25
UNIVERSITI PUTRA MALAYSIA CHARACTERISTICS AND POTENTIAL USE OF GUAVA (PSIDIUM GUAJAVA L) FOR PROCESSING OF CONCENTRATE SALMAH BINTI YUSOF FSMB 1989 2
UNIVERSITI PUTRA MALAYSIA
CHARACTERISTICS AND POTENTIAL USE OF GUAVA (PSIDIUM GUAJAVA L) FOR PROCESSING OF
CONCENTRATE
SALMAH BINTI YUSOF
FSMB 1989 2
CHARACTERISTICS AND POTENTIAL USE OF GUAVA (PSIDIUM GUAJAVA L) FOR PROCESSING OF
CONCENTRATE
SALMAH BINTI YUSOF
DOCTOR OF PHILOSOPHY UNIVERSITI PERTANIAN MALAYSIA
1989
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
Dedic ated to be loved husband :
s ons :
Zakaria Abd . Rah man
Azlan Sazali Izham
Razwan Ahmad Faisal
and daughte r :
L iyana Yasmin
ACKNOWLEDGEMENTS
The author wishes to exp res s her gratitude and thanks to
Dr. Abdullah Abu Bakar and Dr. Suhaila Mohamed for their
s upervis ion , c ons truc tive c ritic isms and guidance in c arrying
out this study.
Gratitude and thanks are als o due to As s o c iate Pro fes s o r
Oh Beng 'Tatt , fo rmerly a lec turer at the Department o f Animal
Sc ience , Faculty o f Veterinary Medic ine and Animal Sc ienc e ,
UPM for allowing the fir s t part o f the s tudy to be c onduc ted
at his guava farm; to Puan Aminah Ju s oh o f th e s ame faculty
for helping with the u s e o f Elec tron Mis c r oscope; to A s s o c iate
Profes s o r Dr. Ruth Kiew and Ms. Sulika Madhavan , Department of
Biology , Faculty o f Sc ience and Environmental Studies , UPM,
for extending their help during the identific ation o f s tone
c ells and to Puan Zaharah Talib , Statis tic s Department,
for helping with th e Statis tical Analy s is Sys tem
graphic s .
MARDI
( SAS )
The author is als o ind ebted to the s upport and
c ooperation given by c olleages and s taff o f the Fac ulty of
Food S c ienc e and Biotechnology in many way s es pec ially to Puan
Naimah Ahmad for typing the manu s c r ip t and to UPM for
extend ing the fund needed to c ar ry out the research.
iii
Last but not least, the author would like to express her
gratitude to her hus band and children for their encouragement ,
love and understanding during the cours e of this s tudy .
iv
TABLE OF CONTENTS
Page
ACKNOWLEDGEMENTS iii
LIST OF TABLES
LIST OF FIGURES
LIST OF PLATES
x
xii
xv
xvi
xvii
LIST OF ABBREVIATIONS
ABSTRACT
ABSTRAK
CHAPTER
1
2
xx
INTRODUCTION 1
LITERATURE REVIEW 12
Growth and Development of Guava . . . . . . . . . . . 1 2
Proximate Composition
Nutritional Value
13
15
Important Biochemic al Composition . . . . . . . . • . 1 6
Acid Content . . . • . . . • . • . • • . . . • • • . . . . . . . • 16
Pigment 1 6
Flavour Components . . . . . . . . . . . . . . . . . . . . . 1 7
Tannins
Pectic Substances
v
1 8
20
3
4
Page
Problems As s oc iated With Guava Product . • . . . 21
Stone Ce l l s 21
Non-enzymatic Browning 23
Pulp Separation . . • . . • . • . • . . . . . . . . . . . . . 24
PHYSICO-CHEMICAL CHANGES DURING DEVELOPMENT AND MATURATION OF GUAVA ( PSIDI UM GUAJAVA L ) • . • . . . . • . • • • . . . . . . • . • . .
