Relation of fresh fruit quality factors to the canning quality of the Italian prune

Graduation date: 1953Approximately 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.\ud 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.\ud 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.\ud 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.\ud 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.\ud 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.\ud 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.\ud 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.\ud 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.\ud 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.\ud 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.\ud 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