Formation of Previously Undescribed Δ⁷-Phytosterol Oxidation Products and Tocopherylquinone Adducts in Pumpkin Seed Oil during Roasting, Screw-Pressing, and Simulated Culinary Processing at Elevated Temperatures

Abstract

The influence of pumpkin seed roasting conditions (110–140 °C) and screw-pressing on the formation of previously undescribed Δ7-phytosterol oxidation products and tocopherylquinone adducts with nucleophilic phosphatidylethanolamine species was investigated. The roasting process of pumpkin seed paste at a temperature above 120 °C for 30 min considerably enhanced the formation of Δ7-oxysterols. Targeted analysis [electron impact mass spectrometry (MS), 1D-nuclear magnetic resonance] led to the identification of five novel markers of pumpkin paste roasting, among which (3β,5α,22E,24S)-stigmasta-7,22-dien-6-one-3-ol (6-oxo-α-spinasterol), stereoisomers of (3β,5α,22E)-7,8-epoxystigmast-22-en-3-ol (7,8-epoxy-α-spinasterol), and (3β,5α)-22,23-epoxystigmast-7-en-3-ol (7,8-epoxy-α-spinasterol) were reported in edible oils for the first time. Simulated culinary processing provided novel stereoisomers of (3β,5α,22E)-stigmasta-7,22-dien-3,6-diol, unusual (3β,5α,22E)-stigmasta-7,22-dien-6,15-dione-3-ol, and (5α,22E)-stigmasta-7,22-dien-3-one accompanied by minor stereoisomers of (3β,5α)-7,8;22,23-diepoxystigmastan-3-ol. Moreover, a clear relationship between the pumpkin seed oil stability index and synergistic effect of glycerophospholipids with present tocochromanols was found. High-resolution atmospheric pressure chemical ionization–MS experiments clearly demonstrated the formation of various γ-tocopherylquinone adducts with primary amines, namely, octylamine. The mitigation strategy of potentially detrimental oxysterols from pumpkin seed oil included optimization of processing parameters while maintaining the formation of desirable sensory-active compounds.

Novel Approaches for Elongation of Fish Oils into Very-Long-Chain Polyunsaturated Fatty Acids and Their Enzymatic Interesterification into Glycerolipids

“…The overall process is schematically shown in Figure S3. Purified samples of both FOC-FAME and commercial FOC were characterized by the determination of their fatty acid composition as well as key indicators of hydrolytic (acid value) and oxidative stability (peroxide value, iodine value, induction period) as previously described …”

“…Purified samples of both FOC-FAME and commercial FOC were characterized by the determination of their fatty acid composition as well as key indicators of hydrolytic (acid value) and oxidative stability (peroxide value, iodine value, induction period) as previously described. 44 Elongation of polyunsaturated esters was based on a previously developed protocol. 40,41 45 Reaction conditions were modified according to Noel and Combes.…”

Effects of Extraction Strategies on Yield, Physicochemical and Antioxidant Properties of Pumpkin Seed Oil

“…PSO has been recognized as a high-quality vegetable oil for both medicine and food in the world. The processing technology of PSO had significant effect on its composition and content of lipid companions, which further determined the nutritional and functional activity of PSO [ 6 ]. Exploring the effects of different processing techniques on the nutritional components of PSO is of great significance to maximize the nutritional and functional properties of PSO.…”

“…For example, the 2,2 -diphenyl-1-picrylhydrazyl (DPPH) radical assay is used to measure the radical scavenging activity of antioxidant agents, the ferric reducing antioxidant power (FRAP) assay is employed to assess the antioxidative capacity of antioxidants, and the 2,2 -azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assay is used to evaluate the ability to clear ABTS W 2 of 12 world. The processing technology of PSO had significant effect on its composition and content of lipid companions, which further determined the nutritional and functional activity of PSO [6]. Exploring the effects of different processing techniques on the nutritional components of PSO is of great significance to maximize the nutritional and functional properties of PSO.…”