Kernel Damage Research Articles

Fumonisins in corn: correlation with Fusarium sp. count, damaged kernels, protein and lipid content

Natural fungal and fumonisin contamination were evaluated in 109 freshly harvested corn samples from Paraná State and correlated to damaged kernels (%). In addition, healthy and damaged kernels of 24 corn samples were selected in order to compare the mycoflora profile and fumonisin levels. The correlation among protein/lipid content and fumonisin levels was also analyzed in the 15 most frequently cultivated corn hybrids. Total fungal colony count in 109 freshly harvested corn samples ranged from 1.9x10(4) to 3.5x10(6) CFU/g, Fusarium sp. count from 1.0x10³ to 2.2x10(6) CFU/g, and fumonisin levels from 0.13 to 20.38 µg/g. Total fungal colony/Fusarium sp. count and fumonisin levels showed positive correlation (p < 0.05). In addition, there was a positive correlation between damaged kernels (%) and total fungal colony/Fusarium sp. count (p < 0.05). Fumonisin levels in healthy kernels ranged from 0.57 to 20.38 µg/g, while in the damaged kernels it ranged from 68.96 to 336.38 µg/g. No significant correlation among the fumonisin levels and the protein or lipid content was observed. The results showed the importance of constant monitoring of toxigenic fungi and fumonisin contamination in corn and corn-based foods in order to assure the quality and safety of products and to minimize the potential hazards to human and animal health.

Effect of <I>Bacillus thuringiensis</I> Transgenic Corn for Lepidopteran Control on Nontarget Arthropods

Field populations of nontarget arthropods in transgenic corn with the MON 810 event expressing the Cry1Ab endotoxin from Bacillus thuringiensis variety kurstaki (Bt) were compared with those in conventional, near isogenic corn. The study was conducted at two locations in Georgia in 2001 and 2002 using visual counts, pitfall traps, and corn ear insect evaluations. Results were analyzed by trial using a repeated-measure analysis of variance (ANOVA) and a combined ANOVA of all trials. The only insect whose numbers were strongly affected by the Bt corn was the corn earworm, Helicoverpa zea (Boddie), a target insect. When averaged over all trials, larvae and adults of sap beetles, Carpophilus spp. (mostly C. lugubris Murray), and larvae of the otitid fly Euxesta stigmatis Loew were less abundant on Bt than non-Bt corn ears. Kernel damage caused by H. zea was less in Bt corn, which presumably made Bt corn ears less attractive to these insects. There were no consistent significant differences in nontarget phytophagous and predaceous arthropods in the visual counts and pitfall traps between Bt and non-Bt corn. One exception was Nabis spp., which was less abundant in Bt than non-Bt corn in the combined analysis. Flea beetles, mostly corn flea beetle, Chaetocnema pulicaria Melsheimer, were more abundant on Bt than non-Bt corn in the combined analysis but presumably were not adversely affected by the Bt corn. With the exception of nabids, these results indicate that transgenic Bt field corn containing the MON 810 event did not have an adverse effect on populations of nontarget phytophagous or predaceous arthropods in the Georgia corn system.

Effect ofBacillus thuringiensisTransgenic Corn for Lepidopteran Control on Nontarget Arthropods

Field populations of nontarget arthropods in transgenic corn with the MON 810 event expressing the Cry1Ab endotoxin from Bacillus thuringiensis variety kurstaki (Bt) were compared with those in conventional, near isogenic corn. The study was conducted at two locations in Georgia in 2001 and 2002 using visual counts, pitfall traps, and corn ear insect evaluations. Results were analyzed by trial using a repeated-measure analysis of variance (ANOVA) and a combined ANOVA of all trials. The only insect whose numbers were strongly affected by the Bt corn was the corn earworm, Helicoverpa zea (Boddie), a target insect. When averaged over all trials, larvae and adults of sap beetles, Carpophilus spp. (mostly C. lugubris Murray), and larvae of the otitid fly Euxesta stigmatis Loew were less abundant on Bt than non-Bt corn ears. Kernel damage caused by H. zea was less in Bt corn, which presumably made Bt corn ears less attractive to these insects. There were no consistent significant differences in nontarget phytophagous and predaceous arthropods in the visual counts and pitfall traps between Bt and non-Bt corn. One exception was Nabis spp., which was less abundant in Bt than non-Bt corn in the combined analysis. Flea beetles, mostly corn flea beetle, Chaetocnema pulicaria Melsheimer, were more abundant on Bt than non-Bt corn in the combined analysis but presumably were not adversely affected by the Bt corn. With the exception of nabids, these results indicate that transgenic Bt field corn containing the MON 810 event did not have an adverse effect on populations of nontarget phytophagous or predaceous arthropods in the Georgia corn system.

