Effect of Microwave Roasting on Chemical Composition, Oxidative Stability, and Sensory Properties of Golden and Brown Flaxseed Oils: A Comparative Study

T.T.  Ly; L.  Yang; G.  Sun; P.T.  Vinh

doi:10.18502/jfqhc.13.1.21376

T.T. Ly Department of Nutrition and Food Hygiene, School of Public Health, Southeast University, Nanjing 210009, China
L. Yang Department of Nutrition and Food Hygiene, School of Public Health, Southeast University, Nanjing 210009, China
G. Sun Department of Nutrition and Food Hygiene, School of Public Health, Southeast University, Nanjing 210009, China
P.T. Vinh Institute of Biotechnology and Food Technology, Thai Nguyen University of Agriculture and Forestry, Thai Nguyen City, Vietnam

DOI: https://doi.org/10.18502/jfqhc.13.1.21376

Keywords: Flaxseed Oil Microwaves Oxidant Sensory Processing Fatty Acids

Abstract

Background: Flaxseed (Linum usitatissimum L.) Oil (FSO) is valued for its high content of Polyunsaturated Fatty Acids (PUFAs) and natural antioxidants but is susceptible to oxidative degradation during processing. The objective of this study was to evaluate the effects of microwave heat treatment on the compositional characteristics, oxidation stability, and sensory quality of Golden and Brown FSOs.

Methods: Two flaxseed varieties were roasted at 2450 MHz for 3, 6, 9, and 12 min. The proximate composition (moisture, ash, fiber, protein, and oil), fatty acid profile, Tocopherol (TC) and Total Phenolic Contents (TPC), and oxidative stability parameters (Peroxide Value [PV], Acid Value [AV], Anisidine Value [AnV], Iodine Value [IV], and Malondialdehyde [MDA]) were determined using standard AOAC and ISO methods. Sensory attributes (color, transparency, odor, flavor, and overall acceptability) were evaluated by a trained panel using a 5-point hedonic scale.

Results: Microwave roasting affected FSO composition and quality in a time-dependent manner. Fiber, ash, and protein did not change significantly, whereas moisture decreased from 6.24% to 3.51% (Golden) and 6.02% to 3.03% (Brown), and FSO content increased from 32.54% to 35.38% and 33.43% to 36.60%, respectively. Saturated Fatty Acids (SFA) were increased and Polyunsaturated Fatty Acids (PUFA) decreased with prolonged roasting, suggesting partial oxidation of Unsaturated Fatty Acids (USFA). Tocopherol (TC) and Total Phenolic Contents (TPC) were decreased, while oxidative parameters ((Peroxide Value [PV], Acid Value [AV], Anisidine Value [AnV], and Malondialdehyde [MDA])) increased and Iodine Value (IV) decreased over time. Sensory evaluation was highest at 3 min, suggesting short-term roasting optimally balances oil yield, nutritional quality, and sensory attributes.

Conclusion: Optimized control of microwave roasting can optimize FSO production, balancing nutritional quality, sensory properties, and industrial applicability.