Thesis (DR. P.H.)--University of Michigan.

Thesis (M.S.)--University of North Carolina Wilmington, 2009. / Title from PDF title page (January 12, 2010) Includes bibliographical references (p. 85-95)

Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains x, 229 p. : maps. Includes abstract. Includes bibliographical references.

The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract, appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on October 9, 2009) Thesis advisor: Dr. Andrew D. Clarke. Includes bibliographical references.

Thesis (MAppSc)--AUT University, 2009. / Includes bibliographical references. Also held in print (x, 78 leaves : ill. ; 30 cm.) in the Archive at the City Campus (T 664.94 KHE)

Thesis (Ph. D.)--University of Lund, 1983. / Includes bibliographical references.

No description available.

Thesis (MScFoodSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Fresh ready-to-cook fish fillets are prone to rapid loss of freshness and other quality attributes, as well as accelerated growth of spoilage micro-organisms under sub-optimal storage conditions. Cape hake (Merluccius capensis) is an important seafood in South Africa; however, rapid loss of quality and eventual spoilage is a problem limiting the economic potential. Thus, the aim of this study was to investigate the effects of active (40% CO2 + 30% O2 + 30% N2) and passive (0.039% CO2 + 20.95% O2 + 78% N2) modified atmosphere packaging (MAP) under different storage temperatures (0°C, 4°C, and 8°C) on the quality attributes of Cape hake (Merluccius capensis) fish fillets. This was achieved by investigating the effects of MAP (with or without absorbent pads) and storage temperature on quality attributes (microbial, physicochemical and sensory), changes in composition and concentration of volatile compounds (VOCs) and shelf life of Cape hake fillets. Modified atmosphere packaging, storage temperature and the use of absorbent pads had a significant (p < 0.05) impacts on physicochemical properties of Cape hake fillets during refrigerated storage. Highest storage temperature (8°C) led to accelerated deterioration of packaged Cape hake fillets. Generally, active MAP better maintained the quality attributes of Cape hake than passive MAP at 0°C and 4°C. Headspace gas composition of O2 and CO2 were significantly influenced by the storage time, temperature, MAP conditions and their interactions (p < 0.05). Irrespective of storage temperature, active-MA packaged fillets had lower pH values in comparison to fillets stored under passive-MAP. Drip loss was higher in active-MA fillets packaged without absorbent pad. Passive-MAP fillets did not show any drip loss. Absorbent pad was used to add value to MAP storage as MAP resulted in drip. The use of absorbent pad combined with low storage temperature maintained the firmness of hake fillets, across all temperatures. The interaction of MAP, absorbent pad and storage temperature had a significant effect on the aerobic mesophillic bacteria counts. Based on the aerobic mesophillic bacteria count fillets stored under active-MAP at 0°C (5.2 log cfu/g) was limited to day 12, while the fillet stored under passive-MAP at 0°C (log cfu/g) was limited to greater than day 3. Overall sensory acceptability of fillets decreased with increase in storage temperature across all treatments. Additionally, MAP had a significant (p < 0.05) impact on sensory attributes such as appearance and odour acceptability, with active-MA packaged fillets stored at 0°C having highest overall acceptability. A total of 16 volatiles were identified in Cape hake fillets, including 4 primary VOCs and 12 secondary VOCs. The VOCs associated with spoilage include tri-methylamine (TMA) (ammonia like), esters (sickeningly sweet) and sulphur group (putrid). MAP had a significant (p< 0.05) influence on volatile composition and concentration. Active-MA packaged fillets performed better during storage and had lower TMA value of 0.85% on day 12 in comparison with 7.22% under passive-MAP on day 6 at 0°C. The results obtained demonstrated that changes in volatile compounds were significantly (p< 0.05) influenced by storage duration, temperature and MAP. The development of high levels of VOCs and off-odour corresponded with high aerobic mesophillic bacteria count (≥ 5.5 log cfu/g). Based on these developments the