UNIVERSITI PUTRA MALAYSIA CHARACTERISTICS AND POTENTIAL USE OF GUAVA (PSIDIUM GUAJAVA L) FOR PROCESSING OF CONCENTRATE SALMAH BINTI YUSOF FSMB

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1 UNIVERSITI PUTRA MALAYSIA CHARACTERISTICS AND POTENTIAL USE OF GUAVA (PSIDIUM GUAJAVA L) FOR PROCESSING OF CONCENTRATE SALMAH BINTI YUSOF FSMB

2 CHARACTERISTICS AND POTENTIAL USE OF GUAVA (PSIDIUM GUAJAVA L) FOR PROCESSING OF CONCENTRATE SALMAH BINTI YUSOF DOCTOR OF PHILOSOPHY UNIVERSITI PERTANIAN MALAYSIA 1989

3 CHARACTERISTICS AND POTENTIAL USE OF GUAVA (PSIDIUM GUAJAVA L) FOR PROCESSING OF CONCENTRATE By SALMAB BINTI YUSOF Thesis Submitted in Fulfi ent of the Requirements for the Degree of Doctor of Philosophy in the Faculty of Food Science and Biotechnology Universiti Pertanian Malaysia June 1989

4 Dedicated to beloved husband : Zakaria Abd. Rah man sons : Azlan Sazali Izham Razwan Ahmad Faisal and daughter: Liyana Yasmin

5 ACKNOWLEDGEMENTS The author wishes to expres s her gratitude and thanks to Dr. Abdullah Abu Bakar and Dr. Suhaila Mohamed for their supervision, cons truc tive critic isms and guidance in carrying out this study. Gratitude and th anks are als o due to As sociate Profes sor Oh Beng 'Tatt, formerly a lec turer at th e Department of Animal Science, Faculty of Veterinary Medic ine and Animal Scienc e, UPM for allowing the first part of the study to be conducted at his guava farm; to Puan Aminah Ju soh of th e same faculty for helping with the use of Elec tron Mis croscope; to Associate Profes sor Dr. Ruth Kiew and Ms. Sulika Madhavan, Department of Biology, Faculty of Sc ience and Environmental Studies, UPM, for extending their help during the identific ation of stone cells and to Puan Zaharah Talib, Statis tic s Department, MARDI for helping with th e Statis tical Analysis System (SAS ) graphic s. The author is als o indebted to the support and cooperation given by colleages an d staff of the Fac ulty of Food Science and Biotechnology in many way s espec ially to Puan Naimah Ahmad for typing the manu script and to UPM for extend in g the fund needed to carry out the research. iii

6 Last but not least, the author would like to express her gratitude to her husband and ch ildren for their en couragement, love and understanding during the course of this study. iv

7 TABLE OF CONTENTS Page ACKNOWLEDGEMENTS LIST OF TABLES iii x LIST OF FIGURES LIST OF PLATES LIST OF ABBREVIATIONS xii xv xvi ABSTRACT ABSTRAK xvii xx CHAPTER 1 INTRODUCTION 1 2 LITERATURE REVIEW 12 Growth and Development of Guava Proximate Composition 13 Nutritional Value 15 Important Biochemical Composition Acid Content Pigment 16 Flavour Components Tannins Pectic Substances v

8 Page Problems As sociated With Guava Product Stone Cells 21 Non-enzymatic Brown ing 23 Pulp Separation PHYSICO-CHEMICAL CHANGES DURING DEVELOPMENT AND MATURATION OF GUAVA (PSIDIUM GUAJAVA L) Introduction Ma terials and Methods Materials Sampling Physical Analysis Chemical Analysis Re sults and Discussion Physical Changes During Growth Chemical Changes During Growth SUIrlDla ry. i 54 4 EFFECT OF FRUIT MATURITY ON THE STRUCTURE OF STONE CELLS In troduction 55 Ma terials and Me thods Materials 56 Determination of Stone Cells 61 vi

9 Page Results and Discussion S ummary EFFECT OF MATURITY ON THE QUALITY AND ACCEPTABILITY OF GUAVA PUREE Introduction Materials and Methods Materials Physical and Chemical Analysis Samp ling Procedure Preparation of Puree Measurement of Colour Measurement of Viscosity Sensory Evaluation Re sults and Discussion Hardness and Mois ture Content Total Soluble Solids and Sugar Content Titratable Ac idity 78 Tannin 81 Ascorbic Acid 84 Sensory Evaluation of Puree 84 Colour 86 vii

