DEVELOPMENT AND EVALUATION OF PINEAPPLE (Ananas comosus [L.] Merr.) POMACE BASED EXTRUDER BY OLUWAFEMI BABATUNDE ODUNTAN B.Sc., M.Sc. Agric. Engineering (Ife) COREN, MNIAE R. Engr. A dissertation in Department of Agricultural and Environmental Engineering Submitted to the Faculty of Technology in partial fulfillment of the requirements for the Degree of MASTER OF PHILOSOPHY of the UNIVERSITY OF IBADAN 2014 i CERTIFICATION I certify that this research work was carried out by Mr. O. B. Oduntan in the Department of Agricultural and Environmental Engineering of University of Ibadan. _________________________ Supervisor Professor A. I. Bamgboye Department of Agricultural and Environmental Engineering of University of Ibadan, Nigeria ii ABSTRACT In large scale juice processing, about 65% of the pineapple is extracted as juice, while the remaining 35% is the by-product called pineapple pomace. Pomace generated from juice processing constitutes a disposal problem and environmental pollution and there is no processing equipment designed in addressing this problem through the utilisation of this by- product. This study was designed to develop a mash extruder for pineapple pomace based flour. Pineapple pomace was analysed for its proximate composition using standard methods. Pomace flour was produced by drying and grinding fresh pomace from a juice processing plant. The physical and mechanical properties of the pineapple pomace flour using cassava flour as the binder were carried out by standard methods. An experimental laboratory press was used to evaluate the extrusion point pressure at different pineapple pomace/cassava flour ratio mash (5:1, 6:1 and 7:1), the moisture content of the mash (50, 55 and 60%), die size (4, o 6 and 8 mm) and temperatures (60, 80, 100 and 120 C). Response Surface Method was employed to optimise the experimental data with extrusion point pressure as the response variable while temperature, moisture content, die size and pomace ratio were the independent variables. The results obtained were used to design and test a single screw pineapple pomace extruder. Operational power, compression ratio, throughput and efficiency of the extruder were determined using standard methods. Data were analysed using ANOVA. Pineapple pomace contained 12.4% moisture content, 4.8% ash, 1.4% fat, 9.2% crude protein, 6.0% crude fibre and 66.2% carbohydrate. The static angle of repose and coefficient of friction at various combinations of pomace and cassava flours increased linearly for the entire surface with moisture content and varied with structural surface in the moisture range of 12.4 to 26.3% (d.b). The minimum value of coefficient of friction for stainless iron steel was 0.44 for pineapple pomace based flour. The extrusion point pressure was 7.51 ± iii 0.62MPa, temperature, die sizes and pomace ratio significantly (p < 0.05) influenced o extrusion point pressure. Optimum conditions for the extrusion point pressure were 100 C; 4.0 mm die size, 55.0% moisture content and 6:1 pomace ratio at maximum desirability of 1:00. The power required to operate the extruder was 4.0 kW at a compression ratio of 3:1. Machine throughput was 26.1 kg/h with the extruding efficiency of 87.9%. An efficient 4.0 kW pineapple pomace based extruder has been developed, which can be used to process and conserve pineapple pomace. Keywords: Pineapple pomace-flour, Extruder-development, Point-pressure. Word count: 400 iv ACKNOWLEDGEMENT I wish to acknowledge with generous assistance and encouragement of my supervisor, Prof. A.I. Bamgboye. This work has been greatly impacted by his reviews, comments, helpful suggestions and corrections. My sincere appreciation