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The degradation of chlorophyll often results in
the undesirable color change of green vegetables
during processing and storage. The research in the
color preservation of these vegetables concerned mainly
on chlorophyll. However, chlorophyll forms a complex
with protein in the plant. During thermal processing,
chlorophyll pheophytinizes easily in acid condition.
Therefore, elevating pH value and adding salts with
buffering ability are commonly used to retain
chlorophyll.
The present research investigated the effect of
pH elevation and phosphate addition on the chlorophyll-
protein complex in spinach juice first. Then, gliadin
and glutenin were added into a chlorophyll model
solution in which the pH had been elevated or phosphate
had been added, and the formation of chlorophyll- alien
protein complexes and the effect of alien proteins on
chlorophyll degradation were investigated.
The results showed that high pH and phosphate
addition is effective to preserve the protein and
chlorophyll of the chlorophyll- protein complex in
spinach juice. It needs no heating to form chlorophyll-
gliadin complex in the model solution in which the pH
has been adjusted or phosphate has been added. With
elevating of the pH value, the amount of chlorophyll
which binds to glutenin increases. Neither gliadin nor
glutenin addition may improve the thermal stability of
chlorophyll.
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