Effect of Maillard reaction on reducing power of malts and beers

Abstract

AbstractČechovská L., Konečný M., Velíšek J., Cejpek K. (2012): Effect of Maillard reaction on reducing power of malts and beers. Czech J. Food Sci., 30: 548-556.HPLC with amperometric detection was used to evaluate the reducing power of 23 beers and aqueous extracts of 17 barley malts. While brew pale malts were only slightly higher in electrochemical reducing capacity than natural barleys (about 1.3 g BHAE/kg), caramel malts with the colour of 60-450°EBC showed 7.5-17.2 g BHAE/kg. The superior reducing power of the darker caramel malts was partly due to the presence of a Maillard-derived 2,3-dihydro-3,5-dihydroxy-6-methyl-(4h)-pyran-4-one (DDMP), which was responsible for 21-55% of their electrochemical capacity. Among common brew malts, only the Munich type showed a significantly increased electrochemical capacity -6.8 ± 0.8 g BHAE/kg. In addition to the malts, the brewing can also affect the electrochemical capacity of beers, which ranged from 0.4 ± 0.1 to 1.9 ± 0.3 g BHAE/l. Simple indigenous malt-derived phenolics were responsible for 48-57% of capacity in pale lagers and for 33-45% of it in dark and other specialty lagers. DDMP was not detected in most pale lagers, while it was responsible for up to 11% of the electrochemical capacity in dark and special beers. Highmolecular-weight fraction (> 1kDa) of beers comprised 19-39% (pale lagers) and 14-21% (dark and special beers) of the capacity. The reducing power of malts and beers determined by the amperometric method was confirmed by a good correlation with the results of DPPH• scavenging assay.

Overall Antioxidant Properties of Malt and How They Are Influenced by the Individual Constituents of Barley and the Malting Process

“…Around 80% of the phenolic compounds identified in beer is derived from malt, while the remaining 20% comes from hops (De Keukeleire ; Quifer‐Rada and others ). Moreover, malt can contribute to about 95% and 86% of the antioxidant capacity of dark and pale beers, respectively (Čechovská and others ), while hopping did not significantly affect the phenolic content or the antioxidant activity of beer (Leitao and others ). Accordingly, malt can be described as the principal source of antioxidants in beer.…”

“…It was reported that the antioxidant capacity of malt can increase during kilning and roasting, not only because modification or release of phenolic compounds, but also due to the development of reductones and MRPs through the Maillard reaction (Maillard and others ; Woffenden and others ; Samaras and others ; Vanderhaegen and others ; Inns and others ). Herein, MRPs have been identified as the major contributors to the antioxidant activity of roasted malts (Coghe and others , ; Samaras and others ), with a positive influence on the maintenance and development of malt reducing properties (Čechovská and others ).…”

“…In agreement, aqueous pale malt extracts exhibited a slightly higher electrochemical reducing capacity compared to raw barley, while roasted malts showed almost a 13‐fold higher reducing capacity, whereas MRPs contributed 55% of the total reducing power. In comparison, malt‐derived phenolics were responsible for around 50% and 40% of the reducing power of beers produced form pale and dark malt, respectively (Čechovská and others ).…”

Phenols and Melanoidins as Natural Antioxidants in Beer. Structure, Reactivity and Antioxidant Activity

“…Around 70-80% of the phenolic compounds present in beer are derived from malt, while the remaining 30-20% come from hops [5,6]. Moreover, malt can contribute to around 95% and 86% of the antioxidant capacity of dark and pale beers, respectively [7], while hopping did not affect significantly the antioxidant activity of beer [8].…”

On the contribution of malt quality and the malting process to the formation of beer staling aldehydes: a review

“…pale malt delivers around 80-85% of polyphenols to beer, whereas dark speciality malt delivers approx. 95%), whereas hops contribute only a minor fraction of the total beer polyphenols (88)(89)(90). Melanoidins and reductones (intermediates of Maillard reactions) are present in all types of malt, however, in particular in dark speciality malts as they are mostly formed during the roasting process through intensive heating.…”