Master the key points of selecting mycotoxin adsorbents in one article!
mold Mycotoxins are products of the natural metabolism of molds, and more than 500 mycotoxins have been discovered so far. A variety of mycotoxins commonly exist in grains and feeds, and the additive or synergistic effects of different mycotoxins will greatly enhance the toxicity of mycotoxins, resulting in the impact of mycotoxins on immunity, reproduction, digestion, etc. animal performance.
At present, there are many kinds of Mycotoxin binder, and the competition in the market is fierce. It is inevitable that the concept prevails, which makes everyone confused. However, according to the main components, they can be divided into three categories: first, aluminosilicates, including zeolite , The main component of clay-based adsorbents such as montmorillonite is sodium calcium aluminosilicate hydroxide, and its adsorption effect is closely related to the interlayer structure, surface area, and ion polarity. Large surface area and electrostatic adsorption force can strongly adsorb mycotoxins with ionic polarity, especially highly polar mycotoxins, such as aflatoxin; second, organic types, such as activated carbon, lignin and yeast cell wall extract—β - Glucomannan. Organic adsorbents selectively adsorb low-polarity mycotoxins, such as zearalenone, fumonisin, deoxynivalenol, T2 toxin, etc. Third, enzymes or biodegradation. Currently, studies have reported that lactic acid bacteria, acetic acid bacteria, baker's yeast, Saccharomyces cerevisiae, Aspergillus oryzae and Bacillus subtilis can degrade aflatoxins.
So, how to choose these three types of mycotoxin adsorbents? We might as well learn more about adsorption and adsorption principle.
Aluminosilicates such as zeolite, montmorillonite, diatomaceous earth, kaolin, etc., have a certain selective adsorption capacity for mycotoxins because of their large surface area ratio and ion adsorption capacity . Aluminosilicates mainly include the following types:
Kaolin has ductility, but its adsorption capacity is relatively poor, so it is generally used as a raw material for making porcelain, and is rarely used as a mycotoxin adsorbent.
The structure of zeolite powder is special like a honeycomb, which can effectively absorb into its honeycomb structure with positive molecules, such as minerals (copper, iron, zinc, manganese, magnesium) and ammonia (NH3+ and NH4+). Zeolite powder can effectively adsorb molecules with positive electrodes, so the filter element of the water filter we use in our daily life contains zeolite powder to treat minerals in hard water.
Also known as Bentonite, it was discovered in 1898 by American geologist Knighthl near the Rocky Mountain River in Wyoming, USA. It was named Betonite because it was produced in "Fort Beton". Bentonite is a non-metallic mineral with montmorillonite as the main mineral component, especially the sodium salt bentonite will expand after absorbing water and form a gel. Bentonite has adsorption and cation exchange properties. It can be used as purification and decolorization agent, binder, thixotropic agent, suspending agent, stabilizer, filling material, feed, catalyst, etc. It is widely used in agriculture, light industry, cosmetics, pharmaceuticals and other fields. The industry initially used this characteristic of bentonite to improve the quality of pellets or as an anti-caking agent.
The research on the use of aluminosilicate minerals for the adsorption of mycotoxins began in the 1970s (Masimango et al, 1978; Mumpton and Fishman, 1977). It was found that bentonite can adsorb polar aflatoxins, thus Started as a mycotoxin binder. At present, there are more studies on the adsorption of aflatoxins (Kubena et al, 1990; Huff et al, 1992; Ledoux et al, 1999; Huwig et al, 2001; Girish and Devegowda et al, 2004). The adsorption of mycotoxins by bentonite is mainly based on its hydrophilic negatively charged surface, which is suitable for the adsorption of mycotoxins with polar groups , such as a good selective adsorption capacity for aflatoxin B1 (Ramos and Hernández et al. al, 1997; Philips, 1998; Wang Yanbo et al., 2002; Chi Desheng et al., 2002). Different clay mold removers have different adsorption rates for aflatoxin. In the adsorption test of aflatoxin B1, the adsorption capacities of untreated bentonite, hydrated calcium bentonite, hydrated sodium bentonite, and hydrated sodium calcium bentonite were 67.39 %, 55.51%, 80.83% and 68.55% (Chaturvedi et al, 2002).
