Abstract:
Macrotyloma uniflorum (Horse gram) shows remarkable health effective
antioxidant potential. As raw seeds are hard to cook; pretreatments are used to
reduce cooking time. However, the scientific information of the effects of
these pretreatments on phytochemicals and antioxidant activity is not
available. Hence, this study was designed to determine the impact of selected
pretreatments, i.e. soaking and germination, on phytochemicals and
antioxidant potential in commercially available horse gram seeds. Using
purchased seed samples from a retail shop in Matara, Sri Lanka., qualitative
phytochemical screening, quantitative determination of total phenolic content
(TPC), total flavonoid content (TFC), and antioxidant activity using DPPH
assay and FRAP assays were performed with triplicates of methanolic extracts
of a) soaked (8h), b) soaked (8h) and germinated (24h and 48h) seeds, after c)
cooking or d) in uncooked conditions. The results were compared with those
of raw seeds. Data were statistically analyzed by One- way ANOVA, 2-sample
and paired T tests using Minitab 17 software. Phytochemical screening
revealed the presence of highly important bioactive compounds irrespective
of the type of pretreatment. TPC, TFC and FRAP contents were significantly
higher in the raw seeds compared to other treatments. In treated samples, TPC
was the highest in the cooked seeds after 24h germination pretreatment
(P=0.001). TFC and FRAP were highest in the cooked after 8h soaking
pretreatment (P < 0.001 for both). IC50 values of DPPH assay showed no
significant difference (P < 0.05) between soaking and 24h germination. The
best antioxidant capacity (300 mg/mL) was observed in the raw soaked seeds
for 8h. Hence, the soaked (8h) seeds are better to cook for human consumption
due to relatively less effect on phytochemicals and antioxidant properties
compared to other selected treatments and germination does not affect much
on major antioxidant groups.
