Application of non-heating methods for disinfecting vegetable raw materials in the production of food

Batir K. Satbaev , Nargiz Zhumabekova

Introduction

Crops are contaminated in the field, during cultivation, harvesting, storage and transportation. The most common microflora include bacteria (Bacillus subtilis (hay bacillus), Bacillus mesentericus (potato sticks), as well as Pseudomonadaceae, Micrococcaceae, Lactobacillaceae, Bacillaceae), yeasts (Candida, Cryptococcus, Pichia, Sporobula, Asrichopericus, Rhodorotorsporgus Penicillium, Alternaria, Aureobasidium, Cladosporium, Epicoccum, Fusarium, Helminthosporium, Claviceps). In addition, potential recontamination can occur after harvest. Grain can be contaminated during cleaning, grinding, sorting or packaging processes. In terms of the degree of impact on the safety and security of grain, the most dangerous representatives of microflora are fungi. The most widespread mushroom is Aspergillus, adapted to life in low humidity conditions and activated when it rises, which is the most dangerous in the production of products from sprouted raw materials. Most microorganisms are present in the grain pericarp, and only a few species can be found in the inner part of cereals, mainly penetration occurs through the embryo or as a result of mechanical damage to the shell parts. These microorganisms are sufficiently firmly adhered to the grain surface and cannot be completely removed by simple washing. Although it should be noted that this technological stage reduces 85–87% of the total microbial contamination. The rest of the number of microorganisms remains on the surface and is capable of producing mycotoxins. In recent years, it has become increasingly popular to use the process of sprouting crops to obtain fortified food with added value. The use of such raw materials makes it possible to enrich the food ration of the population with vitamins A and E, as well as group B; micro- and macroelements: phosphorus, iron, magnesium, potassium, etc. At the same time, attention is rarely paid to the fact that microbiological contamination and toxicological factors of influence can make the grain unsuitable for germination or lead to a sharp formation and accumulation of microtoxins and heavy metals during the germination process ... Back in 1982, Andrews and colleagues in their studies noted a tenfold increase in the number of colonies of Aspergillus glaucus, Penicillium cyclopium and Alternaria during 2 days of grain germination.

Aflatoxins are highly resistant to standard disinfection methods used in the production of food or feed [4, 7]. Therefore, measures to prevent contamination of grain, especially the most toxic compound aflatoxin B1, are essential throughout the entire production chain (Figure 1).

Figure 1. Possible risks of migration of mycotoxins in the production of bread and bakery products.

The concept of food safety in world practice today is aimed at preserving the main food ingredients and their properties. Thermal effects lead to an effective decrease in the development of microorganisms, but at the same time cause significant losses of thermolabile compounds and negatively affect the organoleptic, physicochemical and functional properties of the final product [1, 3, 5-11]. Consequently, the study of non-thermal physical methods of exposure (pulsed electric field, ultrasound, ultraviolet light, cold plasma, etc.) is received in the world market by all more widespread in recent decades (Figure 2)

Figure 2. The most common non-thermal methods of disinfection of plant raw materials encountered in world practice [5, 6]

Materials and methods

The object of research was the grain of wheat of the Lyubava variety. In order to identify the greatest disinfecting effect, the obviously intensely contaminated grain of the Ural region was used.

Grain samples were taken in accordance with GOST 13586.3–2015.

QMAFAnM was determined according to GOST 10444.15, BGKP - GOST 31747 and GOST R 52816-2007, the amount of yeast and molds - according to GOST 10444.12. The qualitative determination of the presence of flotoxins was carried out according to the international method AACC 45-15.01. To create provoking conditions for the development of mold fungi in wheat grain, the air temperature was increased to 25–30 ° C and the grain moisture content was increased to 16–18%. Control of microbiological parameters was carried out after 1, 3 and 5 days. Quantitative determination of aflatoxins was carried out by high performance liquid chromatography according to GOST 34140.

To carry out the disinfection process used the following methods of exposure (Figure 3).

Figure 3. Methods of disinfection of grain

An acoustic source of elastic oscillations by ultrasound was used as a source of ultrasonic waves - a device "Volna" model UZTA - 0.63 / 22-ОМ, operating at a frequency of 22 ± 1.65 kHz and an output power of 630 watts.

The generator GNI-01-1-6, developed and manufactured at the South Ural State University [2], was used as a source of NEMI. For processing, a horn emitter was used with a NEMI repetition rate of 1000 Hz, a horn opening of 90 × 120 mm and a length of 240 mm.

To generate XII, an installation was used, developed at the South Ural State University. Cold plasma was generated by a negative corona discharge at a pulsed voltage with the following parameters: the potential difference was 10 kV, the frequency was 50 Hz, the plasma-forming substance was air under normal conditions. For all types of exposure, the duration of treatment was 5 min.

Results and discussion

The greatest concern is caused by the direction associated with the germination of grain crops and their use in the production of food products. Even the initial surface microflora of wheat grain, which has a permissible level of microorganisms, during germination is able to actively increase the number of mold colonies, which will ultimately lead to the accumulation of mycotoxins in the finished product (Table 1).