There are some problems with clay-based adsorbents, such as adding a large amount (5-20 kg/ton of feed), which will adsorb nutrients such as minerals (Chestnut et al., 1992 - affect the utilization rate of manganese, zinc and magnesium; Moshtahian et al., 1991 - affect the utilization of phosphorus Utilization; Kramer, 1993 - affects copper and sodium utilization) and may contaminate dioxins and heavy metals, for those less polar mycotoxins, such as zearalenone (Bursian et al, 1992), ocher Adsorption of Aspergillus toxin A (Huff et al, 1992; Bursian et al, 1992; Bauer, 1994), T-2 toxin (Kubena et al, 1990) and diacetyl oxalenol (Kubena et al, 1993a) bad. The reason is that clay-based adsorbents capture and bind mycotoxins through electrostatic charges on mycotoxin molecules. However, there are no homopolar groups on molecules such as zeiberellin and T-2 toxin, so this type of binding agent is ineffective or ineffective against these mycotoxins. The research on the adsorption performance of diatomite shows that its adsorption capacity for various toxins is as follows: aflatoxin B1> mantutoxin> aflatoxin M1> T-2 toxin> zearalenone and ochratoxin ( Natour and Yousef, 1998). All in all, aluminosilicate adsorbents have a good adsorption capacity for aflatoxin, and many in vivo test results have confirmed the actual effect of this type of adsorbent (Rizzi et al, 2003), but they have a negative effect on Gibberella zea Insufficient adsorption capacity of toxins such as ketene, ochratoxin, and trichothecenes.
Based on the above facts, we briefly summarize the characteristics of aluminosilicate adsorbents:
(1) Adsorb aflatoxins, and cannot simultaneously adsorb various types of mycotoxins present in the feed;
(2) The effective addition amount is large, occupying too much formula space;
(3) While absorbing mycotoxins, it combines with nutrients such as vitamins and minerals in the feed to interfere with the utilization of nutrients;
(4) It may contain dioxins, heavy metals and other pollutants, which may pollute the feed to a certain extent.
β-Glucomannan is a functional carbohydrate obtained by degrading and purifying the cell wall components by a specific process after the yeast cells are broken by enzymatic hydrolysis . β-glucan is a highly branched polymer in which most or even all residues have side chains containing 2 to 5 mannose residues linked by α-1,2 or α-1,3 glycosidic bonds. Yeast The polysaccharide extracted from the cell wall has a special structure that has a high affinity with mycotoxins, and can adsorb mycotoxins through hydrogen bonds, ionic bonds, and hydrophobic interactions. This polysaccharide can recognize various sites of mycotoxins with different molecular structures, and directly adsorb or directly bind mycotoxins. A multidisciplinary study conducted by the French Institute of Agricultural Sciences (INRA) has demonstrated hydrogen bonding and van der Waals superposition interactions in the adsorption of glucomannan to different mycotoxins (Yiannikouris et al., 2003, 2004, 2006).
In recent years, a large number of studies have proved that β-glucomannan can effectively adsorb different types of mycotoxins , including the most common aflatoxins, T-2 toxins, zearalenone, deoxynivalenol, fumonisins and Ochratoxin etc. Because β-glucomannan is porous and has a huge surface area, it is conducive to the rapid adsorption of mycotoxins. The researchers found that 1Kg of esterified glucomannan has a surface area of up to 22,000 square meters in contact with mycotoxins. The latest test results show that the ability of 0.5Kg esterified glucomannan to adsorb mycotoxins is equivalent to 8Kg clay-based adsorbents. In addition, β-glucomannan does not adsorb other ingredients in the feed. Esterified glucomannan can also improve the activity of glutathione transferase, reduce liver damage, prevent the reduction of dopamine caused by mycotoxins, and relieve growth inhibition. These characteristics of β-glucomannan meet people's requirements for an ideal adsorbent.