storage life of Cape hake fillets packaged under active-MAP with absorbent pad and stored at 0°C was limited to 12 d, while the passive-MAP (control) fillets stored at 0°C was limited to 3 d. The use of active-MAP, in combination with absorbent pads and 0°C storage in addition to good hygienic practices, was effective in maintaining the postharvest quality of Cape hake fish fillets and led to higher shelf life. / AFRIKAANSE OPSOMMING: Vars, gereed-vir-kook vis filette is geneig om gou hulle varsheid en ander gehalte kenmerke te verloor en die vervoegde groei van mikro-organismes wat bederf tydens stoor veroorsaak, vind plaas. Kaapse stokvis (Merluccius capensis) is in Suid-Afrika ‘n gewilde seekos maar die ekonomiese potensiaal daarvan word deur die feit dat dit so gou in gehalte afneem en bederf, beperk. Dus word daar met hierdie studie gepoog om die effek van aktiewe (40% CO2 + 30% O2 + 30% N2) en passiewe (0.039% CO2 + 20.95% O2 + 78% N2) aangepasde verpakking (MAP) onder verskillende stoortemperature (0°C, 4°C, en 8°C) op die gehalte kenmerke van Kaapse stokvis (Merluccius capensis) filette te ondersoek. Dit is gedoen deur om die effek van MAP (met of sonder kussinkies) en stoortemperatuur op die gehalte kenmerke (mikrobies, fisiochemies en sensories) asook veranderinge in komposisie en konsentrasie van vlugtige samestellings (VOCs) en die raklewe van Kaapse stokvis filette te ondersoek. Aangepasde atmosfeer verpakking, stoortemperatuur en die gebruik van absorberende kussinkies het ‘n groot impak (p < 0.05) op die fisiochemiese kenmerke van Kaapse stokvis tydens stoor in yskaste gehad. Hoë stoortemperature (8°C) het aanleiding gegee tot die vinnige bederf van verpakte Kaapse stokvis filette. Oor die algemeen het aktiewe MAP die gehalte van die Kaapse stokvis filette teen 0°C and 4°C beter bewaar. Die komposisie van O2 en CO2 is heelwat deur stoortyd, temperatuur, MA toestande en die interaksies tussen bogenoemde, beïnvloed (p< 0.05). By alle temperature het aktiewe MA verpakte filette laer pH waardes getoon in vergeleke met filette wat in onder passiewe MA verpak is. Die drupverlies was hoër in aktiewe MA filette verpak sonder absorberende kussinkies. Passiewe MAP filette het nie enige drupverlies getoon nie. Absorberende kussinkies is gebruik om waarde by te voeg tot MAP stoor aaangesien MAP gelei het tot drup. By alle temperature het die gebruik van absorberende kussinkies tesame met lae stoortemperature bygedra tot die behoud van fermheid. Die interaksie van MAP, absorberende kussinkies, en stoortemperatuur het ‘n groot effek gehad op die aerobiese mesofiliese bakterië telling. Weens die aerobiese mesofiliese bakterië telling is stoor van filette onder aktiewe MAP teen 0°C (5.2 log cfu/g) beperk tot dag 12, terwyl filette gestoor onder passiewe MAP teen 0°C ( log cfu/g) beperk is tot dag 3. Oor die algemeen het die sensoriese aanneemlikheid van filette sonder inasgneming van die behandeling, verklein met ‘n toename in stoortemperature. MAP het ook ‘n groot impak op die sensoriese kenmerke soos voorkoms, reuk, en aktiewe MA verpakte fillets gestoor teen 0°C is oor die algemeen die aanneemlikste. ‘n Totaal van 16 vlugtige substanse is in Kaapse stokvis identifiseer. Dit het vier primêre VOCs en 12 sekondêre VOCs ingesluit. Die VOCs wat met bederf assosieer word, sluit tri-metilamien (TMA) (soos ammoniak), esters (soet) en die swael groep (smetterig) in. MAP het ‘n groot (p < 0.05) invloed op die vlugtige komposisie en konsentrasie. Aktiewe MA verpakte filette het beter tydens stoor presteer en het ‘n laer TMA waarde van 0.85% op dag 12 gehad, in vergelyking met 7.22 % onder passiewe MAP op dag 6 teen 0°C. Die resultate toon dat veranderinge in vlugtige samestellings grootliks beïnvloed word (p < 0.05) deur stoortyd, temperature en MAP. Die ontwikkeling van hoë vlakke van VOCs, slegte reuke en verlies aan varsheid gaan tesame met hoë aerobiese mesofiliese bakterië telling (≥ 5.5 log cfu/g). Gegrond op hierdie tellings is die stoorleeftyd van Kaapse stokvis filette beperk tot dag 12, terwyl passiewe MAP (die kontrole) filette gestoor teen 0°C, beperk is tot dag 3. Om op te som, die gebruik van aktiewe MAP tesame met absorberende kussinkies en 0°C stoor asook goeie higiëniese praktyk, kon die na-oes gehalte van Kaapse stokvis filette behou en het gelei tot ‘n langer rakleeftyd.

