Development and performance evaluation of a walnut kernel oil extractor

Walnut is known because of its high polyunsaturated fatty acid content, reduce blood pressure, LDL cholesterol and help to prevent some cancers. China is a leading walnut producer in the world with annual production of 1.786 million tonnes (MT). India ranks 11^th with production of 33000 tonnes per year. Total estimated area and production during 2018-2019 under walnut cultivation in the Union Territory of Jammu & Kashmir was 84777 ha and 0.279 MT, respectively. In walnut oil production, it is very important to find appropriate parameters to extract the oil efficiently from kernels. In this study, walnut oil was obtained through the combination of mechanical and manual energy. The development was targeted to achieve maximum oil yield, high extraction efficiency, quality oil at minimum cost. The effects of moisture content (3.0, 5.0 and 7.0 %) of walnut kernels, clearance (6.0, 8.0 and 10.0 mm) reduction unit and motor rpm (200, 250 and 300 rpm) in present experiments were evaluated. The response surface methodology was used for optimization of process parameters for oil yield, extraction efficiency and specific energy. The optimum conditions were experimentally validated. The maximum and minimum oil yield was 43.5 ml and 22.5 ml per 100 grams, respectively. The results stated that the maximum oil yield was obtained at 3% moisture content, 6.0 mm clearance and 250 rpm while as minimum was found at 7%, 10 mm and 250 rpm, respectively.