also goes to the Head of Department, and all the post graduate lecturers of the department for their admonitions and constructive criticisms at various stages of this work. My special thanks goes to my lovely wife, Mrs. Oluwakemi Oduntan who has been my most insightful and faithful supporter and my children for their prayers supports. To God who gives life, knowledge, understanding and wisdom, be all praise, honour and glory, Amen. v DEDICATION To My God Who Make My Way Prosperous, Wisely and Successful vi TABLE OF CONTENTS Page Title Page i Certification ii Abstract iii Acknowledgement v Dedication vi Table of Contents vi List of Tables ix List of Plates x List of Figures xi List of Abbreviations xii CHAPTER ONE: INTRODUCTION 1 1.1 General Background 1 1.2 Statement of the Research Problem 2 1.3 Research Objective 3 1.4 Expected Contribution to Knowledge 3 CHAPTER TWO: LITERATURE REVIEW 4 2.1 The Pineapple Plant 4 2.1.1 Pineapple varieties 5 2.1.2 Nutritional, medical and industrial value of pineapple 5 2.1.3 Post harvest processing. 6 2.2 Utilisation of Pineapple 9 2.2.1 Livestock feeds 9 2.2.2 Environmental impact 12 2.3 Extrusion Cooking 13 vii 2.4 Extrusion Cooking Products 15 2.5 Extrusion Cooking Methods 17 2.5.1 Boiling water cooker 18 2.5.2 Steam cooker 18 2.5.3 Adiabatic extrusion 19 2.5.4 High-shear cooking extrusion 19 2.5.5 Low-shear, high-pressure cooker 19 2.5.6 Low-shear, low-pressure cooker 20 2.5.7 Continuous steam pre-cooking 20 2.6 Modern Food Extrusion 20 2.6.1 Single-screw Extrusion cooker 20 2.6.2 Twin-screw Extrusion cooker 23 2.6.3 Agro-Industrial uses of Cassava 25 2.6.4 Animal feed extrusion 26 2.7 Effect of Extrusion of Food Products on their Nutrient Composition 26 2.8 Implication of Existing Work on Current Research 27 CHAPTER THREE: MATERIALS AND METHODS 29 3.1 Sample Preparation 29 3.2 Preliminary Experiments 29 3.2.1 Proximate composition 29 3.2.1.1 Crude protein determination 29 3.2.1.2 Crude fat or ether extracts determination 30 3.2.1.3 Determination of ash 31 3.2.1.4 Fibre determination 31 3.2.2 Selected physical properties 32 viii 3.2.2.1 Bulk density 32 3.2.2.2 Particle size distribution 32 3.2.2.3 Moisture content determination 33 3.2.2.4 Coefficient of static friction 33 3.2.2.5 Static angle of repose 33 3.2.3 Selected mechanical property 34 3.2.3.1 Determination of extrusion point pressure 34 3.3 Experimental Design and Optimization 36 3.4 Design Theory and Calculation 38 3.4.1 The hopper 38 3.4.2 Worm shaft of the extruder 39 3.4.3 The screw worm 38 3.4.4 The load that can be lifted by the screw 40 3.4.5 The pressure to be developed by the screw thread 40 3.4.6 The pressure of the barrel 41 3.4.7 The volumetric capacity of extruder 42 3.4.8 The power required of the extruder 42 3.5 Discharge Efficiency 43 CHAPTER FOUR: RESULTS AND DISCUSSIONS 44 4.1 Proximate Analysis 44 4.2 Bulk Density 44 4.3 Particle Size Distribution 44 4.4 Coefficient of Static Friction 48 4.5 Optimization of Extrusion Point Pressure by RSM 55 4.6 Analysis of Variance 57 ix 4.7 Interactive Effect of Temperature and Die size 65 4.8 Interactive Effect of Moisture Content and Pomace Ratio 67 4.9 Interactive effect of temperature and die sizes on contour plot 67 4.10 Machine Description 72 4.10.1 Main frame 72 4.10.2 Feed unit 72 4.10.3 Extrusion unit 72 4.10.4 Power transmission and electric combination 76 4.11 Efficiency of the Machine 76 4.12 Cost Analysis 76 CHAPTER FIVE: CONCLUSIONS AND RECOMMENDATIONS 80 5.1 Conclusions 80 5.2 Recommendations 80 REFERENCES 81 APPENDICES 91 Appendix A: Statistics analysis Extrusion point pressure (RSM Design expert 8.0) 91 x LIST OF TABLES Table Title Page 2.1 Nutrient Content of Pineapples Compared with Apples, Oranges and Bananas 6 4.1 Proximate Analysis of the Pineapple Pomace Flour. 