Abstract The effects of four drying methods, such as hot air drying, microwave drying equipment, vacuum drying and vacuum freeze drying, on the physical and chemical properties and antioxidant activities of pear jujube powder were studied. The results showed that the effect on vitamin C content was vacuum freeze-drying > microwave drying > vacuum drying > hot air drying, and there was no significant difference in the total sugar content, which reduced the titratable acid content.
Different drying methods have significant effects on total phenol and total flavonoids in pear jujube powder. The antioxidant activity of vacuum freeze-dried pear jujube powder was significantly better than hot air drying and vacuum drying. The total phenolic acids in hot air drying, vacuum drying, microwave drying and vacuum freeze-dried pear jujube powder were 39.91, 87.46, 92.56, 110.82 mg/kg, respectively. On the whole, vacuum freeze-drying technology not only retains the physical and chemical properties of pear jujube powder, but also helps to maintain the antioxidant activity of pear jujube powder.
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