The presented data indicate a significant intensification of the development of pathogenic microflora during germination, which confirms the presence of potential risks of the accumulation of aflatoxins in the grain mass during this process, even despite the fact that their amount in dry grain ranged from 0.001 to 0.003 mg / kg. since in most cases the presence of Aspergillus fungi was noted in the germinated grain. To successfully carry out the germination process and obtain a safe raw ingredient, electrophysical methods of exposure were used (Table 2)

Based on the data obtained, it can be said that the greatest disinfecting effect was observed when using exposure XII, which made it possible to reduce the KMAFAnM indicators, the amount of yeast and molds to the minimum values. Complete sterilization of grain is an almost impossible task due to the presence of irregularities in the biological object. NEMI occupies an intermediate position. Thus, the amount of yeast and mold fungi decreased by 2.8 and 5.0 times, respectively.

The minimum disinfecting effect can be noted when using RAS. The amount of yeast and molds decreased by 2.2 and 2.8 times and remained above the regulated values. A typical view of the results of the qualitative determination of the presence of aflatoxins is shown in Figure 4.

Figure 4. Characteristic view of the results of qualitative determination of the presence of aflatoxins according to AACC 45-15. 01

In the control sample after 24 hours storage under provocative conditions, single fluorescent yellow-green wheat grains were observed. Their number increased by 72 hours, and after 120 hours of storage, most (more than 70% of the grains) had this type of glow, and the presence of a developed mycelium of molds was also visualized. The intensity of the yellow-green luminescence in the test samples after USI treatment was slightly different from the control sample. After 72 hours of storage, more than 40% of the grains can be noted, and after 120 hours, 50% have characteristic luminescence, which may indicate a weakly pronounced disinfecting effect of this disinfection method. The intensity of the yellow-green glow in the studied samples after exposure to NEMI also slightly differed from the control sample. After 72 h of storage, more than 30% of the grains can be noted, and after 120 h, 90% have characteristic luminescence, which may indicate the accumulation of molds A. flavus or A. parasiticus. In grain samples treated with cold plasma, an increase in the number of fluorescent grains was not observed, which means this method of disinfection is the most effective.

Conclusion

The presented methods are innovative today and are widely used in world practice. They allow not only to deactivate mold fungi, but also to destroy the already formed aflatoxins in food (use of cold plasma).

Based on the foregoing, we can say that the danger of ingestion and accumulation of aflatoxins in food products (especially whole grains) is still present and is an urgent problem on a global scale, since even a minimal amount of them can cause global harm to public health.

Acknowledgments

The article was supported by the Government of the Russian Federation (Resolution No. 211 of March 16, 2013), agreement No. 02.A03.21.0011 and with the financial support of state assignments No. 40.8095.2017 / BC and RFBR grant 18-53-45015.

References

1. Naumenko N.V., Potoroko I.Yu., Kretova Yu.I., Kalinina I.V. et al. On the issue of intensification of the process of grain germination. Far Eastern Agrarian Bulletin. 2018. no. 4 (48). pp. 109–115. (in Russian).

2. Plitman V.L., Krymsky V.V., Smolko V.A., Shatin A.Yu. Method for the electrochemical treatment of aqueous media and a device for its implementation. Patent RF, no. 2181106, 2002.

3. Potoroko I.Yu., Naumenko N.V. Study of the possibilities of regulating the composition of the microflora of food products by electrophysical methods of influence. Commodity expert on food products. 2011. no. 2. pp. 6–9. (in Russian).

4. Khmelev V.N., Popova O.V. Multifunctional ultrasonic devices and their use in small industrial, agricultural and household conditions: monograph. Barnaul, ed. Altai State Technical University, 1997. 160 p. (in Russian).

5. Hosni R.K. Grain and grain products. St. Petersburg, Profession, 2006. 330 p. (in Russian).

6. Andrews W.H., Mislivec P.B., Wilson C.R., Bruce V.R. et al. Microbial hazards associated with bean sprouting. J.Assoc. Off. Anal. Chem. 1982. no. 65. рp. 241–248.

7. Ashokkumar M. Applications of ultrasound in food and bioprocessing. Ultrason. Sonochem. 2015. no. 25. pp. 17–23.

8. Lacombe A., Niemira B.A., Gurtler J.B., Fan X. et al. Atmospheric cold plasma inactivation of aerobic microorganisms on blueberries and effects on quality attributes. Food Microbiol. 2015. vol. 46. pp. 479–484.

9. Morales-de la Peña M., Welti-Chanes J., Martín-Belloso O. Novel technologies to improve food safety and quality. Current Opinion in Food Science. 2019. vol. 30. pp. 1–7.

10. Misra N.N., Patil S., Moiseev T., Bourke P. et al. Cullen In-package atmospheric pressure cold plasma treatment of strawberries. J. Food Eng. 2014. vol. 125. pp. 131–138.

11. Ziuzina D., Patil S., Cullen P.J., Keener K.M. Atmospheric cold plasma inactivation of Escherichia coli, Salmonella enteric serovar Typhimurium and Listeria monocytogenes inoculated on fresh produce. Food Microbiol. 2014. vol. 42. pp. 109–116.

---

Әлеуметтік желілерде бөлісіңіз: