Assessment of freshness and quality of meat and fish is a major activity of both food regulatory agencies and the food industry. Various methods are used for measuring fish and meat quality, each with its particular advantages and limitations. However, methods based on monitoring the products of proteolysis have received relatively little attention. The objective of the present study was to identify specific protein and peptide products of proteolysis as indicators of freshness and quality during chilled storage of fresh fish and meat. / Samples of meat and fish were subjected to chilled storage; at intervals of 0, 2, 4, 8, 12 and 16 days, samples were subjected to protein and peptide extraction, and separation of individual sarcoplasmic and myofibrillar proteins by SDS and native electrophoresis. These extracted proteins along with acid soluble nitrogen (ASN) were separated by RP-HPLC, fractions were collected and identified by electrospray ionization mass spectrometry (ESI-MS). / RP-HPLC separated at least thirty fractions from the ASN extract of fresh fish. ESI-MS revealed the presence of at least twenty-five polypeptides with molecular weights (MW) ranging from 2 to 32 kDa. The relative area % of the polypeptides with MW 32.8 kDa and 42.8 kDa decreased during the storage while polypeptides of MW of 10.9 kDa and 16.7 kDa increased during storage. Changes in polypeptides of MW 12, 34.2 and 42.8 kDa was also observed. The sarcoplasmic protein extracted from ground and whole meat contained at least 12 polypeptides with MW ranging from 11 to 42 kDa. The relative area % of polypeptide of MW of 35.7 kDa decreased during storage. The results suggest that changes in proteins and polypeptides of MW 10.9, 12, 16.7, 32.8, 34.2 and 42.88 kDa in fish and 35.7 kDa in meat could serve as indicators of spoilage.

The Republic of Guinea is located on the west coast of Africa at about 11° North latitude. A large portion of Guinea's supply of protein is dried fish. The actual drying method operates under open air, the foodstuff being unprotected from unexpected rains, windborne dirt and dust, and from infestation by insects, rodents, and other animals. More, the deforestation rate is increasing year after year, depleting the source of fuel for drying. Practical ways of drying fish cheaply and sanitarily would be welcome.The present work develops a prototype solar dryer on the basis of natural convection of air. The device is comprised of a glazed flat plate collector, a furnace with translucent walls, and an air tunnel adjoining the two. Air entering the collector is heated and flows into the furnace where energy is absorbed by pieces of fish placed on horizontal racks. The air exits through an opening in the top of the device carrying moisture with it.Using the prototype solar dryer, a fish drying experiment was conducted at the Center for Energy Research, Education, and Service (CERES) at Ball State University. The primary objectives were to investigate drying rates, times, and loads expected for a dryer constructed using simple techniques and materials readily available in the Republic of Guinea. The drying experimental results are in many ways similar to those reported by previous authors.The solar dried product appears to be superior to the product of current drying methods and the foodstuff is protected from infestation or contamination during drying.Future work suggested by the project experience includes refinement of the dryer design and additional fish drying experimentation. An economic analysis would also yield information on the feasibility of widespread use of solar dryers for drying of fish in the Republic of Guinea. / Department of Physics and Astronomy