Int roduction
Materia l s and Methods
Materia l s
Sampl ing
Phy s ical Analy s i s
Chemical Analy s is
Re sults and Discus s ion
Phy s ical Changes During Growth
Chemical Change s During Growth
29
29
30
30
31
31
32
32
32
40
SUIrlDlary • • • • . i • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 54
EFFECT OF FRUIT MATURITY ON THE STRUCTURE OF STONE CELL S . . • . . • • . . . . . . . . . . . 55
Introduc tion 55
Ma terial s and Me thods . . . . . . . . . . . . . . . . . . . . . . 56
Materials 56
Det e rminat ion of Stone Cel l s 61
vi
5
Result s and D is cus s ion
S umma ry
EFFECT OF MATURITY ON THE QUALITY AND ACCEPTABILITY OF GUAVA P UREE
Int roduc tion
Mate rials and Methods
Mate rials
Phy s ic a l and Chemic a l Ana ly s is
Sampling P rocedure
Preparation of Puree
Measurement of Colour
Measurement of Vis c o s ity
Sensory Evaluation
Re sults and Discus s ion
Hardnes s and Mois ture Content
Total Soluble Solids and Suga r
Page
62
6 6
68
6 8
69
69
69
70
70
70
71
71
72
72
Content . • . • . . • . . . • • . • . • • . . . . . . .... .. . 75
Tit ratable Ac idity 78
Tannin 81
As corbic Ac id 84
Sensory Evaluation o f Puree 84
Co lour 86
vii
6
7
Page
Vis co s ity. Soluble Pectin and Cellulo s e . • . . . . . . • . • . • • • . . . • . . . . • . . . . . 89
Sununary
INFLUENCE OF pH. BRIX AND PROCES S I NG TEMPERATURE ON THE PHYS I CAL. CHEMI CAL AND SENSORY CHARACTERI STICS OF GUAVA CONCENTRATE .............................. .
Introduction
Materials and Methods
Materials
Methods
93
94
94
95
95
96
Exp erimental Des ign . • . . . • • . . . . . . • . • . . . . 96
Evaluation
Results and Dis cu s s ion
Statis tical Analysis
Respon s e Contou r s
Sununary
EFFECTS OF TEMPERATURE. STABILI ZERS AND ANTIBROWNING AGENTS ON THE S TORAGE S TABI LITY OF GUAVA CONCENTRATE • . . . . . • . . . . •
Introduction
Materials and Method s
Materials
Methods
viii
99
101
101
105
119
121
121
122
122
122
8
Page
Results and Discus s ion 125
Qual ity Changes During Storage of Guava Puree • • . . . . . . • . • . • . . • . • • . . . . . . . . 125
E ffect of Ant ib rowning Agents . . . . . . . . . 1 42
E ffe ct of Stabilizers on Stored Guava Puree 146
l\JIIID.a ry . • • • • • . • • . • . . • • • . • . . • • • • . • . • • • . • . • 149
CONCLUSION AND RECOMMENDATIONS 150
BIBLIOGRAPHY 153
APPENDICES 1 6 4
PUBLICATIONS 189
BIOr,RAPHICAL SKETCH 228
ix
Table
1
2
3
4
5
6
7
8
9
10
11
12
LIST OF TABLES
Area Under Guava Cultivation According to States and Number of Farmers Involved in Guava Cultivation in Peninsular
Page
Malaysia in 1 987 • • • . • • . . • • • • . • . • . . . . • . • . . . 3
Area Under Guava Cultivation According to District and Number of Farmers Involved in 1 987 . . . . . . • • • • . . . • . . . . . • . . . . . .
Area (hectares) Under Guava Cultivation According to State and Type of Guava Planted in 1987 • . • . • . . . . . . . . . • • . . • . . . . . . . •
Total Production of Guava (metric tons ) According to State and Type of Fruit in 1 987 • . . • • • . . . • • . • . . . . • . . . . • . . . • . . . . • . • .