Feasibility of impact-acoustic emissions for detection of damaged wheat kernels

A non-destructive, real time device was developed to detect insect damage, sprout damage, and scab damage in kernels of wheat. Kernels are impacted onto a steel plate and the resulting acoustic signal analyzed to detect damage. The acoustic signal was processed using four different methods: modeling of the signal in the time-domain, computing time-domain signal variances and maximums in short-time windows, analysis of the frequency spectrum magnitudes, and analysis of a derivative spectrum. Features were used as inputs to a stepwise discriminant analysis routine, which selected a small subset of features for accurate classification using a neural network. For a network presented with only insect damaged kernels (IDK) with exit holes and undamaged kernels, 87% of the former and 98% of the latter were correctly classified. It was also possible to distinguish undamaged, IDK, sprout-damaged, and scab-damaged kernels.

The Effects of Damaged Kernel Caused by Combine Harvester Settings on Milled Rice Free Fatty Acid Levels

ABSTRACTMilled rice surface oil and free fatty acid (FFA) contents determine rice acceptability to the brewing industry. Both could subsequently contribute to beer off‐flavors and thus compromise milled rice brewing quality. Controlling milled rice FFA by harvesting practices could be important in maintaining brewing quality as some rough rice is damaged by hull removal and/or bran disruption during harvesting. To determine the effect of harvester speed on kernel damage, the long‐grain rice variety Cocodrie was harvested at 3 different combine harvester settings and the percent of damaged kernel (w/w) was measured. Combine harvester cylinder speed had a significant effect on rough rice kernel damage. The percentages of damaged kernels for 550, 850, and 1000 rpm cylinder speeds were 1.2%, 4.0%, and 9.0%, respectively. The FFA level of milled rice with varying amount of damaged kernels was investigated over 6 mo of storage. The faster harvester cylinder speeds resulted with time in significantly greater FFA levels in “as‐harvested” rice. The FFA content of 1000 rpm as‐harvested rice almost reached the 0.1% (w/w) level. The greater the amount of damaged kernel, the greater was the milled rice FFA level, and it was significantly greater than milled rice with no damaged kernels during accelerated storage. The as‐harvested rice with 1000 rpm had the highest FFA level, followed by 850 and 500 rpm.

Management of five stored‐product insects in wheat with pirimiphos‐methyl and pirimiphos‐methyl plus synergized pyrethrins

Hard red winter wheat was treated with pirimiphos-methyl at 4, 6 and 8 mg kg(-1), synergized pyrethrins at 0.38, 0.75, 1.13 and 1.5 mg kg(-1), and combinations of the two insecticides, to conduct laboratory bioassays against four beetle pests of stored grain, red flour beetle Tribolium castaneum (Herbst), rusty grain beetle Cryptolestes ferrugineus (Stephens), lesser grain borer Rhyzopertha dominica (F), and rice weevil Sitophilus oryzae (L), and one moth pest, Indianmeal moth Plodia interpunctella (Hubner). Beetle adults and P interpunctella larvae survived well on control wheat, producing a large number of progeny (65-1037 insects per container). Kernel damage in control wheat among the insect species ranged from 9 to 99%. On pirimiphos-methyl-treated wheat, mortality of R dominica adults was > or =72%, but that of the other beetle species and P interpunctella larvae was 100%. Progeny were not produced on pirimiphos-methyl-treated wheat, and the kernel damage was negligible (< or =1%). Synergized pyrethrins were ineffective against the five insect pests. Pirimiphos-methyl combined with synergized pyrethrins was not superior to pirimiphos-methyl alone against the five insect pests. Pirimiphos-methyl is not registered in the USA for use on wheat, but our results suggest that it could be a viable grain protectant at rates of 4-8 mg kg(-1).

