Shrimp quality and safety management along the supply chain in Benin
Dabade, D.S. - \ 2015
Wageningen University. Promotor(en): Marcel Zwietering; D.J. Hounhouigan, co-promotor(en): Heidy den Besten. - Wageningen : Wageningen University - ISBN 9789462574205 - 158
garnalen - penaeus - penaeus monodon - voedselkwaliteit - voedselveiligheid - bacteriëntelling - kwaliteitscontroles - kwaliteitszorg - benin - microbiologie - risicobeheersing - risicoanalyse - kwantitatieve methoden - shrimps - penaeus - penaeus monodon - food quality - food safety - bacterial counting - quality controls - quality management - benin - microbiology - risk management - risk analysis - quantitative methods
This thesis focuses on quality and safety management of tropical shrimp (Penaeus spp.) using Benin (West Africa) as an example of a shrimp exporting country. The entire supply chain, from fishing areas (brackish waters) to shrimp processing plants, was investigated. The steps of the chain prior to shrimp processing at the freezer plants were critical for shrimp quality and safety because of prevailing temperature abuse and inappropriate hygienic conditions. Combining culture-dependent (plate counts) and culture independent (DGGE, clone libraries analysis) approaches, it was found that bacterial concentration in shrimps was higher than that of their surrounding water and sediment. Conversely, bacterial diversity was higher in water or sediment than in shrimps. At species level, distinct bacterial communities were associated with sediment, water or shrimp samples. Spoilage evaluation of shrimps showed that during storage at 0ºC, Pseudomonas spp. were dominant, whereas at 7ºC and 28ºC, H2S-producing bacteria were the dominant group of microorganisms. An empirical model predicting shrimp shelf-life as a function of constant storage temperature was developed. Isolates producing strong off-odor were identified by 16S rRNA sequencing as mainly lactic acid bacteria (LAB) and Enterobacteriaceae at 28ºC or 7ºC and Pseudomonas spp. and LAB (Carnobacterium maltaromaticum) at 0ºC. The fastest growing isolates namely, Pseudomonas psychrophila and C. maltaromaticum were selected for their spoilage activity and for modeling studies. P. psychrophila had a higher growth rate and a higher spoilage activity at 0 to 15ºC, while at 28ºC, C. maltaromaticum had a higher growth rate. Models predicting the growth of pseudomonads in shrimps as a function of temperature were constructed. These models were validated under dynamic storage temperatures simulating actual temperature fluctuation in the supply chain. Using different risk classification approaches, the main foodborne pathogen risks identified were Vibrio parahaemolyticus and Salmonella. The management of the risks posed by the main pathogens was addressed using different scenarios to meet the set food safety objectives. Based on quantitative and ecological studies, this thesis developed tools that can be used in decision-making regarding tropical shrimp quality and safety management.
A major SNP resource for dissection of phenotypic and genetic variation in Pacific white shrimp (Litopenaeus vannamei)
Ciobanu, D.C. ; Bastiaansen, J.W.M. ; Magrin, J. ; Rocha, J.L. ; Jiang, D.H. ; Yu, N. ; Geiger, B. ; Deeb, N. ; Rocha, D. ; Gong, H. ; Kinghorn, B.P. ; Plastow, G.S. ; Steen, H.A.M. van der; Mileham, A.J. - \ 2010
Animal Genetics 41 (2010)1. - ISSN 0268-9146 - p. 39 - 47.
taura-syndrome virus - pig skeletal-muscle - linkage map - glycogen-content - penaeus - markers - mutation - resistance - discovery - growth
Bioinformatics and re-sequencing approaches were used for the discovery of sequence polymorphisms in Litopenaeus vannamei. A total of 1221 putative single nucleotide polymorphisms (SNPs) were identified in a pool of individuals from various commercial populations. A set of 211 SNPs were selected for further molecular validation and 88% showed variation in 637 samples representing three commercial breeding lines. An association analysis was performed between these markers and several traits of economic importance for shrimp producers including resistance to three major viral diseases. A small number of SNPs showed associations with test weekly gain, grow-out survival and resistance to Taura Syndrome Virus. Very low levels of linkage disequilibrium were revealed between most SNP pairs, with only 11% of SNPs showing an r2-value above 0.10 with at least one other SNP. Comparison of allele frequencies showed small changes over three generations of the breeding programme in one of the commercial breeding populations. This unique SNP resource has the potential to catalyse future studies of genetic dissection of complex traits, tracing relationships in breeding programmes, and monitoring genetic diversity in commercial and wild populations of L. vannamei
Controlled reproduction of penaeid shrimp: a contribution to its improvement
Alfaro Montoya, J. - \ 2001
Wageningen University. Promotor(en): E.A. Huisman; J. Komen. - S.l. : S.n. - ISBN 9789058084002 - 149
aquacultuur - dierfysiologie - garnalen - penaeus - geslachtelijke voortplanting - gametogenese - schaal- en schelpdierenteelt - aquaculture - animal physiology - shrimps - penaeus - sexual reproduction - gametogenesis - shellfish culture
This dissertation deals with controlled reproduction of penaeid shrimp. New knowledge about natural reproductive activity of Penaeus occidentalis in Gulf of Nicoya, Costa Rica, is presented. Since in vitro fertilization of open thelycum shrimp proved unsuccessful, a hypothesis is given to explain experimental results. In P. setiferus , the Male Reproductive Blackening Disease was studied, and bacterial infection was found to be associated with the male's condition. Production of spermatophores in captivity was explored in two species, P. stylirostris and P. vannamei . Adequate husbandry as well as successive ejaculation improved spermatophore quality. Deterioration of spermatophores was observed as part of a normal process for renewal in P. vannamei , without pathological implications. In order to further improve spermatophore quality, the injection of 17-alpha-methyltestosterone and 17-alpha-hydroxyprogesterone at 0.01 and 0.1 µg g -1 body weight was evaluated. 17-alpha-methyltestosterone significantly improved the quality of spermatophores, whereas 17-alpha-hydroxyprogesterone did not. Serotonin injection was evaluated as an alternative to female's eyestalk ablation for induction of ovarian maturation and spawning in P. vannamei . This neurotransmitter induced lower maturation and spawning with 3 doses of 50 µg g -1 body weight, than eyestalk ablation. In other to lay a basis for cryopreservation, penaeid embryos were evaluated in terms of their tolerance to cooling, cryoprotectants, and hypersaline solutions. T. byrdi morulae and advanced embryos (10 h) were tolerant to cooling at 10 °C, but were very sensitive to 0 °C. Embryos showed high tolerance to methanol and intermediate tolerance to dimethyl sulfoxide. Morulae were more resistant to hypersaline treatment at 55 ppt than advanced embryos.