Compressive stress, repetitive strain, and optimum expression of oil from bulk volumes of sesame seeds

Abstract

Compressive expression of oil from bulk seeds is a self‐limiting process and commonly adopted techniques for optimizing oil recovery result in alterations of the product and its quality. In this study, effects of select magnitudes of compressive stress and repetitive strain on mechanical response and performance during cold compressive expression of oil from sesame seeds were investigated and responses modeled using forward stepwise regression technique. Significant gains in oil yield and performance were achieved through repeated induction of strain and by increasing magnitudes of the applied stress. Cumulative improvement in the performance of the scheme over existing single cycle compression techniques ranged between 34.1 and 161.9% over the range of treatments investigated. Corresponding improvement in mechanical response was also achieved. Specific mechanical energy demand was less with every additional compression cycle. The pressure ratio at the oil point during each compression cycle was an important indicator of recoverable oil. Practical applications A technique for maximizing the yield of oil from oilseeds and efficiency during cold compressive expression is presented which may be incorporated in the design of compression devices or similar systems, which would permit repeated induction of stress with a view to optimizing process efficiency without denaturing the product or altering its quality. The pressure ratio at the oil point is also presented, which is a fitting indicator of requisite stress for optimizing yield and performance.