10 Page Viscosity. Soluble Pectin and Cellulo se Sununary 93 6 INFLUENCE OF ph. BRIX AND PROCES SING TEMPERATURE ON THE PHYS ICAL. CHEMI CAL AND SENSORY CHARACTERISTICS OF GUAVA CONCENTRATE Introduction 94 Materials and Methods 95 Materials 95 Methods 96 Exp erimental Des ign Evaluation 99 Results and Discussion 101 Statis tical Analysis 101 Response Contours 105 Sununary EFFECTS OF TEMPERATURE. STABILIZERS AND ANTIBROWNING AGENTS ON THE STORAGE STABI LITY OF GUAVA CONCENTRATE Introduction Materials and Method s Materials 122 Methods 122 viii

11 Page Results and Discussion 125 Quality Changes During Storage of Guava Puree Effec t of Ant ib rowning Agents Effe ct of Stabilizers on Stored Guava Puree 146 l\jiiid.a ry CONCLUSION AND RECOMMENDATIONS 150 BIBLIOGRAPHY 153 APPENDICES 164 PUBLICATIONS 189 BIOr,RAPHICAL SKETCH 228 ix

12 LIST OF TABLES Table Page 1 Area Under Guava Cultivation According to States and Number of Farmers Involved in Guava Cultivation in Peninsular Malaysia in Area Under Guava Cultivation According to District and Number of Farmers Involved in Area (hectares) Under Guava Cultivation According to State and Type of Guava Planted in Total Production of Guava (metric tons ) According to State and Type of Fruit in Composition of Guava per 100g of Edible Portion Means of Sensory Panel Score for Flavour and Aroma Effect of ph, Temperature, Brix Combination on Seven Dependent Variables Levels of Independent Variables and Their Codes Central Composite Rotatable Design for Three Factors Analysis of Variance for Seven Dependent Variables Regression Coefficients for Five Dependent Variables Means of Sensory Panel Scores for Colour, Flavour and Aroma x

13 Table Page 13 Mean Values and Standard Deviation (±) for Various Physical and Chemical Changes During Development and Maturation Mean Values and Standard Deviation (±) for Various Physical and Chemical Characteristics of Guava at Different Stages Mean Values and Standard Deviation (+) for Colour 'L' Value of Concentrate After Treatment with Antibrowning Agents Mean Values and Standard Deviation (±) for Height of Separation of Pulp Mean Values and Standard Deviation (+) for Various Physico-chemical Characteristics of Guava Concentrate During Storage xi

14 LIST OF FIGURES Figure Page 1 Weight of Guava Fruits During Development and Maturation Diameter of Guava Fruits During Development and Maturation Log Transformation for Weight and Diameter 36 4 Average Density of Guava Fruits During Development and Maturation Texture of Guava Fruits During Development and Ma tura tion Moisture Content of Guava Fruits During Development and Maturation Chlorophyll Content of Guava Fruits During Development and Maturation Titratable Acidity of Guava Fruits During Development and Maturation ph of Guava Fruits During Development and Maturation Sugar Content of Guava Fruits During Development and Matu.:ation Total Phenol Content of Guava Fruits During Development and Maturation Pectin Content of Guava Fruits During Development and Maturation Ascorbic Acid Content of Guava Fruits During Development and Maturation Texture of Guava Fruits at Different Stages of Maturity xii

15 Figure Page Moisture Content of Guava Fruits at Different Stages of Maturity Protopectin Content of Guava Fruits at Different Stages of Maturity Total Soluble Solids Content of Guava Fruits at Different Stage s of Maturity Sugar Content of Guava Fruits at Different Stages of Maturity Titratable Ac idity of Guava Fruits at Different Stage 9f Maturity ph of Guava Fruits at Diffe ent Stages of Maturity Tannin Content of Guava Fr ifs at ifferent Stage s of Maturity Ascorbic Ac id Content of Guava Fruits at Different Stages of Maturity Colour of Puree from Fruits at Different Stages of Maturity Viscosity of Puree from Fruits at Different Stage s of Maturity Cellulose Content of Guava Fruits at Different Stages of Ma turity Soluble Pectin Content of Guava Fruits at Different Stages of Ma turity Contours for Colour Re sponse at Cons tant ph (A) and Brix (B ); Constant Temperature (C ) and Brix (D) Contours for Colour Response at Cons tant Brix and Constant ph Contours for Overall Acceptability Re sponse at Cons tant ph xiii

