Einkorn (Triticum monococcum L.) and nectarine flour mixture - antioxidant activity, microbiological and sorption characteristics

Abstract

The current paper presents the initial scientific research on a new enriched flour mixture with nectarine powder, comprising physicochemical parameters, antioxidant capacity, microbiological load, and sorption characteristics data. A mixture of 70% Einkorn flour and 30% fruit powder of Bulgarian origin as a functional food supplement was blended. The presence of bioactive components was proved by the in vitro analysis of antioxidant activity through DPPH, ABTS, FRAP, and CUPRAC methods. The microbiological indicators, the total count of mesophilic aerobic and facultative anaerobic microorganisms, yeasts and molds, Escherichia coli, Salmonella spp., coagulase-positive staphylococci and coliforms, were within the permissible norms and no presence of pathogenic microorganisms, were detected in the flour mixture. Adsorption and desorption processes were studied at 10, 25 and 40°C and aw = 0.112-0.868 following static gravimetric methods. The obtained S-shaped equilibrium sorption isotherms confirm the constant trend that with increasing equilibrium moisture content, the temperature decreases in conditions of constant water activity. Based on the obtained sorption capacity data, a calculation of the monolayer moisture content was made using the linearization of the BET model. One of the modified three-parametric models of Oswin, Halsey, Henderson, and Chung-Pfost was selected as a suitable model for describing all sorption isotherms.

Sorption comparative study of nectarine powder and flour mixtures with its participation

“…The preparation of whole wheat flour and nectarine powder mixture and the approximately physicochemical composition are described in detail in [15].…”

“…The modeling of the sorption isotherms was performed using three parametrical modified models of Chung-Pfost (1), Halsey (2), Oswin (3), and Henderson (4) with these selective equations as follow [15][16][17]:…”

“…where: М is the average moisture content, %; aw is the water activity, decimal; A, B and C are coefficients; t is the temperature, °C [13][14][15][16][17].…”

“…The program looks for models that fit the data well, with an average relative error (P%) below 10%. The three criteria used by Chen and Morey to compare the models are the standard error of moisture (SEM) (5) and the mean relative error (P, %) (6) [15][16][17].…”

“…𝑀 𝑖 and 𝑀 ̂𝑖 are experimentally and predicted value of the EMC; N -data points; df -degrees of freedom (number of data points minus number of parameters in the model) [15][16][17].…”