Golden color is the introduction of fried food to everyone's senses, to everyone's first impression, the formation of fried food color and the chemical changes that occur during the frying process are inseparable, while the frying process of a variety of elements and affect the formation and transformation of its color.
01, the formation of color and frying processbinmei color changes
The color of fried food is generally formed by the non-enzymatic browning reflection, which contains the Melard reflection, caramelization reaction, etc..
The color of fried food is mainly generated in the second and third stages of the Merad reflection. The product of the first stage of the Melad reaction by fructosylamine 1,2-enolization, the product of hydroxymethyl furfural can be used as a symbol of food browning; the third stage is usually the generation of melanin, which makes fried food darker and darker color.
At the same time, the frying process does not coexist with the amines of sugar substances also undergo thermal degradation, these thermal degradation key to generate some volatile substances and finally converge to generate a burnt smell of caramelization, that is, caramelization reaction. The color of caramelization reaction varies with the process of reflection, and the color slowly deepens, thus forming a brownish-yellow caramel color.
In the frying process, the color of the product will change as the Melad reaction and caramelization reaction and other chemical changes take place. In general, the yellow and red colors of the ingredients are significantly enhanced during frying, giving a bright and cheerful appearance.
Krokida et al. studied the color change of potato sticks during frying and found that as the frying temperature increased, the brightness balance value increased as the L* value decreased and the equilibrium a* value increased as the a* value increased, and the b* value, which reflects the yellow color level, increased significantly.
Baik et al. found that when studying tofu frying at 147-172°C, the brightness (L*) decreased by, the red value (a*) increased by, the totalspirulina concentrate color change (ΔE*) increased by, and the yellow value (b*) increased and then decreased to the equilibrium point with the frying time. Wang Qinzhi et al. found in the study of color change of fried button meat that when the frying temperature reached 200 ℃, the button meat Qin color difference ΔE*, Δa* value and Δb* value increased significantly than when low temperature frying (frying temperature of 160 and 180 ℃), and the skin of button meat began to gradually darken when frying at 230 ℃ beyond 14 min.
02, the factors affecting the color of the frying process
The main factors affecting the color of fried food are: the characteristics of the raw materials themselves, frying substances, frying process parameters, processing methods, etc.
First, the characteristics of the raw materials themselves
Frying raw materials in the reducing sugar for fried products have an important impact on the color, easy to oxidation browning of raw materials also have an important impact on the color of fried foods. Yu Shanming et al. found that with the increasing content of reducing sugar in potatoes, the color of fried potato chips slowly deepened, when the reducing sugar content between 0.7% and 1.2%, the best color.
Second, the substances produced in frying
Some of the substances generated in the frying process, such as acrylamide and fried food color. serpen et al. found that the a* value and ΔE* value of fried food and the amount of acrylamide generation is positively correlated (r = 0.7870), indicating that the generation of acrylamide affects the transformation of food red.
Third, frying process parameters
The frying time and temperature describe the two most important parameters of the frying process and also the two most important parameters affecting the color of fried goods. pedreschi et al. studied the transformation of potato slices in the frying process and found that as the temperature increased, the rate of a* increase alsospirulina powder blue increased; similarly, as the frying temperature increased, the a* and ΔE* values also increased. When Sun Zhen et al. studied the color change of chicken wings during frying, they found that: with the increase of frying temperature and frying time, the L* value of fried chicken legs decreased and the a* value increased; with the increase of frying temperature, the b* value increased.
In summary, the brightness value of the product L* decreased, the b* value representing yellow and a* value representing red increased, and the ΔE* value representing the color gap increased as the frying time and temperature increased.