Optimal pretreatment determination of kiwifruit drying via online monitoring.
BACKGROUND
Pre-treating is a crucial stage of drying process. The best pretreatment for hot air drying of kiwifruit was investigated using a computer vision system (CVS), for online monitoring of drying attributes including drying time, colour changes and shrinkage, as decision criteria and using clustering method. Slices were dried at 70 °C with hot water blanching (HWB), steam blanching (SB), infrared blanching (IR) and acid ascorbic 1% w/w (AA) as pretreatments each with three durations of 5, 10 and 15 min.


RESULTS
The results showed that the cells in HWB-pretreated samples stretched without any cell wall rupture, while the highest damage was observed in AA-pretreated kiwifruit microstructure. Increasing duration of AA and HWB significantly lengthened the drying time while SB showed opposite results. The drying rate had a profound effect on the progression of the shrinkage. The total colour change of pretreated samples was higher than those with no pretreatment except for AA and HWB. The AA could well prevent colour change during the initial stage of drying. Among all pretreatments, SB and IR had the highest colour changes.


CONCLUSIONS
HWB with a duration of 5 min is the optimum pretreatment method for kiwifruit drying. © 2016 Society of Chemical Industry.
Dept. of Biosystems Engineering, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran.
Mohammad Hossein
MH
Nadian
Dept. of Biosystems Engineering, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran. abaspour@um.ac.ir.
Mohammad Hossein
MH
Abbaspour-Fard
Dept. of Biosystems Engineering, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran.
Hassan
H
Sadrnia
Dept. of Biosystems Engineering, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran.
Mahmood Reza
MR
Golzarian
Dept. of Biosystems Engineering, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran.
Mohammad
M
Tabasizadeh
D029042:Actinidia / Q000737:chemistry*; D005511:Food Handling / Q000379:methods*; D005638:Fruit / Q000737:chemistry*; D006358:Hot Temperature; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D013997:Time Factors; D014867:Water
D014867:Water
SAS clustering; computer vision system; kiwifruit slices; pretreatment