INVENTARISASI HAMA PASCAPANEN JAGUNG DALAM PENYIMPANAN DI TINGKAT PETANI DAN PEDAGANG DI KUPANG

This research was conducted at pest and plant disease laboratory, faculty of agriculture Nusa Cendana University in Kupang. Corn sample is taken from fanner in Amarasi, Kupang Timur, Kupang Barat and from the trader in Oesapa, Oesao, Penfui. This research intends to inventory pest after yields corn and to know the damage level of corn in farmer and trader. This research used a 32 kg corn sample for quotation methods. The observed variable is pest insect species, imago population, damage seed percentage, Weight decrease percentage, water level, temperature and moisturizer. Pest insect population and species observed on 1 kg corn. While seed damage and weight decrease per cent on 100 g corn seed and 5 g for water level. Data result tabulated and descriptively analyzed. The result of the research showed 1 pest insect species in the farmer corn storage is S.zeanmys and 2 species in trader corn storage is S.zeanmys and T confusum. Highest population S.zeamays founded in Penfui trader by 50,50/kg and lowest population 4,50/kg in farmer at Amarasi. T.confusum population only founded in trader not in farmer level. Highest population 2,17/kg in Penfui trader and lowest 0,17/kg in Oesapa trader. While highest seed damage percentage founded in Penfui trader by 11,13% and lowest 1,22% in farmer at Amarasi and highest weight decrease percentage founded in Oesapa trade by 0,77% and lowest 0,25% in farmer at Kupang Barat

Immunoaffinity Column Coupled with Liquid Chromatography for Determination of Fumonisin B1 in Canned and Frozen Sweet Corn

A modified liquid chromatographic (LC) method for determining fumonisin B1 (FB1) in corn was applied to canned and frozen sweet corn. The corn is extracted with methanol–water (8 + 2), and the extract is filtered. The filtrate is diluted with water and passed through an immunoaffinity column. After the column is washed with water, FBi is eluted with methanol–water (8 + 2). The eluate is evaporated to dryness by using a vacuum concentrator, and the residue is dissolved in acetonitrile–water (1 +1). FB1 is derivatized with o-phthaldialdehyde. The derivative is separated on a reversed-phase C18 LC column using acetonitrile–water–acetic acid (50 + 50 + 1) and quantitated with a fluorescence detector. Recoveries of FB1 from canned and frozen corn spiked over the range of 50–200 ng/g were 76–88%. The limit of determination was about 25 ng/g, and the limit of detection was about 4 ng/g. The method was applied to 97 commercial canned and frozen sweet corn samples collected from different areas of the United States. Sixty samples contained no FB1. Low levels (trace–82 ng FB1/g corn) were found in 35 samples; 235 ng FB1/g was found in 1 canned corn sample, and 350 ng FB1/g was found in 1 frozen corn sample.

Five-Year Study of Mycotoxins in Virginia Wheat and Dent Corn

Every year during the 5-year period 1976-1980, approximately 100 samples each of corn and wheat from trucks delivering the grains at elevators in Virginia were collected by personnel of the Federal Grain Inspection Service and shipped to NRRC. Samples were analyzed as soon as possible for aflatoxin, zearalenone, and ochratoxin A. The 3 mycotoxins were not detected in any wheat sample. Zearalenone and ochratoxin A were not found in any corn sample; however, aflatoxin was detected in at least 25% of the corn samples from every crop year. In 1976-1980, the incidence of aflatoxin at levels of 20 ng/g or more (the Food and Drug Administration guideline) ranged from 18 to 61%; aflatoxin incidence above 100 ng/g was 5-29%. The average aflatoxin levels in corn samples collected in the 5 years varied from 21 to 137 ng/g. Moisture content of the samples was not determined, so aflatoxin levels given may be higher than they were at harvest. However, there are obviously differences from year to year. In freshly harvested corn samples collected by fieldmen of the Statistical Reporting Service in yield surveys in 1978 and 1979, aflatoxin incidence above the FDA guideline was 10 and 13%, and above 100 ng/g was 4 and 7%. The average aflatoxin level in all samples collected in 1978 was 13 ng/g and in 1979, 36 ng/g. Some aflatoxin can be expected yearly in Virginia corn, but the incidence and levels vary from year to year.

Determination of Zearalenone in Corn: Collaborative Study

Corn samples spiked at levels of 100, 300, 1000, and 2000 μg zearalenone/kg were sent to 22 collaborators for analysis by the Eppley method. All samples were yellow corn except one white corn sample spiked at 2000 μg/kg. Results from 16 collaborators were statistically analyzed. Only 4 of 16 collaborators detected zearalenone in the sample containing 100 μg/kg, but 11 detected the toxin in the sample containing 300 μg/kg. Average recoveries from all samples were 129% at 300 μg/kg, 101% at 1000 μg/kg, and 88% at 2000 μg/kg. The between-laboratory coefficients of variation were 53.0% at 300 μg/kg, 38.2% at 1000 μg/kg, and 27.0% at 2000 μg/kg. Five naturally contaminated corn samples, one in triplicate, were also provided. The mean level of zearalenone in the naturally contaminated samples ranged from 431 to 7622 μg/kg. The mean coefficient of variation for all samples was 40.5%. Two collaborators measured quantities of zearalenone on thin layer chromatographic plates densitometrically. Their results were not included in the statistical analysis, but the results indicated that densitometric measurement, given proper dilutions of solutions, could be used. The method has been adopted as official first action.