Thermal and Mechanical Effects on Retention of Food-Grade ?-carotene during Extrusion Processing
To determine the separate thermal effects of extrusion, nonisothermal experiments were conducted by heating wheat flour mixed with 0.46% (w/w) food-grade ?-carotene in an oil bath nonisothermally at 149°C at 28% (w/w) moisture content. To determine the total (thermal plus mechanical) effects of extr...
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Veröffentlicht in: | International journal of food engineering 2010-06, Vol.6 (3) |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | To determine the separate thermal effects of extrusion, nonisothermal experiments were conducted by heating wheat flour mixed with 0.46% (w/w) food-grade ?-carotene in an oil bath nonisothermally at 149°C at 28% (w/w) moisture content. To determine the total (thermal plus mechanical) effects of extrusion on retention of trans-?-carotene, the same mixture was extruded at 30/50/70/90/110°C and 50/70/90/110/130°C (barrel temperatures feed to exit) at screw speeds of 200, 250, 300, and 400 rpm on two separate days with a dough moisture content 30% (w/w). The rate constant at 100°C, 3.56 x 10-4s-1, and activation energy, 18.82 kJ/gmol, obtained from the nonisothermal experiments were used to calculate trans-?-carotene retention due to thermal effects during extrusion. For both temperature profiles, total trans-?-carotene retention ranged from 58 - 97%. Thermal effects accounted for less than 5% of the loss, showing that mechanical effects were the predominant cause of trans-?-carotene degradation. A linear statistical model worked well for separate days of extrusion; however, an exponential model was more effective for combined days of extrusion. Overall, food-grade ?-carotene was more stable than that of pure trans-?-carotene. |
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ISSN: | 1556-3758 1556-3758 |
DOI: | 10.2202/1556-3758.1568 |