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
4
8
1 0
1 4
86
9 7
9 8
9 9
102
1 0 4
1 4 1
Table
13
14
15
16
17
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
Page
172
179
186
187
188
Figure
1
2
3
4
5
6
7
8
9
10
LIST OF FIGURES
Weight of Guava Fruits During Development and Maturation . . . . . . . • . . . • . . . . • . • • • . . . . . . . . . •
Diameter of Guava Fruits During Development and Maturation • . . • • . • . . . • • . . . • • . . • . . . . . . . . . •
Log Transformation for Weight and Diameter
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 • . . . . . . . . . . . . • . . . .
Page
33
35
36
38
39
41
42
44
45
47
11 Total Phenol Content of Guava Fruits
12
During Development and Maturation . . . . . . . . . . . . 49
Pectin Content of Guava Fruits During Development and Maturation .................. . 51
13 Ascorbic Acid Content of Guava Fruits
14
During Development and Maturation . . . . .. . . . . . . 53
Texture of Guava Fruits at Different Stages of Maturity .......................... . 73
xii
Figure
15
16
17
18
19
20
21
22
Moi sture Content of Guava Fruit s at Different S tage s o f Maturity . . • • . . . . . . . . . . . . . . . .
Protope c t in Content o f Guava Fruits at Different S tage s o f Maturity . . • . . . . . . . . . . . • . .
Total Soluble Solids Content o f Guava Fruits at Different S tage s o f Maturity . . . . . . . . . . . . . .
Sugar Content o f Guava Fruit s at Different Stage s of Maturity . . . . . • . . . • . . . . . . • . . . . . . . . . .
Titratable Ac idity o f Guava Fruits at Different S tage� 9f Maturity . • • . . • . . . . . . . . • . •
pH of Guava Fruit s at Diffe�ent St ages of Maturity . . . . . . . . . • . . . 0 • • • • • • • • • • • • • • • • • • • • •
Tannin Content of Guava Fr�ifs at �ifferent S tage s of Maturity . . . . • . . . . . . . . . . . . . . . . . . . . . .
Ascorbic Ac id Cont ent o f Guava Fruits at Different S tage s o f Maturity . . . . . . . . . . . . . . . .
23 Colour of Puree from Fruit s at Dif ferent
24
25
26
27
28
29
S tage s of Maturity
Viscos ity of Puree from Fruits at Different Stage s of Maturity . . . . . . . . . . . . . . . . . . . . . . . . . .
Cellulo s e Content o f Guava Fru i t s at Different S tages o f Ma turity . • . . . . . . . . . . . . . .
Soluble Pect in Content of Guava Fruits at Different S tages o f Ma turity • . . . • . . . . . . . . . . .
Contours for Colour Re s pon s e at Cons tant pH (A) and Brix (B ) ; Con s t ant Temperature (C ) and Brix (D) ............................ .
Contours for Colour Re s pons e at Cons tant Brix and Constant pH . . . . . . . . . . • . . . . . . . . . . . . .
Contours for Overall Acceptabil ity Re sponse at Cons tant pH . • . . . . . . . . . . . . . . . . • . .
xiii
Page
74
76
77
79
80
82
83
85
87
90
91
92
107
109
112
Figure
3 0
3 1
32
33
3 4
3 5
3 6
3 7
3S
3 9
4 0
4 1
4 2
4 3
4 4
Contours for Overal l Accep tab il ity Response at Con s tant B r ix . • . • • . . . . . . . . . . . � .
Contours for Optimum Flavour Response
Colour ' a ' Value o f Guava Concentrate Sto red at 28°C and 3 8°C . • . . • . • . . . . . . . . . . . . .
Colour ' L ' Value o f Guava Conc ent rate Stored at 2S o C and 3S o C • • . • . . • • . . • . . . . . . . .
