Lactic acid fermentation reduces acrylamide formation and other Maillard reactions in French fries

Blanched and nonblanched potato rods (var. Beate) were fermented with Lactobacillus plantarum strain NC8 (10(9) colony-forming units [CFU]/mL) at 37 degrees C for 45 and 120 min. Potato rods were pre-fried at 170 degrees C for 3 min, cooled, and subsequently deep-fried for 2 min 15 s. Potato juice (var. Beate) was fermented with the same strain (10(8) CFU/mL) at 30 degrees C for 1 to 5 h. Lactic acid fermentation of nonblanched potato rods for 45 min reduced acrylamide level in French fries with 48%, and with 71% after 120 min. By blanching potato rods before fermentation, reductions in acrylamide after 45 min and 120 min were 79% and 94%, respectively. Blanching, and especially fermentation, reduced visually judged browning of the French fries. Fermentation of potato juice reduced pH from 5.70 to 4.05 after 3 h. Simultaneously, glucose declined from 610.8 mg/100 mL to 7.9 mg/100 mL, fructose from 457.8 mg/100 mL to 0.0 mg/100 mL, and sucrose from 132.0 mg/100 mL to 29.2 mg/100 mL. Asparagine content remained largely unaffected between 0 h (1217.5 mu mol/100 mL) and 4 h (1175.6 mu mol/100 mL) and increased slightly (1470.3 mu mol/100 mL) after 5 h fermentation. Levels of several other amino acids involved in Maillard reactions, that is, alanine, arginine, phenylalanine, and serine, decreased during fermentation. It is concluded that acrylamide formation during production of French fries can be effectively lowered by lactic acid fermentation of potato rods before deep-frying. The reduction is due to reduced levels of reducing sugars rather than reduction of available asparagine.