CETvol87 CHEMICAL ENGINEERING TRANSACTIONS VOL. 87, 2021 A publication of The Italian Association of Chemical Engineering Online at www.cetjournal.it Guest Editors: Laura Piazza, Mauro Moresi, Francesco Donsì Copyright © 2021, AIDIC Servizi S.r.l. ISBN 978-88-95608-85-3; ISSN 2283-9216 Creating Incremental Revenue from Industrial Cherry Wastes Sajad Bagheria, Mona Alinejadb, Mojgan Nejada,b, Bahar Aliakbarianc,* a Department of Chemical and Material Science and Engineering, Michigan State University b Forestry Department, Michigan State University, 480 Wilson Road, East Lansing, MI, 48824, United States c The Axia Institute, Department of Supply Chain Management, Michigan State University, 715 East Main Street, Suite 115, Midland, MI 48640, United States Bahara@msu.edu An increase in the production rate of cherry and cherry products has led to considerable amounts of waste that accumulates rapidly especially during the harvest season. The waste including pits is used as fuel, fertilizer, and partly discarded in the environment. Although the cherry fruit is shown to be a rich source of polyphenols, there is limited information about the polyphenol content of the waste, especially the pits. This study aims to integrate a sequence of novel processing technologies (extraction and encapsulation) for the valorization of cherry pits, i.e. turn them into valuable antioxidant products that can be used in healthcare, cosmetics, and packaging applications. The operative parameters of the extraction process to obtain the maximum polyphenols and encapsulation to protect the extracts were optimized. The results of this study confirmed the feasibility of the extraction and encapsulation to recover a notable concentration of polyphenols with enhanced antioxidant properties. These antioxidants can be used as antibacterial compounds to develop active packaging. 1. Introduction Fruits are an essential source of phenolic compounds with high antioxidant capacity and among all, cherries are of special importance having high phenolic compounds with anti-inflammatory properties (Zhang et al., 2019). Many researchers have been investigating the antioxidant activity of various types of cherries (tart and sour) and their by-products such as cherry pomace through different approaches (de Souza et al., 2014). However, the antioxidant properties of cherry pits have not been investigated yet. Most of the cherries are being processed before selling in the market, which means huge amounts of cherry pits are produced by industry each year. Currently, cherry pits are being used as animal feed, fuel, or preparation of activated carbons, although ultimately most are rendered as waste. However, Cherry pits could be considered a natural source of polyphenolic compounds with antioxidant properties. Extraction of polyphenols is aimed to recover bioactive compounds such as antioxidants from biomasses. Nowadays there are more attempts to use environmentally friendly extraction methods such as pressure-assisted, ultrasonic, and microwave. These non-conventional extraction techniques could guarantee a sustainable approach resulting in the maximum recovery of bioactive compounds using minimum organic solvent and process cost (Casazza et al., 2010). Among different non-conventional extraction techniques, combined High-Pressure and High-Temperature (HPHT) extraction has gained attention. The synergistic effect of HPHT results in better dissolving and penetration of the solvent thus enhances the solubility of the target compounds in the solvent (Aliakbarian et al., 2011). Due to antioxidant properties, polyphenols tend to be unstable and their effectiveness and bioactivity dwindle over time during the processing and storage periods (Fang and Bhandari, 2010). Encapsulation is one of the most effective techniques to resolve the instability deficiency by coating the bioactive compound with a physical barrier that can protect the entrapped bioactive compound from environmental conditions such as oxygen, light, and moisture (Rezende et al., 2018). Encapsulation processes used to protect polyphenols generally include spray-drying, freeze-drying, supercritical fluids, emulsions, and chemical methods such as in situ polymerization, and polycondensation (Paini et al., 2015). Among these techniques, spray-drying is the most commonly implemented technique for polyphenols coating (Munin and Edwards-Lévy, 2011). Spray drying is an efficient and economically sustainable technique to DOI: 10.3303/CET2187093 Paper Received: 7 November 2020; Revised: 21 February 2021; Accepted: 21 April 2021 Please cite this article as: Bagheri S., Alinejad M., Nejad M., Aliakbarian B., 2021, Creating Incremental Revenue from Industrial Cherry Wastes, Chemical Engineering Transactions, 87, 553-558 DOI:10.3303/CET2187093 553 convert liquid extracts into a dry powder while protecting active ingredients with a coating agent. It has been widely used in the food industry. Dry powders are more stable compared to liquid products and are easier for storage and transportation (Paini et al., 2015). Conventional coating agents, such as maltodextrin or gum arabic have been used to enhance the solubility and bioavailability of the product (Ballesteros et al., 2017; Tolun et al., 2016). For this research, maltodextrin and inulin were used as coating agents to enhance the encapsulation properties. Inulin is a well-known compound with functional properties such as prebiotic effects. To the best of our knowledge, this is the first study focusing on cherry pits valorization as one of the most important by-products of cherry processing. This work aimed to optimize the extraction and encapsulation of phenolic compounds from cherry pits using HPHT extraction and spray drying techniques. The effect of coating agent and inlet temperature were studied. Powders were then characterized for polyphenolic compounds and their antiradical power. 