16 Figure Page 30 Contours for Overall Acceptab ility Response at Constant Brix Contours for Optimum Flavour Response ' Colour a ' Value of Guava Concentrate Stored at 28 C and 38 C Colour ' L ' Value of Guava Concent rate Stored at 2SoC and 3S oc Ascorbic Ac id Content of Guava Concentrate Stored at 28 C and 38 C Total Carbohydrate Content or Guava Concent rate Stored at 28 C and 38 C Amino Nitrogen Content of Guava Concentrate Stored at 28 C and 38 C ph of Guava Concentrate Stored at 2SoC and 38 C S Total Solub le Solids Content of Guava Concent rate at 2SoC and 3SoC Titratable Ac idity of Guava Concent rate Stored at 2SoC and 3SoC Viscosity of Guava Concent rate Stored at 28 C and 38 C Effect of Ant ibrown ing Agents on Colour of Guava Concentrate Reaction of Cystein Hydrochloride with Polypheno ls Effect of Stabilizers on Guava Pulp Stab ility at 28 C Effect of Stabilizers on Guava Pulp Stability at 38 C xiv

17 LIST OF PLATES Plate Page 1 Stage 1: Dark Green Guava Fruit Stage 2: Green Guava Fruit Stage 3: Light Green Guava Fruit Stage 4: Yellowish Green Guava Fruit Stage 5: Light Yellow Guava Fruit Stage 6: Bright Yellow Guava Fruit & 8 Types of" Stone Cells Found in Guava (Both x 40) Initial Thickening of Certain Parenchyma Cells (x 300) Prominent Thickening of Parenchyma Cells (x 400) Structure of Cell Wall (x 3000) Stone Cells in Actual Arrangement in the Tissue of Guava (x 72) & 14 Appearance of Fully Developed Stone Cells (x 300, 200 r spectively) Pulp Separation During Storage of Guava Concentrate xv

18 LIST OF ABBREVIATIONS kg g mg m mm ml mt cm sq min hr ppm ha N J.L r.p.m. kilogram gram milligram meter millimetre millilitre metric tonne centimeter square minute hour parts per million hectare normality micron revolution per minute xvi

19 Ab stract of the The sis Presented to the Senate of Universiti Pe rtanian Malaysia in Fulfilment of the Requirement s for the Degree of Doctor of Philosophy CHARACTERISTICS AND POTENTIAL USE OF GUAVA (PSIDIUM GUAJAVA L) FOR PROCESSING OF CONCENTRATE By SALKAH BT. YUSOF June, 1989 Supe rvisor Abdul lah Abu Bakar Ph. D. Co- supervisor: Suhaila bt. Mohamed Ph. D. Faculty Food Science and Biotechnology Studies were conducted to determine the cha racte ristics of guava (Psidium guajava L) cv. Vietname se of its potential use for processing it into guava concentrate. A maturity study showed that the guava took 16 weeks to reach maturity. The be st indice s of maturity we re size, mo isture, sugars and tannin content s. The mo isture content at the mature stage was 94%. The fructose, glucose and sucrose contents were 2.02%, 1.08% and 1.54%, respect ively. The tannin content in the ma tured guava was low (37. 0 mg/10 gm sample) but the vitamin C content was high (76 mg /100 g samp le ). xvii

20 The struc ture of stone cells in guava fruits we re examined mic roscopically. The stone cells became more prominent with inc rease in fruit ma turity, hence the prepared puree we re pulverised in orde r to improve its texture. Studie s on the quality of puree produced from fruits at different stage s of maturation showed that a puree of des ireable quality wa s obtained from fruits at the ye l low green stage (stage 4). Artificial ripening was necess ary to soften the fruits to make them ideal for pro cessing into conc entrate or puree. Fruits at the yellow green stage had an inc rease in solub le pectin content to 67%. This inc reased the viscosity of puree. The vitamin C cont ent also inc reased from 79.7 mg mg /loo g sample. The puree showe d less tendency to turn brown due to the low tannin contents (21 mg /10 g samples). The optimum conditions of ph, processing temperature and total soluble solids content (brix) to produc e an acceptable guava concentrate was de termined using a Re sponse Surface Methodology. Maximum ove rall acceptability was obtained from guava concentrate having an optimum ph ; processing temperature - 79.loC and brix - 35 B - 55 B was chosen. Storage studies on guava concentrate showe d that browning and pulp sepa ration we re the main prob lems, followed by losses in ascorbic ac id content and titratable ac idity. The re we re no sign ificant change s in amino nitrogen content. total suga rs. xviii

21 brix and ph. Temperature showed no influence on the rate of loss of viscosity. The use of 0.1% and 0.3% sodium carboxymethyl cellulose (NaCKC) was effective in stabilizing the pulp for 9 weeks. xix

