EFFECTS OF DIFFERENT OAK VARIETIES (QUERCUS Spp.) ON CHEMICAL AND SENSORY QUALITY OF RAKSHI (FINGER MILLET WHISKY)

Abstract

The aim of this research was to evaluate the effects of Nepalese origin oak cubes on rakshi maturation, comparing it with American white oak effects. Rakshi, made from finger millet, was distilled twice and its alcohol content was adjusted to approximately 73% v/v. Along with a control, five types of oak cubes and one non-oak variety were used for a one-year maturation period. A little amount of the whisky samples were taken every three months and analyzed qualitatively and semi-quantitatively for their sensory characteristics to evaluate maturation progression. The whisky base spirit for this research was produced from finger millet grain using traditional distilling methods practiced in Nepal. Proximate analysis of the raw millet confirmed its suitability as a fermentation substrate. Following a 40-day fermentation, the mash had stable pH and alcohol levels proportional to sampling depth after 40 days of fermentation. The matured whisky was analyzed for pH, total dissolved solids (TDS), conductivity, color development, and chemical composition using spectrophotometry and gas chromatography-mass spectrometry (GC-MS). The findings support that chemical composition, including maturation, resulted in significant increase of certain constituents like ethyl acetate, acetic acid, some higher alcohols (isoamyl alcohol) with reported incerease of about 41%, 56%, 75% respectively, while strongly reduced concentrations of methanol (from 50.29 to 11.5ppm) reached safe levels in treated samples. Sensory evaluations covering appearance, aroma, mouthfeel, body, aftertaste, and overall acceptability revealed that all treated samples outperformed the control, with Sample D (Quercus lamellosa, Phalat) showing strong similarity to the reference (Sample B, American oak) in both chemical and sensory attributes. Radar chart analyses further illustrated the progressive enhancement of desirable flavor characteristics such as vanilla, smoky, and fruity notes, particularly in Nepalese oak-treated samples. The findings underscore the potential of Nepalese oak and other varieties as a viable alternative to imported oak species in whisky maturation, with recommendations for further studies on oak seasoning and potential for barrel aging