Temperature is a critical parameter in the SCW extraction process
(Shalmashi et al., 2008). In this study, the release of phenolic
compounds from potato peel could be observed in the color of the
extracts as a function of temperature. Fig. 3 shows the color of the
extracts and residues obtained from potato peel extraction with SCW
at pressure of 6 MPa and temperatures of 100 to 240 °C. At 100 °C, a
very light brown color of the extract was observed. As temperature
increased from 100 to 120 °C, the color of the extract became darker
(Fig. 3a) while the color of the residual potato peels became lighter
(Fig. 3b). At high temperatures (140 to 180 °C), higher concentrations
of phenolic compounds were recovered and color of the extract was
found to be even darker (Fig. 3a) than at lower extraction temperatures.
But, at temperatures of 180 to 240 °C, the color of the extract
becomes very dark (low content of phenolic compounds). Sample
pyrolysis (above 180 °C) resulted in degradation of phenolic compounds.
Also, as stated earlier by Pritchard and Adam (1994),
reactions of reducing sugars with amino acids (Maillard reaction) at
high temperatures occur. A direct relation of extraction temperature
with respect to color and yield of phenolic compounds was observed
up to 180 °C. This relation between the water color and phenolic
compound levels in potato peel was earlier reported by Thomas
(1981). This author compared the cooking water of whole potatoes
with the cooking water of pre-peeled potatoes, suggesting that the
cooking water color is influenced by the phenolic compounds of
potato peel.
Temperature is a critical parameter in the SCW extraction process(Shalmashi et al., 2008). In this study, the release of phenoliccompounds from potato peel could be observed in the color of theextracts as a function of temperature. Fig. 3 shows the color of theextracts and residues obtained from potato peel extraction with SCWat pressure of 6 MPa and temperatures of 100 to 240 °C. At 100 °C, avery light brown color of the extract was observed. As temperatureincreased from 100 to 120 °C, the color of the extract became darker(Fig. 3a) while the color of the residual potato peels became lighter(Fig. 3b). At high temperatures (140 to 180 °C), higher concentrationsof phenolic compounds were recovered and color of the extract wasfound to be even darker (Fig. 3a) than at lower extraction temperatures.But, at temperatures of 180 to 240 °C, the color of the extractbecomes very dark (low content of phenolic compounds). Samplepyrolysis (above 180 °C) resulted in degradation of phenolic compounds.Also, as stated earlier by Pritchard and Adam (1994),reactions of reducing sugars with amino acids (Maillard reaction) athigh temperatures occur. A direct relation of extraction temperaturewith respect to color and yield of phenolic compounds was observedup to 180 °C. This relation between the water color and phenoliccompound levels in potato peel was earlier reported by Thomas(1981). This author compared the cooking water of whole potatoesมีน้ำอาหารของมันก่อน peeled แนะนำที่อาหารน้ำสีมีอิทธิพล โดยม่อฮ่อมของเปลือกมันฝรั่ง
การแปล กรุณารอสักครู่..
