{"id":5587,"date":"2022-08-18T18:00:26","date_gmt":"2022-08-18T18:00:26","guid":{"rendered":"https:\/\/msagros.com.mx\/?p=5587"},"modified":"2022-08-18T21:10:07","modified_gmt":"2022-08-18T21:10:07","slug":"effect-of-biodegradable-coatings-on-the-growth-of-aspergillus-flavus-in-vitro-on-maize-grains-and-on-the-quality-of-tortillas-during-storage","status":"publish","type":"post","link":"https:\/\/msagros.com.mx\/en\/effect-of-biodegradable-coatings-on-the-growth-of-aspergillus-flavus-in-vitro-on-maize-grains-and-on-the-quality-of-tortillas-during-storage\/","title":{"rendered":"Effect of Biodegradable Coatings on the Growth of Aspergillus flavus In Vitro, on Maize Grains, and on the Quality of Tortillas during Storage"},"content":{"rendered":"
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Rosa I. Ventura-Aguilar 1<\/sup>, C\u00e9sar G\u00f3nzalez-Andrade 2<\/sup>, M\u00f3nica Hern\u00e1ndez-L\u00f3pez 3<\/sup>, Zormy N. Correa-Pacheco 3<\/sup>, Pervin K. Teks\u00fcr 4<\/sup>, Margarita de L. Ramos-Garc\u00eda 2,<\/sup>* and Silvia Bautista-Ba\u00f1os 3,<\/sup>*<\/i><\/p>\n

1 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 CONACYT-Centro de Desarrollo de Productos Bi\u00f3ticos, Instituto Polit\u00e9cnico Nacional, Carretera Yautepec-Jojutla, km. 6.8, San Isidro, CEPROBI 8, Yautepec Morelos 62731, Mexico; riventuraag@conacyt.mx<\/p>\n

2 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Facultad de Nutrici\u00f3n, Universidad Aut\u00f3noma del Estado de Morelos, Calle Iztaccihuatl S\/N, Col. Los Volcanes, Cuernavaca Morelos 62350, Mexico; jingsible@gmail.com<\/a><\/p>\n

3 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Centro de Desarrollo de Productos Bi\u00f3ticos, Instituto Polit\u00e9cnico Nacional, Carretera Yautepec-Jojutla, km. 6.8, San Isidro, CEPROBI 8, Yautepec Morelos 62731, Mexico; monibrisa@hotmail.com (M.H.-L.); zormynacary@yahoo.com (Z.N.C.-P.)<\/p>\n

4 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Department of Plant Protection, Ege University, Erzene Mahallesi Ege \u00dcniversitesi Merkez Yerle\u00b8skesi, Bornova, 35040 \u02d9Izmir, Turkey; pervin.kinay@ege.edu.tr<\/a><\/p>\n

* \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Correspondence: margarita.ramosg@uaem.edu.mx (M.d.L.R.-G.); sbautis@ipn.mx (S.B.-B.<\/p>\t\t\t\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Abstract:<\/strong> The fungus Aspergillus flavus<\/em> causes serious damage to maize grains and its by-products, such as tortilla. Currently, animal and plant derivatives, such as chitosan and propolis, and plant extract residues, respectively, are employed as alternatives of synthetic fungicides. The objective of this research was to evaluate the efficacy of several formulations based on propolis-chitosan-pine resin extract on the in vitro growth of A. flavus<\/em>, the growth of maize grain plantlets and the quality of stored tortillas at 4 and 28 \u25e6C. The most outstanding formulation was that based on 59.7% chitosan + 20% propolis nanoparticles + 20% pine resin extract nanoparticles; since the in vitro conidia germination of A. flavus<\/em> did not occur, disease incidence on grains was 25\u201330% and in tortillas, 0% infection was recorded, along with low aflatoxin production (1.0 ppb). The grain germination and seedling growth were markedly reduced by the nanocoating application. The percentage weight loss and color of tortillas were more affected by this coating compared to the control, and the rollability fell within the scale of non-ruptured at 4 \u25e6C and partially ruptured at 28 \u25e6C. The next step is to evaluate the toxicity of this formulation.<\/p>\n

Keywords:<\/strong> Zea mays L; chitosan; propolis; pine resin extract; disease incidence: aflatoxins; nanocoatings<\/p>\t\t\t\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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1.Introduction<\/h2>

There are phytopathogenic fungi that, in addition to altering the quality of the horti[1]cultural commodity, produce toxic compounds, known as mycotoxins. In the case of the Aspergillus<\/em> species, A. flavus<\/em> principally produces the mycotoxin aflatoxin which causes serious health issues for the humans and animals that consume it [1]. This fungus exists on an extremely large range of agricultural hosts including various fruit, tree nuts, cereals, and mainly stored grains such as maize [2,3].<\/p>

The conidia of A. flavus<\/em> enter through the pedicel or from a wound in the maize grain and germinate inside, where the hyphae begin to grow after 3 to 7 days. Later, the fungus generates conidiophores that release conidia to contaminate other maize grains. The optimal temperature range for its development is between 10 and 55 \u25e6C. Aflatoxins develop once the fungus begins to develop conidiophores, but they also occur when the fungus feels stressed, either by a competitor, lack of nutrients and water, or the presence of chemical fungicides [1].<\/p>

