| Author | Message | ||
     Russell Wilkie (rwilkie) New member Username: rwilkie Post Number: 5 Registered: 2-2009 |
Hi Jerry, Well yes, aflatoxin B1 I believe is in the top 5 carcinogens in the world. We found that peanuts grown in highly humid areas, and thus areas where crops were under minimal water stress usually were free from aflatoxin contamination. Groundnuts grown in drought affected areas on the other hand were the most likely to be highly contaminated. We believed that water stressed plants would be less likely to produce adequate quantities of phytoalexins and therefore less likely to fend off attack from fungal species that thrive on metabolising peanuts. Only limited correlations between aflatoxin-moisture, aflatoxin-oil, aflatoxin-linoleic acid and aflatoxin-oleic acid were found, although there was information at the time to suggest linoleic acid was involved in the metabolic process that produced aflatoxin. Cheers, Russell | ||
| Jerry Jin (jcg2000) Junior Member Username: jcg2000 Post Number: 7 Registered: 1-2009 |
Fungi grow under humid environment. The moisture content in a peanut might correlate to its mycotoxin level. Have you found there is a correlation between them? If there is a correlation, one can measure moisture instead to know the possibility of aflatoxin contamination. Aflatoxin is a very strong carcinogen. | ||
| Russell Wilkie (rwilkie) New member Username: rwilkie Post Number: 4 Registered: 2-2009 |
We spent significant time looking into the use of NIR to quantify aflatoxin in milled peanuts. The sample itself was found to be challenging, as aflatoxin did not spread evenly throughout when milled and tumble mixed. Some peanuts have aflatoxin 'hotspots' in which aflatoxin accumulates in very small black, yellow, brown or green sections but not others. This is primarily caused by mechanical and/or insect damage during growth. Peanuts can also become completely contaminated throughout the flesh due to invasion of the fungus into the growing tip during pegging. For these reasons it was difficult to assess whether the contaminated or uncontaminated sections had been scanned during NIR analysis. This brought a whole new meaning to the word 'NIR sampling'. The aflatoxin content for each milled sample was also difficult to assess, as subsamples may contain 0ppb, 10,000ppb or anything in between. The negative binomial distribution of aflatoxin made it very difficult to arrive at a suitable quantitative model, whereby >95% samples were 0ppb. To help address this, we found logarithmic conversion of aflatoxin values did help. After much development time, we arrived at a NIR model that could qualify with 91% success whether a milled peanut sample had greater than or less than 8ppb aflatoxin contamination. The legal limit for aflatoxin in food in Australia at the time was 15ppb. This also meant we screened 9% samples incorrectly about the 8ppb threshold. Results were achieved on >400 samples. The production of aflatoxin initially occurs during times of crop stress arising from poor farming practices or poor environmental conditions and then continues to escalate if peanut handling/storage conditions are poor. We theorised that a multitude of factors relating to aflatoxin's presence would be measurable by NIR, even if aflatoxin itself was not. This theory led to the above results. Hope this helps. Cheers, Russell | ||
| David W. Hopkins (Dhopkins) New member Username: Dhopkins Post Number: 77 Registered: 10-2002 |
Nieves, I knew that Phil Williams had done a lot of work on vomitoxins, so I asked him to respond to your question. I hope this helps you. Here is his reply: David, you can forward this if you like. I have no experience with aflatoxin in maize, but have done some work on vomitoxin in wheat and barley. The fungus (Fusarium graminearum is the main one in Canada) affects the texture of the grain slightly, which changes the diffuse reflectance of the signal from the whole kernels. This allows us to detect vomitoxin (deoxynivalenol, or DON) with a certain degree of accuracy. This is not sufficiently reliable for quantitative work. With a range of from 0 to 10 ppm of DON the best SEP we have been able to achieve is about 0.6 ppm. The problem is that the slope (of NIRS :reference DON as determined by an ELISA test) is not very good (between 0.85-0.90). This means that the calibration models are not very transferable. There is some value in screening farmers' deliveries of feed wheat to feed mills, who are restricted to use of Fusarium-affected wheat below 5 ppm. Even with a SEP of 0.6 ppm the margin of error is sufficient for feed mills to determine whether the wheat is low enough to blend with non-affected, or slightly affected wheat, to bring the total below 5 ppm. In this way the farmers can get some payment for their wheat (otherwise it has to be destroyed), and the feed mill gets some cheap wheat, so everybody wins a bit! Phil | ||
| Nieves N��ez Romero (Edurne) New member Username: Edurne Post Number: 1 Registered: 1-2006 |
Sr.Power, five years before we are working with mycotoxins in corn y barley.Could you send us information about your work?Could you detected aflatoxin/vomitoxin with NIR?.Regards, Marta y Nieves | ||
| Bill Power |
Salut! Is it possible to analyze Vomitoxin/Aflatoxin in Corn/Wheat by NIR?! For Vomit,I'm looking @ <2ppm,Afla <30ppb! As these are singular,one would reasonably assume a distinct spectral signature,but,the question is,is the signal discernable from the "Noise"?! My "Lads"are on the case, inputing the "Necessaries".but I am much afeared we are reinventing the wheel,or,rather,barking up a Gumtree! Thanx! | ||
| Bruce H. Campbell (Campclan) |
I would doubt you could detect them with NIR. Water, with a very strong, separated band has a detection level about 1ppm and maybe a little lower depending on the matrix. A rule of thumb I use is: Detection limits very often range between 100 and 500 ppm. Bruce | ||
| Bill Power (Billy) |
Thank you Mr.Campbell!! We will still attempt this,as the spectra are stored for protein,fat,fibre@moisture} calibrations by my "Ingredient Specialist"! The mycotoxin results,on the same sample,come from the Micro Lads,via ELISA,hemce"Pas de Puisse"to input these constituents! Perhaps,there might be a "Blinding" functional group hung out on the" Tetracyclic Backbone" that,perchance,is a unique beacon in the monochromatic gale?! AHH!,there goes the Tea Break! Kidding aside,you probably DON"T realize how valuable this board is for us Workers in a Production Q/A lab!! Cut off by our Manager from all information,the little gray men counting beans Rule,OK [I pleaded for a subscription to JNIRS,she being a perfect speciemen proving that Darwin was WRONG,vetoed this],this site is "IT"! THANX!! | ||
| Sergio Lopez |
Dear Sir, We are a pharmaceutical company from León (NW of Spain), Laboratorios SYVA, SA; and are interested in technical information about NIR. First, I would like to know what kind of applications we can use by NIR technique in biopharmaceutical products (i.e. animal health vaccines, immunologics, etc.) What common technics could be replaced by NIR equipments? Thanks a lot for your attention. Best regards. |