Effect of ozone on chemical and functional properties of wheat flour
1997
Wootton, Michael | Wichian Voraputhaporn(Khon Kaen Univ., Khon Kaen (Thailand). Faculty of Technology. Dept. of Food Technology)
Effects of ozone on some chemical and functional properties of flours from Australian standard white (ASW), Australian hard (AH) and Rosella wheats were examined. Lipids were immediately oxidised by ozone (12 ppm) as indicated by rancid odour, a significant (p LT0.05) increase of peroxide value (PV) and fat acidity (FA). The levels of FA were highly positively correlated (p LT 0.001) with the ozone levels and decreases in flour pH. Ozonation affected water holding capacity and swelling power of flours and their starches. However, the apparent amylose content in starch and diastatic activity of flour were not affacted. Brabender Viscograph and RVA peak viscosities of flours and starches were increased by ozonation. Gelatinisation temperature of ozonated starch tended to incresase. Greenness, yellowness, carotenoids and flavonoids of the flours were significantly decreased by ozonation. Carotenoids were more easily oxidised by ozone than flavonoids (C-glycosylflavonoids) due to the greater stability of the latter. Wet gluten content was not changed by ozonation (25-100 ppm) but the decreased sulphydryl (-SH) and increase in disultphide (S-S) were significant (p LT 0,05). This was indicated by increased glutenin fraction in protein extracts studied by SE-HPLC. However, SDS-PAGE studies showed that the molecular weight distribution of wheat proteins was not affected by ozonation. There were indications of decreased colour, especially yellowness, but increased hardness, chewness and strength in noodles made from ozonated flours.
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