Detoxification Treatments for Solid Foods and Feeds: Comparison
Please note this is a comparison between Version 3 by Mohamed Koubaa and Version 5 by Beatrix Zheng.

Mycotoxins in solid foods and feeds jeopardize the public health of humans and animals and cause food security issues. The inefficacy of most preventive measures to control the production of fungi in foods and feeds during the pre-harvest and post-harvest stages incited interest in the mitigation of these mycotoxins that can be conducted by the application of various chemical, physical, and/or biological treatments. These treatments are implemented separately or through a combination of two or more treatments simultaneously or subsequently. The reduction rates of the methods differ greatly, as do their effect on the organoleptic attributes, nutritional quality, and the environment.

  • mycotoxins
  • mitigation treatments
  • decontamination rates
  • single treatments
  • physical treatments
  • chemical treatments
  • biological treatments
  • Solid foods
  • feeds

1. Chemical Treatments

Chemical decontamination is used in many industries [1][26]. It can be used for the destruction of mycotoxins or their neutralization [2][39]. Many chemical agents are used for the decontamination of solid foods and feed, such as limewater [3][40], organic acids [4][41], ozone [5][42], and ammonia [6][43]. All these treatments are discussed below in this section (Table 1).
Table 1.
Chemical treatments for the reduction of mycotoxins in solid foods and feeds.
62][115]. In this section, thwe researchers  scrscreen various studies using biological control strategies to mitigate the mycotoxins in solid food and feeds (Table 3).
ZEN-detoxifying bacillus strains were used to detoxify highly contaminated maize with an initial concentration of 5 mg kg−1 of ZEN. The degradation of ZEN is related directly to the esterase activity, which has been found in all tested strains, with the maximum activity in B1 and B2 strains. The highest ZEN degradation rate was attained in B2 strains, reaching 56%. B2 strains showed their efficiency in the detoxification of other mycotoxins with different rates—AFB1: 3.8%, DON: 25%, FB1: 39.5%, T2 toxin: 9.5%. The presence of ZEN enhanced the fermentation process of the contaminated maize compared to the non-contaminated grains [63][116].
CotA laccase is found in the endospore coat of Bacillus. It protects spores from UV light and hydrogen peroxide and has an oxidizing capacity. CotA laccase was immobilized onto chitosan microspheres and used to degrade ZEN in artificially contaminated cornmeal samples. The free CotA laccase form achieved a degradation rate of 70%, while the immobilized form was faster and more effective, achieving a higher degradation rate reaching 90%. The most important advantage is the reuse of the immobilized enzyme. Guo et al., showed that the degradation rate decreased to 54% following multiple uses of the immobilized CotA laccase in the third cycle, reaching only 21% in the fifth one [64][117]. Lactic acid bacteria (LAB) were used to mitigate mycotoxins in wheat-based products. The Pediococcus acidilactici LUHS29 strain achieved the highest reduction rates of mycotoxins when used alone in sourdough fermentation for 48 h. It removed 15-AcDON, AOH, D3G, toxins H-2 and HT-2, completely removed ENNB1, and reduced the DON by 44–69%. The combined fermentation using this LAB with Lactobacillus Plantarum LUHS135 strain showed great efficiency and increased the reduction rate of DON to 79–100% [65][118]. In a study conducted by Alberts et al., enzymatic detoxification was examined using Fumonisin Esterase FumD to degrade FB in maize. This enzyme can hydrolyze and remove the tricarballylic acid groups when added to maize during the conditioning step (for 250 min) during the dry milling process. The use of 40 U/kg of FumD in maize resulted in a 99% degradation of FBT in total hominy feed but did not accomplish any degradation of FBT in super maize meal [66][119].
The fungal growth and/or the mycotoxin production was controlled in bread using specific yeast strains and achieving reduction rates varying between 16.4 and 33.4% for DON, 18.5 and 36.2% for NIV, and 14.3 and 35.4% for ZEA [67][120]. The heat treatment of peanut samples at 100 °C for 15 min before solid-state fermentation by Zygosaccharomyces rouxii showed great efficiency in the mitigation of AFB1, and the reduction rate reached 97.52% [68][121].
Table 3. Microbial and enzymatic treatments for the reduction of mycotoxins in solid foods and feeds. 
Treatment Feeds/Foods Contaminants Experimental Parameters Reduction Rates Advantages References
Bacteria: ZEN-detoxifying Bacillus (ZDB) strains Maize ZEN The highest level of ZEN degradation B2 strain-reduction rate = 56%
  • Esterase activity is demonstrated in all strains;
  • The stronger esterase activity: B1 and B2 strains;
[63][116]
    B2 strain detoxifies other mycotoxins Reduction rates:

AFB1: 3.8%;

DON: 25%;

FB1: 39.5%;

T2 toxin: 9.5%
  • Fermentation of ZEN-contaminated maize by B2 strain compared to ZEN-free maize: Better fermentation characteristics: (lactic acid > 110 mmol·L−1; acetic acid < 20 mmol·L−1; pH < 4.5).
Bacteria: Bacillus licheniformis

spore CotA laccaseapplication of immobilized laccase in contaminated corn meal
Corn meal ZEN Treatment with immobilized CotA laccase onto chitosan microspheres for 12-h Degradation rate: 90%
  • Immobilized CotA laccase is much faster and more effective than free CotA laccase in degrading ZEN;
  • Immobilization has higher thermal stability over free CotA laccase, maintaining about 87% of its initial activity after heat treatment at 80 °C for 30 min;
  • Reusability: Immobilized CotA laccase could be recovered from corn meal solution and repeatedly used.
[64][117]
    Treatment with free CotA laccase for 12-h Degradation rate: 70%
    Reuse of immobilized enzymes for 5 cycles Decreased degradation rate on each after each cycle:

Cycle 1: 90%;

Cycle 2: 77%;

Cycle 3: 54%;

Cycle 4: 30%;

Cycle 5: 21%
Bacteria—Fermentation: Lactic acid bacteria Wheat-based products DON 15

-AcDON

AOH

D3G,

toxins H-2 and HT-2:

Enniatin

ENNB1
Pediococcus acidilactici LUHS29 strain The strongest mycotoxins decontamination effect
  • Pediococcus acidilactici LUHS29 strain has the strongest mycotoxins decontamination effect;
  • Combined fermentation showed more efficiency and complete elimination of DON.
[65][118]
  Prolonged fermentation at 35 °C for 48 h with Pediococcus acidilactici LUHS29 strain DON: 44–69%

15-AcDON, AOH, D3G, toxins H-2 and HT-2: Removal

Enniatin: 5–70%

ENNB1: complete removal
  Combined fermentation (Lactic acid bacteria 7 (JCM 1149) and Pediococcus acidilactici LUHS29 (DSM 20284)) Complete elimination or effective reduction of DON: 79–100%
Enzyme Maize FB FB degradation during dry milling of maize  
Technique Feeds/Foods Contaminants Experimental Parameters Reduction Rate Advantages/Disadvantages References
Ozonation Powdered sun-dried herbs and spices AFs Ozone concentration = 3 ppm/time 210 min Highest level of aflatoxin reduction:

93.75% for licorice

90% for peppermint
Advantages:

Fumigation with Ozone: 3 ppm/time: 280 min— Sanitation and reduction of microbial load;

Active against a wide range of microorganisms, viruses, Gram-negative and Gram-positive bacteria, spores, and fungi;

Instability of Ozone—transformation into O2-O3 has a Gras status;

The major biologically active constituent attributed to the medical properties of the chamomile flower was increased.

Disadvantages:

Reduction of chamomile essential oil by 57.14% and peppermint by 26.67%.
[7][44]
Ozonation Parboiled Rice Mycotoxins Parboiled rice grains treated with ozone Significant reduction of mycotoxins contamination, regardless of the time and period of application and the mycotoxin evaluated Advantages:

After soaking samples in ozone for 3 and 5 h:

Higher head rice yield, luminosity and hardness, decreased cooking time, percentage of defective grains, and soluble protein.
[8][45]
Ozonation Aqueous medium TrichotheceneMycotoxins

(TC)
Saturated aqueous ozone (≈25 ppm) Degradation of TC mycotoxins to materials that were not detected by UV or MS Disadvantages:

Ozone is a toxic gas, so all preparations were conducted in a fume hood.
[9][46]
    At lower levels (≈0.25 ppm) of aqueous ozone Intermediate products were observed  
    Ozonation was sensitive to pH.    
    pH 4 to 6 Maximum reduction rates  
    pH 9 No reaction  
Ozonation Wheat DON ↓ initial concentrations of DON solution treated with ↑ concentrations of ozone, and ↑ times ↑ DON degradation rates Advantages:

No significant changes in the protein content, sedimentation value, pasting properties, and water absorption;

Improvement in the flour quality. Slight ↑ in dough development time and stability time;

No decrease in the quality of wheat for end-users;

Products produced from ozone-treated wheat flour (noodles) have a longer shelf life, lower darkening rate, and microbial growth;

No harmful residues, easy to use, and no waste.

