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Effect of Drying Temperature on Physicochemical Properties of Starch Isolated from Pasta¹

¹Published with the approval of the director of the Agricultural Experiment Station, North Dakota State University, Fargo, ND. ²Graduate research assistant, Department of Cereal Science, North Dakota State University, Fargo. Current address: National Starch & Chemical Co., Bridgewater, NJ. ³Associate professor, Food & Agricultural Products Research Center, Oklahoma State University, Stillwater, OK 74078-6055. Corresponding author. E-mail: rayasdu@okstate.edu ⁴Associate professor, Department of Plant Sciences, North Dakota State University, Fargo, ND 58105.

Semolina from four durum wheat genotypes (cvs. Ben, Munich, Rugby, and Vic) were processed into spaghetti that was dried by low (LT), high (HT), and ultrahigh (UHT) temperature drying cycles. Starch was isolated from dried pasta and unprocessed wheat and semolina references. Pasta-drying cycles had no significant effect on the amylose content of starches. Significant increases in enzyme-resistant starch were observed in HT- and UHT-dried pasta (2.27 and 2.51%, respectively) compared with LT-dried pasta (1.68%). Differential scanning calorimetry (DSC) gelatinization characteristics of pasta starches showed a significantly narrow range (T_r), but no changes in onset and peak temperatures (T_o and T_p, respectively) and gelatinization enthalpy (ΔH₁) were observed. When compared with unprocessed reference samples (wheat and semolina), all pasta starches shifted to higher gelatinization T_o and T_p, with narrow T_r and no changes in δH₁. The second endothermic DSC peak indicated no increase in amylose-lipid complexation (δH₂) due to drying cycle. Starches isolated from LT and HT pasta exhibited lower peak viscosities than those from UHT-dried pasta. Genotypes Ben and Rugby demonstrated higher pasting temperature and lower peak and breakdown viscosities than Vic and Munich.