Efficacy and fumigation characteristics of ozone in stored maize

This study evaluated the efficacy of ozone as a fumigant to disinfest stored maize. Treatment of 8.9 tonnes (350 bu) of maize with 50 ppm ozone for 3 d resulted in 92–100% mortality of adult red flour beetle, Tribolium castaneum (Herbst), adult maize weevil, Sitophilus zeamais (Motsch.), and larval Indian meal moth, Plodia interpunctella (Hübner) and reduced by 63% the contamination level of the fungus Aspergillus parasiticus Speare on the kernel surface. Ozone fumigation of maize had two distinct phases. Phase 1 was characterized by rapid degradation of the ozone and slow movement through the grain. In Phase 2, the ozone flowed freely through the grain with little degradation and occurred once the molecular sites responsible for ozone degradation became saturated. The rate of saturation depended on the velocity of the ozone/air stream. The optimum apparent velocity for deep penetration of ozone into the grain mass was 0.03 m/s, a velocity that is achievable in typical storage structures with current fans and motors. At this velocity 85% of the ozone penetrated 2.7 m into the column of grain in 0.8 d during Phase 1 and within 5 d a stable degradation rate of 1 ppm/0.3 m was achieved. Optimum velocity for Phase 2 was 0.02 m/s. At this velocity, 90% of the ozone dose penetrated 2.7 m in less than 0.5 d. These data demonstrate the potential usefulness of using ozone in managing stored maize and possibly other grains.     

Controlling deterioration of high-moisture maize with ozone treatment

Two experiments were conducted to determine the effect of ozone treatment on controlling deterioration of high-moisture maize under extreme and moderate environmental conditions experienced during harvest. In the first experiment, 0.77-kg maize samples held at 22% moisture content were treated with ozone at 0.08, 0.16, 0.31, 0.62, 0.94, 1.25 and 1.56 mg kg maize⁻¹ min⁻¹ (60-1120 ppm ozone in air during application) for periods of 5 or 24 h, with an additional treatment of 1.56 mg min⁻¹ repeated every 3 d, and stored at 32 °C for 9 d under continuous aeration. Ozone treatment decreased dry matter loss compared to the control, but not to a level that would likely justify ozone treatment at the rates and treatment times used. In the second experiment, 2.43-kg maize samples held at 26% moisture content were treated with ozonation rates of 0.25, 0.5, 1, and 2 mg kg maize⁻¹ min⁻¹ (1090-8680 ppm ozone during application) for 24 h, stored at 15.5 °C for 30 d and passively aerated every 3 d. Additional ozone treatments at the 2 mg kg maize⁻¹ min⁻¹ rate were applied for 1 h on 3-, 6-, and 12-d intervals throughout the experiment. Single ozone treatments of 1 and 2 mg kg maize⁻¹ min⁻¹ were equally effective, reducing dry matter loss by 1.3 percentage points compared to the control after 30 d of storage. Repeat treatments at 2 mg kg maize⁻¹ min⁻¹ did not reduce dry matter loss compared to the single treatment.     

Bread improvers: Comparison of a range of lipases with a traditional emulsifier

This study compares three generations of lipase enzymes with the emulsifier, diacetyl tartaric esters of mono-glycerides (DATEM), on white wheat flour bread. Baking recipes with addition of DATEM (4500 ppm), Lipopan F-BG (15 ppm), Gryndamyl Exel-16 (115 ppm), Lipopan Xtra-BG (25 ppm) and Lipopan 50-BG (27.5 ppm) were test-baked after 60 and 150 min fermentations, to study their effects on the baking characteristics of volume, oven rise, crust colour, crumb texture and colour, shelf-life, flavour and aroma. The enzymes and emulsifier preparation caused significant increase in bread oven rise and specific volume with the exception of Lipopan 50-BG, which failed to improve loaf volume in the short fermentation method. There was no significant difference between other lipase enzymes and DATEM as a bread volume improver. Increase in fermentation time resulted in increase in volume in all samples, except for Lipopan-Xtra.     

