I super(2)-Lactoglobulin nanofibrils: Effect of temperature on fibril formation kinetics, fibril morphology and the rheological properties of fibril dispersions

• Published in: Food hydrocolloids Vol. 27; no. 1; pp. 242 - 249
• Main Authors: Loveday, S M, Wang, X L, Rao, MA, Anema, S G, Singh, H
• Format: Journal Article
• Language: English
• Published: 01.05.2012
• Subjects: Dispersions; Fluorescence; Fragmentation; Heating; Morphology; Nanostructure; Rheological properties; Self assembly
• ISSN: 0268-005X
• DOI: 10.1016/j.foodhyd.2011.07.001

Almost all published studies of heat-induced I super(2)-lactoglobulin self-assembly into amyloid-like fibrils at low pH and low ionic strength have involved heating at 80 degree C, and the effect of heating temperature on self-assembly has received little attention. Here we heated I super(2)-lactoglobulin at pH 2 and 75 degree C, 80 degree C, 90 degree C, 100 degree C, 110 degree C or 120 degree C and investigated the kinetics of self-assembly (using Thioflavin T fluorescence), the morphology of fibrils, and the rheological properties of fibril dispersions. Self-assembly occurred at all temperatures tested. Thioflavin T fluorescence increased sigmoidally at all temperatures, however it decreased sharply with >3.3 h heating at 110 degree C and with >5 h heating at 120 degree C. The sharp decreases were attributed partly to local gelation, but destruction of fibrils may have occurred at 120 degree C. Thioflavin T fluorescence results indicated that maximal rates of fibril formation increased with increasing temperature, especially above 100 degree C, but fibril yield (maximum Thioflavin T fluorescence) was not affected by temperature. At 100 degree C and 110 degree C, fibrils were slightly shorter than at 80 degree C, but otherwise they looked very similar. Fibrils made by heating at 120 degree C for 1 h were also similar, but heating at 120 degree C for 8 h gave predominantly short fibrils, apparently the products of larger fibrils fragmenting. Heating at 100 degree C gave consistently higher viscosity than at 80 degree C, and heating for >2 h at 120 degree C decreased viscosity, which may have been linked with fibril fragmentation seen in micrographs.