Disadvantages:

Ozone treatment in solution is faster than gaseous treatment of scabbed wheat.
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With an initial level of DON up to 2000 μg/kg
Treatment efficacy is not affected
Ammoniation Corn AFs The use of aqua-ammonia Effective and inexpensive Advantages:

Effective and inexpensive, and it can be applied on the farm at low cost by sealing the grain in plastic.

Disadvantages:

Corn treated with ammonia turns dark because the sugar (altrose) is caramelized and the grain temperature increases by about 10 °F at the time of treatment;

Not an FDA-approved process and treated corn cannot be legally shipped out of state;
  • Personal safety precautions must be taken as ammonia reacts with copper, and a motor in the air stream could cause an explosion;
  • Corn treated with aqua ammonia requires drying for storage after treatment.
[19][55]
         























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0.1 and 1 M citric acid—at boiling temperature—Time: 20 min















Conversion of AFB1 to AFB2a > 98%







 
Many traditional methods, such as cleaning and sorting, are used. These methods are capable of physical separation by removing the contaminated portions from the crops and preventing the transfer of the pathogens to the non-contaminated portions. These are not able to neutralize or degrade the mycotoxins already produced in the crops; they only isolate the contaminated portions [24][25][26][28,66,67]. Several industrial processes require the use of conventional cooking at temperatures below 100 °C. Most mycotoxins are heat stable, and it is not possible to mitigate them by these conventional heat treatment processes [27][68].
The physical detoxification methods explained in this section (Table 2) include thermal treatments or invasive methods such as extrusion [27][68], and non-thermal treatments or non-invasive methods such as photocatalysis [28][69], cold plasma [29][30][70,71], electrolyzed oxidizing water [31][72], and irradiation [32][33][73,74]. These technologies are beneficial since they are safely used for many food matrices without causing negative effects on the nutritional and organoleptic quality of treated food. The limited scalability at the industrial level may be considered a disadvantage of many physical treatments [34][75].
  • Highest enzyme concentration: 32 U/100 g maize: Complete conversion into HFB1;
  • Cost-effectiveness of upscaling the FumD FB dry milling method to an industrial level requiring up to 40,000 U FumD/ton maize, will depend on the safety benefits of consuming the milling products as well as the commercial value of the total hominy feed lacking FBT.
[66][119]
Fumonisin esterase FumD     Enzyme concentration: 40 U/kg Reduction rates FBT:
  • 99% in total hominy feed;
  • 48% in semolina;
  • 7% in special maize meal
  • No reduction in super maize meal.
Yeast Wheat grains and bread Fusarium

Mycotoxins:

DON, NIV

ZEN
Bread prepared by baking with the addition of an inoculum of the test yeast Reduction rates:

DON: 16.4% to 33.4%;

NIV:18.5% to 36.2%;

ZEA: 14.3% to 35.4%
  • The biocontrol yeasts strains may arrest fungal growth, reduce mycotoxin production, or both.
[67][120]
Yeast Peanut meal AFB1 Peanut samples are heated at 40, 60, 80, 100, or 110 °C for 10 min   [68][121]
      The residual rates after heat treatment at the following temperature for 10 min: (T:% of residual AFB1 80 °C: 61.08%; 100 °C: 63.46%; 110 °C: 49.63%  
      The residual rates after fermentation by Z. rouxii: (Temperature: % of residual AFB1) (40 °C:32.73%)-(60 °C:20.85%)-(80 °C:16.18%)-(100 °C:5.13%)-(110 °C:5.10%)
      100 °C The optimal temperature achieved the highest reduction rate
      Peanut samples are heated at 100 °C for 5, 10, 15, or 20 min
      The residual rates after heating at 100 °C for different times: (time: % of residual AFB1) (5 min: 21.06%)-(10 min: 5.13%)-(15 min: 2.48%)-(20 min: 2.44%)
      15 min The optimal time
      Optimal treatment (100 °C -15 min): Residual % of AFB1: 2.48%
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