Evaluation of a new insecticide formulation (F2) as a protectant of stored wheat, maize, and rice

A new commercial formulation, F2, was evaluated as a protectant of stored wheat, stored maize, and stored rough (paddy) rice. This formulation comprises the technical active ingredients 0.03% deltamethrin, 0.37% piperonyl butoxide, and 0.95% chlorpyriphos-methyl, plus 10% mineral oil and 88.0% of the diatomaceous earth Protect-It^®. Tests were conducted with dust and slurry formulations at 50 and 100 ppm, 57% and 75% relative humidity, and 22°C, 27°C, and 32°C. On wheat, survival of the lesser grain borer, Rhyzopertha dominica (F.), ranged from 0% to 30.0%, survival of the rice weevil, Sitophilus oryzae (L.), was 0-6.2%, and survival of the red flour beetle, Tribolium castaneum (Herbst), was 0-97.5%. Few F₁ adults of any of the three species were found in the treated samples. Survival of the maize weevil, Sitophilus zeamais (Motschulsky), on treated corn was 0-32.5%, while survival of T. castaneum was 0-88.7% in the 50-ppm dust and slurry treatments, and 0-51.4% in the 100-ppm treatments. Again, few F₁ adults of either species were found in treated maize. Survival of R. dominica on treated rough rice averaged 0-4.1% and survival of S. oryzae on treated rice was 0-48.8%, but the majority of weevils that survived were in one replicate. F₁ adults in the treatments ranged from 0 to 24.4. Results show that the combination insecticidal product F2 was extremely effective on all three commodities at the rate of 100 ppm, as either a dust or slurry, and could be used as a commodity protectant.     

Influence of aqueous ozone, blanching and combined treatments on microbial load of red bell peppers, strawberries and watercress

The effectiveness of ozone in aqueous solution treatment on microbial inactivation was studied for three combinations microorganism/food: Listeria innocua/red bell peppers (artificially inoculated), total mesophiles/strawberries, and total coliforms/watercress, with two concentrations (0.3 and 2.0 ppm). Blanching treatments (50-60 °C) were also individually applied and in combination with ozone, for studying possible synergistic effects. In relation to ozone treatments, the highest microbial reductions were obtained for the highest concentration with the highest treatment time (3 min). Under those conditions, L. innocua/peppers, total mesophiles/strawberries and total coliforms/watercress were reduced respectively 2.8 ± 0.5, 2.3 ± 0.4 and 1.7 ± 0.4 log-cycles. However, a substantial portion of the microbial populations were reduced by water washing alone, and the presence of ozone generally added an additional reduction of 0.5-1.0 log-cycles.If ozone at the highest concentration is used, the treatment impacts on L. innocua/peppers and total mesophiles/strawberries load reductions were equivalent to a blanching at 50 °C (for the same treatment times).Combining blanching and ozone did not generate synergistic effects, and in some situations microbial reductions were lower than the ones observed when treatments were applied independently.     

Insecticidal and residual effect of three pyrethroids against Sitophilus oryzae (L.) (Coleoptera: Curculionidae) on stored wheat

Laboratory tests were conducted to assess the use of the pyrethroids, deltamethrin, beta-cyfluthrin and alpha-cypermethrin at the rates of 0.125 and 0.25 ppm, as grain protectants in stored wheat against the rice weevil, Sitophilus oryzae (L.). For this purpose, clean untreated wheat was sprayed with these insecticides and stored for 6 months. During this period, four bioassays were carried out, in order to evaluate the residual efficacy of each pyrethroid. In each bioassay, treated wheat was infested with S. oryzae adults, and dead insects were counted after 1, 2 and 7 d of exposure. In addition, S. oryzae progeny production was estimated on each bioassay, until the production of the F₄ generation. The results indicated that deltamethrin and beta-cyfluthrin, both at 0.25 ppm, were significantly more efficient than the other treatments. Efficacy was notably higher after 7 d of exposure, than after 1 and 2 d. At the same exposure level, 1, 2 and 3.5 months after treatment, at 0.25 ppm, mortality for deltamethrin was approximately 89%, 92% and 86%, respectively, while the corresponding percentages for beta-cyfluthrin were 97%, 83% and 62%, and for alpha-cypermethrin 50%, 49% and 33%. However, at the rate of 0.125 ppm, mortality was ?58% in all cases. In all treatments appearance of F₁-F₄ generations was observed, with the exception of both deltamethrin and beta-cyfluthrin at 0.25 ppm, where only a few F₁ adults were noted, without the production of subsequent generations.     

