Influence of processing on the generation of γ-aminobutyric acid in green coffee beans
ABSTRACT A determination of the concentrations of free amino acids in differently processed green coffees indicated the nonprotein amino acid -aminobutyric acid (GABA), a well-known plant stress metabolite, to be present in raw coffee beans (Coffea arabica L.) in significantly varying amounts. The GABA content of unwashed Arabica beans (green coffee produced by the dry processing method) was always markedly higher than that of washed Arabicas (wet processing method) as well as that of untreated seeds. This result underlined the assumption that during postharvest treatment a significant metabolism occurs within coffee seeds. A putative relation between drought stress of the coffee seeds and postharvest treatment methods is discussed. The GABA content of green coffee beans may serve as a potent tool to characterize the type of postharvest treatment applied in coffee processing.
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ABSTRACT: Using individual grain analyses, the degree of inherent biological variation in germinating barley seeds has been established. Even under homogenous laboratory conditions, the activities of the germination-related enzymes α-amylase, β-amylase and β-glucanase varied by a factor of two to three. The comparison with single grain analyses of different industrially produced malts (steeping systems without aeration, with air suction and pressurised aeration) revealed that the heterogeneity of these malts nearly tripled. This increase may be due to the gradients in O2 and CO2 that arise in large industrial steeping vessels. The most homogenous malting in the industrial systems was achieved without any aeration during steeping. Therefore, to improve homogeneity, the common practise of steep aeration should be omitted. Germination progression was quite different within the three exhaustively aerated attempts, which indicated that gaseous composition was not the only factor affecting germination progression.Food Chemistry 03/2014; 147C:25-33. · 3.26 Impact Factor
- Revista Brasileira de Botânica 12/2011; 35(4):357-376.
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ABSTRACT: Coffee is one of the most frequently consumed drinks in the world. Coffee silverskin (CS) is the only by-product produced during the coffee beans roasting process, and large amounts of CS are produced by roasters in coffee-consuming countries. However, methods for the effective utilization of CS have not been developed. Reuse of CS, which is the primary residues from the coffee industry, is important for the environment and economy. Recently, there have been some attempts to reuse CS for biological materials and as a nutrient source for solid-state fermentation. The purpose of this review is to provide an overview about CS, its chemical composition, biological activity, and attempts at its reuse of CS.Food Research International 07/2014; · 3.05 Impact Factor