Obstructive non-woven fiber barriers for reducing red-winged blackbird damage to sweet corn

Red-winged blackbirds ( Agelaius phoeniceus L.) annually destroy substantial amounts of sweet corn ( Zea mays L.) during the summer. No-choice feeding trials were conducted to assess the efficacy of spraying sweet corn ears with obstructive polymer fibers (ethylene vinyl acetate, EVA) as a means of reducing damage by blackbirds. Experiments were conducted with captive blackbirds and standing sweet corn between 18 September and 10 October 1997 and 1998. Relative to control ears, fiber treatment reduced the percentage of ears with husk damage by 10–12% ( P<0.03), and kernel damage by 10–11% ( P⩽0.01). However, once birds had penetrated the husk, the percentage of kernels lost was similar for fiber-treated and control ears. Currently, this technique is not cost effective. However, with improvements in application of this technology, obstructive non-woven EVA fibers could reduce bird damage to sweet corn and other crops, and may compliment existing integrated pest management techniques.

Association of a Burrower Bug (Heteroptera: Cydnidae) with Aflatoxin Contamination of Peanut Kernels

Aflatoxin contamination of peanut kernels, Arachis hypogaea L., was associated with feeding by a burrower bug, Pangaeus bilineatus (Say). Kernel samples were divided into three grade categories: total sound mature kernels (TSMK), other kernels (OK), and damaged kernels (DK); and each of these grade categories was subdivided based on evidence of burrower bug feeding. Within TSMK, 100% of detectable aflatoxin contamination was associated with burrower bug kernel feeding, and kernels with feeding sites had a significantly higher concentration of aflatoxin than kernels without feeding sites (7.5 vs 0.0 ppb). Within the OK grade category, differences in aflatoxin contamination were not significant due to the inability to conclusively examine these kernels for feeding sites. Within the DK grade category, aflatoxin concentration was significantly higher in kernels with feeding sites than in kernels without observable feeding sites (286.5 vs 0.4 ppb), and 99.9% of contamination was associated with burrower bug feeding. Across all grade categories, aflatoxin levels were 65X higher in kernels with observable burrower bug feeding, and 98% of all aflatoxin contamination was associated with burrower bug feeding. The DK grade category had the highest concentration of aflatoxin and accounted for 45% of total contamination. Burrower bug-induced aflatoxin contamination of the TSMK grade category is particularly significant because this source would be most difficult to remove from the food supply. Contamination of the DK category is also economically significant because this grade component is specifically examined for Aspergillus at the buying point, and growers are severely penalized for detection.

Diallel Analysis of Fusarium Head Blight Resistance in Soft Red Winter Wheat

Fusarium graminearum Schwabe, the causative agent of Fusarium head blight (FHB), is an economically important pathogen of wheat (Triticum aestivum L.). Breeding FHB resistant wheat requires knowledge of the underlying genetic control of FHB resistance. While soft red winter (SRW) wheat breeders have begun to characterize germplasm for resistance, little information is available on the value of cultivars as parents in breeding for FHB resistance. Two diallel series of crosses, each involving nine SRW parents, were evaluated in both the greenhouse and field near Lexington, KY. The progeny and parents from the diallels were point inoculated with F. graminearum in both environments. FHB severity, deoxynivalenol (DON) level, and kernel damage were recorded. FHB severity ranged from 4.9 to 84.3% in the greenhouse and from 16.4 to 86.7% in the field. Significant general and specific combining ability effects were observed in both diallels in both environments. The nature of the resistance varied with diallel and with screening environment. On the basis of ratios of variance components, resistance in diallel 1 depended primarily on additive genetic effects, while in diallel 2 in the field dominance effects prevailed. Correlations between the greenhouse and field screening environments were low (0.36 in diallel 1 and 0.14 in diallel 2). Genotype × environment interactions were highly significant and due almost exclusively to rank change interactions. These results do not support indirect selection in a greenhouse environment for resistance expressed in the field.