Influence of grain type on the susceptibility of different Sitophilus oryzae (L.) populations, obtained from different rearing media, to three diatomaceous earth formulations

Bioassays were carried out to assess whether the commodity, from which adults of the rice weevil Sitophilus oryzae emerged, influences the insecticidal efficacy of three diatomaceous earth (DE) formulations: Protect-It™, PyriSec^® and DEBBM. Protect-It™ is a DE formulation that contains 10% silica gel, while PyriSec^® and DEBBM are enhanced DEs that contain natural pyrethrum and the plant extract bitterbarkomycin, respectively. The S. oryzae populations tested were reared on wheat, barley or maize and the susceptibility of each to the DE formulations was assessed on all three commodities. The DE application doses were: 500 ppm for Protect-It™ and PyriSec^®; 150 and 75 ppm for DEBBM. Mortality of S. oryzae adults was counted 7 and 14 d after their exposure on the treated commodities. Bioassays were carried out at 25 °C and 55% r.h. Barley-reared S. oryzae were the most tolerant of all formulations and treated commodities, whereas maize-reared were the most susceptible ones. DE effectiveness was always lower in maize than in wheat or barley irrespective of the commodity from which the populations were obtained. Furthermore, Protect-It™ and PyriSec^® were more effective than DEBBM in wheat or barley, but not in maize.     

Movement and distribution of adult Cryptolestes ferrugineus (Coleoptera: Laemophloeidae) in stored wheat in response to temperature gradients, dockage, and moisture differences

The movement and distribution of adult Cryptolestes ferrugineus were determined in 100×100×1000 mm wheat columns with or without 5 °C/m temperature gradients (from 27.5±0.2 to 32.5±0.2 °C or at 27.5±0.2 °C) under: (1) 5% and 10% uniform dockage (14.5±0.2% moisture content (m.c.), wet basis); (2) half of the columns with 5% or 10% dockage and the other half without dockage; (3) 12.5%, 14.5% or 16.5% m.c. wheat without dockage; and (4) half of the columns with 12.5% or 14.5% m.c. wheat and the other half with 16.5% m.c. wheat.Adults introduced in the middle of the horizontal wheat columns with or without uniform dockage showed no bias in the direction of net displacement, with the distribution pattern gradually becoming more uniform when time increased from 1 to 144 h. In vertical columns with 0%, 5% and 10% uniform dockage, the adults preferred to move down in the first 24 h; however, they moved up after 24 h. Grain with a high percentage of dockage (10%) decreased beetle movement speed. A low percentage of dockage (5%) did not influence insect movement and distribution. Positive geotaxis was more important than the attraction of dockage.Adults responded to both temperature gradients and moisture differences in columns of wheat with temperature gradients and moisture content differences. The response was different at different moisture conditions. Adults were more sensitive to moisture differences and moved faster in 12.5% m.c. wheat than in 14.5% m.c. wheat. Adults stayed in warmer sections in both high and low moisture grain. At different moisture conditions, adults changed their preference (e.g., preferred high moisture grain in dry grain, and preferred warmer temperature in damp grain).     

Colour of fat,and colour,fatty acid composition and sensory characteristics of muscle from heifers offered alternative forages to grass silage in a finishing ration

The effect of type of silage offered to beef heifers during the finishing period on aspects of beef quality was determined. In two experiments, a diet based on grass silage (GS) was compared with a diet based on maize silage (MS) or whole-crop wheat silage (WCW). Compared to the GS-based diet, increasing the amount of MS linearly increased fat whiteness while the increase in fat whiteness due to WCW was dependent on the stage of crop maturity at harvesting. There was no effect of diet on muscle colour or on muscle pH measured at 48 h post-mortem, drip loss, taste panel traits after 14 days ageing or shear force values at 2, 7 or 14 days ageing. The alternative silages decreased the n − 3 polyunsaturated fatty acid proportion and increased the linoleic:linolenic acid ratio in intramuscular lipid. It is concluded that type of silage affects fat colour and fatty acid composition of muscle but not the other muscle characteristics examined.     

