Development of broccoli powder using vacuum belt drying
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The study determined if high quality broccoli powder could be produced by vacuum drying. The effect of temperature, maltodextrin and pretreatment on drying kinetics, physical characteristics of the powder and nutritional quality were studied. The Wang and Singh model best fit drying rate data. Powders exhibited a Type III isotherm and were best fit by the GAB model. With 10% maltodextrin, drying efficiency was 200% higher and hygroscopicity was lower than samples without maltodextrin. Blanching with 0.1% (w/v) NaHCO3 and 0.1% (w/v) MgO resulted in greener samples with more vitamin C. Vitamin C content was two-fold greater in powders produced by vacuum drying and freeze drying than in hot-air drying. Steam blanching preserved 12.5% more of the endogenous antioxidants than that by boiling with NaHCO3 and MgO. Hot-air drying reduced the total antioxidant content by 31.5% in comparison with vacuum drying. Freeze drying resulted in the lowest sulforaphane content.