ABSTRACT
This study aimed to evaluate the effect of ethanolic propolis extract (EPE) as a natural antimicrobial and antioxidant agent on the physicochemical, microbial, and sensory characteristics of toast bread, as well as phenol content and antioxidant activity. In this regard, 0.1, 0.3, and 0.5% of EPE were used in the bread doughs and the quality characteristics of the breads were assessed. The bread with 0.5% EPE showed the highest phenolic content (24.02 mgGAE/g.d.m) and antioxidant activity (59.03%). These amounts were 12.96 mgGAE/g and 16.45% higher than those of the control (without EPE), respectively (p < .05). The hardness, fracturability, and chewiness of the bread samples were influenced by the levels of EPE on the third and fifth days of storage. EPE decreased the L* and a* of bread samples, but an increasing trend was observed in the b*, chroma, and browning index by elevating the levels of propolis. Propolis extract showed an inhibitory effect on mold growth in samples. The bread with 0.5% of EPE had the lowest mold count after 5 days of storage which was not significant compared to the first day. There was no significant difference in sensory evaluation between the overall acceptance of bread samples. Therefore, EPE has the potential to be used as a natural additive with antimicrobial and antioxidant characteristics in toast bread.
ABSTRACT
The present study was conducted to evaluate the addition of a mixture of oleaster (OL; E. angustifolia L.) and black cumin (BC; Nigella sativa) flours on the quality characteristics of toast bread. The concentration of OL and BC mixture (1:1 w/w ratio) was 0 (T1), 1.5% (T2), 2% (T3), and 2.5% (T4) of total flour content. The bread samples containing the mixture of OL and BC flours had more protein content (8.49%-9.65%) than the control (6.81%; p < .05). The highest phenolic compounds and DPPH free radical scavenging capacity were observed in T4 and T3 samples, respectively. The OL and BC flours decreased the brightness, yellowness, and chroma and increased the redness compared to the control. The mixed flour concentration influenced the bread's hardness and chewiness. Adding OL and BC flours increased the calcium content in the bread (467.65-600.41 ppm) compared to the control (363.9 ppm; p < .05). The OL and BC flour mixture created a more compact texture in the bread samples. In the sensory evaluation, there was not a significant difference between the overall acceptability of the bread containing the mixture of OL and BC flours and the control (p > .05). Finally, it is recommended to utilize a mixture of 2% of OL and BC flours in toast bread to improve its nutritional properties.