Asc orbic Ac id Content o f Guava Concent rate Sto red at 28°C and 3 8°C . . • • • . . • • . . . . . . . . . .
Total Ca rbohydrate Content or Guava Concent rate Stored at 28°C and 38°C
Amino Nit rogen Content of Guava Concent rate Sto red at 28°C and 38°C . . . . . . . . . . . . . . . . . . .
pH of Guava Conc entrate Sto red a t 2SoC and 38°C . . . . . • . . . . . . . . . . . . . . . . • . . . . . . . . . . . .
Total Solub le Solids Content of Guava Concent rate at 2SoC and 3SoC . • . . . . . . . . . . .
Titratable Ac idity o f Guava Conc ent rate Sto red at 2SoC and 3S o C . . . . • • . . . . . . . . . . . .
Viscos ity of Guava Concent rate Sto red at 28°C and 3 8°C . • . . . . . . . . . . . . . . • . . . . . . . . . . . . .
Effec t o f Ant ibrowning Agent s on Colour o f Guava Concentrate . . . . . . . • . . . • . . . . . . . . . . .
React ion o f Cy s t ein Hydrochloride with Polypheno l s . . . . . . . . . . . . . . . . . . . . . . . . . . .
Effect o f Stabil izers on Guava Pulp S tab i l ity at 28°C . . . . . . . . . . . . . . . . . . . . . . . . .
Effec t o f Stab i l izers on Guava Pulp Stability at 38 °C . . . . . . . . . . . . . . . . . . . . . . . . .
xiv
Page
115
118
126
1 2 7
128
131
132
1 3 4
1 3 5
1 3 6
1 4 0
14 3
1 4 4
1 4 7
148
LIST OF PLATES
Plate Page
7
1 Stage 1: Dark Green Guava Fruit . . . . . . . . . . . . . 57
2 Stage 2: Green Guava Fruit . . . . . . . . . . .. . . . . . . 57
3 Stage 3: Light Green Guava Fruit . . . . . . . . . . . . 58
4 Stage 4: Yellowish Green Guava Fruit . . ........ 58
5 Stage 5: Light Yellow Guava Fruit . .. . . . ..... . 59
6 Stage 6: Bright Yellow Guava Fruit . . . . . . . . . . . 59
& 8 Types of" Stone Cells Found in Guava (Both x 40) . . . . . . . . . . . . . . . . . . . . ... . . . . . 64
9 Initial Thickening of Certain Parenchyma Cells (x 300) . . . . • • • • • . . . . . . . . . . . . . 64
10 Prominent Thickening of Parenchyma Cells (x 400) . . . . . . . . . . . . . . . • • . . . . . . . . . . ... . . 64
11 Structure of Cell Wall (x 3000) ............... 65
12 Stone Cells in Actual Arrangement in the Tissue of Guava (x 72) ................... 65
13 & 14 Appearance of Fully Developed Stone Cells (x 300, 200 r�spectively) .............. 65
15 Pulp Separation During Storage of Guava Concentrate . . . . . . . . • . . . . . . . . . . . . . . . . . . . 138
xv
LIST OF ABBREVIATIONS
kg kilogram g gram mg milligram m meter mm millimetre ml millilitre mt metric tonne cm centimeter sq square min minute hr hour ppm parts per million ha hectare N normality
J.L micron r.p . m. revolution per minute
xvi
Abstract of the The sis P re s ented to the Senate of Unive rsiti Pe rtanian Malay s ia in Fulfilment of the
Requi rement s for the Degree o f 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 Sc ience and B iotechnology
Studie s were conducted to determine the cha racte ri stics o f
guava ( P s id ium guajava L) cv. Vietname s e of its potential use
for proce s s ing it into guava concentrate . A matur ity study
showed that the guava took 16 weeks to reach maturity .