Persistence and efficacy of spinosad residues in farm stored wheat.

Degradation and insecticidal effectiveness of spinosad residues were evaluated in Kansas during November 2000 to November 2001 in farm bins holding wheat (34-metric ton capacity). About 50 kg of hard red winter wheat from each of three bins were brought to the laboratory and treated separately with 1-ml aqueous suspensions of spinosad to provide rates of 0.1, 0.5,1, 3, 6 mg (AI)/kg of wheat. Wheat treated with distilled water served as the control treatment. Untreated and spinosad-treated wheat samples (250 g each) were placed in three plastic pouches of two different mesh sizes, and buried 2.5 cm below the grain surface. Pouches with large mesh openings were used to monitor insect infestations and kernel damage in untreated and spinosad-treated samples. Pouches with small mesh were used for extracting spinosad residues and for conducting laboratory bioassays with adults of the lesser grain borer, Rhyzopertha dominica (F.) and red flour beetle, Tribolium castaneum (Herbst) at 28 degrees C and 65% RH. Wheat temperature and relative humidity near the pouches during the 1 yr of storage ranged from -10 to 32 degrees C and 50 to 70%, respectively. Moisture of wheat samples varied from 12.4 to 13%. Observed spinosad residues on wheat samples were 25% less than the calculated rates of 0.1 to 6 mg/kg. However, these residues were stable during the 1 yr of storage, and killed all R. dominica adults exposed for 14 d in the laboratory. Mortality of T. castaneum adults increased with an increase in spinosad rate. The linear regression slope of LD50s (0.3-2.7 mg/kg) against storage time was not significantly different from zero, indicating no loss in spinosad toxicity to T. castaneum adults. Insect species, insect numbers, and kernel damage over time in wheat samples inside pouches with large mesh openings were highly inconsistent, and failed to accurately characterize spinosad performance. Laboratory bioassays with R. dominica and T castaneum adults using grain from pouches with small mesh openings accurately gauged spinosad persistence and insecticidal activity under the field conditions.

PH—Pastharvest Technology: Performance Evaluation of a Local Maize Sheller

Manual shelling of maize is a time-consuming and tedious operation. The few existing mechanized shellers on Nigerian farms are imported and out of reach of the rural peasant farmers that are characterized by small holdings and low income. The power requirement of such shellers is high and hence, the prime mover is very expensive. The work reported here is on the performance evaluation of a locally fabricated maize sheller. Cob breakup, shelling efficiency, kernel damage and separation loss were measured for three varieties of local maize ( Zea mays) over three harvest dates. Harvest date was found to have significant effects on most of the variables studied because of the variations in moisture contents. The kernel damage and cob breakup decreased significantly with later harvest date. The shelling efficiency was not significantly affected by changes in the harvest date for ‘Nsukka Super’ and ‘Nsukka Local’ maize varieties but the effects on the ‘Agbuda Special’ maize variety were more variable. The shelling capacity was not significantly influenced by harvest date or maize variety. Generally, the performance of the maize sheller was not influenced by maize the variety; therefore, the maize sheller can comfortably be used to shell local maize varieties.

Effectiveness of spinosad on four classes of wheat against five stored-product insects.

