Research was initiated to find a secondary bleach to remove brown discoloration on sulfur dioxide brined sweet cherries. In addition, studies were carried out to determine the effects on texture of not only the secondary bleaches, but also the primary bleach (sulfur dioxide). Three bleaches were found to remove the pigments in question leaving a snow white fruit at the end of the process, These were sodium and calcium hypochlorite and sodium chlorite. The study of the brining effects on the original fruit showed that most firming occurred within the first four and one half weeks. These constituents affecting firmness, the pectins and cellulose, did not appreciably change during the curing process. Only the uptake of calcium into the pectin was noted after the first few weeks. Analyses showed that secondary bleaching with the hypochlorites was too destructive to the cherry tissue. Sodium hypochlorite was extremely harsh, as it destroyed up to one half of the original cellulose and lowered the calcium level in the pectin. Calcium hypochlorite was found to be less severe, although some destruction did occur. Another problem encountered with the hypochlorites was the difficulty in controlling the reaction unless constant care was maintained. No change in the constituents affecting texture was found with sodium chlorite bleaching agent. Texture was still firm and although the process took longer than the hypochlorite process, very little attention was needed. Sodium chlorite was determined to be the best bleaching agent for secondarily bleaching brined cherries. No off-flavors developed when the fruit was processed into maraschino cherries. / Graduation date: 1968

Graduation date: 1939

Graduation date: 1959

Recent studies have shown that intermediate moisture foods, while stable to microbial growth, are susceptible to chemical changes resulting in loss of quality. This study observed the effects of different water activities, citric acid contents, fat contents, and pH on lipid oxidation and non-enzymatic browning of a meat product. An intermediate moisture beef patty was produced by equilibrating and cooking the raw meat in various glycerol, water, citric acid and sodium chloride solutions. Experimental results showed that peroxide values increase with increasing water activities between Aw 0.655 and 0.818. Citric acid did not affect the formation of peroxides but prevented peroxide breakdown. There was a loss of the brown colour of the cooked meat patty and an increase in yellowness possibly due to oxidation. The loss of colouring and yellowing was greatest at low pH and high water activities. Non-enzymatic browning was not apparent. Lipid oxidation was the primary cause of the product deterioration. The shelf life was limited to three to four months by the development of rancid odours. / Land and Food Systems, Faculty of / Graduate

Selected cultivars of apples, peaches, and cherries were prepared as edible fruit portions, and preserved in flexible pouches under refrigeration. Preserving adjuncts such as sucrose, potassium sorbate, calcium chloride, citric acid and ascorbic acid were added as concentrated solutions to apple slices, peach slices or pitted cherries in Polyester/Polyethylene or Polyester/ Al foil/Polypropylene pouches that were evacuated and nitrogen-flushed prior to sealing. Some of the pouches were placed directly in 4°C storage whereas others were heated in steam or water to provide various blanching treatments prior to refrigerated storage. At various times up to 12 weeks after processing, the fruits were examined for physical, chemical, microbiological and sensory quality. Of the two package structures studied the aluminum foil-containing pouch proved superior to the Polyester/Polyethylene laminate in preserving fruit quality. Results for a series of mild thermal blanch treatments varied with fruit type in terms of microbial stability and sensory quality attributes. For apples, blanching to a center temperature of 80°C proved to be the most satisfactory, whereas 70°C was optimal for peach quality. Cherries, blanched to a center temperature of 80°C, were of good microbial stability. Both. Golden Delicious and Spartan cultivars prepared as apple slices were found to have good flavor, color and textural characteristics after 12 weeks of refrigerated storage. Of the three peach cultivars examined, Fairhaven and Redhaven freestone peaches produced slices of good quality after processing and refrigerated storage of 12 weeks. Fortuna, a clingstone cultivar, had an unsuitable rubbery texture after the storage period. Lambert sweet cherries and Montmorency sour cherries proved to be unsuitable because of problems arising from microbial growth and loss of textural quality. In summary, it was determined that Golden Delicious and Spartan apple cultivars and Fairhaven and Redhaven peach cultivars can be processed into high quality refrigerated fruit products suitable for storage in aluminum foil-containing flexible pouches at 4°C for up to 12 weeks. / Land and Food Systems, Faculty of / Graduate

No description available.

No description available.

No description available.

The application of ionizing radiation as a preservation method for food is described and examined. The prospects and problems of introducing radiation technology for food preservation are discussed under the following aspects: (1) technical feasibilities; (2) irradiator design requirements; (3) facilities' cost analysis, and (4) legislation. Within the specified limits, ionizing radiation provides an efficacious food preservation treatment which will not lead to radioactivity induction or prejudice the safety and wholesomeness of the food. A brief introduction and description of the design approach of an industrial scale irradiator is given with an illustrative example. Assessments of the cost of radiation treatment of food of some commercially available irradiators are cited and analyzed. The international regulatory efforts and the present status of clearance, standardization and legislation of food irradiation is reviewed and discussed. It is concluded that food irradiation is ready for commercial applications and could be effectively regulated by pertinent health and safety authorities.

The application of pulsed electric fields (PEF) in food processing is a novel technique that requires careful study. In addition, improved understanding of the effect of PEF parameters on both physical and qualitative attributes of agrifood products is a requirement for the application and control of this emerging technology. PEF parameters investigated were pulse widths of 100, 200, and 300 mus, with electric field strengths of 0.75 and 1.5 kV/cm. The amount of pulses used for apples was up to 60, whereas up to 120 pulses were used for potatoes. Initially, apple and potato slices were exposed to various combinations of PEF parameters in order to evaluate the change in their electrical conductivities as an indicator of the disruption of the cell membrane. Subsequently, the impact of PEF on color and texture attributes was studied. In the final set of experiments, PEF was applied as a pre-treatment in order to accelerate the diffusion of moisture in a convective air-drying process at 70°C. / Results regarding the electrical conductivity and the changes in color revealed the similar effect of applying pulses with 100, 200 and 300 mus of duration. Increasing the number of pulses and/or the electric field strength resulted in increased electrical conductivity and discoloration rates of samples. PEF reduced the compressive strength of apple tissues between 21 to 47%. However, the compressive strength of potato tissues did not seem to be affected by the application of PEF. When PEF was applied as a pre-treatment, it caused an increase of up to 30% in the moisture diffusion coefficients of potatoes. In the case of apples, PEF pre-treated samples did not show any increase in drying rates.