The be s t indice s of maturity we re s ize , mo isture , suga rs and
tannin content s . The moi s ture content at the mature stage was
94% . The fructo se , glucos e and sucro s e contents were 2 . 02% ,
1 . 08% and 1 . 54% , respect ively . The tannin content in the
matured guava was low ( 37. 0 mg/10 gm s ample ) but the vitamin C
c ontent was high ( 76 mg / 100 g s amp le ) .
xvii
The s t ruc ture o f s tone c e l l s in guava fruit s we re examined
mic ros c opically . The s tone c e l l s became more prominent with
inc rease in fruit matur ity , hence the prepared puree we re
pulve rised in o rde r to improve i t s texture . S tudie s on the
qua lity of puree produc ed from fruits at diffe rent s tage s of
maturat ion showed that a puree of de s ireable quali ty wa s
obtained from fruit s at the ye l low green s tage ( s tage 4 ) .
Art ific ial r ipening was nec e s s a ry to soften the fruits to make
them ideal for p ro c e s s ing into conc entrate o r puree . F ruit s at
the yel low green s tage had an inc rease in solub le pectin
content to 67% . Thi s inc re a s e d the v i s c o s i ty of puree . The
vitamin C c ont ent also inc rea sed from 79 . 7 mg - 131 . 1 mg / lOO g
s ample . The puree showe d l e s s tendency to turn brown due to
the low tannin c ontent s (21 mg / 10 g s amples) .
The optimum condit ions o f pH , p roc e s s ing tempe rature and
total soluble s o l ids c ontent ( b rix ) to p roduc e an acceptable
guava concent rate was de t e rmined u s ing a Re sponse Surface
Methodo logy . Maximum ove rall ac ceptability was obtained from
guava c oncent rate having an opt imum pH - 3 . 3 - 3 . 9 ; proc e s s ing
tempe rature - 79 . loC and brix - 35 ° B - 55 ° B was cho s en .
Storage s tudies on guava c oncent rate showed that browning
and pulp sepa rat ion we re the main prob lems , followed by lo s s e s
in a s c o rbic ac id c ontent and titratable ac idity . The re we re no
s ignificant change s in amino nit rogen content. total suga rs.
xviii
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
Abs t rak Te s is Yang Dikemukakan Kepada Senat Unive r s it i Pertanian Malay s ia S ebagai Memenuhi Syarat
Keperluan Untuk Ijazah Doktor Fal s a fah
CIRI-CIRI DAN POTENSI PENGGUNAAH BUAH JAHBU (PSIDIUM GUAJAVA L) JENIS VIETNAM UHTUK PEHPROSESAN
PATI JAMBU
Oleh
SALHAH BT. YUSOF
Jun , 1989
Penye l ia Abdul l ah b in Abu Bakar Ph. D .
Penye lia Bersama : Suhaila bt . Mohamed Ph . D .
Fakulti Sains Makanan dan Biotekno logi
Kajian te lah dijalankan untuk mengkaji c iri-c iri buah
j ambu ( P s idium guajava L) kul t ivar Vie tnam tentang potens inya
untuk pemprose s an pati jambu . Kajian kematangan menunjukkan
buah jambu mengambi l ma s a 16 minggu untuk mencapai kematangan .
Petunjuk kemat angan yang te rbaik ialah saiz , kandungan
kelembapan , gula dan tannin. Kandungan kelembapan buah di tahap
kemat angan ialah 94% . Kandungan frukto s a , gluko sa dan sukro sa
ialah ma s ing-ma s ing 2 . 02% , 1 . 08% dan 1 . 5 4% . Kandungan tannin
didapa ti rendah (3 7 . 0 mg / l O g s ampel) tet api kandungan vitamin
C ada lah tinggi ( 7 6 mg / lO O g sampe l) .
