The effect of air-drying parameters on antioxidant activity and changes in antioxidant compounds ofbroccoli (Brassica oleracea L.) were studied. Broccoli samples were dried to 70 g kg?1 moisture content usingtemperatures ranging from 50 to 100 ?C and air flow-rates from 1.20 to 2.25m s?1, resulting in drying times from25 to 90 min. Temperature, owing to its positive effect on the oxidation kinetics, was negatively correlated withascorbic acid and free and total polyphenol contents but not with kaempferol, even though the sample driedat the highest temperature showed the lowest kaempferol content. The air flow-rate was positively correlatedwith the total (TPP) and free (FPP) polyphenol contents because it led to a reduction in the drying time. Nocorrelation was found between air flow-rate and kaempferol content. Air flow-rate and temperature positivelyaffected the antioxidant activity by reducing the drying time. High-temperature, short-time processes maximisedthe antioxidant activity of broccoli owing to the negative effect of drying time on antioxidant activity. Theantioxidant activity of broccoli was positively and significantly correlated with the FPP content but not with TPPand kaempferol. The evaluation of hydroxymethylfurfural content as an indicator of the occurrence of a Maillardreaction in dried broccoli did not support the hypothesis of a contribution of MRPs to the antioxidant activity ofdried broccoli.`a[...]
Effect of drying conditions on bioactive compounds and antioxidant activity of broccoli (Brassica oleracea L.)
SACCHETTI, Giampiero
2006-01-01
Abstract
The effect of air-drying parameters on antioxidant activity and changes in antioxidant compounds ofbroccoli (Brassica oleracea L.) were studied. Broccoli samples were dried to 70 g kg?1 moisture content usingtemperatures ranging from 50 to 100 ?C and air flow-rates from 1.20 to 2.25m s?1, resulting in drying times from25 to 90 min. Temperature, owing to its positive effect on the oxidation kinetics, was negatively correlated withascorbic acid and free and total polyphenol contents but not with kaempferol, even though the sample driedat the highest temperature showed the lowest kaempferol content. The air flow-rate was positively correlatedwith the total (TPP) and free (FPP) polyphenol contents because it led to a reduction in the drying time. Nocorrelation was found between air flow-rate and kaempferol content. Air flow-rate and temperature positivelyaffected the antioxidant activity by reducing the drying time. High-temperature, short-time processes maximisedthe antioxidant activity of broccoli owing to the negative effect of drying time on antioxidant activity. Theantioxidant activity of broccoli was positively and significantly correlated with the FPP content but not with TPPand kaempferol. The evaluation of hydroxymethylfurfural content as an indicator of the occurrence of a Maillardreaction in dried broccoli did not support the hypothesis of a contribution of MRPs to the antioxidant activity ofdried broccoli.`a[...]I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
