Food demand prediction is a significant issue for both business process improvement and sustainable development. Data science methods, including artificial intelligence methods, are often used for this purpose. The aim of this research is to develop models for food demand prediction based on a nonlinear autoregressive exogenous neural network. The research focuses on processed foods, such as bread or butter. The architectures of the developed models differed in the number of hidden layers and the number of neurons in the hidden layers, as well as with different sizes of the delay line, were tested for a given product. The results of the research show that depending on the type of product, the prediction performance slightly differed. The results of the R ² measure ranged from 96,2399 to 99,6477, depending on particular products. The proposed models can be used in a company’s intelligent management system for the rational control of inventories and food production. This can also lead to a reduction in food waste.

The pH of the medium is the key environmental parameter of chemical selectivity of oxalic acid biosynthesis by Aspergillus niger. The activity of the enzyme oxaloacetate hydrolase, which is responsible for decomposition of oxaloacetate to oxalate and acetate inside the cell of the fungus, is highest at pH 6. In the present study, the influence of pH in the range of 3–7 on oxalic acid secretion by A. niger W78C from sucrose was investigated. The highest oxalic acid concentration, 64.3 g dm⁻³, was reached in the medium with pH 6. The chemical selectivity of the process was 58.6% because of the presence of citric and gluconic acids in the cultivation broth in the amount of 15.3 and 30.2 g dm⁻³, respectively. Both an increase and a decrease of medium pH caused a decrease of oxalic acid concentration. The obtained results confirm that pH 6 of the carbohydrate medium is appropriate for oxalic acid synthesis by A. niger, but the chemical selectivity of the process described in this paper was high in comparison to values reported previously in the literature.

Omnipresent globalisation causes integration of societies, economies and cultures, and air transport significantly facilitates it. Before the COVID-19 pandemic, air transport was one of the most dynamically developing types of transportation. The quality of airport services was measured, as it supports the development of air transport and airports in particular. As today the future of the air transport industry is not clear, it is essential to have the last picture of service quality assessment criteria before the airports' lockdown to sustain their development after reassumption. The study covered the operation of a regional international airport in Europe before the lockdown due to the COVID-19 pandemic. A diagnostic survey was used in the study, and the data were collected through a questionnaire of 40 questions. The study covered 263 passengers who had used the services of the examined airport at least once before the lockdown. The collected data were statistically analysed. The main findings are that the passengers consider components of the quality of airport services in groups and not individually. In some groups of factors, the level of satisfaction varies depending on the frequency of airport use. The results are in accordance with the findings of other authors researching different airports. They should be considered when managing the airport and identifying the causes of low-quality services to improve them and eliminate or at least reduce passenger dissatisfaction, especially in the face of resumption of airport operations after the COVID-19 pandemic.

Citric acid is currently produced by submerged fermentation of sucrose with the aid of Aspergillus niger mold. Its strains are characterized by a high yield of citric acid biosynthesis and no toxic by-products. Currently, new substrates are sought for production of citric acid by submerged fermentation. Waste materials such as glycerol or pomace could be used as carbon sources in the biosynthesis of citric acid. Due to the complexity of the metabolic state in fungus, there is an obvious need to optimize the important medium constituents to enhance the accumulation of desired product. Potential optimization approach is a statistical method, such as the central composite rotatable design (CCRD). The aim of this study was to increase the yield of citric acid biosynthesis by Aspergillus niger PD-66 in media with waste glycerol as the carbon source. A mathematical method was used to optimize the culture medium composition for the biosynthesis of citric acid. In order to maximize the efficiency of the biosynthesis of citric acid the central composite, rotatable design was used. Waste glycerol and ammonium nitrate were identified as significant variables which highly influenced the final concentration of citric acid (Y₁), volumetric rate of citric acid biosynthesis (Y₂), and yield of citric acid biosynthesis (Y₃). These variables were subsequently optimized using a central composite rotatable design. Optimal values of input variables were determined using the method of the utility function. The highest utility value of 0.88 was obtained by the following optimal set of conditions: waste glycerol—114.14 g∙L⁻¹and NH₄NO₃—2.85 g∙L⁻¹.

Informatyka Ekonomiczna = Business Informatics, 2020, Nr 4 (58), s. 111-126