Study On Physicochemical Properties And Digestibility Of Potato Granules

Potato is cultivated widely in China and its acreage and flesh yield ranks as first in the world.Potato granules is the dehydrated potato product and it is rich in nutrients.With the presentation of potato staple food strategy,there are many studies on potato granules in China.However few studies are reported about the digestibility of potato granules.In this study,physicochemical properties and digestibility of untreated and treated by physical methods potato granules were investigated.The results were as follows:(1)The difference between potato granules,wheat flour and rice flour were significant.Potato granules was composed of starch fragments with highest content of RDS,reducing sugar,solubility,swelling power,oil-holding capacity,freeze-thaw stability and retrogradation and the lowest value of peak viscosity,valley viscosity,breakdown,final viscosity,setback and content of SDS(slowly digestible starch).Wheat flour showed highest content of fat,protein,RS(resistant starch)and pasting temperature,which packaged in starch granules surface irregularity.Rice flour showed big irregular granules and the lowest value of solubility,swelling power,oil-holding capacity,freeze-thaw stability and retrogradation.(2)There was a significant effect on the physicochemical properties and digestibility of potato granules by the treatment of ultrasound.The results showed that: ultrasound increased sugar content,peak viscosity,while reduced swelling power,solubility capacity,oil hold capacity,pasting temperature and breakdown of potato granules.When the time was 80 min,crystallinity,the contenr of RS got to the peak,however breakdown and setback got to the lowest value.The content of SDS and peak viscosity reached the peak,when moisture content was 30 %.When power was 400 W,the content of SDS got to the highest value,increased by 11.31 times.The breakdown and setback reached the lowest level when power was 200 W.(3)There was a significant effect on the physicochemical properties and digestibility of potato granules by the treatment of heat-moisture.The degree of crystallinity,solubility,content of RSand SDS increased,but swelling power,oil holding capacity,freeze-thaw stability,peak viscosity,trough viscosity,final viscosity,breakdown,setback,content of reducing sugar and RDS decreased.When the moisture content was 30 %,the solubility,content of reducing sugar and RS reached the highest level,however peak viscosity,trough viscosity and final viscosity reached the lowest level.Maximum of reducing sugar content and solubility appeared,when the temperature was 110 ?.When the temperature was 120 ?,all of freeze-thaw stability,peak viscosity,trough viscosity,final viscosity,breakdown and setback reached the lowest level.The content of RDS reached the lowest level decreased by 61.61 %,however the content of RS reached the highest level increased by 5.15 times,when the temperature was 100 ?.(4)There was a significant effect on the physicochemical properties and digestibility of potato granules by the treatment of annealing.The results showed that: annealing made the crystal structure of potato granules more closely and changed the crystal type of potato granules.The degree of crystallinity,granule size,peak viscosity,trough viscosity,final viscosity,breakdown,pasting temperature,content of reducing sugar,and SDS and RS increased.Freeze-thaw stability,oil holding capacity,solubility,swelling power,setback and content of RDS decreased.When the moisture content was 75 % and the temperature was 40 ?,the content of RDS reached the lowest level decreased by 70.65 %.When the moisture content was 65 % and the temperature was 40 ?,the content of RS reached the highest level increased by 1.21 times.(5)The effect of dry heating treatment on the physicochemical properties and digestibility of potato granules was significant.Dry heat treatment changed the structure of potato granules.The content of reducing sugar,solubility,swelling power,oil holding capacity,freeze-thaw stability,peak viscosity,paste temperature and digestibility decreased.With the time and temperature(120~180 ?)prolonged,the destruction of the potato granules was more serious.When the temperature was 120? and the time was 2.5 h,the content of RS reached the highest level,increased by 4.28 %.(6)With the potato granules and wheat flour as control,the difference between the digestibility of potato granules and wheat flour in different blending ratios was significant.When the ratio of the blends was 1:9,RDS content,oil absorption,solubility,swelling degree,pasting temperature and digestion rate significantly decreased by 43.2 %,45.9 %,45.1 %,44.1 % and 32.9 %,and SDS at the highest level,increased by 68.9%.When the ratio was 9:1,setback got the lowest level,decreased by 29.5 % as compared to potato granlues.RS content reached the highest level,increased by 6.66 times as compared to potato granlues,however decreased by 6.35 % as compared to wheat flours.