Abstract
The effect of water activity (Aw) on the antioxidative ability of various high-molecular-weight polysaccharides, proteins, spices, table luxuries and food industry by-products was examined in a powder model system. Each of these samples was mixed with linoleic acid in the ratio of 4: 1 (w/w)and incubated at various levels of Aw and 50°C.
No antioxidative ability of the potato starch, cellulose, curdlan and konjalc powder polysaccharides was apparent at Aw 0.2-1.0.
The antioxidative ability of the soy protein isolate (SPI), and zein and casein proteins was correlated with Aw. Their peroxide values (PV) remained low during storage at Aw 1.0, and in the case of zein, at not less than Aw 0.8.
In the case of garlic, turmeric, ginger, green tea, coffee and cocoa, their antioxidative abilities were apparent during storage in the Aw range of 0.2-1.0.
Except at a low Aw level, the antioxidative ability of sake lees and wheat bran was apparent during storage, while that of rice bran was shown regardless of Aw.
