From the dark muscle of British Columbia herring a highly active enzyme capable of peroxidising unconjugated unsaturated fatty acids was isolated. This ‘lipoxidase’, which was shown to be a nitrogenous complex possessing no heavy metals or sulphydryl group as the active centre, is heat-labile and can act only in presence of activators such as certain iron-containing organic nitrogenous compounds. Two such compounds, namely haemoglobin and cytochrome ‘C’ were isolated. The enzyme exhibits optimum activity at 15°C. and pH 6.9. There is also an optimum concentration of enzyme, substrate, and of the activators for maximum enzyme activity. The presence of the activators appears to change the kinetics of the reactions. The inhibition of the enzymic reaction brought about by cyanide and azide is possibly due to the inactivation of the iron-containing activators rather than of the enzyme itself. / Science, Faculty of / Zoology, Department of / Graduate

No description available.

A novel method for isolating fish proteins by shifting pH to high acid or high alkali pH was the focus of the study. Biochemical and physicochemical properties of various pH-treated soluble fish proteins as a function of ionic strength were determined. Effect of ionic strength and various storage conditions on gelation properties and stabilization of fish protein isolate (FPI) were also elucidated. At low ionic strength (IS 10 mM NaCl), the solubility of Pacific whiting (PW) proteins was low between pH 5 and 10, but increased significantly as the pH was shifted to either acidic or alkaline pH. The isoelectric point (pi) shifted toward acidic direction as IS increased to 600 mM. High IS (600 mM NaCl) resulted in protein aggregation at low pH but improved myosin heavy chain (MHC) solubility at pH 6 - 10. Changes in total sulfhydryl (SH) content and surface hydrophobicity (S [subscript o]) were associated with the different molecular weight distributions of the soluble proteins. At pH 4 and IS 10-100 mM, MHC was soluble but degraded. At pH 10, the formation of high MW polymers was observed at IS [greater than or equal to] 150 mM. Gels obtained from FPI prepared at pHl1/IS150 and conventional surimi (CS) were superior to FPI prepared at pH 3 and/or other IS levels. There was no correlation between protein solubility and gel properties of FPI. Gelation mechanisms of acid and alkali-treated FPI were identical under the same IS condition. FPI prepared at pH 3 or 11 could be partly refolded at pH 7. No significant difference in texture was observed between alkali-treated protein isolates (AKPI, pH 11) kept frozen at pH 5.5 and 7.0. Strongest gel was found for AKPI with cryoprotectants (C) and without freeze/thaw (FT) cycles at both pH storage (5C & 7C), while poor gel was obtained from AKPI without cryoprotectants (NC) and with FT (5NC-F & 7NC-F). 5NC-F & 7NC-F demonstrated the lowest S [subscript o] and total SH probably suggesting that proteins were more aggregated as a result of hydrophobic interactions and disulfide bonds. Scanning electron microscope (SEM) revealed the most discontinuity of gels from AKPI without cryoprotectants and with FT and showed less protein stability when stored at pH 5.5 than at neutral pH. Raman spectral analysis demonstrated that refolding of AKPI by pH adjustment to 7.0 was achieved, but not identical to the native protein. CS contained higher α-helix content (~50%) than AKPI (~20-30%). Frozen storage induced a decrease and an increase in the α-helix of CS and AKPI samples, respectively. Alkali-treated proteins were slightly less stable than CS during frozen storage. / Graduation date: 2005

