EXPERIMENTAL VALIDATION OF THE COMPUTATIONAL SCREENING OF BIOBASED SOLVENTS FOR THE EXTRACTION OF PROCYANIDINS B1 AND B2 FROM BRAZIL NUT CAKE

Brazil nut (Bertholletia excelsa) cake, a co-product of oil extraction by cold mechanical pressing, has potential as a source of bioactive phenolic compounds, including procyanidins B1 and B2. Valorizing this co-product may contribute to the more efficient use of a raw material native to the Amazon rainforest and to the development of more sustainable extraction processes. In this context, this study aimed to experimentally evaluate the performance of biobased solvents for extracting procyanidins B1 and B2 from Brazil nut cake, following a preliminary computational screening using the COSMO-SAC method. Initially, 29 biobased solvents were computationally screened at different water proportions (30, 40, 50, 60, and 70% v/v), and a water proportion of 70% was selected for experimental validation. Based on the screening results, 10 solvents were selected: 8 promising candidates (betaine, choline chloride ([Ch]Cl), γ-valerolactone, 1,3-propanediol, 1,3-butanediol, acetic acid, fructose, and glycerol) and 2 solvents with less favorable computational results (citric acid and tartaric acid). To prepare the biobased solvents, the components were weighed according to the established proportions and stirred in a shaker at 60 °C and 240 rpm for 30 min until homogeneous mixtures were obtained. Extraction experiments were performed in duplicate using 1.5 g of Brazil nut cake and 15 mL of biobased solvent. The extractions were conducted in a heating block at 60 °C, with stirring at 500 rpm, for 1 h. The extracts were then centrifuged, filtered, and analyzed by Ultra- Performance Liquid Chromatography- Mass Spectrometry (UPLC-MS) to quantify procyanidins B1 and B2. Glycerol yielded the highest levels of both procyanidins, reaching 5.96 µg/g dry basis (DB) for procyanidin B1 and 5.76 µg/g DB for procyanidin B2. The second-highest level of procyanidin B1 was obtained with 1,3-propanediol (4.80 µg/g DB), whereas γ-valerolactone yielded the second-highest level of procyanidin B2 (3.72 µg/g DB). Citric acid resulted in the lowest levels, with 1.01 µg/g DB of procyanidin B1 and 0.63 µg/g DB of procyanidin B2. Tartaric acid also showed relatively poor performance, yielding 1.90 µg/g DB of procyanidin B1 and 1.10 µg/g DB of procyanidin B2. The experimental results were consistent with the computational screening results for the solvents evaluated, highlighting the potential of COSMO-SAC as a tool for guiding the selection of biobased solvents. Overall, this study identifies glycerol and γ-valerolactone as promising alternatives for extracting procyanidins from Brazil nut cake, contributing to the valorization of this co-product and the development of more sustainable extraction strategies.