Maize is a product consumed heavily in Mexico, due to its high nutritional content and versatile use in a wide variety of foods. One of the by-products derived from maize with the highest level of consumption in the country is the tortilla. However, as reported by Mart\u00ednez et al. [3], in Mexico, tortilla can be contaminated by A. flavus<\/em>. The authors stated that in various maize producing states of the country, this fungus is responsible for crop losses of up to 50%. Additionally, grains infected with A. flavus<\/em> can also be contaminated with high doses of aflatoxins [4]. For example, Mendez-Albores et al. [5] reported aflatoxin content in the range of 2 to 9 ppb and 6 to 36 ppb in tortillas, made using the traditional and ecological making processes, respectively. Furthermore, Anguiano-Ruvalcaba et al. [6] reported that in the state of Tamaulipas, the maize from the field exhibited concentrations of 45\u201365 mg of AFB L\/kg, and after being stored for two months in conditions of high temperature and humidity, the concentrations exceeded 250 mg of aflatoxin B1\/kg. Added to this, the lack of adherence to the NOM-247-SSA1-2008 (Norma Oficial Mexicana 2008) [7] makes the control of aflatoxins difficult to follow.<\/p>

To solve this problem, various approaches have been tested to control A. flavus<\/em>, the most common method being the use of chemical products such as, among others, im[1]idazoles, thiabendazole, and sodium o-phenylphenate [8]. However, aside from being expensive, these synthetics that can generate strains resistant to fungicides after several years of exposure exert phytotoxic effects on grain germination, and restrict maize im[1]ports and exports [3,9]. Alternative methods include agronomic practices [10], biological control with the antagonist Bacillus [11], and application of natural compounds including, among others, plant extracts, essential oils [12,13], and animal derivatives (chitosan and propolis) [14,15].<\/p>

With respect to natural compounds, it has been demonstrated that formulations alone or combined based on propolis (a resinous compound created by bees that is rich in active compounds such as flavonoids, phenolic acids, and terpene derivatives) [16], chitosan (a polysaccharide obtained from partially deacetylated chitin) [17,18], and pine resin extracts (a plant secretion from tree bark, particularly of conifers) [19] provided an effective control over the development of A. flavus<\/em> in vitro and of various horticultural products artificially infected by this fungus, including ficus and tomato [15,20,21]. In all of these studies, not only was the incidence of A. flavus<\/em> disease notably reduced compared to the untreated ones but also the production of the aflatoxins was remarkably low with corresponding values less than 20 ppb.<\/p>

In agriculture, nanotechnology has shown great potential for the development of new technologies. Applications include, among others, the production and development of food processing systems, chemicals (fertilizers, herbicides), and growth regulators. Currently, nanotechnology has also focused on the application of new and natural compounds that reduce or control the incidence of diseases caused by fungi during the postharvest storage of horticultural commodities [22].<\/p>

To increase its antimicrobial capacity, the nanotechnology can be used with the ad[1]vantage that some of the above-mentioned natural compounds can be encapsulated, as it has been proven that nanoparticles provide a larger contact surface, greater dispersion, and better conservation of the active product [23,24]. For instance, significant effects have been demonstrated in controlling the growth of A. flavus<\/em> with nanostructured formulations based on propolis at 1.2% and chitosan, achieving an inhibition of c.a. 40% at 10 days of incubation [15].<\/p>

For these reasons, the objectives of this research were to evaluate the efficacy of formulations based on propolis-chitosan-pine resin for: (1) the growth of A. flavus<\/em> on nutrient media; (2) the incidence of A. flavus<\/em> on maize grains and its effect on grain growth; and (3) the incidence of A. flavus<\/em> on maize tortillas, storage quality, and the production of aflatoxins.<\/p>

2.Results<\/h2>
2.1 Effect of Natural-Based Coatings on In Vitro A. flavus Development <\/em><\/strong><\/h5>

For these studies, there were significant differences (p < 0.001) among the treat[1]ments of the variables: mycelial growth and spore germination. The mycelial growth of A. flavus<\/em> was affected by the coatings containing chitosan + pine resin extract (T7), chitosan + propolis + pine resin extract (T9), and chitosan + nanoparticles of propolis and nanoparticles of pine resin extract (T10) (Table 1, Figure 1a). Compared to the control, the highest inhibition of A. flavus<\/em> was in nutrient media with chitosan + propolis + pine resin extract (T9) with a corresponding inhibition value of approximately 75%. With respect to spore germination, this was completely deterred throughout the whole incubation period when treated with chitosan + nanoparticles of propolis + nanoparticles of pine resin extract (T10) (Figure 1b). By contrast, the spore germination with the remaining treatments reached approximately 73% at the end of the incubation period of 10 h.<\/p>

Table 1.<\/b> Formulations applied for in vitro studies on Aspergillus flavus<\/i>.<\/p>\t\t\t\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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