mean level of total AFs (12.45 μg/kg) followed by KS-282 (11.2 μg/kg), basmati PK-385 (9.8 μg/kg), Irri-6 (9.7 μg/kg) and the lowest mean level was found in Irri-9 (8.9 μg/kg). Furthermore, the results have shown that the variety with lowest level of AFs has the highest level of tocopherol content; i.e. Irri-9 (53.2 mg/100 g), basmati PK-385 (45.9 mg/100 g), Irri-6 (45.3 mg/100 g), KS-282 (40.4 mg/100 g) and super basmati rice (40.2 mg/100 g). The data has shown correlation (r = −0.62, p < 0.05) between vitamin E content and AFs concentration in different rice varieties. The results are interesting and need further study to investigate the mechanistic background of vitamin E content and its effect on aflatoxins contamination.     

Functional characterization of extruded rice noodles with corn bran: Xanthophyll content and rheology

The rheological changes in rice noodles by the substitution of corn bran and the effect of temperature on the xanthophyll content (lutein and zeaxanthin) of the corn bran-rice flour noodles were evaluated. The use of corn bran increased the water holding capacity of rice flour at room temperature while the opposite results were observed after heating. The pasting parameters of rice flour-corn bran mixture were reduced with increasing levels of corn bran and the mixture paste exhibited more dominant liquid-like behavior. The noodles containing corn bran exhibited lower expansion ratio and softer textural properties. The levels of lutein and zeaxanthin in raw corn bran were 336.9 and 123.1 μg/100 g, respectively and were significantly reduced (P < 0.05) by heating. While lutein and zeaxanthin were not detected in the control noodles without corn bran, their levels in corn bran-incorporated noodles ranged from 56.2 to 137.3 μg/100 g and from 37.9 to 61.9 μg/100 g, respectively and were significantly reduced by 37.7–45.4% (P < 0.05) after cooking. Thus, the heat-labile characteristics of two xanthophylls were clearly observed. This study provides useful information on the processing performance and xanthophyll content of corn bran, possibly extending its use in a wider variety of foods.     

Occurrence and distribution of aflatoxin contamination in groundnuts (Arachis hypogaea L) and population density of Aflatoxigenic Aspergilli in Malawi

Groundnut (Arachis hypogaea L.) is susceptible to pre- and post-harvest infections by Aspergillus spp. Aflatoxin B₁ (AFB₁), is the contaminant produced by the fungus in infected grains posing a threat to human and animal health. This paper reports of a study undertaken in Malawi to determine the occurrence and distribution of Aflatoxigenic Aspergilli in the soil and AFB₁ contamination in groundnuts. A total of 1397 groundnut samples collected from farm homesteads, local markets, warehouses and shops in 2008 and 2009 were analyzed for AFB₁ contamination using the enzyme linked immunosorbent assay (ELISA), and A. Aspergilli population densities in 1053 soil samples collected from the same sites were estimated using serial dilutions plated on A. Aspergilli medium. Farmer socio-economic profile information was also collected to determine relationships to AFB₁ contamination. The results revealed 46% and 23% of the total samples, from 2008 to 2009, respectively, had AFB₁ contamination levels greater than 4 ppb, and those above 20 ppb were 21% for 2008 and 8% for 2009, respectively. Fitted smooth curve relationships show that there is a clear increase in the chance of groundnut contamination when the population density of A. Aspergilli in the soil increased beyond 3000 (log (cfu) > 8). The measured level of A. Aspergilli in soil varied by location, as well as ecologies within location. Low-altitude ecologies, which were warmer and experienced low precipitation levels, had the highest densities of A. Aspergilli, whereas cooler high-altitude ecologies had the lowest density of these fungi. Similarly high AFB₁ contamination, was recorded across the country with 11–28% of all samples collected from the warm low to mid-altitude ecologies recording contamination ≥20 ppb and low contamination (2–10% of samples) in the mid to high altitude cool ecologies. From a crop management perspective, this study also suggests that both less experienced and older farmers were more likely to produce groundnuts contaminated with aflatoxin. These findings have implications in the design of intervention strategies to avoid short- and long-term human health effects from aflatoxin exposure.     

