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

• Published in: Food science & technology 2009-12, Vol.42 (10), p.1703-1711
• Main Authors: Nasar-Abbas, S.M., Siddique, K.H.M., Plummer, J.A., White, P.F., Harris, D., Dods, K., D'Antuono, M.
• Format: Article
• Language: English
• Subjects: color; Colour darkening; Cotyledons; faba beans; food storage; light; phenolic compounds; Phenolics; postharvest treatment; Pulse; Seed coat; storage temperature; testa; Vicia faba; water activity; water content
• ISSN: 0023-6438; 1096-1127
• DOI: 10.1016/j.lwt.2009.05.013

Faba 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 (± 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 (▵E ab ∗ values). Seeds with 8% SMC had more stable testa colour compared to seeds with higher SMC. Exposure to artificial light (350 μ mol m −2 s −1) substantially accelerated the colour darkening. Cotyledons stored at 37 ± 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.