| Garcinia indica, commonly known as Kokum, is a tropical fruit native to India. The rinds of fruit are rich source of red anthocyanin pigments which are characterized as cyanidin-3-glucoside and cyanidin-3-sambubioside. The fruit juice is strongly acidic (pH = 1.87) due to the presence of hydroxycitric acid, an organic acid known for its weight suppressing action. Recently a new, yellow, fat soluble pigment called garcinol has been separated from the fruit rinds. Garcinol is a polyphenolic compound known to possess antioxidant activity. Presence of bioactive compounds in the fruit promotes its use as a colorant and antioxidant in a food product. The antioxidant potential of Kokum has been previously studied but the effect of processing on its antioxidant activity is still unknown. Thus effects of extrusion processing on the color and antioxidant activity of rice extrudates fortified with spray-dried encapsulated fruit powder were studied.;A lab-scale Brabender single screw extruder was used for the extrusion. The control variables were barrel temperature (120°C--180°C), feed moisture (18--24%) and Kokum powder content (3--5%). The total phenolic content (TPC) and antioxidant activity of rice extrudates were measured by Folin-Ciocalteau method and ORAC, respectively. The color of extrudates (hue and chroma) was also measured to quantify the redness of samples. Effects of control variables on physical properties of extrudates such as bulk density, breaking strength and expansion index were also studied.;The extrudates showed excellent red color when extruded at temperatures up to 150°C beyond which anthocyanins degraded resulting in lesser red color. TPC and ORAC of samples showed maximum retention at 120°C and 180°C and minimum at 150°C. The loss of TPC and ORAC varied from 33 to 61% and 12 to 75%, respectively. Maximum breaking strength and maximum bulk density were observed at low temperature (120°C) and high moisture (21%). Expansion index was maximum at high temperature (150°C) and low moisture (18%). The effect of powder on bulk density and expansion index was not as prominent as that of temperature.;Thus, Kokum can be used as colorant and antioxidant for extruded product however; the loss of antioxidants is substantial. |
