Abstract:

The effects of 5 drying methods including hot air drying, vacuum microwave drying, vacuum freeze drying, hot
air combined with vacuum microwave drying and hot air combined with explosion puffing drying on physical properties,
major nutritional components and microstructure of dried lotus seeds were studied. The results showed that color difference
value of dried lotus seeds decreased in the order of vacuum freeze drying, hot air combined with explosion puffing drying,
hot air drying, vacuum microwave drying, and hot air combined with vacuum microwave drying; hardness decreased in
the order of hot air drying, vacuum microwave drying, hot air combined with vacuum microwave drying, hot air combined
with explosion puffing drying and vacuum freeze drying; crispness increased in the order of vacuum freeze drying, vacuum
microwave drying, hot air drying, hot air combined with vacuum microwave drying and hot air combined with explosion
puffing drying; specific volume decreased in the order of vacuum freeze drying, hot air combined with explosion puffing
drying, hot air combined with vacuum microwave drying, vacuum microwave drying and hot air drying; rehydration capacity
decreased in the order of vacuum freeze drying, hot air combined with explosion puffing drying, hot air combined with
vacuum microwave drying, vacuum microwave drying and hot air drying. There was very little difference in the contents
of protein and crude fibers in lotus seeds dried by the 5 drying methods. The microstructure of lotus seeds dried by vacuum
freeze, hot air combined with vacuum microwave drying and hot air combined with explosion puffing drying revealed
obvious honeycomb structure, but there was a small amount of gaps in the seeds dried by vacuum microwave, and hot airdried
products had compact structure. Overall, hot air combined with explosion puffing drying can be used as a suitable
processing method for the development of snack foods containing lotus seeds.

Key words: lotus seeds, drying method, quality characteristics