Development and Evaluation of a Fluidized Bed System for Wheat Grain Disinfection

Abstract: Durum wheat grain from the field is naturally contaminated with bacteria, yeast, and mold. The reduction in aerobic plate count (APC) and yeast and mold count (YMC) is often necessary before processing wheat. Gaseous ozone, ozonated water, and acetic acid solution are nontraditional antimicrobial agents for grains and are safe for humans and the environment. Better disinfection may be possible by applying antimicrobial agents to grain in a fluidized state. Fluidization increases the exposure of grain surfaces, resulting in uniform and quick contact of grain with antimicrobial agents. Therefore, a fluidized bed was developed with automated spraying system (to spray treatment waters), and a port for gaseous ozone injection. The pressures and velocities within the fluidized bed system were measured to characterize the system. The treatments used on fluidized grain were: distilled water (control), gaseous ozone (6 ppm), ozonated water (23 mg/L), gaseous ozone + ozonated water (6 ppm, 23 mg/L), acetic acid solution (0.5%), acetic acid + ozonated water (0.5%, 26 mg/L), and gaseous ozone + acetic acid + ozonated water (6 ppm, 0.5%, 26 mg/L). The last of these treatments was most effective with 1.7 and 3.3 log reduction in APC and YMC, respectively. This combined treatment can be used to replace the chlorinated water that industry uses during tempering of grain. Ozonated water alone resulted in a 0.3 log reduction in both APC and YMC. Gaseous ozone alone did not cause a significant reduction in APC and YMC.     

Evaluation the quality characteristics of wheat flour and shelf-life of fresh noodles as affected by ozone treatment

In this study, the effects of ozone treatment on the microorganism mortality in wheat flour and shelf-life of fresh noodles were investigated, as well as the physicochemical properties of wheat flour and textural qualities of cooked noodles. Results showed that the total plate count (TPC) can be largely reduced in wheat flour exposed to ozone gas for 30 min and 60 min. Whiteness of flour and noodle sheet, dough stability, and peak viscosity of wheat starch were all increased by ozone treatment. Free cysteine content in wheat flour was shown to decrease significantly (P < 0.05) as the treatment time increased and remarkable protein aggregates were observed in both reduced and non-reduced SDS–PAGE patterns. In addition, ozone treated noodles were generally higher in firmness, springiness, and chewiness, while lower in adhesiveness. Microbial growth and darkening rate of fresh noodles made from ozone treated flour were delayed significantly.     

Effectiveness of spinosad dust against different European populations of the confused flour beetle, Tribolium confusum Jacquelin du Val

Six populations of the confused flour beetle, Tribolium confusum, obtained from Greece, Italy, Portugal, Denmark, Germany and France were tested for their susceptibility to a spinosad dust formulation, containing 0.125% spinosad. For this purpose, adults and larvae of T. confusum were exposed on wheat treated with two dose rates of the dust formulation, 0.06 and 0.19 ppm of a.i. corresponding to 50 and 150 ppm of the formulation, at 25 °C and 65% r.h. Mortality of the exposed individuals was assessed after 7, 14 and 21 days of exposure on the treated substrate. The increase of dose and exposure interval increased mortality, while adults were more tolerant to spinosad than larvae. Significant differences were noted among populations, for both adults and larvae. The most tolerant to spinosad was the strain from Greece, while the least tolerant were the strains from Germany and Denmark. After 7 days of exposure, on wheat treated with 50 ppm, mortalities of adults of the Greek, German and Danish strains were 2%, 25% and 62% respectively, while the respective figures for 150 ppm were 1%, 31% and 81% respectively. In the case of larvae, of the same strains, mortality at 50 ppm was 6%, 27% and 28% and at 150 ppm 11%, 23% and 40%, respectively. The results of the present study suggest that different strains and stages of T. confusum differ widely in their susceptibility to spinosad-treated wheat.     

Incidence, concentration and effectiveness of malathion residues in wheat and maize (corn) exported from the United States

The incidence, concentration, and effectiveness of malathion treatments were measured in wheat and maize samples obtained from 79 port terminals in the United States. The presence of biologically active residue levels of malathion was inferred by bioassay assessment in 28% of 2058 wheat samples and in 8.4% of 2383 maize samples examined during the 2-year period, January 1977–December 1978. Malathion occurred most often in wheat from port terminals in the Pacific and Gulf regions where treatments were frequently part of the grain sale agreement and where grain was often treated immediately prior to sampling. At terminals where the grain was not treated just prior to sampling, the incidence of malathion on grain arriving at the ports was only 11.6% for wheat and 7.7% for maize.

