Masters Theses

Date of Award

12-1980

Degree Type

Thesis

Degree Name

Master of Science

Major

Food Science and Technology

Major Professor

John R. Mount

Committee Members

S. L. Melton, H. O. Jaynes

Abstract

The objective of this investigation was to analyze the chemical and functional properties of a flour made from the defatted meal of pumpkin seeds from the cultivar Lady Godiva (Cucurbita pepo L.) in order that its potential as a novel food source might be evaluated.

The proximate composition of two crop years (1978 and 1979) was determined. Defatted flour of pumpkin seed 1978 and 1979 had 8.91 and 4.56 percent moisture, 62.21 and 61.90 percent crude protein, 8.97 and 9.23 percent ash, 8.41 and 4.53 percent total lipid, 3.57 and 3.96 percent crude fiber, and 7.93 and 15.82 percent nitrogen-free extract.

The mineral content (K, Ca, Mg, Na, Fe, and Zn) of the two flours was determined by atomic absorption spectrophotometry. Calcium, iron, and potassium (279, 16, and 1500 mg/100g, respectively) in the pumpkin seed meals were found at levels comparable to the levels found in the soy reference. The levels of magnesium, sodium, and zinc (540.9, 144.9, and 22.9 mg/100g, respectively) in the pumpkin seed meal were found in much greater levels than in the soy concentrate (269, 6, and 6.5, respectively).

Nitrogen solubility profiles of the defatted pumpkin seed meals showed pumpkin 78 acquiring its isoelectric point at pH 3 and its maximum solubility at pH 10. Pumpkin 79 also acquired its isoelectric point at pH 3 and its maximum solubility was at pH 10.

Water holding capacity revealed pumpkin 79 capable of holding 4.85 grams water/gram flour, which was not significantly different (0.05 level) from the 4.47 grams water/gram flour that a soy concentrate (used as a reference in this study) was capable of holding.

The whippability value for pumpkin 79 (194.30 percent volume increase) was significantly different (0.01 level) from soy concentrate (118.66 percent volume increase). Thefoamproducedbyeachofthe flours was very stable.

Pumpkin 78 was found to be significantly lower than pumpkin 79 in water holding capacity and whippability. This difference was thought to be due to the longer storage time of pumpkin 78 and the initially higher lipid content pumpkin 78. Thus it was not included in the comparison between pumpkin seed meal and soy concentrate on water holding capacity and whippability.

The mean value of oil holding capacity for pumpkin 78 and 79 was 4.26 grams oil/gram flour, and oil holding capacity for the concentrate was 3.05 grams oil/gram flour. The value for the pumpkin flour was significantly greater than the soy concentrate at the 0.01 level.

The results of emulsifying capacity (EC) showed pumpkin 78 and 79 were able to emulsify approximately the same amount of oil (67.14 ml oil/g flour and 67.85 ml oil/g flour, respectively). The soy concentrate was found to emulsify a significantly smaller amount of safflower oil than pumpkin 78 or 79. The EC for soy was 32.94 ml oil/g flour.

Heat stability of water extracts of both pumpkin seed meal and soy concentrate proved to be very stable even after one hour in boiling water. It is felt that the functional property of heat stability deserves further scrutiny.

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