Proteolysis of myofibrillar proteins in Pacific whiting surimi occurs when the 50- 70°C temperature range is reached during standard cooking procedures (e.g. 90°C for 15 min). This proteolytic activity results in the softening of surimi gels. Bovine plasma protein (BPP) is the most effective of the food-grade inhibitors used to prevent this reaction, and enhance gel strength in PW surimi. The objective of this study was to determine the effective components of bovine plasma that enhance gel strength in PW surimi. Five bovine plasma fractions were evaluated for components that contribute to gel strength enhancement in PW surimi. Fraction I, which consists mostly of fibrinogen and albumin, was found to also contain plasma transglutaminase (PTGase) activity. Part of fraction I gel-enhancing ability may be attributed to an unknown component which inhibited papain independently of Ca²⁺ and inhibited 40% of surimi proteolytic activity. Fibrinogen or albumin did not inhibit papain activity or enhance gel strength of surimi. For fraction I-S, which is a more concentrated PTGase fraction, gel-enhancement of PW surimi was completely dependent on the presence of Ca²⁺. Autolytic inhibitory activity of fraction I-S in surimi was completely eliminated by the presence of Zn²⁺. Fraction II+III (1%) inhibited over 50% of surimi autolytic activity and displayed a small amount of PTGase activity. Fraction II+III (1%) gel enhancing abilities were low when compared to the other fractions and BPP, and only slightly effected by EGTA. Fraction IV (1%), which contains approximately 50% albumin and 15% α₂-macroglobulin, inhibited over 70% of surimi autolytic activity. It enhanced gel strength at a 1% (w/w) concentration when set for 20 hr at 4°C before cooking, and was not affected by EGTA. This fraction displayed no apparent PTGase activity. Fraction IV-1 (1%), which contains approximately 20-30% α₂-macroglobulin, gel strength enhancement surpassed the other fractions and BPP when set for 20 hr at 4°C and 2 hr at 25°C before being cooked at 90°C for 15 min. The gel strength enhancing abilities of fraction IV-1 were significantly affected by EGTA. Fraction IV-1 (1%) inhibited over 80% of surimi proteolytic activity. The gel strength of 1 mM (0.03%) E-64, which is a cysteine protease inhibitor, was equivalent to that of BPP (1%) after setting at 4°C for 20 hrs before cooking. E-64 (1 mM) inhibited 83% of the autolytic activity of PW surimi and BPP (1%) inhibited 78%. These data indicate that a cysteine protease inhibitor can increase gel strength, and suggests that BPP is acting as a cysteine protease inhibitor. Ca²⁺ dependent gel strength enhancement was attributed to transglutaminase (TGase) activity, both added PTGase and endogenous TGase. Gel strength enhancement that was Ca²⁺ independent was attributed to cysteine protease inhibitors, specifically α₂-macroglobulin. Overall, it was determined that gel strength in PW surimi was greatly enhanced by both concentrated PTGase (I and I-S) and concentrated α₂-macroglobulin (IV-1) fractions, with a combination of these fractions being most effective in gel strength enhancement, when the surimi is first set at 4°C or 25°C before cooking at 90°C for 15 min. These data suggest that the mechanisms of gel strength enhancement of BPP are from cysteine protease inhibition, possibly from α₂-macroglobulin, and from crosslinking of myosin in surimi from both added (PTGase) and endogenous TGase activity. / Graduation date: 1996

Graduation date: 1993

Graduation date: 1938

Graduation date: 1953

Graduation date: 1949

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1988. / Bibliography: leaves [145]-151. / Photocopy. / Microfilm. / xi, 151 leaves ill. 29 cm

Bdellovibrionaceae (BD) are unique, predatory, endoparasitic, Gram-negative bacteria. As the world's smallest living hunter they prey on other Gram-negative bacteria giving them potential as biological control agents. Prior to this study, however, there were no reports of BD in New Zealand. The overall aim of this research was to isolate BD from New Zealand sources, characterise them and investigate their potential role as a biological control agent. The history, characteristics, life cycle and mechanism of predation of this organism are reviewed and the possibility of the industrial applications of BD, are discussed. In this study, a halophilic species of BD was isolated from fourteen coastal sea water sites around New Zealand. Thirteen isolates were characterised using proven characterisation techniques including general, microscopic and molecular techniques. It was found that the isolates were taxonomically identical or very closely related to each other and belong to the genus Bacteriovorax. The predation pattern of BD isolates was examined against a group of Gram negative bacteria in solid and liquid media. The predation patterns and efficiencies of the different BD isolates were similar, which confirms that the BD isolates are closely related, are selective in their predation, and prey on some Gram-negative bacteria but not all. The rapid loss of culture viability of BD is well known, but no studies have been reported to date on the survival of pure cultures of BD at different temperatures. The survival rate of BD in dense suspensions at different temperatures without host bacteria was investigated and it was observed that pure BD cultures can be stored with minimal reduction in numbers at temperatures ranging from 4°C to 20°C. However, significant reductions in numbers were observed at -1 8"C, 30°C and 37°C after 13 to 16 days. The effects of the 13 New Zealand BD isolates on the growth of a population of Photobacterium phosphoreum were examined to select the best isolate for in vitro application. All of the isolates tested had considerable reduction effect against P. phosphoreum. Some isolates were more effective than others, despite their taxonomic similarity to each other. The isolate OT2 was selected for further studies based on these results. The in vitro efficacy of BD was assessed against late exponential cultures of a seafood spoilage bacterium, P. phosphoreum, originally isolated from Cod fillets from Denmark. Loglo reductions of P. phosphoreum and some other Gram-negative bacteria ranged from 4.5 to 4.8 after 9 h of incubation at 25OC. BD was effective in reducing the numbers of P. phosphoreum at pH 5.5 to 8.5 and salinity 0.9 to 4.5% (wlv). A significant interaction was observed between the prey and predator concentrations and nutrient concentration. Prey concentrations were observed to be the most vital factor in predation and the most favourable predation conditions were at a prey concentration of -8 loglo colony forming units (CFU)/mL, together with a predator concentration of 3 - 7 loglo plaque forming units (PFU)/mL and a prey : predator ratio of >5.0. The thresholds of the prey and predator concentrations for predation were observed to be 3.7 loglo CFUImL and 3.9 loglo PFUImL, respectively. The trials carried out in this study focused on the efficiency of BD on a pure culture of one organism, P. phosphoreum and not on mixed cultures of Gramnegative spoilage bacteria, the normal condition observed in saltwater fish. There has been very little research in this field and the results of these trials suggest further investigation into the effect of BD on mixed cultures of Gram-negative spoilage organisms is warranted. Since only one isolate of BD (OT2) was examined against only one spoilage bacterium (P. phosphoreum) in liquid medium, the evidence of these findings must be restricted to these particular conditions. Future studies, using a range of BD isolates against a mixture of spoilage and pathogenic organisms in solid medium are warranted. The biopreservation capability of BD in extending the shelf life of king salmon was evaluated. A significant effect was observed at 20°C but not at 10°C. At 20°C the shelf life was extended through extension of the lag phase of growth of the prey bacteria and a reduction in total numbers attained. Sensory evaluation of the salmon product being tested confirmed that the shelf life was extended. However, at 10°C there was no reduction in prey organisms, which suggested that the strain of BD used is ineffective at refrigeration temperatures.

