SHORT COMMUNICATION Exploratory Analysis for Characterization of Solvent-Treated Products (Meal and Extract) from Rapeseed Press-Cake: Preliminary Investigation Using Principal Component Analysis Manashi Das Purkayastha • Nipu Dutta • Dipankar Kalita • Charu Lata Mahanta Received: 19 February 2013 / Accepted: 3 February 2014 Ó Springer Science+Business Media Dordrecht 2014 Abstract The purpose of this investigation was to gain insight into the applicability of different solvents for obtaining useful bio-based products like protein (as func- tional food ingredient), polyphenols (as natural antioxi- dant), or phytosterols (for pharmaceutical use) from rapeseed press-cake (the major residual biomass from oil industries). This biomass valorization would in-turn add to the sustainability and aggregate value to the waste man- agement cycle. Commonly used solvents were employed for extraction and were segregated on the basis of their efficacy in removing polyphenols, tannins and residual oil from the cake, protein enrichment in the meal and also according to their chemical variability in GC–MS spectra of the solvent extracts, using principal component analysis. While still in the early stages of investigation, the obtained results reflect solvent treatment of oil-cakes as a promising strategy for biomass valorization in oilseed processing industries and other bio-refineries. Keywords Rapeseed press-cake Á Solvent extraction Á GC–MS Á PCA Introduction Rapeseed ranks currently the third source of vegetable oil (after palm and soy) and the third leading source of oil meal (after soy and cotton) [1]. Rapeseed cake is the solid waste remaining after cold pressing of rapeseed to produce vege- table oil. Typically, cold pressing reduces the oil content from 40–45 to 14–15 % [2]. The oil remaining in the rape- seed cake can eventually be recovered by solvent extraction. Currently, rapeseed cake is valorized as animal feed, because of its high proteins and triglycerides content. Recycling of by-products derived from various industries is crucial. Rapeseeds are much richer in phenolic compounds compared to other oilseeds. Most of these phenolics remain in the meal after pressing. Extracts obtained from these oil processing residues exhibit remarkable antioxidant activity, which has been well-documented by several authors [3]. Krygier et al. [4] found that rapeseed flour contains no insoluble-bound phenolic acids and therefore, solvent extraction procedures would be effective in removing essentially most of the phenolic compounds from rapeseed, a technique which could be employed to produce a bland and light-coloured food-grade palatable protein-rich flour or protein concentrate. Selection of an extraction solvent is the preliminary parameter which should be critically considered before an extraction is started; as there is no single universal solvent applicable for all food matrices. Most researches on rapeseed press-cake have concentrated either on rapeseed protein extraction, using alkaline solutions, or on antioxidant phenolics extraction, using aqueous methanol or acetone [1, 5]. If exhaustive extraction of phenolics is desired then the protein extraction (or yield) gets affected, and vice versa if attention is paid only on protein removal from the meal. None of the study till today has mentioned on the progressive extraction or utilization of both these valuable components/ Electronic supplementary material The online version of this article (doi:10.1007/s12649-014-9293-8) contains supplementary material, which is available to authorized users. M. Das Purkayastha Á D. Kalita Á C. L. Mahanta (&) Department of Food Engineering and Technology, School of Engineering, Tezpur University, Tezpur 784028, Assam, India e-mail: charu@tezu.ernet.in N. Dutta Department of Chemical Sciences, School of Science and Technology, Tezpur University, Tezpur, Assam, India 123 Waste Biomass Valor DOI 10.1007/s12649-014-9293-8