Textural Properties of Amylomaltase Modified Starches compared to Gelatine
Special Symposium - Innovations in Food Technology (LMC Congress)
Innovations in Food Technology - Poster Session (Food - P2)
Keywords: Amylomaltase modified starches
Starch modified by amylomaltase (AM; 4-α-glucanotransferases; E.C. 2.4.1.25) is expected to find application in the food industry as a replacement of gelatine. Due to its multifunctional properties gelatine is a widely used ingredient in the food industry. However, it is relatively expensive and its acceptance among consumers is steadily decreasing e.g. because of possible risk of transmission of bovine spongiform encephalopathy (BSE) to human.
AM from Thermus thermophilus and branching enzyme (BE; 1,4-α-D-glucan branching enzyme; EC 2.4.1.18) from Rhodothermus obamensis were used to modify starches extracted from various botanical sources including potato, high amylose potato (HAP), maize, waxy maize, wheat and pea. A chemically oxidized potato starch (Gelamyl 120) was also modified. Amylopectin chain length distribution of 51 enzyme- and 7 normal starches (parent samples) were analyzed. The textural profiles of all starches were compared with two gelatine gels.
Modifying starch with AM caused broadening of the amylopectin chain length distribution, creating a unimodal distribution with an increased population of longer chains (degree of polymerization (DP) > 30) and of very small chains (DP 4-5) and a decreased proportion of small and medium chains (DP 10-30). The increase in longer chains was a combined effect of amylose to amylopectin chain transfer and transfer of cluster units within the amylopectin molecules. AM modification of most of the starches, result in improved gel texture compared to the 7 parent starches, except for Gelamyl 120 and waxy maize. The gel texture of wheat was, on the other hand, reduced. However, extensive AM treatments, considerably reduced the gel texture, but without changing the amylopectin chain length distribution. AM modified HAP gels made gels about twice as hard as gelatin gels, whereas gels of pea starch were almost identical to gelatin gels. Modification of pea starch using BE result in starches with shorter amylopectin chains and pastes unable to form gel network at the concentration of 12%.
Principal Component Analysis (PCA) was performed on the amylopectin chain length data. Enzyme modified and normal starches were separated when plotting the scores of PC 1 vs. 2, which together explain 94% of the total variation. Samples are mainly described according to the amount of longer chains. PCA of the textural data of all 60 samples identified three groups, when plotting the scores of PC 1 vs. 2. Group one and two consisted exclusively of gelatins and HAPs, respectively, whereas the rest of the samples comprised the third group.
Presented Thursday 20, 13:30 to 14:40, in session Innovations in Food Technology - Poster Session (Food - P2).