Aflatoxin in maize,a multifaceted answer of Aspergillus flavus governed by weather,host-plant and competitor fungi

Aspergillus section Flavi is able to produce aflatoxins (AFs) in vitro down to 0.85 a_w with a potential maximum occurring between 0.95 and 0.99 a_w, while in the field AFs increased significantly with kernel humidity below 0.95 a_w. In order to clarify this apparent discrepancy, a 3-year field trial with artificial inoculation of maize ears with Aspergillus flavus strains was organised. The co-occurrence of Aspergillus section Flavi and Gibberella fujikuroi species complex (Gfsc) was observed. The incidence of A. flavus was significantly influenced by the year and negatively related to Gfsc incidence. In 2012, when the highest temperature and the lowest rain were registered, aflatoxin B₁ (AFB₁) content was the highest and a_w < 0.95 in kernels was measured early throughout the growing season. In 2013 and 2014, the temperature was lower and rain more abundant, and a_w decreased below 0.95 only close to harvest and AFB₁ contamination was limited. The possibility of describing/predicting reasonably well a_w dynamic based on temperature, (degree day) was confirmed. With a_w > 0.95, a positive correlation between AFB₁ production rate and a_w was found, but a negative correlation resulted with a_w < 0.95. Other factors than a_w play a role, but a_w = 0.95 should be considered as an indicator of suitable conditions for rapid aflatoxin accumulation.     

Influence of grain quality,heat, and processing time on the reduction of aflatoxin B1 levels in ‘tuwo’ and ‘ogi’: Two cereal-based products

During the production of tuwo from laboratory-contaminated corn (AFB₁:150 mcg/kg) and sorghum (AFB₁:87.5 mcg/kg) grains, reductions in the aflatoxin-B₁ levels of pastes boiled for 30 min and 60 min were found to be 68.0% and 80.8%, respectively. In the preparation of ogi from contaminated corn and sorghum grains, reductions of about 72.5% and 71.4%, respectively, were obtained after fermentation at ambient conditions. Reconstitution of ogi paste into a porridge (akamu) considerably reduced the AFB level.     

Biofortification of sweet corn hybrids for provitamin-A,lysine and tryptophan using molecular breeding

Traditional sweet corn is poor in provitamin-A, lysine and tryptophan, deficiency of which causes serious health problems. Here, parental lines of two shrunken2 (sh2) -based sweet corn hybrids viz., ASKH-1 and ASKH-2 were targeted for introgression of crtRB1 and opaque2 (o2) genes through marker-assisted backcross breeding. Gene-based markers; umc1066 (SSR) and 3′TE-InDel were utilized for foreground selection of o2 and crtRB1, respectively in BC₁F₁, BC₂F₁ and BC₂F₂ generations. Background selection employing 102–113 polymorphic SSRs led to >90% recovery of recurrent parent genome. Reconstituted hybrids recorded high mean provitamin-A (18.98 μg/g) with a maximum of 7.7-fold increase over original hybrids (3.12 μg/g). High mean lysine (0.39%) and tryptophan (0.10%) with an average enhancement of 1.71- and 1.79-fold, respectively was recorded among reconstituted hybrids over original versions (lysine: 0.23%, tryptophan: 0.06%). Improved hybrids exhibited high phenotypic resemblance with their original hybrids. The average cob yield (11.82 t/ha) and brix (17.66%) of improved hybrids was at par with their original versions (cob yield: 11.27 t/ha, brix: 17.04%). These biofortified sweet corn hybrids rich in provitamin-A, lysine and tryptophan hold immense significance as multinutrient-rich balanced food. This is the first report to stack sh2, crtRB1 and o2 genes to improve nutritional quality in sweet corn.     