2. Materials and methods 2.1 Reagents Folin-Ciocalteu reagent, catechin, sodium carbonate, ethanol (EtOH), 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH), aluminum chloride, sodium hydroxide, caffeic acid, and gallic acid were purchased from Sigma Aldrich, USA. Cherry pits were kindly provided by a local cherry process company in Traverse City located in Northern Michigan, USA. 2.2 Extraction of polyphenolic compounds Cherry pits were collected from the cherry processor company. Pits were oven-dried for 24 hours at 60 °C. Dried pits were ground to coarse particles using ball mill Spex 8000M. Fine powders were obtained using 20 and 80 mesh sizes. The first batch of experiments was done using conventional solid-liquid extraction at room temperature using two different solvents: 1) 100 % ethanol (EtOH) and 2) water: ethanol EtOH:H2O (50:50 v/v). Three different cherry pit particle sizes (420, 841, and 420 < size < 841 μm) were used. The extraction time and the solid to liquid ratio (S/L) were fixed at 24 hours and 0.1 g/mL, respectively (Aliakbarian et al., 2011). The extracts were filtered using a vacuum filter with a 450 nm membrane and the liquid was stored in a close container at 4°C before analysis. Tests on the extracts were performed in the following 14 hours. The best particle size and solvent determined from the conventional extractions were selected for further extraction experiments. Non-conventional extraction tests were performed in HPHT reactor model 4560 (PARR Instrument Company, Moline, IL, USA). The air in the headspace of the reactor was replaced by nitrogen to avoid excess of oxidation during the process and the reactor was hermetically closed. For this step, six runs were performed varying time (30 and 135 minutes) and temperature (100, 125, 150 °C). Extracts were filtered using a vacuum filter with a 450 nm membrane and stored at the close container at 4 °C before analysis. Extract analysis was done in the following 14 hours of the extraction. 2.3 Quantification of total polyphenols (TP), total flavonoids (TF), and antiradical power (ARP) Total polyphenols yield (TP) of the extracts were measured using Folin–Ciocalteu assay (Swain and Hillis, 1959). The extract was filtered using a 0.450 μm PTFE membrane syringe filter (Fisher Scientific Co., USA) before being used for the assay. UV-Vis Spectroscopy (Perkin Elmer) at a wavelength of 725 nm was used. Calibration curves were determined using gallic acid with a linear slope of 0.0018 (mg/L) -1 and R2 value of 0.99. TP is expressed as gallic acid equivalent (GAE) weight per weight of dried biomass (DB) (mg GAE/gDB). Total flavonoids (TF) were measured according to the colorimetric method developed by Yang et al. (2009) and Aliakbarian et al. (2011) and expressed as milligrams of catechin equivalent (CE) per gram of dried biomass (DB) (mg CE/gDB). The extract was filtered using a 0.450 μm PTFE membrane syringe filter (Fisher Scientific Co., USA). The same UV-Vis spectrophotometer was used at a wavelength of 510 nm. The calibration curve for this measurement was established using a standard solution of catechin with predefined concentrations with a linear slope of 0.0016 (mg/L)-1 and R2 value of 0.99. Antiradical power (APR) was measured following DPPH assay (Brand-Williams et al., 1995; Sluiter et al., 2008). Original DPPH and sample absorbance were recorded in wavelength of 515 nm using the same UV-Vis spectrophotometer described above. ARP is expressed as gram of DPPH per liter of extract (gDPPH/Lextract). 2.4 Encapsulation using spray drying and product characterization The extract with the highest TP content was filtered using 11 μm pore size filter paper (Fisher Scientific Co., USA) before mixing with the coating agents. Two coating agents maltodextrin (75 g/L) and inulin (75 g/L) were slowly added and mixed into the extracts. Then the solution containing polyphenol extract and coating agent was fed at the rate of 7 mL/min into an Armfield FT80 Tall Form Spray Dryer. The nozzle size was 12 μm. The fluid was dried using hot airflow at two different temperatures (inlet temperature) of 130°C and 150°C. 554 Dry powder was collected from the chamber and stored at 4°C in closed dark vessels before analysis. Post spray drying, a portion of the powder was immediately separated and rheumatically sealed until ready for water activity measurement. The water activity of the spray-dried samples was measured using an Aqualab 4TE (Meter Group, Pullman, WA, USA). Once ready, the samples were placed in the calibrated water activity meter for recording. The Aqualab 4TE is a chilled mirror dew point sensor that allows for a ±0.003 accuracy of the measurement. Samples were taken after 14 and 21 days of storage at 4°C and the TP and TF were measured. 2.5 Statistical analysis Statistical analysis was performed using MATLAB and SAS using a multivariate analysis of variance. All samples were tested in three replicates and the average and standard deviation were determined. Results were compared statistically using a two factorial ANOVA table by MATLAB software and p-value ≤ 0.05 was considered as a statistically significant difference. 3. Results and discussion 3.1 Effect of particle size and solvent on TP content Table 1 shows the TP yield of cherry pits extracts using conventional extraction at room temperature. Based on the statistical analysis at 0.05 confidence interval, the TP means are all significantly different when different particle sizes were used. Ground pits with a smaller particle size (420 µm) showed significantly higher TP yield. When particles were additionally ground from 840 µm to 420 µm, TP yield was increased by 136 % and 216 % for EtOH: H2O and EtOH extraction, respectively. The smaller the particles, the more surface area (per unit mass) is exposed to extracting solution which results in higher polyphenols yield. Also, as for smaller particles the solute can more easily diffuse through the solid matrix which ultimately increases the TP yield (Gião et al., 2009). Similar results were found in the literature regarding the extraction of polyphenols from different biomasses (Casazza et al., 2010; Makanjuola, 2017). Table 1. TP yield of ground cherry pits at different particle sizes and solvents. For each solvent treatment , means in a column followed by different letters (from a to c) are significantly different at p < 0.05. Particle Size: x (µm) 100 % EtOH extraction TP Yield (mg GAE/gDB) EtOH:H2O (50:50 v/v) extraction TP Yield (mg GAE/gDB) x<420 2.56 ± 0.05a 3.57 ± 0.05a 420