AQUACULTURE OF PACU (Piaractus mesopotamicus)

204 Pages·1997·0.33 MB·English

AQUACULTURE OF PACU (Piaractus mesopotamicus) AND A COMPARISON OF
ITS QUALITY: MICROBIOLOGICAL, SENSORY AND PROXIMATE
COMPOSITION
by
Sharma V. S. Pullela
Thesis submitted to the Faculty of the
Virginia Polytechnic Institute and State University
in partial fulfillment of the requirements for the degree of
MASTER OF SCIENCE
in
Food Science and Technology
APPROVED:
________________________
George J. Flick, Jr., Chairman
_____________________ ______________________
Custodio F. Fernandes George S. Libey
_____________________ ______________________
Stephen A. Smith Charles W. Coale, Jr.
February 3, 1997
Blacksburg, Virginia
Keywords: Pacu, Aquaculture, Microbiology, Sensory, Proximate Composition
AQUACULTURE OF PACU (Piaractus mesopotamicus) AND A COMPARISON OF
ITS QUALITY: MICROBIOLOGICAL, SENSORY, AND PROXIMATE
COMPOSITION
by
Sharma V. S. Pullela
George J. Flick, Jr., Chairman
Department of Food Science and Technology
(ABSTRACT)
Pacu (Piaractus mesopotamicus) initially weighing 72.0 g were fed three diets - a)
0.5% vegetable (zucchini), b) commercial 32% (P32) and c) commercial 36% (P36)
protein diets for 24 weeks and their growth performance compared. Processing yields
and proximate composition were determined following dressing of pacu. The
microbiological quality of pond cultured pacu was compared to aquacultured hybrid
striped bass, tilapia, and rainbow trout grown in pond and recirculating aquaculture
systems. Sensorial analyses for differences in flavor, preference, and color were also
determined. Protein concentration significantly influenced the weights, lengths, specific
growth rate, feed conversion ratio, and protein efficiency ratio (p < 0.05). Diet
insignificantly influenced the processing yields (p > 0.05). The moisture, protein and
total lipid contents were significantly affected (p < 0.05) by the dietary protein. The
indicative bacterial quality differed significantly for pacu as well as the water used for
culturing pacu (p < 0.05) among dietary treatments. Aquaculture production systems
significantly influenced the indicative and pathogenic bacterial quality. Listeria
monocytogenes, Salmonella spp., Yersinia enterocolitica, and Escherichia coli O157:H7
were not isolated from any of the sampled fish. The qualitative and quantitative results
of Clostridium botulinum were influenced by the production system (p < 0.05). Flavor of
pacu was comparable to that of hybrid striped bass, tilapia, and rainbow trout, but
superior to catfish. Cooking significantly improved the color of the ground fish fillets.
ACKNOWLEDGEMENTS
I extend my deep appreciation to my major professor Dr. George J. Flick, Jr., for
his guidance and continuing support throughout this study. I also thank the members of
my committee - Dr. Custodio F. Fernandes, Dr. George S. Libey, Dr. Stephen A. Smith,
and Dr. Charles W. Coale, Jr., for their advice and recommendations during the course of
this project.
I give special recognition to Dr. Fernandes for his extremely valuable advice in
designing and execution of the project. His continuous support was a great source of
inspiration.
I am also grateful to Mark Kidd and students at the Virginia Tech Aquaculture
Center for providing assistance during the course of the project, the faculty, staff, and
fellow graduate students of Department of Food Science and Technology for their
participation in sensory evaluations. I also extend my appreciation to Drs. Flick, Libey,
and Fernandes and Brian Brazil, Lisa Scott, and Aretha Turner for their valuable help
processing the pacu. I also thank Kathy Lawlor and Brian Smith for their patience and
help during the Clostridium botulinum study. I am also grateful to Dr. Hengjian Wang for
assisting me with the protein assay.
I give special recognition to my parents and relatives for their encouragement,
patience, and endless love.
iv
TABLE OF CONTENTS
Abstract ii
Acknowledgements iv
Table of Contents v
List of Tables and Figures xii
INTRODUCTION 1
SECTION I. Review of Literature 2
Aquaculture in the United States 4
Exotic Species in the United States Aquaculture 5
Pacu (Piaractus mesopotamicus) 6
Growth Requirements 7
Protein 7
Temperature 8
Oxygen 8
Reproduction 9
v
Aquaculture 11
Hazards Associated with the Consumption of Seafood 11
Microbiological Quality of Aquacultured Fish 12
Foodborne Pathogens in Aquacultured Fish 14
Listeria spp. 14
History 14
Morphology 15
Growth Characteristics 15
Ecology 16
Incidence of Listeria monocytogenes in Foods 17
Pathology 18
Epidemiology 19
Salmonella spp. 20
History 20
Morphology 21
vi
Growth Characteristics 21
Ecology 22
Incidence of Salmonella in Water 22
Incidence of Salmonella in Foods 24
Pathology 24
Epidemiology 25
Clostridium botulinum 26
History 26
Morphology 26
Ecology 27
Incidence of Clostridium botulinum in Foods 28
Pathology 30
Epidemiology 31
Yersinia spp. 32
History 32
vii
Morphology 33
Growth Characteristics 33
Ecology 34
Incidence of Yersinia in Foods 34
Pathology 35
Epidemiology 36
Coliforms, Fecal Coliforms and Escherichia coli 37
History 37
Morphology 37
Growth Characteristics of E. coli 38
Ecology 38
Incidence of Escherichia coli in Foods 39
Pathology 40
Epidemiology 41
References 42
viii
Section II. Effect Of Dietary Protein Content On Growth Performance And Proximate
Composition Of Aquacultured Pacu (Piaractus mesopotamicus) 57
Abstract 57
Introduction 59
Materials and Methods 62
Results 67
Discussion 72
References 75
Section III. Effect of Diet on the Indicative and Pathogenic Microbiological Quality of
Aquacultured Pacu (Piaractus mesopotamicus) 89
Abstract 89
Introduction 91
Materials and Methods 93
Results and Discussion 101
References 111
ix
Section IV. Effect of Production System on the Indicative and Pathogenic Microbiological
Quality of Aquacultured Finfish 121
Abstract 121
Introduction 123
Materials and Methods 125
Results and Discussion 131
Conclusions 138
References 139
Section V. Comparison of Aquacultured Pacu Fillets with other Aquacultured Fish Fillets
Using Subjective and Objective Sensorial Traits 148
Abstract 148
Introduction 150
Materials and Methods 153
Results and Discussion 155
Conclusions 159
References 160
x