Optimization on Processing Conditions of Blanching and Freezing for Sweetpotato Chips

Developement of Snack Foods Produces from Sweetpotatoes Part II

Abstract

The study was conducted in order to find suitable processing conditions of blanching and/or freezing treatment to improve the texture of sweetpotato chips made of sweetpotato slices having a thickness of 2.0mm. The results obtained were as follows: (1) Optimal blanching time before freezing was 20-30 sec. in boiling water, 60-120sec. in ordinary pressure steam and 20-40sec. in hot oil (120°C), respectively. (2) Freezing temperature did not affect the texture of chips appreciably in the range of -5°C to -40°C. (3) The effect of freezing time under -22°C on the chips texture was not appreciable in case of freezing time more than 30min. which was long enough to freeze the slices. (4) Chips fried by deep-fat frying at 145°C-155°C after thawing were remarkably improved on crispness as much as hardness which decreased to approximately onefourth of untreated ones depending on the varieties of sweetpotato. (5) Sweetpotato varieties having high starch content such as Norin No.1, Gifu No.1 and Koganesengan resulted in a high quality of chips concerning fiavor and appearance when evaluated by the sensory test.