Average malathion residues were 2.50 ppm in 210 samples of wheat and 1.03 ppm in 139 samples of maize and ranged from 2.71 ppm in Gulf wheat to 0.66 ppm in Pacific maize. Residues on wheat treated just prior to sampling, show inconsistent and generally inadequate malathion deposits resulting from port terminal treatments. No consistent relationship was evident between grain handling capacities and malathion residues.     

Inactivation of internalized and surface contaminated enteric viruses in green onions

With increasing outbreaks of gastroenteritis associated with produce, it is important to assess interventions to reduce the risk of illness. UV, ozone and high pressure are non-thermal processing technologies that have potential to inactivate human pathogens on produce and allow the retention of fresh-like organoleptic properties. The objective of this study was to determine if UV, ozone, and high pressure are effective technologies compared to traditional chlorine spray on green onions to reduce enteric viral pathogens and to determine the effect of location of the virus (surface or internalized) on the efficacy of these processes. Mature green onion plants were inoculated with murine norovirus (MNV), hepatitis A virus (HAV) and human adenovirus type 41 (Ad41) either on the surface through spot inoculation or through inoculating contaminated hydroponic solution allowing for uptake of the virus into the internal tissues. Inoculated green onions were treated with UV (240 mJ s/cm²), ozone (6.25 ppm for 10 min), pressure (500 MPa, for 5 min at 20 °C), or sprayed with calcium hypochlorite (150 ppm, 4 °C). Viral inactivation was determined by comparing treated and untreated inoculated plants using cell culture infectivity assays. Processing treatments were observed to greatly affect viral inactivation. Viral inactivation for all three viruses was greatest after pressure treatment and the lowest inactivation was observed after chlorine and UV treatment. Both surface inoculated viruses and viruses internalized in green onions were inactivated to some extent by these post-harvest processing treatments. These results suggest that ozone and high pressure processes aimed to reduce the level of microbial contamination of produce have the ability to inactivate viruses if they become localized in the interior portions of produce.     

Genotypic variation of spring wheats for solvent retention capacities in relation to end-use quality

The solvent retention capacity (SRC) test is useful to measure flour components contributing to end-use functionality especially where the sample number is large and grain quantities are limited. The water, sodium carbonate, lactic acid, and sucrose SRC values ranged 78.0-98.0, 95.0-127.5, 101.5-139.0, and 125.0-163.0 g/100 g, respectively in 50 spring wheat varieties. Water SRC positively correlated with cookie spread ratio (r = 0.29) while Lactic acid SRC and Sucrose SRC positively correlated with cookie thickness (r = 0.31) and (r = 0.23). Negative correlation coefficients were observed in water SRC and cookie thickness (r = −0.27). Lactic acid SRC also negatively correlated with cookie spread ratio (r = −0.34). Sodium carbonate SRC was found to be negatively correlated with cookie diameter (r = −0.19) and cookie spread ratio (r = −0.16). The SRC test is a promising method for the evaluation of soft wheat varieties on the basis of their biochemical characteristics.     

A study of the synergistic antilisterial effects of a sub-lethal dose of lactic acid and essential oils from Thymus vulgaris L., Rosmarinus officinalis L. and Origanum vulgare L.

Commercial essential oils of Thymus vulgaris L., Rosmarinus officinalis L. and Origanum vulgare L. were chemically characterized by GC, GC/MS analyses. The antilisterial activity of the oils, and the sub-lethal concentration of lactic acid were established by the agar-well diffusion method. The bactericidal kinetics of the diluted oils (50 ppm, 100 ppm, 200 ppm and 300 ppm) and their mixtures with 50 ppm of lactic acid were determined by optical density (OD₆₀₀) measurements. The results suggest that a sub-lethal dose of lactic acid noticeably increased the antilisterial activity, especially of rosemary and thyme oils, but that the synergistic effects were reduced with higher concentrations of oils.     

