Effect of Heat Treatment on the Antioxidant Activity, Color, and Free Phenolic Acid Profile of Malt
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- 作者：Elizabeth L. Inns ; Lesley A. Buggey ; Christopher Booer ; Harry E. Nursten ; Jennifer M. Ames
- 刊名：Journal of Agricultural and Food Chemistry
- 出版年：2007
- 出版时间：August 8, 2007
- 年：2007
- 卷：55
- 期：16
- 页码：6539 - 6546
- 全文大小：118K
- 年卷期：v.55,no.16(August 8, 2007)
- ISSN：1520-5118
文摘
Green malt was kilned at 95 
C following two regimens: a standard regimen (SKR) and a rapidregimen (RKR). Both resulting malts were treated further in a tray dryer heated to 120 C, as wasgreen malt previously dried to 65 C (TDR). Each regimen was monitored by determining the color,antioxidant activity (by both ABTS
+ and FRAP methods), and polyphenolic profile. SKR and RKRmalts exhibited decreased L* and increased b* values above approximately 80 C. TDR malts changedsignificantly less, and color did not develop until 110 C, implying that different chemical reactionslead to color in those malts. Antioxidant activity increased progressively with each regimen, althoughwith TDR malts this became significant only at 110-120 C. The RKR malt ABTS+ values werehigher than those of the SKR malt. The main phenolics, that is, ferulic, p-coumaric, and vanillic acids,were monitored throughout heating. Ferulic acid levels increased upon heating to 80 C for SKR andto 70 C for RKR, with subsequent decreases. However, the levels for TDR malts did not increasesignificantly. The increase in free phenolics early in kilning could be due to enzymatic release ofbound phenolics and/or easier extractability due to changes in the matrix. The differences betweenthe kilning regimens used suggest that further modification of the regimens could lead to greaterrelease of bound phenolics with consequent beneficial effects on flavor stability in beer and, moregenerally, on human health.
C following two regimens: a standard regimen (SKR) and a rapidregimen (RKR). Both resulting malts were treated further in a tray dryer heated to 120 C, as wasgreen malt previously dried to 65 C (TDR). Each regimen was monitored by determining the color,antioxidant activity (by both ABTS+ and FRAP methods), and polyphenolic profile. SKR and RKRmalts exhibited decreased L* and increased b* values above approximately 80 C. TDR malts changedsignificantly less, and color did not develop until 110 C, implying that different chemical reactionslead to color in those malts. Antioxidant activity increased progressively with each regimen, althoughwith TDR malts this became significant only at 110-120 C. The RKR malt ABTS+ values werehigher than those of the SKR malt. The main phenolics, that is, ferulic, p-coumaric, and vanillic acids,were monitored throughout heating. Ferulic acid levels increased upon heating to 80 C for SKR andto 70 C for RKR, with subsequent decreases. However, the levels for TDR malts did not increasesignificantly. The increase in free phenolics early in kilning could be due to enzymatic release ofbound phenolics and/or easier extractability due to changes in the matrix. The differences betweenthe kilning regimens used suggest that further modification of the regimens could lead to greaterrelease of bound phenolics with consequent beneficial effects on flavor stability in beer and, moregenerally, on human health.