Graduation date: 1938

Graduation date: 1953

Graduation date: 1949

In this study, a number of experiments were undertaken to investigate possible methods for effective improvement of the texture and flavour of canned late-run chum salmon. These included removal of the skin and bones from the fish, processing of the boneless-skinless steaks in retort pouches, brine treatment using two washes with an 8% salt solution for one hour each time, and a precanning treatment in which the boneless-skinless steaks were soaked in a solution of 10% tripolyphosphate and 2% brine for two minutes. Only fish of advanced sexual maturity were used. The canned salmon was steam processed at 120°C for 65 minutes in an FMC laboratory retort. This was based on a known commercial process for 307 x 115 cans. Heat penetration studies were carried out to design the process schedules for the pouched samples. It was found that the pouched product required 48% less thermal processing time than the canned product to achieve similar lethality. Sensory results showed that the removal of the skin and bones did not produce any significant improvement in the flavour and acceptability of the fish. There was no significant difference between the polyphosphate/brine samples and the untreated (control) samples for all attributes tested. The brine treatment also did not improve the texture of the samples. However, there was less detection of late-run flavour in the brine treated samples when compared to the control. Comments offered by panelists described these samples as having a salty/briny flavour. Pouched samples had a firmer, drier and more fibrous texture than the canned product. They also scored better in terms of late-run flavour. Acceptance of the fish however was only moderate. As a consequence, although this study demonstrated an improvement in the texture and flavour of the pouched late-run chum in comparison to the canned product, it was concluded that a more acceptable pouched product could probably be obtained by using late-run salmon of less advanced sexual maturity. Results of linear regression analysis showed that significant relationships were obtained between sensory firmness, fibrousness and chewiness and instrumental hardness, maximum slope and chewiness. However, none of the sensory parameters were well predicted by the instrumental results. / Land and Food Systems, Faculty of / Graduate

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

Three different species of fish (sea trout, Spanish mackerel and catfish) were studied. Samples undergoing normal spoilage were compared with samples which had undergone a sanitizing treatment with alcohol. Differential temperature storage studies were conducted at 290 °F (-1.7 °C) and 32 °F (0 °C). Fish quality was assessed by means of microbiological, chemical and sensory analyses. Quality assessment via measurement of proteolytic and lipolytic enzymes was attempted, but these enzyme activities were not detected in any of the samples. It was not possible to differentiate between the contributions of microbial and autolytic spoilage. Alcohol treated samples (reduced numbers of microorganisms) had shelf-lives extended by 6-10 days over untreated samples. The shelf-life of samples stored at 290 °F was extended by 6-10 days over the shelf-life of samples stored at 32 °F. Treated samples stored at 290 °F received highest sensory scores and untreated samples stored at 320 °F received the lowest scores. It was seen that the three fish species studied had different shelf-lives: sea trout-6 days, Spanish mackerel - 10 days and catfish - 16 days. Decomposition rates differed significantly between species and this factor must be taken into account when marketing strategies are developed by firms engaged in fresh fish sales. / Master of Science

The focus of this thesis was on the economic feasibility of three food processing projects. They involved freezing of pork loin and fish using cryogenic freezing and stored at $-$18, $-$12 and $-$7$ sp circ$C, and modified atmosphere packaging (MAP) of pork loin using a combination of nitrogen and carbon dioxide gases, chitosan dip and stored at 5, 10, and 15$ sp circ$C. A production plan with similar layout and capacity was adopted for the Montreal area. The benefit-cost analysis (BCA) of each project was carried out assuming that each plant operated approximately 2000 hours per annum at full capacity. Net present value (NPV) and benefit cost ratio (B/C ratio) at 8% discount rate, and internal rate of return (IRR) were determined for each project. The calculations show the NPV of $2.4 million, $1.8 million, and $3.4 million; B/C ratio of 1.09, 1.09, and 1.10; IRR of 15 %, 13 %, and 18 % for frozen pork loin, frozen fish and MAP pork respectively. All IRRs were higher compared to the 1995 return rates of TSE of 9.7 % and the average return of capital of 8.8 % for some food and beverage industries. These economic values are sensitive to changes in working hours, price of raw materials and finished products. It is also found that MAP products could be stored at temperatures up to 15$ sp circ$C. Frozen products could be stored at temperatures of $-$12$ sp circ$C and below only if the length of distribution chain can be reduced. This would decrease electricity costs up to 36% at each level of distribution. It can be concluded that the three projects are economically profitable.