There are also many studies on this type of adsorbent to reduce the damage of mycotoxins to livestock and poultry.
Studies at the University of Missouri in the United States have shown that esterified glucomannan can slow down the loss of weight gain in weaned piglets caused by vomitoxin or zearalenone.
Andrea Volkl and PetrKarlovsky of the University of Hohenheim in Germany compared the ability of esterified glucomannan to bind zearalenone: they found that esterified glucomannan can bind 70% of zearalenone and produce adsorption within 10 minutes Works and stays bound for 72 hours.
Dr. Lon Whitlow of North Carolina State University in the United States reported that adding 0.05% esterified glucomannan to cow feed contaminated with aflatoxin can reduce aflatoxin M1 in milk by 58%. This result is similar to the result of sodium bentonite reducing aflatoxins in milk, but the effective addition of sodium bentonite is very high.
Esterified glucomannan can effectively reduce the toxicity caused by various mycotoxins commonly found in broiler diets. Studies have shown that adding 0.05% esterification to broiler diets naturally containing 168mg/kg aflatoxin, 8.4mg/kg ochratoxin, 54mg/kg zearalen and 32mg/kg T-2 toxin Glucomannan, it was found that the presence of mycotoxins significantly reduced the production performance of broilers, while the addition of esterified glucomannan group effectively alleviated the growth inhibition caused by mycotoxins and restored the urea nitrogen level to normal.
Adding 0.1% esterified glucomannan to broiler diets by Stanley et al. can increase daily weight gain and reduce the hazards of aflatoxin. In addition, the use of glucomannan can also alleviate the damage of mycotoxins to breeding animals and improve reproductive performance, such as improving the hatchability of broiler breeders and reducing the death rate of broiler breeder hens.
Due to the effective adsorption of mycotoxins by yeast cell wall extracts, the damage of mycotoxins to animal health is reduced, and the deposition of mycotoxins in human edible meat, eggs, and milk is also reduced, ensuring the safety of the food chain.
Enzymes or Live Fungi
Mycotoxin biodegradation refers to the process in which microorganisms, plants and enzymes produced by their metabolism interact with toxins to destroy toxic groups in their molecular structures and generate non-toxic degradation products. At present, there are very few applications of biological methods to degrade mycotoxins in feed at home and abroad, mainly due to the following limiting factors:
Live bacteria and enzymes have poor tolerance to heat and will be destroyed during the granulation process. Some enzymes don't even work at the animal's body temperature.
Live bacteria and enzymes have poor acid tolerance and may be destroyed by gastric acid when passing through the stomach of poultry and livestock. At the same time, when organic acids are used in feed, they will also inhibit and destroy such products.
Enzymes are very specific to their substrates. Since there are many types of mycotoxins and their structures are quite different, basically one type of enzyme can only decompose one type of mycotoxin.
Due to the strong specificity of enzymes to substrates, we must first know which mycotoxins are contained in feed ingredients, and then select the corresponding enzymes for those mycotoxins, otherwise the use of uncorresponding enzymes will have no effect.
It is believed that with the development of science and technology, through the means of biotechnology and genetic engineering, the degrading enzyme gene will be cloned and transformed into a suitable vector for high-efficiency expression, so as to increase the production of mycotoxin-degrading enzymes, and it will be possible to develop high-purity, high-activity Novel detoxifying enzymes.
In addition, there are many so-called composite adsorbents on the market, such as adding a few percent of antifungal agents such as calcium propionate, propionic acid, sorbic acid, benzoic acid, etc., or yeast cell walls, mannan oligosaccharides, etc. , These products seem to have many functions and have attracted the attention of many people, but you can think about it, if the one-thousandth mold remover added to the feed is diluted one hundred times, how much will these ingredients play? effect? ; In addition, through the examples in our life, we can also imagine that if a product has all functions, then its main function will not be so significant. How to choose? I think we can ask ourselves three questions, what is the purpose of our buying products? What kind of problem are we trying to solve? What are the main ingredients in this product? We will naturally understand.