###### Abstract  
Postharvest grain preservation and storage can significantly affect the safety and nutritional value of cereal-based products. Negligence at this stage of the food processing chain can lead to mold development and mycotoxin accumulation, which pose considerable threats to the quality of harvested grain and, thus, to consumer health. Predictive models evaluating the risk associated with fungal activity constitute a promising solution for decision-making modules in advanced preservation management systems. In this study, an attempt was made to combine genetic algorithms and B-spline curves in order to develop a predictive model to assess the myological state of malting barley grain stored at various temperatures (T = 12-30 \({}^{\circ}\)C) and water activity in grain (a\({}_{\text{w}}\) = 0.78-0.96). It was found that the B-spline curves consisting of four second-order polynomials were sufficient to approximate the datasets describing fungal growth in barley ecosystems stored under steady temperature and humidity conditions. Based on the designated structures of B-spline curves, a universal parameterized model covering the entire range of tested conditions was developed. In the model, the coordinates of the control points of B-spline curves were modulated by genetic algorithms using values of storage parameters (a\({}_{\text{w}}\) and T). A statistical assessment of model performance showed its high efficiency (R\({}^{2}\) = 0.94, MAE = 0.21, RMSE = 0.28). As the proposed model is based on easily measurable on-line storage parameters, it could be used as an effective tool supporting modern systems of postharvest grain treatment. p 2023 13, 5264. [[https://doi.org/10.3390/app13095264](https://doi.org/10.3390/app13095264)]([https://doi.org/10.3390/app13095264](https://doi.org/10.3390/app13095264))  
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**Citation:** [PERSON]. (temperature, water, and nutrition stress) and biotic (weeds, pests, and microorganisms) factors [2; 3; 4]. Excess rainfall can cause the ripening grain to be affected by diseases induced by microorganisms, e.g., fungi of the _Fusarium_ genus (head blight or black dot disease) or diseases induced by various types of viruses (barley yellow dwarf, barley yellow mosaic), which may reduce crop yield, deteriorate grain quality, or increase grain susceptibility to spoilage during further storage [4; 5; 6]. Cereal grain stored in a warehouse or silo, along with the accompanying contaminants, pests, and microorganisms, constitutes a system of living organisms, referred to as the ecosystem of stored grain, which may be subject to various, also unfavorable, phenomena. Among microorganisms inhabiting harvested grain fungi, which exhibit the greatest capacity to damage grain and may contribute to economic losses in the cereal industries [7; 8]. These microorganisms are equipped with a well-developed enzymatic apparatus facilitating penetration through the pericarp into the kernels. Thus, even a slight initial contamination with fungal propagules (spores, sclerotia, mycelium fragments) under conditions conducive for their development may lead to their rapid growth, resulting in heating, loss of dry matter of grain, deterioration of its nutritional and technological quality, or even complete spoilage of harvested grain mass [6]. Moreover, the presence of microscopic fungi leads to kernel discoloration and the formation of a moldy off-flavor, which has a negative effect on the quality of derived products [4; 7; 9]. The presence of molds also poses a health hazard to consumers, as toxic metabolites produced by these microorganisms, being extremely stable chemically and practically impossible to remove, may penetrate the human food chain through plant origin products, as well as animal origin products, contaminated with these compounds through contaminated feed [10; 11].