Spinosad is a commercial reduced-risk pesticide that is naturally derived. Spinosad's performance was evaluated on four classes of wheat (hard red winter, hard red spring, soft red winter, and durum wheats) against adults of the lesser grain borer, Rhyzopertha dominica (F.); rice weevil, Sitophilus oryzae (L.); sawtoothed grain beetle, Oryzaephilus surinamensis (L.); red flour beetle, Tribolium castaneum (Herbst); and larvae of the Indianmeal moth, Plodia interpunctella (Hübner). Beetle adults (25) or P. interpunctella eggs (50) were exposed to untreated wheat and wheat treated with spinosad at 0.1 and 1 mg (AI)/kg of grain. On all untreated wheat classes, adult beetle mortality ranged from 0 to 6%, and P. interpunctella larval mortality ranged from 10 to 19%. The effects of spinosad on R. dominica and P. interpunctella were consistent across all wheat classes. Spinosad killed all exposed R. dominica adults and significantly suppressed progeny production (84-100%) and kernel damage (66-100%) at both rates compared with untreated wheat. Spinosad was extremely effective against P. interpunctella on all wheat classes at 1 mg/kg, based on larval mortality (97.6-99.6%), suppression of egg-to-adult emergence (93-100%), and kernel damage (95-100%), relative to similar effects on untreated wheats. The effects of spinosad on S. oryzae varied among wheat classes and between spinosad rates. Spinosad was effective against S. oryzae, O. surinamensis and T. castaneun only on durum wheat at 1 mg/kg. Our results suggest spinosad to be a potential grain protectant for R. dominica and P. interpunctella management in stored wheat.

Corn earworm, Helicoverpa zea (Lepidoptera: Noctuidae) and other insect associated resistance in the maize inbred Tex6.

A 2-yr field and laboratory study investigated insect resistance of the maize, Zea mays L., inbred Tex6, which has previously demonstrated resistance to Aspergillus ear rot and aflatoxin production, relative to susceptible inbred B73. Field studies indicated significantly greater resistance to insect feeding of V4-V8 growth stage Tex6 plants compared with B73 plants in both years, primarily to flea beetles (Chaetonema spp.). Field studies of natural (1999) and artificial (2000) infestations of corn earworms, Helicoverpa zea (Boddie), indicated much lower levels of kernel damage at milk stage (approximately three-fold) and smaller surviving larvae (approximately three-fold) in Tex6 compared with B73 ears. At harvest similar trends in reduction of numbers of damaged kernels per ear, as well as incidence and numbers of kernels per ear symptomatically infected by Fusarium spp. were noted. Laboratory studies indicated little difference in mortality or survivor weight of caterpillars or sap beetle adults caged with milk stage kernels of the two inbreds. However, assays with silks indicated significantly greater mortality of H. zea in both 1999 and 2000, and European corn borer, Ostrinia nubilalis (Hübner) in 1999 (only year tested) when fed Tex6 silks compared with B73 silks. Pollinated Tex6 silks were generally darker colored and more toxic than unpollinated silks. Thus, it is possible that commercially usable inbreds with resistance to insects, which also contribute to the mycotoxin problem through vectoring and damage, could be produced using Tex6 as a source.

Comparison of the Occurrence of Kernel Damage in Rice Plants Grown in a Heated Greenhouse and in a Paddy Field of High Temperature Year.

The percentages of the number of heat-damaged kernels, white-back or basal-white kernels and milky-white kernels in a heated greenhouse were compared with those in a paddy field in a high-temperature year to examine whether the greenhouse observation could represent the varietal difference in the tolerance to the damages in the field condition. Twelve varieties of rice, considered to have various degrees of tolerance to kernel damage due to high temperature, were cultivated in the greenhouse on benches (70cm high, 15cm deep) filled with paddy field soil. The plants were exposed to high temperatures of 27.6∼28.3°C (day/night temperature: 29.7∼30.1°C/25.3∼26.3°C) during the period from heading to maturity. At maturity, the percentages of white-back or basal-white kernels and milky-white kernels were counted in eight plants of each variety. A significant difference (P<0.05) in the percentage of occurrence of white-back or basal-white kernels was recognized among varieties exposed to high temperatures in the greenhouse. There was a significant positive correlation between the occurrence of these kernels in the greenhouse and in the paddy field in 1999 when high-temperature days continued during summer. There was no significant varietal difference in the occurrence of milky-white kernels. These results suggested that the percentages of white-back and basal-white kernels were appropriate indicators and the tolerance to high temperature. We proposed that five varieties, Koshijiwase (resistant), Kokoromachi (moderately resistant), Akitakomachi (moderate), Hitomebore (moderately sensitive) and Hatsuboshi (sensitive) could be the indicator varieties to the tolerance.

