Impact of modification temperature on the properties of acid‐thinned potato starch

E-ISSN： 1521-379x|68|9-10|885-899

ISSN： 0038-9056

Source： STARCH / STAERKE, Vol.68, Iss.9-10, 2016-09, pp. : 885-899

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Abstract

The impact of the hydrolysis temperature on the properties of acid‐thinned potato starches was investigated. Acid‐thinned samples were prepared with 0.54 M HCl for 4 h using the slurry process. The suspension temperature was adjusted to 2, 25, and 50°C, respectively. Simultaneously, samples were produced applying the same conditions without acid (annealing). The carbohydrate solubilization due to hydrolysis at 50°C was remarkable (7.60%, w/w) compared to the other samples (annealed and hydrolyzed, <1%, w/w). No differences in DSC gelatinization temperatures (t_onset, t_{peak maximum}, t_conclusion) were found when modified at 2 and 25°C, independent of annealing or acid‐thinning. However, modification at 50°C enhanced the gelatinization temperatures significantly, whereat the values of the hydrolyzed sample were higher compared to the corresponding annealed one. Investigation of the water hydration capacity gave evidence for higher granule swelling when processed at 50°C. Compared to the annealed counterpart, the hydrolysis‐induced molar mass reduction increased with increasing suspension temperature. Especially at 50°C, both the amylose fraction and the branch chain length of the amylopectin decreased noticeably. A sol‐to‐gel transition of the paste and the ability to form a firm gel was exclusively determined for the sample hydrolyzed at 50°C. Basically, the enhancement of the hydrolysis temperature from 25 to 50°C caused an enormous change of the investigated starch properties. However, the differences found between modification at 2 and 25°C were marginal. The acid‐thinning is assumed to be a cooperating process of both annealing and hydrolysis (chain cleavage).