CONTROLLED HEAT PROCESSING OF JEWEL SWEET POTATOES FOR PUREE PRODUCTION¹

Abstract

Jewel' sweet-potato slices 0.5 rm thick were precooked at 100, 125 and 150C for vatying periods of time, jnish-cooked for I5 min at 15OC, and pureed. Selected chemical and physical properties ofthe purees were compared to a puree prepared from conventionally baked sweet potatoes (1.25 h at 195C). Pureesfrom the controlled heat process were also compared to the baked puree by a sensor?, panel. Of all the treatments, pureehom the I OOC, 6-min precook treatment was the most silimar to puree from baked sweet potatoes with respect ro chemical and physical characteristics. nie sensory pane1.found the two purees to be digerent, but were equal/? divided when asked to express a preference. Subsequent analysis showed that the starch of the baked control had been more completely hydrolyzed than the starch of the other treatments. Diis M'CZS reflected by higher maltose, lower starch content and by decreased starch molecular size and viscosity of the control cornpared Mith the other treatments.

Physical and Sensory Properties of Sweetpotato Puree Texturized with Cellulose Derivatives

“…This is due to more rapid inactivation of amylolytic enzymes during steaming of sweetpotato slices in puree processing, resulting in a lesser starch conversion into sugars (Walter and Schwartz, 1993). Sucrose was, therefore, added to the sweetpotato puree to attain the sweetness usually preferred for baked sweetpotatoes.…”

“…Preliminary studies indicated that the total content of sugars (fructose, glucose, sucrose, and maltose) in the puree of Jewel cultivar was 13.9%, which was lower by 3.2% than that of baked roots. This is due to more rapid inactivation of amylolytic enzymes during steaming of sweetpotato slices in puree processing, resulting in a lesser starch conversion into sugars (Walter and Schwartz, 1993). Sucrose was, therefore, added to the sweetpotato puree to attain the sweetness usually preferred for baked sweetpotatoes.…”

Physical, Chemical and Microbial Changes in Shredded Sweet Potatoes+

“…The shredded sweet potatoes were removed at selected time intervals and analyzed for dry matter, glucose, sucrose, fructose (Walter and Schwartz 1993), alcohol‐insoluble solids (AIS) and starch (Walter et al. 1993).…”

Sweetpotatoes

“…In puree processing, roots of all sizes and shapes can be utilized and, therefore, the entire harvested crop is utilized including the 30-40% off-grade from the fresh root markets (Kays 1985b;Walter and Schwartz 1993). The challenges in puree processing industry are: (1) the difficulty in adjusting the process to account for differences in cultivar types, root handling, curing, and storage; and processing techniques in order to produce consistent, and high quality puree; and (2) the preservation technology that could produce shelf-stable product for convenient incorporation in processed foods.…”

“…Hoover and Harmon (1967) developed an enzyme activation technique using the endogenous amylolytic enzymes for starch hydrolysis in sweetpotato puree processing, and this process is now commonly used in the food industry. As shown in Figure 36.3, the peeled sweetpotatoes can be either cut into cubes of 2 cm, strips of 2 × 2 × 6 cm, and slices of 0.5-0.95 cm thickness (Walter and Schwartz 1993) or mashed using a hammer mill with rotating blades to chop and push the materials through a 1.5-2.3 mm mesh screen (Szyperski et al 1986). Next, the materials are steamed blanched at 65-75 • C which activates the amylases and gelatinizes the starch for hydrolysis.…”