Relationship Between Community Structure and Southern Green Stink Bug (Heteroptera: Pentatomidae) Damage in Macadamia Nuts

The effect of host weed phenology, abundance, and diversity and natural enemies on the population dynamics of the southern green stink bug, Nezara viridula (L.), in Hawaiian macadamia orchards was investigated. We found that the highest kernel damage occurred immediately following abrupt reductions in the flowering and fruiting stages of host weeds. Areas with the greatest diversity of host weeds showed higher damage, presumably because of higher N. viridula population levels. Predation rates on sentinel egg masses were highest over the two seasons in areas where the bigheaded ant, Pheidole megacephala (F.), comprised a large portion of the ant fauna. In one of the orchards, P. megacephala and the longlegged ant, Anoplolepis longipes (Jerdon), occurred in a spatial mosaic where the boundaries shifted back and forth over time. Sentinel egg masses placed in these two adjacent areas showed predation rates were highest in the areas dominated by P. megacephala, and intermediate in the interface zone and lowest where only A. longipes were found. The importance of weed phenology and natural enemy induced mortality is discussed.

Pecan Varietal Differences in Hemipteran Kernel Damage

Pecan, Carya illinoensis Wangenh. (K. Koch), is susceptible to feeding by leaffooted bugs (Hemiptera: Coriedae) and stink bugs (Hemiptera: Pentatomidae) from fruit set to post harvest. These hemipterans are difficult to control with insecticide sprays. We found that 33 pecan varieties had consistent and significant differences in the incidence of hemipteran kernel damage indicating that host plant resistance may help solve this problem. The rank of varieties for average incidence of damage over 4 yrs, from highest to lowest was: ‘USDA 53-11-139’, ‘USDA 57-7-22’, ‘Shawnee’, ‘Moreland’, ‘USDA 40-9-266’, ‘USDA 49-20-112’, ‘Linberger’, ‘Cape Fear’, ‘Robinson’, ‘Shoshoni’, ‘USDA 64-11-17’, ‘USDA 55-12-17’, ‘Caddo’, ‘USDA 62-5-8’, ‘Sioux’, ‘Melrose’, ‘Tejas’, ‘Pawnee’, ‘Forkert’, ‘Kiowa’, ‘Owens’, ‘Candy’, ‘Gloria Grande’, ‘USDA 49-1-182’, ‘Western Schley’, ‘Creek’, ‘USDA 53-3-36’, ‘USDA 41-19-20’, ‘Maramec’, ‘Sumner’, ‘GraBohls’, ‘Kanza’, and ‘USDA 53-9-1’. Many of the more tolerant varieties have desirable kernel quality and often have good production characteristics, while many of the more susceptible varieties are also not horticulturally desirable. Adults of the southern green stinkbug, Nezara viridula (L.), and the leaffootted bug, Leptoglossus phyllopus (L), when placed in cages on pecan nut clusters by sex, differed in their ability to cause damage to ‘Cape Fear’, ‘Creek’, ‘USDA 64-11-17’, ‘Melrose’, and ‘Shoshoni’. Males of both species caused less damage than females, and N. viridula generally caused more damage than L. phyllopus.

Evaluation of Yieldgard Transgenic Resistance for Control of Fall Armyworm and Corn Earworm (Lepidoptera: Noctuidae) on Corn

Fall armyworm, Spodoptera frugiperda (J. E. Smith), and corn earworm, Helicoverpa zea Boddie, perennially cause leaf and ear damage to corn in the southeastern USA. Development of transgenic hybrids expressing insecticidal endotoxin from Bacillus thuringiensis (Bt) offers a new approach to managing these insects in field corn. Transgenic Bt hybrids with either the Bt11 or MON810 event, collectively known as YieldGard Technology, were evaluated for control fall armyworm and corn earworm in southern Georgia during 1998, which coincided with a severe outbreak of fall armyworm. YieldGard Bt resistance consistently reduced whorl infestation and damage to low levels and also reduced ear infestations and larval numbers per ear. However, larval establishment did occur on many ears of resistant plants, but once established in ears, larvae of both species developed more slowly and caused much less kernel damage on resistant than susceptible plants. We found no relationship between YieldGard Bt resistance and corn grain aflatoxin concentrations. Yield responses were variable with the prevention of yield loss being proportional to the severity of insect damage. These results indicate that YieldGard resistance is effective in preventing significant losses to field corn by fall armyworm and corn earworm. Further, evaluation under a variety of growing conditions and insect infestation levels is needed to clearly assess the value of YieldGard technology to corn growers in the Southeast.

