Effect of frying temperature and slice thickness on sensory attributes and acrylamide content in potato crisps of selected Kenyan varieties

Abstract

Acrylamide, a chemical found in several carbohydrates rich foods processed at high temperatures, has been classified as a potential human carcinogen; the need to minimize its presence in the human diet cannot be overemphasized. This study was designed to determine how acrylamide formation is influenced by potato varieties, processing temperatures and slice thickness in potato crisp produced from established Kenyan varieties.  Four potato varieties (Kenya Mpya, Sheherekea, Tigoni and Dutch Robjin) were purposively selected due to their suitability for crisp production and were planted at KARLO Tigoni. The potato tubers were harvested at maturity, cured, peeled and sliced into three slice thicknesses (1-0mm, 1.5mm and 2.00mm) and subjected to three frying temperatures of 160°C, 170°C and 180°C until ready. The dry matter of the tubers ranged between 21.5 and 28.4%. The fructose levels ranged from 0.068 - 0.241 %; glucose levels ranged 0.155%- 0.218%; Sucrose levels ranged from 0.61 to 0.87%. In the potato crisps Kenya Mpya variety fried at 160°C of thickness 2.0mm had the highest moisture content of 2.575%.  Most of the crisps from the four varieties processed at different temperatures and thicknesses were light colored with lightness (L*) parameters greater than 50 and towards red as shown by positive values of redness parameter (a*) indicating that there was excess browning of the products during frying. Acrylamide levels significantly (P≤0.05) differed between the varieties and ranged from 3129 to 13480ppb. There was a significant difference in acrylamide levels (p≤0.05) with temperatures of 180°C resulting in higher acrylamide content compared to those of 160°C and 170°C. Similarly, the slice thickness of 2.0mm had high acrylamide levels and the redness parameter (a*). There was a strong correlation between acrylamide formation and glucose (r=0.761) and fructose (r=0.44) formation.