45 4.2 Bulk Density of Pineapple Pomace 46 4.3 Particle Size Distribution of Pineapple Pomace. 47 4.4 D-Optimal Design Experiment Result 56 4.5 Anova Regression Coefficient Second Order Polynomial and their Significant for Extrusion Point Pressure 58 4.6 Summary of the Design Calculation 77 4.7 Effect of Pomace inclusion rate on the Extruder Efficiency. 78 4.8 Machine Cost Analysis 79 xi LIST OF PLATE Plate Title Page 4. 1 A Picture of the Experimental Pineapple Pomace Extruder. 75 xii LIST OF FIGURES Figure Title Page 2. 1 A Cross-Section of a Single-Screw Food Extruder 14 2. 2 Configurations of Screws, Geometry in the Extruder 16 2. 3 Single-Screw Extruder 21 3.1 Barrel with Open-End Die 35 3.2 Schematic Diagram of the Laboratory Press 37 4.1 Coefficient of Friction Variation with Pineapple Pomace Moisture Content 50 4.2 Coefficient of Friction Variation with Cassava Flour Moisture Content 51 4.3 Coefficient of Friction Variation with Pineapple Pomace/Cassava Ratio of 5:1 at different Moisture Content 52 4.4 Coefficient of Friction Variation with Pineapple Pomace/Cassava Ratio of 6:1 at different Moisture Content 53 4.5 Coefficient of Friction Variation with Pineapple Pomace/Cassava Ratio of 7:1 at different Moisture Content 54 4.6 Predicted vs. Actual Values Plot for Extrusion Point Pressure 61 4.7 Normal Plot of Residuals of Extrusion Point Pressure Response 62 o 4.8 The Predicted Extrusion Point Pressure of Temperature ( C) and Studentized Residual Plot 63 4.9 Pertubation Plot of Extrusion Point Pressure Response. 64 4.10 Response Surface Plot for Pressure as a Function of Temperature and Die Sizes at Moisture Content of 50% and Pomace Ratio 5:1. 66 4.11 Response Surface Plot for Pressure as a Function of Moisture and Pomace Ratio at Moisture Content of 60% and Die Sizes 6mm 68 xiii 4.12 Contour Plot for Pressure as a Function of Temperature and Die Sizes at Moisture Content of 55% and Pomace Ratio 6mm 70 4.13 Response Surface Plot for Optimum Extrusion Point Pressure as a Function of Temperature and Die Sizes at Moisture Content of 55% and Pomace Ratio 6:1 76 4.14 Side View drawing Extruder machine 73 4.15 Plan View drawing Extruder machine 74 xiv LIST OF ABBREVIATIONS Symbol/ Abbreviation Meaning Unit 3 V volume of flask containing the digest x 100 m f W sd weight of sample digested mg 3 V ds vol. of digest for steam distillation m W as weight of ash g W o original weight of sample g moisture content (dry basis) % moisture content (wet basis) % md mass of dry matter kg mw mass of water to be added. kg ds diameter of the screw shaft mm T Torque transmitted by the shaft of extruder Nm 2 δo yield stress for mild steel. Nmm Un screw depth at the discharge end mm a screw depth at the feed end mm n number of screw turns unit less We load that can be lifted by the screw kN T Torque transmitted by the screw shaft Nm Dm mean thread diameter mm μ coefficient of friction unit less o thread (lift) angle 0 o tapering angle 0 xv 2 Pr pressure developed by the screw threads N/mm 2 Ap pressing area mm h screw depth at the maximum pressure mm 2 Pb pressure to be withstood by the barrel N/mm t thickness of the barrel mm 2 δa allowable stress N/mm 2 δo yield stress of mild steel N/mm Di inside diameter of the barrel mm 3/ theoretical volumetric capacity m s diameter of the screw flight m base diameter of the screw shaft m screw pitch m rotational speed rw/s Pe power required to drive the expeller kW 3/ Qt volumetric capacity of the worm shaft m s ls length of screw shaft mm 2 g acceleration due to gravity m/s F material factor unit less xvi