Flaking as a corn preparation technique for dry-grind ethanol production using raw starch hydrolysis

A 2³ full-factorial study was designed to study the effect of corn preparation methods (flaking and grinding) on dry-grind ethanol performance using raw starch hydrolysis (RSH) process. Moisture content (15, 22%), flaker roller gapsetting (0.508 mm, 1.016 mm), and grinding were studied. Fifteen hundred g of corn samples were cracked, roller pressed, and were either ground further or retained, along with control ground corn. A bimodal size distribution was observed for ground corn, regardless of flaking. Moisture at 22% resulted in bigger-sized flakes with d₅₀ between ∼1.3 and 1.8 mm, compared to ∼138–169 μm for ground corn. Not all ground corn resulted in higher ethanol concentration in fermentation beer; the ethanol levels in beer did not reflect the starch hydrolysis trend that favored ground corn. In a related study, the beer ethanol concentration did not show a clear trend with rollermill gapsetting while fermenting the flakes produced at 0.203, 0.305, 0.406, and 0.508 mm gapsettings. Generally, flakes from corn at 22% moisture resulted in higher ethanol content in beer. Rollermill flaking was found comparable to hammermill grinding for dry-grind corn ethanol via raw starch hydrolysis and yeast fermentation.     

Monitoring Cry1Ab susceptibility in Asian corn borer (Lepidoptera: Crambidae) on Bt corn in the Philippines

Between 2002 and 2004, collections of egg masses of Asian corn borer (ACB), Ostrinia furnacalis (Guenée) were made from corn-planting sites on the major Philippine islands of Luzon (Laguna, Pangasinan, Camarines Sur and Isabela provinces) and Mindanao (Bukidnon and South Cotabato provinces). The resulting neonates were bioassayed for susceptibility to Bacillus thuringiensis (Bt) Cry1Ab protein. The median lethal concentrations (LC₅₀s) for the different collections ranged from 0.42 to 2.37 ng/cm². The bioassay results suggest that Philippine corn borer populations were highly susceptible to Cry1Ab protein prior to the widespread deployment of Bt corn. The upper limit of the estimated LC₉₉ (104 ng/cm²) from the pooled bioassay data was selected as a candidate diagnostic concentration and subsequently tested on eleven ACB populations. Results of the validation assays showed that the mortality response of all the tested ACB populations was higher than the expected mortality (99%). Therefore, the concentration of 104 ng/cm² was used to monitor susceptibility in ACB populations in the Philippines. Monitoring of field populations during 2009 in areas where Bt corn had been grown for 3 years found some enhanced survival of neonates at the diagnostic concentration but progeny of the diagnostic-concentration survivors did not survive on Bt corn, indicating that ACB populations in the Philippines remain susceptible to Cry1Ab-containing Bt corn hybrids.     

Chemical properties and water absorption kinetics of transgenic corn grain (2B587 Hx) and its conventional isoline (2B587)

In the hydration process, besides influencing processing conditions, the cultivar may also influence water absorption by the grains and, consequently, yield and quality of the milled products. Therefore, the moisture absorption kinetics of the transgenic corn grain 2B587 Hx and its conventional isoline 2B587 were studied, as well as the chemical characterization of the samples in natural conditions. The water absorption kinetics of the grains was modeled using Peleg's equation at hydration temperatures of 40, 50, 60, and 67 °C. The 2B587 Hx transgenic corn, compared with the 2B587 conventional corn, had higher carbohydrate and ash contents and lower crude fiber content. The water absorption by the grains, which was satisfactorily represented by Peleg's model, occurred more quickly as the temperature increased. Peleg's constant, k₁, which is inversely related to the initial hydration rate, varied from 405.2 to 141.5 min g/g for conventional corn and from 429.5 to 149.5 min g/g for transgenic corn at temperatures from 40 to 67 °C. The choice of the cultivar may depend on the specifications required by the industry for the main final products.     