DETECTION OF PISTACHIO NUTS WITH CLOSED SHELLS USING IMPACT ACOUSTICS

An acoustical sorting system was developed to separate pistachio nuts with closed shells from those with open shells. The system includes a microphone, digital signal processing hardware, material handling equipment, and an air reject mechanism. It was found that upon impact with a steel plate, nuts with closed shells emit sound with higher signal magnitudes for the first 0.33 ms than do nuts with open shells. After this interval, nuts with closed shells emit sounds with lower signal magnitudes than those with open shells. Linear discriminant analysis was used to classify nuts using three features extracted from the microphone signal during the first 1.4 ms after impact. One of the discriminant features is the integrated absolute value of microphone output signal during the first 0.11 ms after impact. The other two features are the number of data points in the digitized microphone signal, between 0.6 and 1.4 ms after impact, that have a slope and signal magnitude below preset threshold levels. The classification accuracy of this system is approximately 97%. Throughput rate is approximately 40 nuts/s. Cost is about $7,000 to $10,000 per channel. This cost is much lower than that of color sorters used to remove other pistachio defects while throughput is comparable. Currently, closed–shell pistachio nuts are removed by mechanical devices. These devices have a lower classification accuracy (95%) and damage kernels in open–shell pistachios by “pricking” them with a needle. The needle hole can give the appearance of an insect tunnel and cause rejection by the consumer. The newly developed system does not cause such damage. Increased sorting accuracy of the acoustic sorter, coupled with low cost, enables a payback period of less than one year.

Influence of Pentatomid Insects on the Physical Dough Properties and Two-layered Flat Bread Baking Quality of Syrian Wheat

Field investigations were carried out of the incidence of pentatomid insects at different stages of development, as well as development of the maturing wheat plant, and revealed that the insects can cause damage to the wheat grain while in both nymphal and adult stages. The influence of pentatomid infestation on quality characteristics of bread and durum wheats is described. The influence of pentatomid-infested kernels on physical dough characteristics and two-layer flat bread baking quality was studied. As little as 5% damaged kernels changed the physicochemical properties of the wheat. Farinograph development and stability times were reduced by 60% and 85%, respectively, while the mixing tolerance index was increased by 300% (from 50 to 310 Brabender units). Two-layered flat bread baking quality was rather more tolerant of small amounts of damaged kernels, but additions of 10% or more had a significant effect on bread quality, and the presence of 20% damaged kernels made it impossible to produce satisfactory two-layered flat bread. Dough-handling properties were affected to the extent that the dough could not be moulded or sheeted, and the bread burned during the short (45 s) baking time.

AUTOMATED SORTING OF PISTACHIO NUTS WITH CLOSED SHELLS

An automated machine vision system was developed to identify and remove pistachio nuts with closed shells from processing streams. The system includes a novel material handling system to feed nuts to linescan cameras without tumbling. The camera output signals are input to digital signal processing boards which extract image features characteristic of closed and open shell pistachios. The classification accuracy of this machine vision system for separating open shell from closed shell nuts is approximately 95%. The system has a throughput rate of approximately 40 nuts per second and cost of about $15,000 per channel. This throughput and cost is comparable to color sorters used to remove other pistachio defects. Currently, closed shell pistachio nuts are removed by mechanical devices. These devices also have a classification accuracy of about 95% but damage kernels in open shell pistachios by “pricking” them with a needle. The needle hole can give the appearance of an insect tunnel and cause rejection by the consumer. The newly developed machine vision system is a non-invasive inspection method.