The dry chain: Reducing postharvest losses and improving food safety in humid climates
Published:February 22, 2018
Summary
1. The problem of postharvest food waste and toxicity A central issue for the 21st century is to continue to feed the growing human population in a sustainable manner, while accommodating the effects of climate change and limiting expansion of agricultural land and water use. Although predictions vary, there is little doubt that the human population will increase to 9 to 10 billion from the pr...
I found this article very interesting, and I learned a lot from it. However, there are two glaring omissions .
1/ DEHUMIDIFYING MACHINES (Electric or Diesel / Electric) are much more efficient than conventional driers, particularly in high RH. They are basically reconfigured Air Conditioners, in which incoming air passes through the Fan Coil, and drops it's moisture. The heat from the Compressor (together with any engine heat) is recycled to reheat the dried air, which is then blown through the grain. These machines can work with existing driers, in lieu of using the burner.
MOULD INHIBITORS
Various chemical additives can be added to moist grain to preserve it's quality, and are widely used in Animal Feed. Organic Acids and their salts (often used in mixtures) are particularly good due to their low toxicity.
These products have become more attractive, due to high energy costs incurred in Drying.
Joe Stanyer Low resource households may need to be served with mobile dryers during rainy season though service providers who rent equipment to prepare land and harvest the food.
Minimizing molds in food/feed is a better strategy than adding mold inhibitors. Although preservatives could be added to processed food/feed, there is continuous decline of nutrients in high moisture products. One could minimize such nutrient losses using low temperature that smallholders cannot manage easily.
We clarified that natural drying could be used in dry seasons/regions. Drying to milling or processing moisture content is the key to achieve safe storage conditions. Seeds do need further drying based on desired storage time. Moisture-proof packaging is needed to maintain the moisture content of dry products (food/feed/seed) achieved by either natural or artificial drying. Usually, the rainy season follows the dry season in most bread basket regions.
In my opinion, we have to look at the entire process. If we do the due diligence of checking the grain from the arrival at the plant, checking moisture levels, broken kernels, protein, etc, we can start avoiding a lot of the problems. Again I reiterate that following a HASAP process could help eliminate many problems. I have observed in the field that many checks in foreign countries are done by the guards at the entrance to the farm and weights. They are not familiar with the 8 points of testing the truck, therefore a lot gets missed. In many countries also determined by using a UV light to see aflatoxin in grains and not other toxins that may be present. Remember all start with the raw material and end up in the feed. Storage conditions also may affect damage by mycotoxins due to insect and rats fecal mater. No matter all ingested mycotoxins will affect the animal organs. Using a good mold absorbent that includes, probiotics, prebiotic, mold inhibitors, clay and cilimarine will help re Genaro the live damaged by mycotoxins. Not only we should lol at the problem, but also look at a good solution. We all know the damaged caused by mycotoxins contamination, therefore we need to find resolutions and implementation.
Everything written above is absolutely true, but these are only general phrases that do not require knowledge and professionalism.
Please do not take my remark with resentment.
You understand that this is true
There is no disagreement that a system approach is needed. However, FAO points to postharvest food management critical to food security. Sadly, dry food grains are damaged annually by flloding in south Asia and elsewhere. Drying food/feed rapidly to "suitability to milling or processing moisture content" and packaging into pesticide-free moisture-proof containers would additionally minimize nutrient losses and molds and insect infestations. Monitoring for mycotoxins and other pesticides would complement nutrition security efforts.
In discussions, forum participants come to a long-drawn-out conclusion: it is necessary to prevent the development of molds on grain and other raw materials. Known methods basically reduce to drying the grain (or preserving harvested herbs). This technique is not always applicable, since the grain can be contaminated with mycotoxins during ripening.
Fungi are constantly present in the soil and therefore easily fall on the grain (and harvested green mass), however, the degree of grain damage by mycotoxins in the same field differs in different years and depends on the climate and the technology of growing grain (including both soil cultivation and preparation of sowing seed). What factors influence the formation of mycotoxins? Why do different mycotoxins form in the same field (suppose the fungi remain the same), and their number is different in different years? We ask the main question: Why do fungi form mycotoxins?
Mycotoxins are broadly defined as antibiotics. Fungi use them to fight competitors for food substrate. Fungi compete with bacteria (including soil bacteria). If the availability of nutrients in the fungi habitat decreases, then biochemical regulation is turned on, and they begin to secrete mycotoxins, which should kill the main competitors for nutrients - bacteria. In good conditions, there is an established equilibrium in the biocenosis and enough nutrients for everyone. However, if for some reason favorable conditions develop for the fungi and they begin to multiply rapidly, then they will not have enough nutrients - as a result, biochemical regulation is activated for the formation of mycotoxins, which will inhibit the growth of bacteria. This will increase the availability of nutrients for fungi. I named bacteria as one of the active factors.
I grew in a laboratory in a thermostat on sterile grain in one case a strain producing aflatoxin and in the other a deoxynivalenol. In each case, the fungi grew actively and did not form the toxin for the first 3 weeks, although these were strains specially selected for the synthesis of toxins. After 21-28 days, mold growth slowed or stopped noticeably and mycotoxin synthesis started. What's the matter? For the period of active reproduction and growth, fungi used available nutrients (or some factors that limit their growth). Biochemical regulation began to work, due to a lack of nutrients, a signal was sent to the formation of mycotoxins. I repeat that the mushrooms grew on a sterile medium, and there were no competitors for the substrate: the fungi themselves used nutrients. But fungi cannot think - universal biochemical regulation works, which, in case of nutrient deficiency, includes the biosynthesis of mycotoxins to fight competitors (which in this case were not in a sterile environment). In the field, even a short period of drought will limit the availability of nutrients for fungi and they will respond by the production of mycotoxins. Metabolism in fungi can be negatively affected by chemical plant protection products or other measures of influence, which will also be accompanied by an increase in the formation of mycotoxins.
A deep study of the question: why mycotoxins are needed for fungi will allow us to develop methods and influence on their formation. One such method may be the creation of strains of similar species of fungi that are not able to form mycotoxins. The treatment of soils and raw materials with such strains will create competition and prevent the formation of mycotoxins by pathogenic natural strains. There may be other interesting findings.
Atoxigenic molds to manage proliferation of toxigenic ones is a noble approach (https://doi.org/10.3389/fmicb.2019.02069). Even if the molds were genetically controlled and insect infestation managed (natural or pesticides), there is invivo nutrient decline in absence of moisture content management. Thus, there is triple effects of moisture content on quality of foodd/feeds.
