Russet Burbank, Norchip, Pontiac, and LaSoda potato cultivars were examined for the parameters mealy and waxy. Russet Burbank was judged dry, hard and particulate, typifying mealiness. Using phase contrast microscopy and scanning electron microscopy, raw mealy cells were determined to be larger and more irregularly shaped than cells from waxy cultivars. Mealy cooked cells were engorged with gelatinized starch, cell walls were more polarized, and cell shapes were better retained after mashing, when compared to waxy cells. NMR-T2 bound water readings from Russet Burbank and Pontiac samples did not differ from each other. Starch granule sizes and shapes varied by cultivar. KeywordsPotato cultivar, texture, starch, microscopy Russet Burbank, Norchip, Pontiac, and LaSoda potato cultivars were examined for the parameters mealy and waxy. Russet Burbank was judged dry, hard and particulate, typifying mealiness. Using phase contrast microscopy and scanning electron microscopy, raw mealy cells were determined to be larger and more irregularly shaped than cells from waxy cultivars. Mealy cooked cells were engorged with gelatinized starch, cell walls were more polarized, and cell shapes were better retained after mashing, when compared to waxy cells. NMR-T2 bound water readings from Russet Burbank and Pontiac samples did not differ from each other. Starch granule sizes and shapes varied by cultivar.

Four potato cultivars from 1984 and 1985 growing seasons were studied. Specific gravity did not correlate with potato size or shear strength, nor could it be used to predict sensory mealiness scores. Shear strength measures of the cooked potatoes showed that the Russet Burbank had a particularly strong structure at low deformations. Starches from the two more mealy cultivars, Russet Burbank and Norchip, had slightly lower gelatinization temperatures than those from the two waxy cultivars, Pontiac and LaSoda. Gelatinization temperatures were higher in potato juices than in water. Starches from the two mealy cultivars gave swelling powers between those of the two waxy cultivars, but yielded higher solubles. Pontiac potato starch exhibited anomalous behavior in its resistance to swelling and in devclopmcnt of viscosity in the amylograph.

A double direct shear device was developed to examine shear strength parameters of mealy and waxy potatoes. Cohesion and coefficients of friction were measured at peak and ultimate shear with two machine speeds. Coefficients of friction of potato types did not differ. However, mealy potatoes displayed greater cohesion than waxy potatoes and a greater difference between peak and ultimate cohesion values. Stem ends of mealy potatoes were the most firm. Shear strength was related to strain rate.

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The effects of amount of cream of tartar, time of cream of tartar addition, and egg white temperature were evaluated with angel food cakes. Two replications of each of 12 treatments were used: factorial combinations of three levels of cream of tartar (representing 1/12, 1/8, or 1/4 tsp per egg white), two times of cream of tartar addition (before beating or at foamy stage), and two egg white temperatures (2° or 22°C). Increased cream of tartar decreased pH; increased specific gravity, cake slice area, and tenderness; and caused whiter interior crumb and darker exterior crust. Cakes made with 22°C (vs. 2°C) egg whites had increased exterior yellow color, decreased specific gravity after flour addition, and decreased preference. Cold egg whites did not decrease cake quality, eliminating the need to warm eggs with attending bacterial risk and decreasing preproduction time.