22 Abstrak Tesis Yang Dikemukakan Kepada Senat Unive rsiti Pertanian Malaysia Sebagai Memenuhi Syarat Keperluan Untuk Ijazah Doktor Falsafah CIRI-CIRI DAN POTENSI PENGGUNAAH BUAH JAHBU (PSIDIUM GUAJAVA L) JENIS VIETNAM UHTUK PEHPROSESAN PATI JAMBU Oleh SALHAH BT. YUSOF Jun, 1989 Penyelia Abdullah bin Abu Bakar Ph. D. Penye lia Bersama : Suhaila bt. Mohamed Ph. D. Fakulti Sains Makanan dan Bioteknologi Kajian telah dijalankan untuk mengkaji ciri-ciri buah jambu (Psidium guajava L) kultivar Vietnam tentang potensinya untuk pemprosesan pati jambu. Kajian kematangan menunjukkan buah jambu mengamb il ma sa 16 minggu untuk mencapai kematangan. Petunjuk kematangan yang terbaik ialah saiz, kandungan kelemb apan, gula dan tannin. Kandungan kelembapan buah di tahap kematangan ialah 94%. Kandungan fruktosa, gluko sa dan sukrosa ialah ma sing-ma s ing 2.02%, 1.08% dan 1.54%. Kandungan tannin didapati rendah (3 7.0 mg /lo g sampel) tetapi kandungan vitamin C adalah tinggi (76 mg /loo g sampe l). xx

23 Struktur sel batu didalam buah jambu telah diteliti dengan menggunakan mikroskop. Sel-sel batu didapati menj adi bertambah besar semakin buah masak, oleh itu pulpa yang disediakan perlu dihaluskan untuk mempe rbaiki tekstur puri. Kaj ian ke atas kualiti puri yang dihasilkan dari buah pada tahap kematangan yang berlainan menunjukkan bahawa puri yang mempunyai kualiti yang diperlukan dapat dihasilkan dari buah pada peringkat kekuningan (peringkat 4). Proses peme raman diperlukan untuk me lembutkan buah supaya mudah diproses kepada pati atau puri jambu. Buah di peringkat ma sak kuning hijau mempunyai kandungan pektin larut air yang bertambah kepada 67%. Ini menjadikan puri lebih pekat. Kandungan vitamin C bertambah dari 79.7 mg mg /100 g sampel. Puri yang didapati juga tidak mudah bertukar warna menjadi perang disebabkan kandungan tannin yang rendah (21 mg /IO g sampe l). Keadaan optimum bagi ph, suhu pemprosesan dan kandungan pepejal larut (brix) bagi mcngha silkan pati jambu yang sesuai telah ditentukan dengan menggunakan kaedah ' Re sponse Surface.' Satu kombinasi yang sesuai bagi pene rimaan keseluruhan yang maks imum, ph ; suhu pemprosesan = C dan brix 35 B - 55 B telah dipilih. Keputusan kajian simpanan keatas pati jambu menunjukkan bahawa peme rangan dan perpisahan pulpa menjadi ma salah utama, diikut i dengan kehilangan kandungan asid askorbik dan xxi

24 ke asidan. Tiada perubahan yang ke tara didapati bagi kandungan amino nitrogen, gula, brix dan ph. Suhu tiada mempengaruhi kadar penurunan kepekatan puri. Penggunaan 0.1% dan 0.3% naterium karboksime tilselulos (NaCKC) didapati berkesan me nghalang pemisahan pulpa sehingga 9 minggu. xxii

25 CHAPTER 1 INTRODUCTION Guava (Ps idium guajava) has been cultivated in Ma laysia for a long time (Allen, 1967) but has never received as much attention as today. The plant wh ich originated from trop ical Ame rica (Ruehle, 1948) ha s spr ad to all tropical and subtropical countries and has become especially important in Cuba (Coit, 1945), Hawa ii (Hayes, 1957) and India (Sams on, 1980). The genus Psidium consists of about 150 species of wh ich only Psidium guaj ava is of economic importance. Nume rous varieties are in existence ranging from the wild or unselected forms having small thick rinded, th in fleshed fruits to highly imp roved produc t ive precocious clone s with large excellent fruits. Previous ly, in Ma laysia, it wa s reported that the re we re 18 varieties grown (Mohd. Noor et al., 1980). Howeve r, due to their relatively low fruit quality coup led with difficult maintenance none of the recommended varieties (Gu 3, Gu 4, Gu 5, Gu 6 and Gu 7) had been grown on la rge scale. Guava fruit is a very rich source of vitamin C. The plant is ve ry hardy and is able to grow in a wide range of soil condition. In countrie s like Cuba and Hawa ii guavas have become a mi llion dollar industry. Locally, it wa s only during late sevent ie s and early 1980 that the re wa s renewed interest 1