FUNCTIONAL AND PASTING PROPERTIES OF PUMPKIN (Cucurbita pepo) SEED PRODUCTS
Atuonwu, A .C and Akobundu, E. N. T
Department of Food Science and Technology
Michael Okpara University of Agriculture, Umudike, Nigeria.
E-mail:adatuonwu@yahoo.com
ABSTRACT
Proteins of plant origin form an alternative to animal proteins for food and non food use. The use of oil seed proteins for non-food applications show growing potential but the protein products are limited at present and are mostly marketed for the food industry as they confer desirable functional properties when added to food. This work focused on the functionality of pumpkin (Cucurbita pepo) seed flour, protein concentrate and isolate in relation to food applications. Pumpkin seed was processed into defatted flour (CPF), which was further processed into protein concentrate (CPC), and protein isolate (CPI) using alkaline water/isoelectric precipitation. The functional properties of these products were evaluated. All samples exhibited a broad range of minimum protein solubility at pH 6-8 and maximum at pH 10. Defatted pumpkin seed flour had significantly (p<0.05) higher water absorption capacity (1.60ml/g) than the protein concentrate (1.20ml/g) and isolate (1.25ml/g). The flour was a better emulsifier with emulsion capacity of 22.0% compared to the protein concentrate and isolate with emulsion capacity of 5.0% and 1.0%, respectively. The most stable emulsions were obtained at pH 12 and at 0.1%, 0.5% and 1.0% sample concentrations. Pumpkin seed protein concentrate and isolate showed poor foaming ability. Maximum foaming capacity was obtained at pH 2.0 in all the samples. Protein isolate had the least and better gelation capacity. Peak viscosity ranged from 32.83-44.25 RVU and was significantly different while the breakdown value and pasting temperature (ranging from 1.75-3.16 RVU and 93.60-94.20oC respectively) showed no significant differences (p>0.05). This work revealed that pumpkin seed has great potentials as a food ingredient. The flour and protein concentrate exhibited better functionality and may be used as functional agents in the formulation of a wide range of new food products or as possible replacement for animal protein in conventional foods.
Keywords: Pumpkin Flour, Protein concentrate, protein isolate, Functional properties,
pasting properties.