Influence of salts on starch degradation: Part II – Salt classification and caramelisation

A previous study demonstrated that presence of sodium chloride enhanced colour formation and starch degradation during heat treatment of a starch based model. It was suggested that the presence of salt encouraged breakdown of the starch, at all levels of organisation, including depolymerisation of the glucose chains to generate smaller molecules, such as glucose. These then would caramelise, explaining the impact of salt on colour formation during the heat treatment of these models. This study aimed at investigating the influence of several types of salt on starch degradation and caramelisation. Native wx maize starch (100 g dry weight) was mixed with 0.030 mol of salt (NaCl, KCl, CaCl2, LiCl, MgCl2, NaI, KNO3, NaBr, KBr, Na2SO4, NaNO3, Na2CO3 or KI, moisture adjusted to 20% wet weight basis). These samples were heated at 230°C for 30 min. The presence of salts significantly enhanced colour formation and the starches' loss of crystallinity during the heat treatment (p < 0.05). NaCl, KCl, CaCl2 and MgCl2 increased significantly the colour formation via caramelisation reactions (p < 0.05). The potency of the salt depended on the salt's cations and followed the Hofmeister series. However, anion variation did not have any significant influence on starch crystallinity loss and colour development. The type of salt also affected colour formation when heated with glucose thereby indicating that the colour reaction, as well as starch changes, is influenced by the ionic environment. Presence of salt might enhance starch degradation either by a direct interaction with the starch granule, or indirectly by accelerating the caramelisation reactions which then produces acidity which helps degrade the starch granules.