Premium
Colour loss during extrusion cooking of β‐carotene‐wheat flour mixes as an indicator of the intensity of thermal and oxidative processing
Author(s) -
GUZMANTELLO R.,
CHEFTEL J. C.
Publication year - 1990
Publication title -
international journal of food science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.831
H-Index - 96
eISSN - 1365-2621
pISSN - 0950-5423
DOI - 10.1111/j.1365-2621.1990.tb01099.x
Subject(s) - extrusion , plastics extrusion , chemistry , carotene , food science , reaction rate constant , residence time (fluid dynamics) , extrusion cooking , wheat flour , kinetics , materials science , organic chemistry , composite material , physics , geotechnical engineering , quantum mechanics , engineering
Summary The thermal and/or oxidative colour loss from a wheat flour/all‐trans β‐carotene (20–80 mg kg −1 ) mix during extrusion cooking follows first order kinetics. The intensity of processing in extrusion is reflected in the overall rate constant ( K ) of colour loss. K ‐values were in the range 3–20x10 −3 s −1 . They increased markedly with decreasing water content of the mix (24–14%), and with increasing barrel temperature (100–220°C). Results were independent of the type of twin‐screw extruder (Werner‐Pfleiderer Continua 37 or Clextral BC‐45). Modelling of the overall rate constant K and of the ‘equivalent plug flow’ residence time was used to define ‘iso‐destructive’ extrusion conditions giving approximately the same residence time and the same mean product temperature. Extrusion under N 2 or O 2 , or in the presence of 1 mg BHT per g of β‐carotene, slightly affected colour loss. Adsorption chromatography on alumina indicated that within a barrel temperature range of 125–200°C, 38–73% of the initial all‐trans β‐carotene was destroyed, and that 2/3 to 1/2 of this loss corresponded to the formation of 9‐cis plus 13‐cis β‐carotene isomers. The formation of smaller amounts of unknown β‐carotene derivatives may be responsible for the colour loss.