We did some work in 2000 comparing spore loads (Penicillium species, the most common of which causes blue mold) on wooden bins and plastic bins. Both sets of bins had been used for a number of seasons, and both came from the same apple storage operation. We pulled them out of their empty bin piles in July and made no attempt to sanitize them before running them through an overhead bin drencher and then evaluating spore load by dilution plating of the drencher water. Some of the bins (both wooden and plastic) still had remnants of decayed fruit stuck on the bin floors.
One would assume that plastic bins, which appear relatively smooth compared to wooden bins, would harbor far less inoculum. In fact, we washed off roughly 2.2 billion Penicillium spores per bin from wooden bins and about 483 million spores per bin from the plastic bins. Thus, plastic bins may appear cleaner, but they can still harbor huge numbers of decay spores and other organisms. We also made an attempt to sanitize both kinds of bins using a quaternary ammonium sanitizer. Although we lowered spore numbers a bit with the sanitizer, we failed to really clean up either wooden or plastic bins in that trial in 2000. In retrospect, I realized that part of the failure in using the sanitizer was that our sanitizer solution was made using well water (presumably 55 F) and the contact time at that low temp was too short to get a good kill. Nevertheless, that work showed that sanitizing plastic bins is not much easier than sanitizing wooden bins. (Not all Penicillium species cause fruit decay, and we did not determine how many of the spores recovered from bins were the primary decay pathogen, P. expansum. Nevertheless, the conclusions about "cleanliness of bins still holds.) One of my gripes about the plastic bins is that most of them have an open-celled grid-work of reinforcing plastic on the underside of the bin floor. This reinforcing grid adds a tremendous amount of surface area for harboring dirt and spores and makes the undersides of the bins difficult to clean apart from using a high-pressure washer that directs the water flow to the undersides of the bins. Although plastic bins are not necessarily "clean" or easier to sanitize, I am still a proponent of using plastic bins. They stack better, support stack loads more reliably, and result in less bruising/scuffing of fruit that are in contact with the sides of the bin. One packinghouse operator told me that after they switched to plastic bins, they were amazed at how the switch had reduced their cullage for scuffing/bruising and that the reduced cullage over several years would go a long way toward helping to pay for the bins. Another area that no one has explored involves the foul "storage odors" that sometimes occur in apple storage rooms where wooden bins are used. Old wooden bins are full of basidiomycete wood decay fungi, and some of those fungi produce rather nasty odors. The wine industry struggled with off odors the came from fungi that were sometimes present in the corks (which are really just processed tree bark) until they learned to sanitize the corks by microwaving (or to avoid the problem by switching to synthetics). I don't think that the foul odors in apple storages have any impact on fruit quality. Although some of those off odors are evident on fruit eaten immediately after they are removed from the storage room, my perception is that any off odors that penetrate into the apple skin disappear quickly after the fruit are removed from storage, washed and packed. Nevertheless, if we are storing FOOD, it seems logical that the storage rooms should smell like apples, not like rotting wood. And speaking of perceptions, while plastic bins may not be free of fungal spores, they definitely LOOK cleaner and in today's world, it seems increasingly true that "perception is reality." On Sep 20, 2013, at 9:43 AM, "Kushad, Mosbah M" <[email protected]<mailto:[email protected]>> wrote: Hi Leslie: I am interested in their sanitation, ease of staking and storage, cost effectiveness, ease of washing, and any other issues related to differences in both material. Thanks, Mosbah Kushad University of Illinois From: [email protected]<mailto:[email protected]> [mailto:[email protected]<mailto:[email protected]>] On Behalf Of Huffman, Leslie (OMAFRA) Sent: Friday, September 20, 2013 8:29 AM To: Apple-crop discussion list Subject: Re: [apple-crop] Apple bins >From a disease viewpoint or what exactly are you interested in? Leslie <image001.gif> Leslie Huffman 519-738-1256 [email protected]<mailto:[email protected]> From: [email protected]<mailto:[email protected]> [mailto:[email protected]] On Behalf Of Kushad, Mosbah M Sent: September-19-13 5:14 PM To: Apple-crop discussion list Subject: [apple-crop] Apple bins I am interested to read the opinion/experience of the group with plastic or wooden and collapsible or non-collapsible bins. Thanks, Mosbah Kushad, University of Illinois _______________________________________________ apple-crop mailing list [email protected]<mailto:[email protected]> http://virtualorchard.net/mailman/listinfo/apple-crop ************************************************************** Dave Rosenberger, Professor of Plant Pathology Cornell University's Hudson Valley Lab P.O. Box 727, Highland, NY 12528 Office: 845-691-7231 Fax: 845-691-2719 Cell: 845-594-3060 http://www.nysaes.cornell.edu/pp/faculty/rosenberger/
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