The effect of entrapped air content on heat penetration characteristics in institutional size retortable pouches packed with pears and green beans was investigated. In addition, products processed in pouches and in number 10 cans were compared using several indices of quality (color, texture, total phenolics, ascorbic acid) and sensory panel evaluations. Heat penetration studies were conducted in an FMC Laboratory Retort. Pouches were placed in horizontal orientation, using both constrained and restrained racking methods. For green beans, a retort temperature of 121°C and 0.68 Atm (25 psig) overriding pressure, of steam and air, were used for processing. For pears a retort temperature of 98°C and 0.68 Atm (10 psig) overriding pressure, of air, were used. For both products, thermal processing times were found to increase approximately 15 % for each 100 milliliter increase in entrapped air content, under constrained conditions. When restrained the increases were much larger. A Stock Rotomat laboratory retort which allowed the pouches to be rotated was also used. Two studies were done: first, pouches were rotated at 15 rpm, second, they were still retorted in vertical orientation. When rotated, the processing times were about one-third those obtained in the FMC retort. When the pouches were processed in vertical orientation little change in process time was noticeable even with large amounts of air, entrapped within the pouch. Color of samples was measured by reflectance to obtain Hunter values. An Allo-Kramer shear press was used to measure the texture or firmness of both pears and green beans. Total phenolics were measured using the Folin-Ciocalteu method. The results showed that pears processed in the presence of air will darken. In comparing products from retortable pouches with those from number 10 cans which had been processed from the same processing lot of raw product, it was found that generally the canned products were better than those processed in the pouch, however differences were slight. Results of this study suggested that in order to obtain a better product from institutional size retortable pouches it is necessary to minimize the amount of air entrapped within the pouch. / Graduation date: 1982

No description available.

Approximately 200 raw prunes were harvested from each of five Italian prune trees near Corvallis every three days for nine consecutive harvest dates. Forty individual fruit from each tree were drawn at random and subjected to a series of fresh fruit quality tests. For each quality factor which was measured, the experiments were set up as nine by five factorial analysis of variance studies with the numbers of observations in a replication depending upon the factor being studied. The correlation of each objective and subjective test with canned fruit flavor was then calculated. The regression line, standard error of estimate, and 90 percent confidence limits were calculated for each tests which had a correlation of 0.80 or better with canned fruit flavor. Several objective tests were used on raw prunes such as soluble solids-acid ratio, pressure test, percent soluble solids, titratable acidity and color of raw prune flesh measured by the Hunter Color-Color Difference Meter in the order named are significantly correlated with the flavor of the canned Italian prune. Analysis of variance and L.S.D. was used to determine that the first two of these tests show good three-day precision as a guide to harvest maturity. The others appear suitable for longer time intervals. Certain objective tests such as pH values and fresh fruit weight are of little value to predict canned fruit flavor and show poor three-day precision as a guide to harvest maturity. The subjective grading of raw prunes by outer skin appearance does not seem to be a precise way to predict canned fruit quality. The three-day precision as a guide to harvest maturity is poor. Respiration of the fresh fruit shows a definite climacteric and the climacteric appeared at approximately the same time the fruit harvested exhibited optimum canned fruit flavor and color. The remaining lot of fruit after the fresh fruit samples were removed was placed in 32°F. cold storage and held for processing the next day. Fruit from each tree each harvest date were processed in twelve No. 2 fruit enameled cans for use in canned fruit analysis studies. Several canned prune quality factors such as percent transmittance of the canned juice, canned fruit skin color as measured by the Hunter Color-Color Difference Meter and titratable acidity of the canned prune pulp can be used to predict or specify the canned fruit flavor. Other objective tests used on canned prunes such as pH values, cut-out soluble solids and cut-out soluble solids-acid ratio are not highly correlated with canned fruit flavor. Subjective tests used on canned prunes were color and flavor of the fruit. These factors were judged by a statistically selected panel of judges. The correlation between color and flavor of the canned fruit was the highest of the study (r= -.9458). The subjective color measurement seems to be very precise in predicting canned fruit flavor. Every subjective and objective test carried out on the raw and canned prunes were correlated with canned fruit flavor because this factor was felt to be of singular importance in canned prune quality. Regression equations are given. / Graduation date: 1953

