Influence of germination on bioactive properties, phytochemicals and mineral contents of Tigernut (Cyperus esculentus L.) tuber and oils

Abstract

The increase in the oil yield of germinated (sprouted) tigernut tubers may be due to the decrease in protein, carbohydrate and mineral contents during the germination process. Antioxidant activity values of both sprouted and raw “Balyumru” tigernut tubers were found higher than those of results of sprouted and raw “Sariseker” tigernut tubers. The phenolic compounds of tigernut tubers changed depending on variety and germination process. Generally, gallic (except raw “Balyumru”), 3,4-dihydroxybenzoic acid, (+)-catechin, 1,2-dihydroxybenzene, syringic acid, caffeic acid, rutin trhydrate, p-coumaric acid, trans-ferulic acid and apigenin-7-glucoside contents of raw “Sariseker” and “Balyumru” tigernut tubers increased compared to sprouted tigernut tubers depending on germination process. The oleic acid amounts of sprouted and raw “Sariseker” and “Balyumru” tigernut tuber oils were determined as 72.47% and 71.36–72.67 and 73.58%, respectively. Ca, K, Mg, Na and P were found at the highest levels in tigernut tubers. The oil and protein contents, fatty acid compositions, total phenol, antioxidant activity, phenolic compounds and the nutrients of raw and sprouted (germinated) “Sariseker” and “Balyumru” tigernut tuber flours were investigated.