Abstract: The effect of flow rate on humidity， drying rate and product quality in microwave drying process was studied under 5 kinds of safe flow rates and 4 types of varying flow rates. The results showed that the flow rate had a significant effect on humidity， drying rate and product quality. The smaller the flow rate was， the higher the humidity was， but the lower the drying rate was， and the product quality was relatively better. Under varying flow rates， the results need to be discussed separately. If the flow rate was increased， the curve of the drying rate was affected obviously， especially in the early and middle stages. If the flow rate was decreased， the humidity would go up obviously or keep stable. In addition， the drying rate would slightly go down， but the effect was not obvious. The quality of carrots was the best when the flow rate was increased stepwise， in which the drying rate was low in the early stage and then rose up stepwise in the middle stage. Besides， the experiments also showed a relationship between the humidity and drying rate. If the flow rate was safe， the humidity was determined by the drying rate. Two curves of humidity and drying rate rose up or fall down synchronously. Under varying flow rates， the humidity and drying rate no longer varied synchronously， and the humidity depended on the combined effect of flow rate and drying rate.

Key words: flow rate, microwave drying, humidity, drying rate, quality