Factors affecting the rheological properties of gels made from hoki (Macruronus novaezelandiae) : a thesis presented in partial fulfillment of the requirements for the degree of Master of Technology at Massey University /

Hoki (Macruronus novaezelandiae) is an important commercial fish in the New Zealand Exclusive Economic Zone. The resource remains underutilized with only a small proportion of the 250,000 tonnes Total Allowable Catch presently being made into added value products. There is interest in producing surimi, a refined, stabilized form of fish mince, from hoki. Surimi is an intermediate raw material used for the production of a range of fabricated foods. The rheological properties of these gel-based foods are of key importance for their consumer acceptability. The quality of surimi is determined predominantly by the gel-forming ability of the myofibrillar protein of the raw material fish used in the process. These properties change with chilled and frozen storage of the fish. The objectives of this study are to develop methodology to test the gel-forming ability of surimi; to investigate the changes in gel-forming ability of hoki with chilled and frozen storage, and to evaluate the rheological methods used in these studies. The implications with respect to a domestic surimi industry are discussed. The rheological properties of gels made from hoki stored for various times, chilled or frozen, were determined using two failure tests, namely the puncture test and the torsion test. The puncture test is an empirical method commonly used in the surimi industry, where a 5 mm diameter spherical probe is driven into the gel at constant plunger speed. The force and deformation at failure are used to describe the mechanical properties of the gels. The torsion test is a fundamental method whereby a pure shear state is obtained by applying a twisting moment about a central axis. The shear stress and true strain at failure are calculated and used to follow the changes in gel properties with time. The strength of gels decreased as the fish spoiled on chilled storage. The decline appears to be slower than that reported for other fish such as Alaska pollock. Even after 10 days storage the gel strength was such that hoki would still have excellent gelling properties based on Japanese classification systems. The storage of headed and gutted hoki at -29°C resulted in a significant loss of gel-forming properties over time. The strength of gels were less than the minimum for Japanese ship-processed surimi after about 100 days storage. Hoki appears to lose gel-forming ability with frozen storage at a similar rate to that of Alaska pollock. Measurement of the pH and formaldehyde concentration of the flesh were good indicators of the gel-forming ability of frozen stored hoki. The true strain at failure showed the highest correlation with storage time. Finally, the puncture and torsion tests were evaluated with respect to their use for specifying surimi quality. Specifically their precision, cost, convenience and correlation with a sensory method, were assessed. The results of the storage studies were pooled to provide data covering a wide range of gel textures. Parameters from both tests showed significant correlations with the sensory method, with the puncture force showing the greatest overall correlation. Both methods showed good response to changes in fish quality. There was a large error associated with the puncture force value when firm gels were tested. Standard deviations of up to 25% of the mean were measured. The other parameters for both tests gave standard deviations of about 10%. This demonstrated the high error normally associated with failure testing, and the difference between a point test where the applied force is concentrated over a small area and the torsion test where the stress is applied over a larger area hence averaging the effect small defects may have on failure of the sample. It was concluded that the puncture test is suitable for routine quality testing of surimi, however both the force and deformation results should be reported. For research and when more accurate specification of quality is needed then the torsion test would be more appropriate. Whichever method is used, it is imperative that the preparation and testing of surimi be carried out in a consistent and uniform manner to allow comparison and communication of results. There is a need for a standard industry-wide method for testing the gel-forming ability of surimi. To make consistent surimi an on-shore operation would require strict control of fish quality. Measurement of fish freshness based on organoleptic assessment and the K value may be a useful basis for a hoki surimi quality assessment program. It is probable that the loss of functional gel-forming ability of hoki during frozen storage at -29°C would be too fast to allow the use of frozen hoki for making surimi over an extended period in a commercial operation. Decreasing the storage temperature may extend the useful storage life, but this would have to be balanced against the increased capital and running costs of storage at these lower temperatures

Path planning for general mazes

Path planning is used in, but not limited to robotics, telemetry, aerospace, and medical applications. The goal of the path planning is to identify a route from an origination point to a destination point while avoiding obstacles. This path might not always be the shortest in distance as time, terrain, speed limits, and many other factors can affect the optimality of the path. However, in this thesis, the length, computational time, and the smoothness of the path are the only constraints that will be considered with the length of the path being the most important. There are a variety of algorithms that can be used for path planning but Ant Colony Optimization (ACO), Neural Network, and A* will be the only algorithms explored in this thesis. The problem of solving general mazes has been greatly researched, but the contributions of this thesis extended Ant Colony Optimization to path planning for mazes, created a new landscape for the Neural Network to use, and added a bird\u27s eye view to the A* Algorithm. The Ant Colony Optimization that was used in this thesis was able to discover a path to the goal, but it was jagged and required a larger computational time compared to the Neural Network and A* algorithm discussed in this thesis. The Hopfield-type neural network used in this thesis propagated energy to create a landscape and used gradient decent to find the shortest path in terms of distance, but this thesis modified how the landscape was created to prevent the neural network from getting trapped in local minimas. The last contribution was applying a bird\u27s eye view to the A* algorithm to learn more about the environment which helped to create shorter and smoother paths

Predicting forage nutritive value from height and maturity of alfalfa in Saskatchewan, Canada

Several authors have shown that fiber levels can be predicted from plant height and maximum maturity in alfalfa (Medicago satvia L.). These estimates have been used to predict animal performance without any reference to error terms. This study evaluates the equations for predicting chemical characteristics from field measurements of plant morphology, and some equations for predicting animal performance from chemical characteristics. Finally, predicting forage utilization directly from field measurements of plant morphology was evaluated. Six sites were chosen from irrigated alfalfa fields in southwestern Saskatchewan. The chemical characteristics measured were neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein (CP), acid detergent lignin (ADL), ash, acid detergent insoluble nitrogen (ADIN), neutral detergent insoluble nitrogen (NDIN), and ether extract (EE). Only ADF and NDF showed predictive value from height and maximum maturity (R2 = 0.86, and R2 = 0.90, respectively). Weiss developed a theoretical model for estimating net energy based on summing the true digestibility of each of the components. This model did not predict digestibility well (R2 = 0.23). A model was developed to predict in-vitro dry matter digestibility directly from height and maximum maturity, however this model only performed moderately well (R2 = 0.61). This shows that in-vitro digestibility is predictable directly from height and maturity, although not without significant increases in error compared to prediction of ADF and NDF. Caution would be advised when using these estimates for further prediction

Why Don\u27t My Dreams Come True

Illustration of man sitting in sofa smoking a cigarette by fireplacehttps://scholarsjunction.msstate.edu/cht-sheet-music/6782/thumbnail.jp

Minority Religion in Public Office

In examining the religions of members of congress, it seems that minority religions are able to attract broad support and depending on location succeed in gaining election at the local, state and federal levels