Transgenic Bt corn varietal resistance against the Mexican rice borer,Eoreuma loftini (Dyar) (Lepidoptera: Crambidae) and implications to sugarcane

The Mexican rice borer, Eoreuma loftini (Dyar), attacks crops including corn, Zea mays L., rice, Oryza sativa L., sorghum, Sorghum bicolor (L.) Moench, and sugarcane, Saccharum spp. Strongly resistant varieties of any kind, native or otherwise, have not been identified. A field plot corn variety test using two transgenic Bt varieties, Pioneer 31G71, expressing the Cry1F insecticidal protein, and Golden Acres 28V81, expressing the Cry1A.105, Cry2Ab2, and Cry3Bb1 insecticidal proteins, and two non-Bt controls, Dekalb DKC 69-72 and BH Genetics 9050, all four commonly grown in the Lower Rio Grande Valley of Texas, showed that, although oviposition preference was not affected, 28V81 resisted larval stalk boring to the extent that Mexican rice borer injury was almost non-existent. Pioneer 31G71 was infested nearly as much as the controls, but larval development to adulthood was reduced by ≈70%. Rearing larvae on 5, 50, 500, and 5000 μg of corn leaf tissue per ml of artificial diet showed that, while the three lowest concentrations did not affect larval growth and development, the high concentration of 28V81 reduced survivorship to the pupal stage, decreased weight of 4-wk-old larvae, and prolonged development to pupation. Lower numbers of pheromone trap-captured adults at the edges of commercial Bt and non-Bt corn fields showed that populations were lower at the Bt cornfields, suggesting a lesser rate of adult production. Because corn is a preferred host plant over sugarcane, sorghum or rice, use of resistant transgenic Bt corn varieties will likely protect the crop from the substantial injury that can be caused by the pest. This study also suggests that Bt genes might result in similarly strong resistance when inserted in other vulnerable crops such as sugarcane.     

The comparison of the effect of added amaranth,buckwheat, chickpea,corn, millet and quinoa flour on rice dough rheological characteristics,textural and sensory quality of bread

Gluten free (GF) flour (amaranth, buckwheat, chickpea, corn, millet and quinoa) was blended with rice flour to compare their impact on dough rheological characteristics and bread quality. The potential of some GF-rice blends in breadmaking has already been studied on blends with prevailing content of rice flour. The impact of added flour may be expected to rise with increasing amount of flour; therefore blends containing 30 g/100 g, 50 g/100 g and 70 g/100 g of GF flour in 100 g of GF-rice blend were tested. Under uniaxial deformation, peak strain was not impacted by the addition of GF flour; stress (12.3 kPa) was, however, significantly (P < 0.05) decreased (2.9–6.2 kPa). The reduction initiated by the presence of buckwheat, chickpea, quinoa and partly amaranth, together with thermally-induced dough weakening initiated by buckwheat and quinoa flour, may be related to significantly better crumb porosity. Overall acceptability of composite breads containing amaranth, chickpea and quinoa was negatively impacted by the aroma and taste of these flours. Higher potential to improve rice dough behavior and bread quality was found in the blend containing buckwheat flour (30 g/100 g; 50 g/100 g). Millet and corn flour deteriorated dough and bread quality.     

Comparison of different rice flour- and wheat flour-based butter cookies for acrylamide formation

Acrylamide (AcA) contents of different rice flour- and wheat flour-based butter cookies baked at 130 °C for 20, 55, or 90 min were investigated. AcA contents of different flour-based cookies increased with baking time. Color parameters in terms of CIE L*, b*, C*, and ΔE values showed significant opposite correlation to the AcA formation in each of the raw flour cookie. The cookies based on white rice flour had the lowest AcA contents ranging from not detectable (ND) to 204 μg/kg, followed by cookies based on brown rice flour (ND to 450 μg/kg), white wheat flour (155 μg/kg to 661 μg/kg), and whole wheat flour (306 μg/kg to 982 μg/kg). Considerably lower AcA levels were found in the rice flour-based cookies than in the wheat flour-based cookies, as well as in the milled flour-based cookies than in the whole-grain cookies. Although the flour source was considered to play a primary role in determining the AcA content, AcA content was apparently not dependent on the quantities of reducing sugars and free asparagine in the starting raw flour and cookies during baking. In summary, given its reducing potential for AcA formation, rice flour could be used in the production of cookies safe from heat-induced contaminants.     

