Role of Solid Fat Content in Oxidative Stability of Low-Moisture Cracker Systems

Abstract

Lipid oxidation is a major pathway for the chemical deterioration of low-moisture foods. Little is known about how the physical properties of the fat used in crackers impact lipid oxidation kinetics. Fully hydrogenated soybean fat + interesterified soybean oil, fully hydrogenated soybean fat + sunflower oil, fully hydrogenated soybean oil, and soybean oil and interesterified fat alone were formulated to have varying solid fat content (SFC) at 55 °C but the same linoleic acid and tocopherol contents, so the fats had similar susceptibility to oxidation. A fluorescence probe showed that lipid mobility increased with decreasing SFC in both cracker doughs and fat blends, suggesting the probe could be used to monitor SFC directly in foods. Decreasing SFC decreased oxidation in crackers. Crackers made from interesterified fat (13.7% SFC) were more oxidatively stable (hexanal lag phase = 33 days) than crackers made from fat blends (hexanal lag phase = 24 days). These results suggest that blended fats result in regions of liquid oil high in unsaturated fatty acids within a food product prone to oxidation. Conversely, interesterified fats where unsaturated and saturated fatty acids are more evenly distributed on the triacylglycerols are more stable. Thus, interesterified fats could allow for the formulation of products higher in unsaturated fatty acids to improve nutritional profiles without sacrificing shelf life.

Mathematical Modeling of Alpha-Tocopherol Early Degradation Kinetics to Predict the Shelf-Life of Bulk Oils

“…Hydrogen is abstracted from unsaturated fatty acids to form alkyl radicals, which then react with oxygen to form lipid hydroperoxides during lipid oxidation. 1 These lipid hydroperoxides eventually degrade into ketones, aldehydes, and alcohols, causing rancidity, color loss, nutritional loss, and texture defects in the final product. 2 The degree of fatty acid unsaturation, prooxidants (e.g., transition metals, heme proteins, singlet and triplet oxygen, free fatty acids, enzymes), antioxidants (e.g., free radical scavengers, singlet oxygen quenchers, metal chelating agents), physicochemical properties (e.g., pH, physical barriers, water activity), and storage conditions (e.g., temperature, light) all influence lipid oxidation.…”

“…Food oils are highly susceptible to lipid oxidation, the primary chemical reaction that determines their shelf life and quality. Hydrogen is abstracted from unsaturated fatty acids to form alkyl radicals, which then react with oxygen to form lipid hydroperoxides during lipid oxidation . These lipid hydroperoxides eventually degrade into ketones, aldehydes, and alcohols, causing rancidity, color loss, nutritional loss, and texture defects in the final product .…”