I CITRUS WASTE COMPOSITION and BIOACTIVE COMPOUNDS: A
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CITRUS WASTE COMPOSITION AND BIOACTIVE COMPOUNDS: A REVIEW Degree project by DANIEL ALFREDO SALAZAR DÍAZ Presented to the engineering faculty of Universidad de los Andes In the partial fulfillment of the requirements for the degree of CHEMICAL ENGINEERING December 2020 Chemical Engineering department i Citrus waste composition and bioactive compounds: a review Copyright © 2018 Daniel Alfredo Salazar Díaz. ii CITRUS WASTE COMPOSITION AND BIOACTIVE COMPOUNDS: A REVIEW Degree project by DANIEL ALFREDO SALAZAR DÍAZ Presented to the engineering faculty of Universidad de los Andes In the partial fulfillment of the requirements for the degree of CHEMICAL ENGINEERING Approved by: Advisor, Rocio Sierra Ramirez, PhD. Co-advisor, Daniel David Durán Aranguren, M.Eng and M.Sc. Jury, Niyireth Alicia Porras Holguin, PhD. Department director, Andrés Gonzalez Barrios, PhD. December 2020 Chemical Engineering department iii ABSTRACT Citrus fruits are used in many industries around the world, obtaining normally peels, seeds and pulps as residues, but these have properties and characteristics that can be used, then it was made a systematic literature review with the objective to identified composition, bioactive compounds and the effectiveness of the extraction methods to removes them. The literature composition identification starts with a general composition description, where is identified the percentage presence of total carbohydrates (pectin, cellulose and hemicellulose), lignin, protein, ashes and extractives in the residue, being total carbohydrates and extractives the components with the major presence found. After, it was made a description by ultimate analysis and proximate analysis. The ultimate analysis give information of the chemical composition, in this was identified that citrus residues are principally composed by carbon and oxygen. The proximate analysis give information about the compounds behavior in a thermochemical process and in this was found that citrus residues are mainly composed by volatile matter and fixed carbon. Finally, it is made a description of the chemical composition of the ashes, finding the high presence of calcium and potassium. The second part of the review is focused on the bioactive compounds and the extraction methods, dividing the analysis in essential oils and phenolic content. For essential oils is determined the yields and individual compounds composition reached from different residues from literature information, being limonene the main component of them and the solid-liquid extraction with acetone or ethanol as solvents the technique recommended. For phenolic content is identified the total content and the individual phenolic compounds iv from different citrus residues from literature information, finding hesperidin, naringin and narirutin as the main compounds by presence and the use of ultrasound assisted and solid- liquid extraction as the techniques recommended to increase this content in the extracts. Finally, it is evaluated the antioxidant activity of the extracts, where are found similar results for grapefruit peel and orange peel and were recommended the same techniques as in phenolic content, corroborating a correlation between them. Keywords: citrus residues, bioactive compounds, antioxidant activity, citrus composition. v TABLE OF CONTENTS ABSTRACT ............................................................................................................................ iv Keywords: ................................................................................................................................ v LIST OF TABLES .................................................................................................................. 2 1. INTRODUCTION........................................................................................................... 4 2. OBJECTIVES ................................................................................................................. 8 2.1 General ........................................................................................................................... 8 2.2 Specifics.......................................................................................................................... 8 3. RESULTS AND DISCUSION ............................................................................................. 9 3.1 Research methodology .................................................................................................... 9 3.2 Composition .................................................................................................................. 10 3.2.1 General citrus residue composition ......................................................................... 11 3.2.2 Ultimate analysis .................................................................................................... 13 3.2.3 Proximate analysis. ................................................................................................. 14 3.2.4 Ash’s chemical composition ................................................................................... 15 3.3 Extraction of citrus waste bioactive compounds ............................................................. 16 3.3.1 Essential oils extraction .......................................................................................... 21 3.3.2 Essential oils composition. ..................................................................................... 23 3.3.3 Phenolic content of citrus residues. ......................................................................... 29 3.3.4 Composition of individual phenolic compounds...................................................... 34 3.3.4 Antioxidant activity of citrus residues ..................................................................... 38 3.3.5 IC50 Values ........................................................................................................... 41 3. CONCLUSIONS ........................................................................................................... 43 4. REFERENCES ............................................................................................................. 45 1 LIST OF TABLES Table 1. Citrus waste composition ........................................................................................... 13 Table 2. Ultimate analysis ....................................................................................................... 14 Table 3. Proximate analysis ..................................................................................................... 15 Table 4. Ash's chemical composition ....................................................................................... 16 Table A1. Essential oil yields .................................................................................................. 55 Table A2. Essential oils composition. ...................................................................................... 56 Table A3. Total phenolic content (TPC) and total flavonoid content (TFC). ............................. 60 Table A4. Individual phenolic compounds. .............................................................................. 62 Table A5. Antioxidant activity of citrus residues. ..................................................................... 66 Table A6. IC50 values ............................................................................................................. 67 2 LIST OF FIGURES Figure 1. Research procedure ...................................................................................... 10 Figure 2. Comparison of yields of extraction methods for essential oils ....................... 22 Figure 3. Limonene percentage…………………………………………………………24 Figure 4. Comparison of extraction .............................................................................. 24 Figure 5. Percentage presence of high………………………………………………….26 Figure 6. Percentage presence of low ........................................................................... 26 Figure 7. Percentage of high presence………………………………………………….27 Figure 8. Presence of low presence .............................................................................. 27 Figure 9. Percentage of sesquiterpenes………………………………………………....28 Figure 10. Percentage of oxygenated ........................................................................... 28 Figure 11. Percentage of other oxygenated……………………………………………..29 Figure 12. Percentage of other compounds .................................................................. 29 Figure 13. Comparison of phenolic content in different residues .................................. 31 Figure 14. Comparison of extraction techniques for phenolic compounds in orange peels .................................................................................................................................... 32 Figure 15. Presence found of individual flavanones in citrus residues .......................... 34 Figure 16. Presence of flavanones……………………………………………………...37 Figure 17. Presence of other flavonoids ....................................................................... 37 Figure 18. Presence found of other phenolic compounds in citrus residues .................. 38 3 INTRODUCTION Citrus is the most widely produced fruit, including a group of several species and growing in more than 80 countries. Citrus fruits have an important role worldwide in providing nutrients and are used in medicine. Into this fruit family,