Roasted flaxseed is a viable food for augmenting ω-3 fatty acid intake; however, their sticky mouthfeel limits broader acceptance. The relationship between flaxseed components and sensory properties remains underexplored. This study compares sensory attributes of several flaxseed cultivars and investigates the correlation between changes in composition and sensory characteristics. Flaxseed mucilage was reduced through extraction, and the effects of different roasting conditions on physical (moisture, hardness, crispness) and chemical properties (cyclolinopeptides, flax lignans, oxidative indices) were examined. Optimal roasting conditions were identified as 160 °C for 20 min, as identified through principal component analysis. Results indicated that the mucilage layer negatively affected mouthfeel, while cyclolinopeptide E and lignans impacted flavor and aroma. Degumming improved mouthfeel but reduced oxidative stability, suggesting partial degumming for optimized sensory quality and shelf life. This study provides insights into enhancing the sensory experience of roasted flaxseeds without compromising nutritional benefits and oxidative stability.
The study presents a novel purification method tailored for a range of linusorbs with comparable polarity, leveraging flash chromatography, a rapid and convenient technique, for large-scale purification of linusorbs. A two-step approach employing silica-phenylhexyl strategy was first used for linusorb (LO, also known as cyclolinopeptide) preparation, yielding fractions of cyclolinopeptide A, E, O with purity exceeding 90 % for each 850 mg linusorbs load. Additionally, other eight fractions containing various LOs exhibited average purities ranging from 60 % to 83 %. Comparative assessment of antioxidant capacity of individual LOs elucidated the role of specific amino acid residues. Met residues initially contributed to LOs' antioxidant effects but declined due to oxidation of Met to MetO. Meanwhile, Trp residues exhibited stronger antioxidant capacity, enhancing the capacity of LOs lacking Met. Furthermore, the Phe-Phe structure was identified as contributing to the antioxidant effect of linusorbs. This study not only provides an efficient and scalable method for the purification of LOs but also offers insights into their antioxidant mechanisms.
Linusorbs (LO), cyclolinopeptides, are a group of cyclic hydrophobic peptides and considered a valuable by-product of flaxseed oil due to numerous health benefits. Currently applied acetone or methanol extraction could contaminate the feedstocks for further food-grade application. Using flaxseed cake as feedstock, this study established a practical method for preparing LO from pressed cake. Firstly, LO composition of 15 flaxseed cultivars was analyzed. Next, cold-pressed cake was milled and screened mechanically. The kernel and hull fractions were separated based on the disparity of their mechanical strength. Monitored by hyperspectral fluorescence, the LO-enriched kernel fraction separated from cold-pressed flaxseed cake was further used as feedstock for LO production. After ethanol extraction, partition, and precipitation, LOs were extracted from cold-pressed flaxseed cake with a purity of 91.4%. The proposed method could serve as feasible flaxseed cake valorization strategy and enable the preparation of other polar compounds such as flax lignan and mucilage.
Hot-pressed flaxseed oil is favored in Northwest China as cooking oil due to its flavor and oxidative stability. The mechanism of enhancing oxidation stability of hot-pressed flaxseed oil by neoformed Maillard reaction products (MRPs) remains mysterious. Maillard model reaction between phosphatidylethanolamine (PE) and reducing sugar of flaxseed, glucose (Glu)/fructose (Fru)/xylose (Xyl), was conducted to investigate the antioxidant characteristics of products. MRPs of PE-Xyl had a superior reactivity and anti-oxidative capabilities, which could improve the oxidative stability of flaxseed oil and inhibited the formation of aldehydes in the accelerated oxidation. Phosphatidylethanolamine-linked pyrrolecarbaldehyde (PLP) was the main antioxidant component in MRPs of Xyl-PE by MS and NMR analysis and verification of antioxidant activity. Furthermore, the results of quantum chemical calculation show that the antioxidant activity center of PLP is the pyrrole group. The findings of this study provide insights into the chemical basis underlying the improved oxidative stability of hot-pressed oils.