12TH INTERNATIONAL CONFERENCE ON RENEWABLE RESOURCES & BIOREFINERIES . GHENT (BELGIUM), 30 – 31 MAY & 1 JUNE, 2016 3 The actual concept of circular economy aims to minimize the amount of residues, having lot of intends focused there attention on biorefineries. The profitability of these biorefineries could be increase if, as a previous step, the minor compounds but with high value added products are extracted. In this work, wheat bran is used as raw material as it constitutes an abundant and underused byproduct from the milling industry. Ferulic acid (FA) is the main phenolic compound present in wheat bran (its structure is shown in figure 1). It exhibit potential commercial applications not only in health but also in food and cosmetic industries, and can be found in three forms: soluble free, soluble conjugated and insoluble bound form, the latest one mostly related to the ester links between it and the arabinoxylans (AX). María Victoria Pazo-Cepeda, O. Benito-Román, A. Navarrete, María José Cocero, Esther Alonso High Pressure Processes Group. Department of Chemical Engineering and Environmental Technology. University of Valladolid (Spain) (*ealonso@iq.uva.es) ADDING VALUE TO CROP BIOREFINERIES: EFFICIENT EXTRACTION OF FERULIC ACID FROM WHEAT BRAN 3 - .Introduction and Aims 1 - .Conclusions 4 • More than 98% of FA in wheat bran is in an insoluble bound form and its released depends on breaking the ester links between it and the polysaccharides chains. • The PLE showed that water is a better solvent than mixtures Ethanol-Water, since the limiting step is hydrolysis. 160°C and 75 minutes are the optimum conditions for the extraction with water in stirred batch reactor, leading to a extraction yield of 14.8%. • FA is extremely sensitive to high temperatures. The hydrolysis needs to be enhanced in order to reduce the time of exposition of the released FA to the high temperature. • Ultrafast SCWH and MAE are promising techniques to this purpose. The extracted FA obtained with SCWH was around 50% of the initial one, which was 3.5-fold higher than the obtained with PLE and required an extremely low reaction time. Further studies are needed to decide the best extraction technique. - .Results and Discussion 3 3 In this work, the FA content in wheat bran was characterized, then a PRESSURIZED LIQUID EXTRACTION (PLE) was performed using different mixtures of ethanol-water, at different temperatures and extraction times in order to evaluate their effect in the amount of extracted FA. Other two techniques: SUPERCRITICAL WATER HYDROLYSIS (SCWH) and MICROWAVE ASSISTED EXTRACTION (MAE) were proposed as they are in accordance with the conclusions obtained from the first study. 1. CHARACTERIZATION. The total amount of FA in the wheat bran matrix is 2570.9 µg/g, being 3.8 and 31.6 µg/g the amount of free and soluble conjugated FA, respectively. Figure 1. Ferulic acid molecule NaOH 2M, 4hs, T amb Figure 2. Main effect plot for FA Water 20%EtOH T (°C) 160 160 t (min) 74.3 101.9 log(R0) 3.64 3.77 Max [FA] 381.7 253.9 Yield (%) 14.8% 9.9% Table 1. Maximum amount of FA obtained with PSAE ACKNOWLEDGEMENTS: The authors thank the Spanish Ministry of Economy and Competitiveness for the Project CTQ2015-64892-R (MINECO/FEDER) and the Project CTQ2013-44143-R. - .Experimental section 2 Characterization of FA in the matrix EtOH 80%, T amb liquid Diethyl eter Free FA Alkaline hydrolysis Soluble conjugated FA Alkaline hydrolysis Total FA Pressurized liquid extraction Stainless steel batch reactor V tot = 140 mL P max = 15 bar Box-Behnken experimental design • Solvent: 20-50-80% EtOH • Temperature: 130—145- 160 ᵒC • Time: 20-40-60 min Study of the effect of each parameter Maximize FA extraction in the conditions tested 2. PRESSURIZED LIQUID EXTRACTION-EXPERIMENTAL DESIGN. Extracted FA ranged from 43 to 236 µg/g. The main effect plot for FA is shown in figure 2: it can be seen that higher temperatures, longer extraction times and less ethanol content in the solvent are needed in order to obtain thegreater amount of FA. Following the trends, further experiments were done using longer times and also water as solvent. The maximum amounts obtained are shown in table 1. www.hpp.uva.es Wheat bran Provided by a milling factory from Valladolid, Spain: Emilio Esteban SA • MEAN PARTICLE SIZE: 1140 mm • MOISTURE: 12.1% Supercritical water hydrolysis Microwave assisted extraction Continuous supercritical water plant • Operation conditions: 400ᵒC 250 bar • Time: 0,15-0,5 s Batch reactor • Pressure limit: 12 bar  Max temperature to be tested 180ᵒC • Time: 5 to 20 min Thermal degradation tests at 160ᵒC Figure 3. Degradation curve of FA at 160ᵒC 3. DEGRADATION CURVE. The degradation curve for a solution of 25 ppm of commercial FA was performed at 160ᵒC (figure 3). It was obtained that at 75 min, only 15% of the initial FA is still present. The high degradation indicates that the hydrolysis is the limiting step, being 75 min the time where the degradation becomes higher than the hydrolysis. 4. HYDROLYSIS LIMITING STEP. As the hydrolysis is the limiting step, but the exposition of the released FA in its free form conduce to high degradation, with the chosen techniques: ultrafast supercritical water hydrolysis (SCWH) and microwave-assisted extraction, the temperature can be increased fast while the exposure of FA to these hard conditions is reduced. Results found with SCWH at 250 bar and 400ᵒC are presented in table 2, and revealed that around 50 % of the initial FA could be obtained by this technique, which is more than 3-fold higher the amount obtained with PLE. Reaction time (s) Convertion (%) log(R0) FA (µg/g) Yield (%) 0,22 0,90 6,32 822,9 32,0% 0,33 0,87 6,34 1195,8 46,5% 0,46 0,84 6,29 1069,5 41,6% 0,48 0,93 6,34 1295,6 50,4% Table 2. SCWH results, obtained with water at 250bar and 400ᵒC