Abstract:
Reducing oil content, minimizing any carcinogenic acrylamide in the high temperature
frying process for potato crisps, and producing good products with considerable
crispiness and acceptable color were the objectives of this research. Vacuum frying with
pre-treatment of potato crisps was investigated as an effective process for oil content
reduction. Pre-drying and subsequent dipping (PSSD) in a sugar solution (‘sugar
dipping’) were considered as an advantageous procedure for the treatment of potato crisps
before frying in order to reduce oil uptake during frying. Vacuum frying was observed as
an excellent process to decrease significantly the acrylamide formation at low
temperature frying of potato crisps. In this study, potato crisps were respectively
blanched, pre-dried, and dipped in a solution of sugar (23.07 wt %) for two seconds,
before vacuum frying at 120oC, 110oC under different vacuum pressures (170mbars,
150mbars, 100mbars and 50mbars in separate experiments). Conventional frying at 180oC
was also used as the control to benchmark the reductions in the oil contents and
acrylamide formation among various techniques. There was a significant reduction in oil
content of the potato crisps observed when the new techniques were applied. The crisps
that had been pre-treated and fried with conventional frying have given the result of 30 wt
% reduction. The crisps that were fried under vacuum frying achieved greater oil
reduction with varying percentages when applying different pretreatments. The lowest oil
content was achieved when the potato crisps were fried at 110oC and 150 mbars giving 58
% reduction on the dry basis compared with control samples. There are various
advantages of the technique with PSSD as we have discovered: it is simple and can be
applied in potato crisp industries in continuous mode in both vacuum and conventional
frying systems. The crisps that had been treated with pre-drying and subsequent sugar
solution dipping and then fried were crunchier and possibly had better perceived taste to
the consumer, due to the small sugar addition.
Pre-drying and vacuum frying have all turned out to be excellent techniques to reduce
acrylamide formation in potato crisps as we have found in this study. Vacuum frying at
120oC and 150 mbars reduced acrylamide formation by 80 to 85%. The 95% reduction
was obtained when the crisps had been pre-dried. Acrylamide was undetectable when
crisps were pre-dried and vacuum fried at 110oC, 150 mbars. The crisps with pre-drying
subsequent sugar dipping and vacuum fried at low temperature had improved color
compared with the control samples, which were produced by conventional frying at high
temperatures.