Sensory odour profiling and physical characteristics of edible oil blends during frying

Edible oil blends containing 80 parts of mustard oil (MO) or groundnut oil (GNO) or sunflower oil (SNO) and 20 parts of sesame oil (SO) or refined red palm oil (RPO) or rice bran oil (RBO) were studied to determine the changes in their physical and sensory characteristics during deep fat frying. Odour evaluation by the trained sensory panel revealed that successive fryings subdued the intensity of typical odour notes of the oil blends. Intensity of sulphury, pungent and vinegar (sour) notes of MO, nutty and sweet notes of GNO, sweet and seedy notes of SNO, seedy and earthy notes of SO, husk-like note of RPO and beany and branny notes of RBO decreased significantly by end of the 7th frying. Apparent viscosity of the oil blends increased on successive frying. Colour measured in CIE system indicated that the dominant parameters were a+ (redness) in RPO blends, b+ (yellowness) in blend containing SO or MO and a− (greenness) in RBO blends. The redness component decreased and yellowness increased with successive frying in SNO + RPO blend and GNO and RBO blend, respectively. Applying principal component analysis (PCA) to the data showed seggregation of various oil blends as distinct groups exhibiting their typical and characteristic attributes. PCA also revealed the pathway of change of oils during different frying cycles. MO and blend of MO + RPO were characterised by sulphury, pungent, harsh odour notes and red colour; GNO occupied a quadrant with fresh-oil-like, green and sweet notes, and SNO was characterised by fresh-oil-like, seedy odour and yellow colour. Addition of SO increased earthy note and lightness value, while blends containing RBO had distinct yellow colour, increased heated note and higher apparent viscosity.