xx
S truktur s e l batu didalam buah j ambu telah dite l i t i dengan
menggunakan mikro skop . Sel-sel batu didapati menj adi bertambah
besar semakin buah mas ak , o leh itu pulpa yang disediakan perlu
dihaluskan untuk mempe rbaiki tekstur pur i . Kaj ian ke atas
kualiti puri yang diha s ilkan dari buah pada tahap kematangan
yang be rlainan menunjukkan bahawa puri yang mempunyai kua liti
yang d ipe rlukan dapat dihas i lkan dari buah pada peringkat
kekuningan ( pe r ingkat 4 ) . P ro s e s peme raman diperlukan untuk
me lembutkan buah s upaya mudah dipro s e s kepada pati atau puri
jambu . Buah di peringkat ma s ak kuning hijau mempunyai
kandungan pektin larut air yang bertambah kepada 67% . Ini
menjadikan puri lebih pekat . Kandungan vi tamin C bertambah
dari 79 . 7 mg - 1 3 1 . 1 mg / 100 g samp e l . Puri yang didapati juga
tidak mudah bertukar warna menjadi pe rang dis ebabkan kandungan
tannin yang rendah ( 2 1 mg /IO g sampe l ) .
Keadaan opt imum bagi pH , s uhu pemp ro s e s an dan kandungan
pepejal larut ( brix ) bagi mcngha s ilkan pati jambu yang s e suai
te lah ditentukan dengan menggunakan kae dah ' Re sponse Surface . '
Satu komb ina s i yang s e suai bagi pene r imaan k e s e lu ruhan yang
maks imum, pH - 3 . 3 - 3 . 9 ; suhu pemprose san = 79 . 1°C dan brix
35°B - 55°B te lah dipilih .
Keputusan kajian s impanan keatas pati jambu menunjukkan
b ahawa peme rangan dan p e rp i s ahan pulpa menjadi masalah utama,
diikut i dengan kehilangan kandungan a s id askorb ik dan
xxi
keasidan. Tiada perubahan yang ke tara didapati bagi kandungan
amino nitrogen, gula, brix dan pH. Suhu tiada mempengaruhi
kadar penurunan kepe katan puri. Penggunaan 0.1% dan 0.3%
naterium karboksime tilselulos (NaCKC) didapati berke san
menghalang pemisahan pulpa sehingga 9 minggu.
xxii
CHAPTER 1
INTRODUCTION
Guava ( P s idium guajava ) h a s been cul t ivated in Ma lay s ia
for a long t ime (Al len , 1 9 6 7 ) but has neve r rece ived a s much
attent ion a s today . The plant which originated f rom t rop ical
Ame rica ( Ruehle , 1948 ) ha s sp r�ad t o all t ropical and s ubtro
p ical count rie s and has become e specially important in Cuba
(Coit , 1945 ) , Hawa ii ( Haye s , 1 9 5 7 ) and India ( Sams on , 198 0 ) .
The genus P s idium cons i s t s o f about 1 5 0 spe c i e s o f which
only P s idium guajava is o f economic importanc e . Nume rous
varie t ie s are in existence ranging from the wild or unse lected
forms having sma l l thick rinde d , th in fle shed fruits to highly
imp roved produc t ive precoc ious c l one s with large exc e l lent
fruit s . Previous ly , in Ma lay s i a , it wa s reported that the re
we re 18 varie ties grown (Mohd . Noo r et a l . , 198 0 ) . Howeve r ,
due to the ir relative ly low fruit qua l ity coup led with
difficult maintenance none of the recommended varie t ies (Gu 3 ,
Gu 4 , Gu 5 , Gu 6 and Gu 7 ) had been grown on la rge s c ale .
Guava f ruit i s a very r ich s ourc e of vitamin C . The plant
i s ve ry hardy and is able to grow in a wide range o f soil
c ondition . In countrie s l ike Cuba and Hawa ii guavas have
become a mi l l ion dollar indus t ry . Loc a l ly , it wa s only during
late sevent ie s and early 1 9 8 0 that the re wa s renewed intere s t
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