Thesis (Laur. Tech. (Food Technology))--Cape Technikon, 1991. / This dissertation reports on a three prong approach to obtain new knowledge on the interdependent effects which buyers' specifications, peach crop attributes and sieve stack arrangement have on the masses of peach halves sorted into classes of average diameter. Applying statistical methods and using suitable application computer programs a computer-aided system was developed to improve on the manual selection of sieve diameters. It was concluded that size sorting peach halves for the purpose of mass classification is inaccurate and counter-productive. It is suggested that modern technology be employed to develop a method to determine peach half masses individually.

Thesis (Laureatus in Technology ( Food))-- Cape Technikon, 1991 / This dissertation reports on a three prong approach to obtain new knowledge on the interdependent effects which buyers' specifications, peach crop attributes and sieve stack arrangement have on the masses of peach halves sorted into classes of average diameter. Applying statistical methods and using suitable application computer programs a computer-aided system was developed to improve on the manual selection of sieve diameters. It was concluded that size sorting peach halves for the purpose of mass classification is inaccurate and counter-productive. It is suggested that modern technology be employed to develop a method to determine peach half masses individually.

No description available.

No description available.

Overall heat transfer coefficient (U) and fluid to particle heat transfer coefficient (h$ sb{ rm fp}$) in canned liquid/particle mixtures, subjected to end-over-end processing, were experimentally evaluated. A methodology was developed to measure heat transfer coefficients, while allowing the movement of the particle inside the can, by attaching it to a flexible fine wire thermocouple. Heat transfer coefficients were evaluated under two conditions: (1) with a single particle in the can, (2) with multiple particles in the can. / In the single particle experiments, a spherical particle was used to evaluate the influence of system parameters and product parameters on associated U and h$ sb{ rm fp}$. Increasing values of all four system variables improved the heat transfer coefficients. The effects of rotational speed and headspace were most significant. The particle density had no significant effect, but liquid viscosity and rotational speed had significant effects on U. The h$ sb{ rm fp}$ values were influenced by rotational speed, liquid viscosity and particle density, with particle density most significant. / With multiple particles (Nylon) in cans, the associated convective heat transfer coefficients (U and h$ sb{ rm fp}$) were evaluated. Heat transfer coefficients increased with decreasing particle diameter, increasing particle concentration and increasing sphericity. / Flow visualization studies were carried out. With a single particle, liquid viscosity, particle density and rotational speed influenced particle motion. With multiple particles, motion/mixing was influenced by particle concentration, size, and shape, liquid viscosity and rotational speed. / Dimensionless correlations were developed for the predictive modeling of convective heat transfer coefficients. For U with a single particle, Nusselt number (Nu) was correlated to Reynolds number (Re), Prandtl number (Pr) and relative can headspace while with multiple particles, Re, Pr, ratio of particle to liquid concentration, relative particle diameter and particle sphericity were found to be significant. For h$ sb{ rm fp}$ with a single particle in the can, three different correlations, one each for a sphere, a cylinder and a cube were developed and the Nu was correlated to Re, Pr, density simplex, relative can headspace and the ratio of the sum of the diameter of rotation and diameter of the can to the can diameter. With multiple particles Nu was correlated to Re or Peclet number, ratio of particle to liquid thermal conductivity, particle to liquid concentration and particle sphericity. / A multi-layer artificial neural network (ANN) was used to model heat transfer parameters under conduction and convection heating conditions. The network was found to predict optimal sterilization temperatures with an accuracy of $ pm$0.5$ sp circ$C, and other responses such as process time and integrated heating time for quality attribute with less than 5% associated errors. Multi-layer neural network models were trained based on the experimental values of U and h$ sb{ rm fp}$, was obtained. The trained network was found to predict U and h$ sb{ rm fp}$ with less than 3% and 5% errors, respectively. The neural network models were more accurate than the dimensionless number models, for predicting U and h$ sb{ rm fp}$. (Abstract shortened by UMI.)

Graduation date: 1949

Graduation date: 1938