An industrial Fourier transform infrared (FTIR) milk analyser has been adapted for the proximate analysis of fresh or cooked meat and meat products. Stable freeze-dried samples of ground beef and bologna were prepared for the calibration of an FTIR spectrometer equipped with a 37-mum transmission cell maintained at a constant temperature of 65°C and were analysed for fat, protein, moisture, and ash by the official methods of analysis of the Association of Official Analytical Chemists (AOAC) prior to instrumental measurement. The requirement to prepare a "milk-like" emulsion of meat for FTIR analysis led to the development of two prototype high-pressure homogenizers specifically designed to produce analytical volumes of emulsions in which the largest residual colloids present in suspension would have dimensions smaller than 1 mum. Emulsified samples were examined by transmission electron microscopy and laser light scattering spectroscopy to determine the size distribution of fat globules and the dimensions of the residual insoluble fragments of protein. / "Milk-like" emulsions of meat passed three times through a high-pressure homogenizer operating at 20,000 psi (138 MPa) had an average fat globule diameter of less than 320 nm. Also, the use of high-pressure homogenization eliminated the need to filter out insoluble proteins from connective tissues prior to the infrared analysis, resulting in a more accurate determination of the protein content in the meat samples. The results of validation studies conducted with both fresh and freeze-dried samples demonstrated that it is possible to analyse meat samples simultaneously for fat, protein, carbohydrates and moisture with good accuracy in approximately 7½; minutes per sample employing existing FTIR instrumentation used for the routine analysis of milk and dairy products.

The application of high pressure (HP) processing on trout and shrimps was investigated in order to study its effect on their quality attributes. Five levels of pressure, holding time and temperature were selected using a central composite rotatable design (CCRD), the central point being. 200 MPa, 30 min and 10°C. This design was used in order to permit the measurement and modeling of changes in various quality parameters as a result of changes in the process variables. The color parameters (L*, a*, and b* values), physical attributes (drip-loss, protein leaching and water holding capacity) and texture parameters (firmness and springiness) in each case were evaluated, and modeled as second order polynomial equations. / Artificial Neural Network modeling was employed to investigate its ability in predicting the quality changes in both pressure-treated trout fillets and shrimp samples, and its performance was with statistical models. / High pressure (HP) kinetics of the microbial destruction in both trout and shrimp was also studied. (Abstract shortened by UMI.)

High pressure (HP) processing, a novel technology, has excellent potential for non-thermal preservation of apple juice, the largest consumed fruit juice in North America. The objective of this research was to evaluate the application of HP treatment for inactivation of enzymes and destruction of microorganisms in apple juice. HP inactivation kinetics of selected enzymes (amylase, pectin methyl esterase and polyphenol oxidase) and microorganisms [Leuconostoc mesenteroides, Pichia membranaefaciens and Zygosaccharomyces badii, Escherichia coli (29055) and Escherichia coli (O157:H7)] in apple juice were evaluated under various test conditions (100--400 MPa, 0--60 min and 6--40°C) using a central composite design of experiments. The enzymes selected were of importance in apple juice preparation and/or storage stability of the processed juice. Microorganisms included those that are responsible for spoilage and/or public health concern as well as those that are indicative of unsanitary handling conditions. / Enzyme inactivation and microbial destruction due to pressure followed a dual-effect model consisting of a pressure pulse effect (PE) and a subsequent semi-logarithmic (first order) inactivation during the pressure hold-time. In general, results showed that inactivation of enzymes and destruction of microorganisms was more prominent at higher-pressure levels, higher temperature and longer treatment times, and at lower pH levels of juice. Pressure pulse effect was dependent on pressure level, with higher PE achieved at higher pressures. During the pressure-hold, as expected, the associated decimal reduction times (D values) decreased with an increase in pressure. Pressure dependency of D values was well described by the conventional death time model. The pressure resistance of enzymes and microorganisms varied, but complete inactivation of enzymes and destruction of microorganisms was possible with the combination of lower pH, higher pressure and higher temperatures. / Commercial PME from a citrus source was more pressure sensitive than PME from microbial source. Spoilage bacteria (L. mesenteroides) were more pressure resistant than the yeasts. E. coli enumerated on an enrichment media (supporting both injured and healthy cells) showed larger survivors and a greater resistance than on a more selective media. An increasing number of cells got injured than killed with the application of pressure treatment until they were all finally injured or killed. High-pressure treatment (pulse at 400 MPa or by holding about 10 min at 350 MPa and 30°C) resulted in complete destruction of the pathogenic microorganism E. coli (O157:H7) ensuring the public health safety of the process.

