TITLE:
Effects of Germination and Roasting on Polyphenolic Compounds of Finger Millet (Eleusine coracana [L.] Gaertn.)
AUTHORS:
Fraser Onyango Juma, Hudson Nyambaka, Peter Chege, Chrispus Oduori, Everlyne Wanzala, Judith Munga, John Kinyuru
KEYWORDS:
Finger Millet, Germination, Roasting, Maillard Reaction, Total Phenolic Content, Total Flavonoid Content
JOURNAL NAME:
Food and Nutrition Sciences,
Vol.17 No.10,
October
19,
2026
ABSTRACT: Germination and roasting are routinely applied to finger millet (Eleusine coracana [L.] Gaertn.) before consumption in Kenya, yet their effects on polyphenols associated with the grain’s reported antidiabetic potential have not been quantified for Kenyan-bred germplasm. This study evaluated the effect of germination duration (0, 24, 48 and 60 h) and roasting treatment (raw, 120˚C for 5 min, 180˚C for 1 min) on the total phenolic content (TPC), total flavonoid content (TFC) and the gallic, ferulic and vanillic acid contents of the representative KALRO variety Kakamega Wimbi-1. TPC was measured by Folin-Ciocalteu spectrophotometry, TFC by aluminium chloride colorimetry, and phenolic acids by RP-HPLC-PDA using methods validated in accordance with ICH Q2(R1). Data from three independent treatment batches were analysed by one-way ANOVA with Student-Newman-Keuls post hoc separation at α = 0.05. Germination increased TPC approximately 6.3-fold (an estimated 18.16 to 115.23 mg GAE/100 g DW; the raw baseline lies below the TPC method LoQ) and TFC 7.9-fold (22.97 to 181.19 mg QE/100 g DW), both p 3+ rather than genuine flavonoid accumulation; because neither flavonoids nor Maillard products were directly quantified, this is offered as an interpretation. The acid-extractable ferulic acid reached a similar endpoint of 3.14 mg/100 g DW under both treatments, consistent with convergence of enzymatic and thermal hydrolysis on a shared arabinoxylan-bound pool, although free and bound fractions were not separately quantified. In Kak W-1 under the conditions tested, 48 h germination provided the clearest increase in measured polyphenolic indices, whereas the large roasting-associated TFC signal requires chromatographic confirmation before it can be interpreted as flavonoid enrichment.