OXIDATIVE AND FLAVOR STABILITY OF TORTILLA CHIPS FRIED IN EXPELLER PRESSED LOW LINOLENIC ACID SOYBEAN OIL*

ABSTRACT

To determine effects of expeller oil pressing and decreased linolenic acid, intermittent batch frying tests were conducted with tortilla chips using soybean oil (SBO), expeller pressed SBO (EPSBO), expeller pressed low linolenic SBO (EPLLSBO), high oleic sunflower oil, corn oil and hydrogenated SBO for up to 35 h of frying. Chips were aged at 25C and trained, experienced analytical sensory panelists evaluated their flavor. Oxidative stability of the chips was determined by hexanal analyses and oil fry life was measured by total polar compounds. The stability of tortilla chips fried in EPLLSBO was significantly better than chips fried in SBO or EPSBO as judged by rancid flavor intensity and hexanal formation after storage. This effect may be due, in part, to less linolenic acid in EPLLSBO and better tocopherol retention compared to EPSBO. The combination of expeller pressing and low linolenic acid (EPLLSBO) produced a significantly more stable fried product than expeller pressing (EPSBO) alone.

PRACTICAL APPLICATIONS

Food manufacturers are interested in oils that can be used for frying as alternatives to trans fat-containing hydrogenated fats. Since polyunsaturated vegetable oils are not sufficiently oxidatively stable for frying, alternatives such as modified fatty acid composition oils, additives and oil processing techniques could be used individually or in combination to increase fry life of the oil and shelf life of foods. Although expeller pressing of SBO or reducing linolenic acid of SBO alone have not given SBO the stability equivalent to HSBO, we found that combining decreased linolenic acid and expeller pressing of SBO produced frying oil and fried tortilla chips with the stability similar to that of hydrogenated fat in early stages of frying.