Zinc complex formation with chlorophyll derivatives in spinach pulp was studied by adding 300 ppm
Zn2+ for production of stable food colorant, followed by the heating at 110 C for 15 min. Zinc complex
formation increased at pH values of 7.0 or greater. Pectinex Ultra SP-L was selected for enzyme-assisted
release of zinc–chlorophyll derivatives from spinach pulp. Effect of enzyme concentration (1–9%), treatment
temperature (30–60 C), and time (30–210 min) on total chlorophyll content (TCC) were optimized
using response surface methodology. A quadratic regression model (R2 = 0.9486) was obtained from the
experimental design. Optimum treatment conditions were 8% enzyme concentration, 45 C, and 30 min,
which yielded a 50.747 mg TCC/100 g spinach pulp. Enzymatic treatment was followed by solvent
extraction with ethanol at a solvent-to-sample ratio of 2.5:1 at 60 C for 45 min for the highest TCC recovery.
Pretreatment with enzyme and extraction in ethanol resulted in 39% increase in Zn–chlorophyll
derivative yield.
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