Use of response surface methodology to investigate the effects of milling conditions on damaged starch,dough stickiness and chapatti quality

Response surface methodology was used to investigate the influence of three factors namely mill aperture, feed rate and moisture content of wheat grain on the damaged starch content of whole wheat flour from Lokwan wheat cultivar, dough stickiness and chapatti (Indian unleavened flat bread) quality. Each predictor variable was tested at three levels. Aperture was varied as 2, 3 and 4 mm in a stone mill, feed rate as 0.21, 0.63 and 1.05 min for 200 g wheat grains and grain moisture content as 8.6, 14.3 and 20% w/w. Flours containing varying amounts of damaged starch ranging from 6.1% to 26.90% were obtained and these were evaluated for dough stickiness and chapatti quality. Dough stickiness was increased with decreased aperture. With decreased aperture and increased grain moisture content softness of the chapatti was improved.     

Persistence and activity towards Sitophilus zeamais (Coleoptera: Curculionidae) of pirimiphos-methyl sprayed at different temperatures on maize

The air temperature in storage units in tropical areas frequently exceeds 50°C during the warmest periods of the day. Since protectant insecticides are sprayed on grains under these conditions, such high temperatures may interfere with the insecticidal activity. To assess this possibility we sprayed maize grains with pirimiphos-methyl 500 EC (0.8 ml c.p./l and 1.5 l/t) at different temperatures (25°C, 30°C, 35°C, 40°C, 45°C, and 50°C) and 55% r.h. The grains were then maintained at 27±1°C and 55±5% r.h. throughout the experiment which lasted 90 days. Residues of pirimiphos-methyl on the sprayed grains were analyzed every 30 days. Grain samples were assessed every 15 days after the insecticide spraying for their effect on the maize weevil, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae). Insect mortality was evaluated after 24 and 48 h of exposure to the treated grain. The level of pirimiphos-methyl residue on maize grains decreased with an increase in storage period and air temperature during the insecticide spraying (varying from 11.0±0.1 to 1.1±0.1 ppm, corresponding to the residue levels at 25°C on the day of the spraying and after spraying at 50°C and 90 days of storage). The same trend was observed for mortality of the maize weevil, which dropped from 95.4±13.3% to 2.5±2.5% after 90 days storage after insecticide spraying at 50°C. These results indicate that temperature at spraying can affect insecticide persistence and activity during storage.     

Behavior of female Rhyzopertha dominica (Coleoptera: Bostrichidae) in a mono-layer of wheat treated with diatomaceous earth

Adult female lesser grain borers (Rhyzopertha dominica [F.]) were observed in a mono-layer of wheat sandwiched between two layers of glass to determine if movement patterns and survival rates differed in wheat that was admixed with diatomaceous earth (DE) compared with untreated wheat. Observations were also made to determine if responses to DE differed depending on the commercial formulation of DE tested at the labeled rates. Mortality was higher in the DE treatments than in the untreated controls, and also varied according to the DE formulation. In wheat treated with 1000 ppm Dryacide^®, 400 ppm Protect-It^®, and 500 ppm Insecto™ (labeled rate for the individual products), mean percentage mortality was 100±0, 71.4±10.1, and 57.1±11.1, respectively. Although total distance traveled and the number of turns taken by the beetles was lower in the Dryacide treatment compared to the untreated controls, the movement patterns were not significantly different among the three DE treatments. Observed differences in mortality are likely related to DE products or amount applied rather than to differences in DE exposure resulting from movement behavior.     

Detection of internal insects in wheat using a conductive roller mill and estimation of insect fragments in the resulting flour

A laboratory roller mill that monitors the conductance of kernels that pass through it was tested for its ability to estimate the number of insect fragments in flour after milling. This system can test a kilogram of whole wheat in approximately 1 min and requires little sample preparation. Hard red winter wheat samples were infested with lesser grain borers and stored at 24 °C. Infestations ranged from 12 to over 2000 infested kernels per 1 kg or per 30,000 kernels. After crushing of samples in the conductance instrument, the samples were milled into flour and sub-samples were sent to two laboratories for insect fragment analysis. The insect fragments were proportional to the number of detection incidences obtained using the conductance instrument and X-ray images. Insect fragment counts per 50 g of flour ranged from 0 to over 5000. For insect fragment counts from 0 to 250, correlations between fragment counts and conductance mill detection were 0.75 and 0.80 from two separate cereal chemistry laboratories. Therefore, the conductance mill is potentially a good method for testing incoming grain for live internally infesting insects; it is able to test 1 kg of grain in about 1 min and can detect low levels (as low as three insects) of live internal infestations in a 1- or 2-kg sample.