Bdellovibrionaceae (BD) are unique, predatory, endoparasitic, Gram-negative bacteria. As the world's smallest living hunter they prey on other Gram-negative bacteria giving them potential as biological control agents. Prior to this study, however, there were no reports of BD in New Zealand. The overall aim of this research was to isolate BD from New Zealand sources, characterise them and investigate their potential role as a biological control agent. The history, characteristics, life cycle and mechanism of predation of this organism are reviewed and the possibility of the industrial applications of BD, are discussed. In this study, a halophilic species of BD was isolated from fourteen coastal sea water sites around New Zealand. Thirteen isolates were characterised using proven characterisation techniques including general, microscopic and molecular techniques. It was found that the isolates were taxonomically identical or very closely related to each other and belong to the genus Bacteriovorax. The predation pattern of BD isolates was examined against a group of Gram negative bacteria in solid and liquid media. The predation patterns and efficiencies of the different BD isolates were similar, which confirms that the BD isolates are closely related, are selective in their predation, and prey on some Gram-negative bacteria but not all. The rapid loss of culture viability of BD is well known, but no studies have been reported to date on the survival of pure cultures of BD at different temperatures. The survival rate of BD in dense suspensions at different temperatures without host bacteria was investigated and it was observed that pure BD cultures can be stored with minimal reduction in numbers at temperatures ranging from 4°C to 20°C. However, significant reductions in numbers were observed at -1 8"C, 30°C and 37°C after 13 to 16 days. The effects of the 13 New Zealand BD isolates on the growth of a population of Photobacterium phosphoreum were examined to select the best isolate for in vitro application. All of the isolates tested had considerable reduction effect against P. phosphoreum. Some isolates were more effective than others, despite their taxonomic similarity to each other. The isolate OT2 was selected for further studies based on these results. The in vitro efficacy of BD was assessed against late exponential cultures of a seafood spoilage bacterium, P. phosphoreum, originally isolated from Cod fillets from Denmark. Loglo reductions of P. phosphoreum and some other Gram-negative bacteria ranged from 4.5 to 4.8 after 9 h of incubation at 25OC. BD was effective in reducing the numbers of P. phosphoreum at pH 5.5 to 8.5 and salinity 0.9 to 4.5% (wlv). A significant interaction was observed between the prey and predator concentrations and nutrient concentration. Prey concentrations were observed to be the most vital factor in predation and the most favourable predation conditions were at a prey concentration of -8 loglo colony forming units (CFU)/mL, together with a predator concentration of 3 - 7 loglo plaque forming units (PFU)/mL and a prey : predator ratio of >5.0. The thresholds of the prey and predator concentrations for predation were observed to be 3.7 loglo CFUImL and 3.9 loglo PFUImL, respectively. The trials carried out in this study focused on the efficiency of BD on a pure culture of one organism, P. phosphoreum and not on mixed cultures of Gramnegative spoilage bacteria, the normal condition observed in saltwater fish. There has been very little research in this field and the results of these trials suggest further investigation into the effect of BD on mixed cultures of Gram-negative spoilage organisms is warranted. Since only one isolate of BD (OT2) was examined against only one spoilage bacterium (P. phosphoreum) in liquid medium, the evidence of these findings must be restricted to these particular conditions. Future studies, using a range of BD isolates against a mixture of spoilage and pathogenic organisms in solid medium are warranted. The biopreservation capability of BD in extending the shelf life of king salmon was evaluated. A significant effect was observed at 20°C but not at 10°C. At 20°C the shelf life was extended through extension of the lag phase of growth of the prey bacteria and a reduction in total numbers attained. Sensory evaluation of the salmon product being tested confirmed that the shelf life was extended. However, at 10°C there was no reduction in prey organisms, which suggested that the strain of BD used is ineffective at refrigeration temperatures.