Buffalo Gourd Root Starch. Part II. Rheologic Behavior,Freeze-thaw Stability and Suitability for Use in Food Products

Buffalo gourd (Cucurbita foetidissima HBK) starch was examined for possible food uses through physico-chemical, rheologic, and organoleptic examination. The gelatinization and rheologic properties of this starch more closely resembled maize starch than those of other root and tuber starches. Detailed studies of pasting behavior revealed: a high initial pasting temperature, a stable gel viscosity throughout the temperature regime, increases in viscosity associated with increased starch concentration, an acid stability similar to that of maize, and substantial increases in final viscosity with the addition of other food ingredients (especially 25% sucrose). Gels subjected to freeze-thaw conditions underwent a significant degree of retrogradation, suggesting the need for chemical modification prior to acceptable use of this starch in frozen products. Organoleptic evaluations of vanilla and chocolate puddings prepared with buffalo gourd starch indicated their potential consumer acceptance.     

Buffalo Gourd Root Starch. Part III. Effects of Plant Age and Spacing upon the Physico-chemical and Rheological Properties

Buffalo gourd (Cucurbita foetidissima HBK) starch was previously shown to have potential for incorporation in food products. As annual cropping systems have been suggested to produce the highest starch yield per unit of land and time, a study of the effects of plant age and spacing upon the physico-chemical and rheological properties was undertaken. Root starch content reached a plateau level (18% of fresh weight) near 2.5 months of growth in 1979, but continued to increase up to 4.5 months of age in 1981. Substantial changes among samples of different age and spacing for other compositional parameters were not observed. However, vine senescense was associated with a decrease in starch level and a concomitant rise in free sugar content. Proximate analysis of starches revealed little variation among samples. Mean granule diameters appeared to increase with increasing plant age. Patterns among samples associated with water binding capacity, alkali number, iodine affinity, inherent viscosity, or gelatinization temperature were not recognized. Internal organization of components within the granule appeared to decrease with increased plant age as shown by the parameters of swelling power, percent solubility, initial pasting temperature, and initial viscosity at 95 °C. All samples formed well developed pastes, which increased viscosity upon cooling, with final gel strength being independent of plant age or spacing.     

Buffalo Gourd Root Starch. Part I. Properties and Structure

The structural and physico-chemical properties of starch isolated from three genetically different populations of buffalo gourd (Cucurbita foetidissima HBK) were explored. The proximate composition of this starch was found to be similar to that of other starches. Granules were depicted to vary in shape (round, oval, truncated) and to resemble maize starch in size. A change in X-ray diffraction behavior from a B- to a C-type pattern was observed upon autoclaving raw gourd starch. Average physico-chemical values were reported as follows: amylose content, 23.1%; water binding capacity, 112; and gelatinization temperature range, 61–69°C. Variation in alkali numbers among samples of this starch was extensive. A highly ordered internal structure of the granule was suggested by low values of swelling power and solubility and high initial pasting temperatures. Pasting curves of buffalo gourd starches were developed which revealed stable gel viscosities throughout the temperature cycle. Amylose fractions were found to be resistant to β-amylase attack and exhibited an average DP η of 1915. Amylopectins were shown to have an average DP η of 2000, and an OCL to ICL of 1.3 to 1.