Oat Flour Enriched with Nectarine Powder of Bulgarian Origin – Antioxidant Activity, Microbiological and Moisture Sorption Characteristics

Adelina Vasileva1, Albena Durakova2, Milena Dimitrova-Dicheva3, Zhivka Goranova4, Hristo Kalaydzhiev5 and Kliment Georgiev1
1 Technical University of Sofia, Branch Plovdiv, Department of Mechanical and Instrument Engineering, 4000 Plovdiv, Bulgaria
2 University of Food Technologies, Department of Process Engineering, 4002 Plovdiv, Bulgaria
3 University of Food Technologies, Department of Milk and Dairy Products Technology, 4002 Plovdiv, Bulgaria
4 Institute of Food Preservation and Quality, Department of Food Technology, 4003 Plovdiv, Bulgaria
5 University of Food Technologies, Department of Analytical and Physical Chemistry, 4002 Plovdiv, Bulgaria


Vasileva, A., Durakova, A., Dimitrova-Dicheva, M., Goranova, Zh., Kalaydzhiev, H. & Georgiev, K. (2022).  Oat Flour Enriched with Nectarine Powder of Bulgarian Origin – Antioxidant Activity, Microbiological and Moisture Sorption Characteristics. Bulg. J. Agric. Sci., 28 (6), 1147–1155

Two regional food products were evaluated to create a flour mixture intended for the production of sponge cake. The functional mixture flour consists of oats flour and nectarine powder of Bulgarian origin. The current scientific research presents the physicochemical composition, antioxidant activity, microbiological, and sorption characteristics of the new flour mixture. The performed analysis on the physicochemical parameters were protein 9.98 g, total carbohydrates 74.40 g, total lipids 3.71 g, ash content 3.49 g and crude fibers 6.21 g, calculated on a dry matter basis of 90.82%. The antioxidant activity was determined using the DPPH, ABTS, FRAP, and CUPRAC methods. All microbiological parameters, namely the total count of mesophilic aerobic and facultative anaerobic microorganisms, yeasts and molds , Escherichia coli, Salmonella spp., coagulase-positive staphylococci, and coliforms, were under permissive norms and no pathogenic organisms were detected. Sorption characteristics, including equilibrium moisture content and monolayer moisture content, were investigated at three different temperatures – 10°C, 25°C and 40°C and water activities in the range of 0.1 to 0.9 following the static-gravimetric method. Estimation of obtained sorption isotherms was performed with a modified three-parametric model of Halsey, Oswin, Henderson and Chung-Pfost, evaluating with criteria of suitability models, namely average relative error (P, %) and moisture standard error (SEM). BET equation was linearized for obtaining the monolayer moisture content values.

Keywords: oats; nectarine; flour mixture; antioxidant activity; sorption isotherms; monolayer moisture content

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