Hydrostatic pressure has been demonstrated to induce major changes in secondary structure of whey proteins resulting in an increased digestibility in vitro, and possibly an improvement of the glutathione (GSH) inducing effect of whey proteins in vivo. Micro filtration and ion-exchange, two commonly used processing techniques in whey protein manufacture, generate whey proteins with different compositions. Two animal studies were designed to compare the digestibility and GSH inducing effects of whey protein isolates (WPIs) treated with three repeated pulse cycling of pressure (3-cycle) or single pulse of high pressure (1-cycle) and pressurized microfiltrated and ion-exchange WPIs. The results indicate that special hydrostatic pressure treatment on the proteins improves its growth stimulating effect, but does not enhance the GSH-inducing effect of WPI in the healthy growing rats. Difference among commercial whey protein products is also an important factor that affects the biological properties of the pressurized whey proteins. In conclusion, both proper pressure treatment and product composition should be considered in order to find the most bio-effective whey protein preparation.

No description available.

Recent studies have demonstrated that applied hydrostatic pressure can affect the functional properties of whey protein isolate (WPI). In this work, the effects of applied hydrostatic pressure on the tertiary and secondary structure of whey proteins were investigated by spectroscopic and rheological techniques to elucidate the molecular basis of such pressure-induced changes in protein functionality. The individual protein components of WPI and various samples of WPI obtained from different sources were subjected to different single-cycle pressure treatments of up to 400 MPa in 100 MPa increments with 30-min holding time as well as to pressures ranging from 450 to 650 MPa without a holding time. Electrospray ionization-mass spectrometry, circular dichroism, and Fourier transform Raman spectroscopic studies of pressure-treated samples of beta-lactoglobulin, the major protein component of WPI, revealed significant changes in tertiary structure. Fourier transform infrared spectroscopic studies revealed that the secondary structure of beta-lactoglobulin was also sensitive to applied pressure and holding time. The secondary and tertiary structure of alpha-lactalbumin, the second most prevalent protein in WPI, was unaffected by applied hydrostatic pressure. The spectroscopic behaviour of the various samples of WPI subjected to pressure treatment was variable and indicated that the response of WPI to applied hydrostatic pressure is dependent on the method used to isolate the WPI from whey. The rheological profiles of beta-lactoglobulin, alpha-lactalbumin, and WPI samples after various pressure treatments were also recorded. Both beta-lactoglobulin and WPI exhibited marked increases in viscosity with increasing pressure, whereas alpha-lactalbumin remained solutions exhibited no significant change in viscosity. These studies have furthered the understanding of the effects of applied hydrostatic pressure on the molecular structure and rheological pr

Thermal processing is the primary mode of preservation of mango products, which can be considerably damaging to the delicate quality of mango. HP processing could thus be a potential alternative for extending the shelf-life of mango products. Establishing HP processing technology need data on microbial inactivation kinetics and shelf-life study of the product. The objective of this research was therefore to evaluate the application of HP treatment for inactivation of microorganisms (pathogenic and spoilage type) and to evaluate the shelf-life of HP treated mango juice. / HP destruction kinetics of three common spoilage microorganisms, Leuconostoc mesenteroides, Zygosaccharomyces bailii and Pichia membranaefaciens and two pathogenic microorganisms, Escherichia coli O157:H7 and Listeria monocytogenes Scott A, were evaluated at 250-550 MPa with 0-60 min holding time at room temperature with species specific initial counts between 10 6 to 108 CFU/mL.

Thesis (Ph.D.)--Drexel University, 2007. / Includes abstract and vita. Includes bibliographical references (leaves 136-142).

Thesis (M.S.)--University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 22, 2009) Includes bibliographical references.

Thesis (M.S.)--Ohio University, November, 1997. / Title from PDF t.p.