Photoacoustic Spectroscopy in the Characterization of Bread with Turmeric Addition

In this research, we will apply photoacoustic spectroscopy and evaluate bread added with turmeric (Curcuma longa Linnaeus) at different concentrations in relation to wheat flour weight (0, 1.25, 2.5, 5, and 10%). The amplitude of the photoacoustic signal was related to measures of antioxidant activity and evaluation of the sanitary quality and also, the texture, color, and sensory acceptability of the breads. It is shown that (i) the photoacoustic signal produced by bread significantly increases with the turmeric concentration, such that it raises more than 100% for a concentration of 10% at the wavelengths of 428 and 515 nm. (ii) The bread antioxidant activity is directly proportional to the level of photoacoustic signal at 515 nm and its value increases from 73.21 to 91.73%, when the concentration increases from 0 to 10%. (iii) The sanitary quality of bread added with 2.5% of turmeric is relatively higher than the ones obtained for other lower concentrations. No fungal colonies were observed in bread mixed with 2.5%, 5%, and 10%, after 6 days of storage. (iv) The addition of turmeric powder for bread making can slow down their textural changes (hardness, elasticity, cohesiveness, resilience, and chewiness) during storage. (v) Bread at 2.5 and 5% of turmeric concentration showed the yellowest color, while the one with a 10% concentration exhibited the most reddish color. Finally, through principal component analysis, it was possible to demonstrate that a concentration of either 5 or 10% of turmeric added to wheat flour could be used to improve its sanitary quality and antioxidant activity.