Faba bean (Vicia faba L.) seeds darken rapidly and phenolic content falls when stored at higher temperature, moisture and light intensity

Abstract

a b s t r a c tFaba beans cv. Fiesta with seed moisture content (SMC) modified to 8, 10, 12 and 14% were packed in polyethylene lined aluminium foil bags and stored at 5,15, 20, 25, 30, 37, 45, 50 or 60 C (AE 2 C) for one year. Samples were analysed for moisture content and seed coat (testa) colour over the storage period using a chroma meter. A continuous increase in L * and b * values was found in all samples with the passage of time whereas a * values first increased and then decreased in samples stored at relatively high temperatures (! 37 C). The initial beige testa colour changed to light brown, dark reddish-brown or almost black depending on storage conditions. The higher the temperature and SMC the faster the rate of change in colour (6E ab * values). Seeds with 8% SMC had more stable testa colour compared to seeds with higher SMC.Exposure to artificial light (350 m mol m À2 s À1 ) substantially accelerated the colour darkening. Cotyledons stored at 37 AE 2 C also darkened with the storage time. A loss in total free phenolics, total tannins and proanthocyanidins was found with increased darkness of testa and cotyledons during storage.

Influence of Storage on Darkening and Hardening of Slow- and Regular-Darkening Carioca Bean (Phaseolus vulgaris L.) Genotypes

“…However, this study shows that, in absolute terms, the a* values in the fifth month of storage were higher in genotypes with lower luminosity, indicating that these two color parameters jointly contribute to visual characteristics of bean darkening, and not only the tegument luminosity. This confirms previous report (Nasar-Abbas et al, 2009), that during bean darkening process the original reddish-brown color of grains change, followed by the loss of lightness.…”

Physicochemical properties and enzymatic bean grains dried at different temperatures and stored for 225 days

“…Such behavior is explained by the presence of high molecular weight tannins with hydroxyl groups that are capable of forming stable bonds with proteins (NASAR-ABBAS et al, 2008). Furthermore, tannins may migrate from the seed coat to the cotyledons, forming cross-links with cellular macromolecules within the cell walls or in the middle lamella during storage.…”

“…These are important parameters that affect the assessment of solubility, color, flavor, mineral bioavailability, and the in vitro digestibility of phaseolin in their native and denatured forms. They are capable of forming complexes, primarily through hydrophobic interactions (NASAR-ABBAS et al, 2009;NJOROGE et al, 2014).…”

Effect of preparation practices and the cowpea cultivar Vigna unguiculata L.Walp on the quality and content of myo-inositol phosphate in akara (fried bean paste)

“…The darkening of cowpeas during storage is attributable to the oxidation of leucoanthocyanins catalysed by air and light although it may also be caused by non-enzymatic browning (Nasar-Abbas et al, 2009). …”