Thesis (D. Tech. Environmental health) -- Central University of technology, Free State, 2011 / Apart from being the primary food source of many cultures around the world, fish contains notable amounts of essential fatty acids that are required by the human body, thus making fish a vital part of the human diet. In South Africa Cape hake is a well-known and highly consumed local fish species, which is transported from coastal areas countrywide where the fresh fish are displayed on ice in various retail stores. Fish is known to be highly susceptible to spoilage and, as a result, the maintenance of the cold-chain in related products is of particular importance. Additionally, recent trends showing a decline in natural fish resources have instigated growing concerns about the sustainability and optimal utilisation of fish as a food source. Against this backdrop, this study aimed at determining the influence of storage parameters on selected triglycerides and their possible metabolic pathways. Also applying prediction modelling of fatty acids and volatiles as instruments to assess exposure of Cape hake fillets to excessive microbial contamination and, in effect, be indicative of the environmental parameters (for example temperature) that may influence such contamination. Randomly selected juvenile hakes were filleted and stored under various simulated retail storage conditions, under either controlled or uncontrolled environmental conditions. For each hake filleted, one fillet was inoculated with an increased load of autochthonous microbiota, and the corresponding fillet was kept at similar temperature conditions. All fillets were monitored over a ten day period, during which fatty acid and volatile samples were collected and analysed. From the resulting triglycerides a selection of fatty acids were profiled and their possible metabolic pathways investigated. Fish maturity, the distribution of the fatty acids and the implication thereof in the nutritional value were also assessed. Conventional chemometric methods utilising mathematical expressions were subsequently utilised in order to predict contamination and whether the cold chain was sustained, while an artificial neural network (ANNs) were designed to predict excessive microbial contamination in the fillets. The results showed that the nutritional value of fish differs notably with its maturity and size. Mathematical equations were furthermore found to be effective assessment instruments to indicate the percentage differences in storage temperature, as well as consequent microbial influences. Thus, this approach may introduce mathematical prediction modelling as a promising mechanism to assess Cape hake spoilage. An artificial neural network (ANN) was successfully designed, that succeeded in distinguishing between Cape hake fillets displayed and stored on ice that have been exposed to excessive contamination and those that have not been exposed. In the latter case, the selected variable was a fatty acid, hexadecanoic acid, used as biochemical indicator. This modulating approach may provide a platform for future shelf-life studies on related muscle tissue. Ultimately, the study endeavoured to add to the body of knowledge regarding the biochemical and microbiological changes related to Cape hake storage, the prediction thereof via contemporary methods and contributing to the safety and effective utilization of this unique and declining South African nutritional resource.

This study has examined the role of traditional aquaculture systems and fish in food security and livelihoods of fishing communities in two states in Nigeria. The research focused on the productivity, sustainability and profitability of the aquaculture systems including social and economic conditions of farmers. The study also compared the relative importance of fish as a high quality protein source with meats in fishing communities in two states in Nigeria. Data were collected from 400 farmers with modern and traditional aquaculture systems in Niger and Lagos states using semi-structured questionnaires. Modern aquaculture consisted of small fish ponds with an average size of 0.1 ha. Liming was not widespread among farmers with fish ponds but fertilisation was done before stocking by applying fertilisers of both organic and inorganic origins. Farmers (90%) obtained their seeds from the hatcheries and the average stocking density was 5730 ha-1. Polyculture was widely practised by farmers and local feeds were used in feeding fish. Fish shelters and fish fences were the traditional aquaculture systems that were widely practised in two states in Nigeria and are poorly researched and recorded. Various materials were used in the construction of traditional aquaculture systems including branches, elephant grasses, worn out tyres, PVC pipes and clay pots and, were constructed in order to aggregate fish. There was no significant (p > 0.05) difference in yield of fish from fish parks and modern aquaculture systems. The study showed that fishermen prefer fishing in the vicinity of fish parks, tube shelters and fish fences because they make more catches around the installations. Cost–benefit analysis showed that traditional aquaculture systems are profitable because the level of investment required to set and maintain them is quite low compared to returns obtained from them. Fifty actively fishing and fifty non–fishing households in traditional fishing communities were randomly selected in Niger and Lagos states for fish consumption survey. A Simple scale was designed and given to each household to measure fish or meat entering the household for consumption. Intra household fish distribution and consumption was obtained by 24 hour recall method. A large number of fish species were consumed in the fishing communities confirming the relative abundance of the species in local rivers, floodplains and lagoons. Tilapia was the most consumed fish species contributing 19 and 32% by weight of the fish consumed in Niger and Lagos state, respectively. Beef was the most consumed meat followed by goat meat. The study reveals high preference for fresh fish and meat. Highest fish consumption occurred in March corresponding to period of lowest meat consumption. Traditional aquaculture systems and capture fisheries were the main sources of fish in the fishing communities contributing 85% by weight to fish consumed. Male heads of households consumed higher amount of fish than other members of the household. Average weight of fish consumed per person per day was 24 g. Fish contributed 77% to total animal protein in diet of the people and was eaten daily by fishermen thus confirming the importance of fish in the food security of fishing communities.