CO2 fertilization does not affect biomass production and nutritive value of a C4 tropical grass in short timeframe

Increased atmospheric carbon dioxide (CO₂) is a consequence of recent anthropogenic environmental changes, and few studies have evaluated its effects on tropical grasses used in Brazilian pastures, the main feed source for major part of ruminant livestock. This study evaluated forage production, chemical composition, in vitro total gas production and organic matter degradability of Brachiaria brizantha under contrasting CO₂ atmospheric conditions in a free air carbon dioxide enrichment (FACE) facility. The forage plants were sown in each of the 12 octagonal rings of the FACE facility: six under ambient atmospheric CO₂ concentration of approximately 390 μmol/mol, hereafter referred to as control (CON) plots, and other six rings enriched with pure CO₂ flux to achieve a target CO₂ concentration of 550 μmol/mol, hereafter called elevated CO₂ (eCO₂) plots. Soil samples were collected to determine carbon and nitrogen concentrations. After seventy days of sowing, a standardization cutting was performed and then at regular intervals of 21 days the forage was harvested (ten harvest dates) and forwarded to laboratorial analyses. Forage above‐ground biomass production (dry matter (DM): 6,143 vs. 6,554 kg/ha), as well as morphological characteristics (leaves: 71% vs. 68%; stem: 28% vs. 31%), chemical composition (crude protein: 162.9 vs. 161.8; neutral detergent fibre: 663.8 vs. 664.3; acid detergent fibre: 369.5 vs. 381; lignin: 60.1 vs. 64.1 g/kg DM; total C: 45.9 vs. 45.9; total N: 2.8 vs. 2.8; total S: 0.2% vs. 0.2%), organic matter in vitro degradability (573.5 vs. 585.3 g/kg), methane (5.7 vs. 4.3 ml/g DM) and total gas (128.3 vs. 94.5 ml/g DM) production did not differ significantly between CON and eCO₂ treatments (p > .05). The results indicated that at least under short‐term enrichment, B. brizantha was not affected by eCO₂.     

The addition of corn fiber gum improves the long-term stability and retrogradation properties of corn starch

This study was designed to test the hypothesis that the stability and physical properties of starch gels could be improved by adding small amounts of corn fiber gum (CFG). In the differential scanning calorimeter measurement, the enthalpy of retrogradation was 7.30 J/g for starch without CFG and 4.30 J/g for starch composite gel with 1.0% CFG. The addition of 1.0% CFG to starch significantly (p < 0.05) decreased the degree of retrogradation during the long-term storage from 61.6% to 36.5%. The addition of CFG retarded the syneresis of the starch system from 17.97% and 34.93%–6.15% and 26.57% after storage for 7 and 14 days respectively. The crystallization peak of starch containing 0.5–1.0% CFG was quite diminished. When compared with the starch gel alone, the addition of CFG significantly lowered the hardness of the composite starch gel from 60.92 to 45.81 N after 14 days storage. The starch gel without CFG showed the lowest rapidly digestible starch content and the highest resistant starch content in comparison to starch/CFG composite gels after 7 and 14 days storage. Over all, the addition of CFG considerably inhibits the retrogradation of corn starch gels during long-term storage.     

Prevalence of fumonisin-producing Fusarium species in Brazilian corn grains

The aims of this study were to perform morphological and molecular characterization of Fusarium species within the Liseola section isolated from corn grains from different geographic regions in Brazil, and to evaluate their potential for fumonisins production. The results showed that Fusarium verticillioides is the predominant species (99%) associated with corn grains, and other toxigenic species, Fusarium proliferatum, was incidental in Brazilian corn. Although there was a high variability in the total fumonisin production among the isolates (0.01–2.39 μg g⁻¹), all fifty isolates analyzed produce fumonisins. The level of total fumonisin production was not correlated with the geographic origin of the isolates.     

