Analysis of Physical Properties, Amino Acids and Volatile Aroma Components of Mulberry Leaf Powder by Different Drying Methods

Abstract

The effects of heat pump drying, microwave drying and vacuum freeze drying on the color, powder properties, amino acid components and volatile components in mulberry leaf powder were compared and analyzed. The results showed that L* and b*were the highest, while a* was the lowest of mulberry leaf powder dried by vacuum freeze drying. Wettability, water holding capacity and oil holding capacity of mulberry leaf powder dried by microwave drying were the worst, while solubility and bulk density were the strongest. Meanwhile wettability, hygroscopicity, water holding capacity and oil holding capacity of mulberry leaf powder dried by vacuum freeze drying were the highest , and the lowest bulk density. The content of total amino acids, essential amino acids and proportions of essential amino acids in microwave dried mulberry leaf powder were 11.68 mg/g, 3.40 mg/g and 29.11%. The contents and relative contents of sweet amino acids, aromatic amino acids and bitter amino acids in microwave drying were higher than others. Microwave drying and vacuum freeze drying were similar in the volatile components of mulberry leaf powder, with high content of alcohols and aldehydes. In conclusion, vacuum freeze dried mulberry leaf powder had better physical characteristics and volatile aroma components, while microwave drying was more suitable for industrial processing of mulberry leaf powder.

Keywords

• mulberry leaf powder
• drying methods
• physical properties
• amino acids
• volatile aroma components