Nabubuya Agnes, Namutebi Agnes, Byaruhanga Yusuf, Schuller Reidar B, Narvhus Judith, Wicklund Trude
Department of Chemistry, Biotechnology and Food Science Norwegian University of Life Sciences Aas Norway.
Department of Food Technology and Nutrition School of Food Technology, Nutrition and Bio-engineering Makerere University Kampala Uganda.
Food Sci Nutr. 2017 Jul 16;5(6):1072-1078. doi: 10.1002/fsn3.492. eCollection 2017 Nov.
Sweet potato ( L.) roots contain amylolytic enzymes, which hydrolyze starch thus having the potential to affect the viscosity of sweet potato porridges provided the appropriate working conditions for the enzymes are attained. In this study, the effect of sweet potato variety, postharvest handling conditions, freshly harvested and room/ambient stored roots (3 weeks), and slurry solids content on the viscoelastic properties of complementary porridges prepared using amylase enzyme activation technique were investigated. Five temperatures (55°C, 65°C, 70°C, 75°C, and 80°C) were used to activate sweet potato amylases and the optimum temperature was found to be 75°C. Stored sweet potato roots had higher soluble solids (⁰Brix) content in the pastes compared to fresh roots. In all samples, activation of amylases at 75°C caused changes in the viscoelastic parameters: phase angle (tan δ) and complex viscosity (η). Postharvest handling conditions and slurry solids content significantly affected the viscoelastic properties of the porridges with flours from stored roots yielding viscous (liquid-like) porridges and fresh roots producing elastic (solid-like) porridges. Increase in slurry solids content caused reduction in the phase angle values and increase in the viscosity of the sweet potato porridges. The viscosity of the porridges decreased with storage of sweet potato roots. These results provide a possibility for exploiting sweet potato endogenous amylases in the preparation of complementary porridges with both drinkable viscosities and appropriate energy and nutrient densities for children with varying energy needs.
甘薯（L.）根中含有淀粉分解酶，这些酶可水解淀粉，因此只要达到酶的适宜工作条件，就有可能影响甘薯粥的粘度。在本研究中，研究了甘薯品种、采后处理条件、新鲜收获和室温/环境储存的根（3周）以及浆料固体含量对使用淀粉酶激活技术制备的辅食粥粘弹性特性的影响。使用五个温度（55°C、65°C、70°C、75°C和80°C）来激活甘薯淀粉酶，发现最佳温度为75°C。与新鲜根相比，储存的甘薯根在糊状物中的可溶性固形物（°Brix）含量更高。在所有样品中，75°C下淀粉酶的激活导致粘弹性参数发生变化：相角（tan δ）和复数粘度（η）。采后处理条件和浆料固体含量显著影响粥的粘弹性特性，储存根的面粉制成的粥呈粘性（类似液体），新鲜根制成的粥呈弹性（类似固体）。浆料固体含量的增加导致相角值降低，甘薯粥的粘度增加。随着甘薯根的储存，粥的粘度降低。这些结果为利用甘薯内源性淀粉酶制备具有可饮用粘度以及适合不同能量需求儿童的适当能量和营养密度的辅食粥提供了可能性。
