喷雾干燥工艺条件对速溶龙眼粉理化特性的影响

Effect of Spray Drying Processing on the Physicochemical Properties of Instant Longan Powder

【目的】分析喷雾干燥进风温度和热风流量对速溶龙眼粉理化特性的影响。【方法】分别考察喷雾干燥不同进风温度和不同热风流量对速溶龙眼粉水分含量、堆积密度、黏性、溶解性、水分吸附特性、玻璃化转变温度和超微结构等理化特性的影响。【结果】当进风温度从160℃升高到190℃、热风流量从23.00 m3.h-1增加到29.00 m3.h-1时,速溶龙眼粉水分含量分别降低25.52%和39.42%;黏度值分别下降55.75%和61.11%;玻璃化转变温度分别升高8.30℃和7.07℃;溶解时间分别增加1.29倍和1.47倍;堆积密度分别提高22.87%和20.15%;同时,单分子层水分含量、微粒形态、L*、a*、b*、色调和色度随之变化。【结论】加工理化特性优良的速溶龙眼粉需严格控制喷雾干燥的进风温度和热风流量等工艺参数。

【Objective】 The effects of inlet temperature and hot air rate on the physicochemical properties of instant longan powder were studied.【Method】 Different inlet temperatures and different hot air rates on the physicochemical properties of instant longan powder were determined,such as moisture content,bulk density,stickiness,dissolution time,isotherms of water sorption,glass transition temperature and microstructure.【Result】 With the inlet temperature increased from 160℃ to 190℃ or hot air rate increased from 23.00 m3？h-1 to 29.00 m3？h-1,the moisture content decreased by 25.52% and 39.42%,stickiness declined by 55.75% and 61.11%,but glass transition temperature increased by 8.30 ℃ and 7.07 ℃,dissolution time increased by 1.29 times and 1.47 times,and bulk density increased by 22.87% and 20.15%.And simultaneously there were changes in L＊,a＊,b＊,hue,chroma values,monolayer moisture content and microstructure of the spray-dried powder for all inlet temperature investigated.【Conclusion】 It is important to control the parameters of spray drying machine for producing excellent instant longan powder.