Thesis (Ph. D.)--University of Wisconsin--Madison, 1961. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1932. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 129-130).

Thesis (PH. D.)--Michigan State College of Agriculture and Applied Science, 1937. / Technical bulletin no. 162, February 1939, of the Michigan Agricultural Experiment Station, Lansing, with cover having thesis note.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1958. / Typescript. Abstracted in Dissertation abstracts, v. 19 (1959) no. 7, p. 1509-1510. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 92-96).

A fruit selection tool, which could be used as a component of a selective strawberry harvesting system, was designed and tested. Design was based upon physical and rheological properties of the Northwest variety of strawberries which is commonly grown in British Columbia. Fruit retention force was measured as a function of time over the harvest season. Three rheological parameters, linear limit, bioyield point and tangent modulus, were calculated from force-deformation curves obtained from flat plate loading tests. These parameters were used to evaluate fruit quality and its variation over the harvest season. Correlations among quality parameters, fruit retention force, and fruit surface colour indicated that colour could be used as an accurate indicator of fruit quality and fruit maturity. Fruit surface colour was, therefore, used as the selection parameter controlling the fruit selection tool. Subjective and objective colour measurements were made. Relative reflectance curves for strawberry surface were obtained from a Unicam automatic recording spectrophotometer by scanning a 2.54 cm. diameter surface of the fruit at fast speed. Spectrum variables obtained from the reflectance curves were used for objective colour evaluation and maturity assessment. The relative reflectances at various wavelengths had good correlation with surface colour, the highest being that between reflectance at 525 nanometers and percent surface red colour. Maturity ratio for strawberries was calculated from reflectance curves and was established as the ratio of reflectances at 650 nm to 525 nm. Maturity ratio best represented the surface colour and was used to define fruit ripeness. An electronic system was designed and used to measure maturity ratio and to identify fruit maturity. Tests conducted on this system in the laboratory indicated a minimum response time of 0.166 seconds per fruit. The influence of illumination and its geometry were also investigated / Land and Food Systems, Faculty of / Graduate

Thesis (Ph.D. in horticulture)--Washington State University. / Includes bibliographical references.

Thesis (Ph. D.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 260-285). Also available on the World Wide Web.

This study was undertaken to investigate the variation in the total sugar and acid content of the frozen Marshall strawberries grown in different areas of the Pacific Northwest. The samples used in this study were collected from different freezing plants located in the states of Oregon and Washington during the 1949 strawberry season. Forty-four samples of Marshall strawberries were analyzed. For total sugar determinations a modification of the Shaffer and Somogyi method was used. The average value found for total sugar was 7.56 per cent. The glass electrode was used for the determination of total acidity. The average value found for total acidity was 0.99 per cent. Soluble solids determined by the Bausch and Lomb hand refractometer had an average value of 9.90 per cent. The average pH value for all samples was 3.36. The sugar and acid content of these Marshall strawberries showed most frequent distribution in the range from 7.1 to 9.0 per cent and 0.91 to 1.1 per cent, respectively. Soluble solids were most frequent in the range from 8.1 to 11.0 per cent. No relationship was found for total sugar and acid content. Soluble solids were found to have a definite relationship with total sugar content. Marshall strawberries grown in different areas of Oregon varied in total sugar and acid content. Generally, strawberries grown in warm areas and mature berries tend to have a higher sugar content. Berries grown on the hillsides and less mature berries tend to have a lower sugar content. The weather conditions apparently affect the sugar and acid content of Marshall strawberries greatly. / Graduation date: 1951

This investigation was conducted to study the effects of blanching and storage temperatures on the color of strawberry juice and concentrate. Strawberry juice and concentrate (42°βrix) were prepared from blanched crushed Tioga strawberries. Crushed strawberries were blanched, in a steam-jacketed kettle, at 70°, 80°, and 90°C for 1 min. Ascorbic Acid (AA), at a level of 0.01%, was added to one batch and hoped to counteract polyphenol oxidase (PPO) activity in the early stages of processing. Samples were then stored at 1°, 21° and 38°C and the chemical composition as well as the color parameters were monitored throughout the study. Blanching at 70°C was found to heat-inactivate PPO in strawberries. Generally, blanching protected the compositional constituents, such as, anthocyanins (ACN), AA, leucoanthocyanins, flavanols and total phenolics. Initially, blanched samples contained higher concentrations of these chemicals than the unblanched (control) samples. Samples blanched at 80°C contained highest concentrations followed by those blanched at 90° and 70°C. This protective effect was markedly reduced in samples blanched with added AA. AA decomposition products seem to initiate other degradation reactions. There was a considerable decrease in the juice chemical constituents upon concentration. A particular striking decrease was observed with AA where samples lost more than 75% of their initial content. All samples experienced gradual losses of their chemical constituents accompanied by loss of the bright red color associated with freshly prepared juice and concentrate. The losses increased with increased storage temperatures. Storage at 38°C, as a result, was found to be a major factor in the loss of the chemical constituents and the rapid deterioration of the color. Concentrate samples developed burnt flavor by the third week and lost all ACN and AA contents by the end of the storage period. The loss was much less on storage at 21°C and least at 1°C. At any storage temperature, samples blanched at 80° and 90°C retained more of their constituents as well as better color quality parameters when compared to the control or those blanched at 70°C. Samples blanched with added AA experienced greater losses of their color values and chemical constituents, particularly ACN and AA, when compared to samples blanched without AA. ACN and AA degradation in samples stored at 1°C followed first order reaction kinetics, while browning formation in these samples and in juice samples stored at 21°C followed zero order reaction kinetics. Rate constants suggest a major role for AA in the deterioration of color. Moreover, they also suggest a protective effect on blanching on the overall quality of the juice and concentrate. Blanching at 80°C for 1 min was the optimum processing temperature investigated, while low storage temperatures are, naturally valuable in retaining better color quality strawberry juice and concentrate. / Graduation date: 1982

Thesis (doctoral)--Helsinki University of Technology, 2002. / Includes bibliographical references. Also available on the World Wide Web.