Effect of Milling and Parboiling Processes on Arsenic Species Distribution in Rice Grains

This study identified the role of milling and parboiling on arsenic (As) content and its species in large numbers of rice samples. Total As contents were 108 ± 33 μg/kg in polished rice grains (PR), 159 ± 46 μg/kg in unpolished rice grains (UR), 145 ± 42 μg/kg in parboiled polished rice grains (PPR) and 145 ± 44 μg/kg in parboiled unpolished rice grains (PUR). The percentages of inorganic As (iAs) were 66% ± 8% in PR and from 72% to 77% in other grain categories. The polishing process reduced the As content in the rice grains, removing outer part of the UR with high amount of As, whereas the parboiling technique transferred the semimetal content within the grain. Total As and iAs contents were not significantly different in UR, PPR and PUR, homogenizing its distribution inside the grains. The results allowed to understand how different operations affect As fate and its chemical forms in grains.     

Production of monoclonal antibodies against AFLM (Ver-1), a middle key protein involved in aflatoxin biosynthesis

Aflatoxins are potent carcinogens, mutagens and teratogens, and are harmful to both humans and animals. As many as 30 genes are involved in aflatoxin biosynthesis. Among them, aflM (ver-1) gene was predicted to encode a 28-kDa NADPH-dependent ketoreductase (AFLM), which catalyzed middle enzymatic steps in aflatoxin biosynthetic pathway. AFLM (Ver-1) was proved to be necessary for conversion of versicolorin A (VERA) to demethylsterigmatocystin (DMST) in aflatoxin B₁ (AFB₁) biosynthesis. For these reasons, aflM gene was cloned and specific monoclonal antibodies for AFLM was developed to better define potential pathways of AFLM involved in AFB₁ biosynthesis. Monoclonal antibodies 11B2-1D7 and 3G5-4E7 were successfully screened out by immunizing mouse. Immunoblot analysis revealed that both had high sensitivity and specificity to identify native AFLM protein in A. flavus with detection limit of 11 ​ng/mL and 8 ​ng/mL respectively. These results showed that it was suitable for quantitative detection of AFLM in A. flavus isolate. Further investigation revealed that aflatoxin accumulations of various A. flavus were not dependent on AFLM biosynthesis. Overall, this is the first report for development for AFLM monoclonal antibody development and application in A. flavus quantitative detection.     

Physicochemical and antioxidant properties of extruded corn grits with corn fiber by CO2 injection extrusion process

Corn grits and corn fiber mixed at different mass ratios (0/100, 15/85 and 30/70) were extruded at different melt temperature (90, 105 and 120 °C) using extrusion with and without CO₂ injection. The L value, reducing sugar content and antioxidant properties decreased after extrusion with or without CO₂ injection. The color and antioxidant properties were relatively stable in the extrusion with CO₂ injection at higher melt temperature (120 °C) in comparison with the extrusion without CO₂ injection. Higher corn fiber content resulted in less loss of total phenolic content. The b, ΔE values and water absorption index increased after extrusion. The increase of the water absorption index was higher after the extrusion process with the CO₂ injection especially at the lower melt temperature. The addition of corn fiber decreased L, b, and ΔE values, but significantly increased antioxidant properties under the same extrusion conditions.     

Effect of particle size,shape and surface roughness on bulk and shear properties of rice flour

The present study was conducted to compare the flowability of basmati and non-basmati rice flour with commercially available rice flour. Dynamic and shear properties were characterized on the basis of particle size, shape and surface roughness (measured by Atomic Force Microscope) depending upon the processing conditions. In contrast to commercial rice flour having less particle size (65.3 μm), the particle sizes (171.1–171.9 μm) of both the samples were not significantly different. However, the flowability of the non-basmati rice flour was significantly affected by its particle shape (0.487), surface roughness (124.23 nm) and compressibility (25.32%), making it more cohesive than basmati rice flour but less cohesive than commercial rice flour (1.34 kPa). Also, basic flow energy was significantly higher in both commercial rice flour and non-basmati flour, thus required more energy (197.42 mJ and 147.54 mJ, respectively) to flow than basmati rice flour (130.15 mJ). Overall, flowability was analysed by applying three different pressures (3, 6 and 9 kPa) and among which commercial rice flour was found less flowable (2.26 at 9 kPa) followed by non-basmati rice flour (2.33 at 9 kPa) and basmati (3.35 at 9 kPa) causing bulk handling difficult.