Influence of dry air and infrared pre-treatments on oxidative stability, Maillard reaction products and other chemical properties of linseed (Linum usitatissimum L.) oil.

In this study, the influence of dry air and infrared pre-treatments on linseed oil (LO) yield, chemical properties, colour, pigment content, total phenolic content (TPC), Maillard reaction products (MRPs), fatty acid composition (FAC), radical scavenging activity (RSA), and oxidative stability index (OSI) were investigated. An increase in dry air and infrared roasting temperature had increased the LO yield, pigment content, a* value, TPC, RSA, OSI, and browning index (BI) while lowered the L* and b* values of LO. Higher OSI (2.24 h), chlorophylls (2.29 mg/kg), carotenoids (3.87 mg/kg), TPC (63.67 mg GAE/100 g), RSA (62.53%), BI (0.330), and MRPs (2.10 mg/kg) were detected in LO by dry air roasting at 180°C for 10 min. Dry air and infrared roasting had slightly affected the FAC of LO. Both dry air and infrared pre-treatments had influenced the LO quality characteristics. However, dry air roasting of linseed at 180°C for 10 min proved more effective in improving oxidative stability, antioxidant activity and other quality characteristics of LO. SUPPLEMENTARY INFORMATION: The online version of this article at 10.1007/s13197-021-05023-6.

Impact of roasting and extraction methods on chemical properties, oxidative stability and Maillard reaction products of peanut oils.

This study was designed to investigate the influence of dry air roasting (140, 160 and 180 °C for 5 and 10 min) and extraction methods (solvent and mechanical) on peanut oil quality characteristics. Oil yield, oxidative stability index (OSI), radical scavenging activity (RSA), and Maillard reaction products were increased while peroxide value (PV) and conjugated dienes were decreased in oil of peanuts roasted at 180 °C for 10 min. Oils extracted mechanically from roasted peanuts had lower PV while higher OSI and RSA than the solvent-extracted oils. The fatty acid composition of oils from roasted peanuts (at 160 and 180 °C for 10 min) changed slightly compared to unroasted peanuts. The level of 5-hydroxymethylfurfural and non-enzymatic browning index was significantly increased in oil from peanuts roasted at 180 °C for 10 min. FTIR spectra showed a slight change in peak intensities with no observed peak shift in oils extracted from peanuts roasted at 180 °C for 10 min. Based on the results obtained, mechanically extracted oil from peanuts roasted at 180 °C for 10 min improves oil quality characteristics and enhances oxidative stability.

Impact of microwave roasting on physicochemical properties, maillard reaction products, antioxidant activity and oxidative stability of nigella seed (Nigella sativa L.) oil.

In this study, oils extracted from nigella seeds (NS) subjected to microwave roasting at 180, 360, 540 and 720 W for 5 and 10 min were evaluated for quality and stability characteristics. The impact of microwave powers on oil yield, pigment content, Maillard reaction products (MRPs), radical scavenging activity (RSA), color, viscosity, total phenolic content (TPC), oxidative stability index (OSI) and fatty acid composition (FAC) of oil was studied. TPC, RSA, OSI, MRPs, viscosity, chlorophyll and carotenoid contents were higher in oil of NS heated at 720 W for 10 min while maximum oil yield and low acid value was observed for NS heated at 540 W for 10 min. FAC was slightly influenced by microwave roasting and FTIR spectra exhibited a minor difference in intensities of peaks at 3009, 2925, 2854, 1745 and 1161 cm-1. The results of the study indicated that microwave roasting improves NS oil quality characteristics.

Influence of microwave roasting on chemical composition, oxidative stability and fatty acid composition of flaxseed (Linum usitatissimum L.) oil.

In this study, flaxseeds roasted at microwave (MW) powers of 180, 360 and 540 W for 5 and 10 min were evaluated for their influence on oil yield, chemical properties, carotenoid and chlorophyll contents, total phenolic content (TPC), radical scavenging activity (RSA), oxidative stability index (OSI), fatty acid composition and Maillard reaction products (MRPs). MW roasting at 540 W for 10 min significantly increased the oil yield, TPC, OSI, RSA, a* value, browning index, carotenoid and chlorophyll contents while decreased the L* and b* values of flaxseed oil (FSO). MRPs were detected only in oil of flaxseeds roasted at 540 W for 10 min. The level of stearic, palmitic, oleic, linoleic and α-linolenic acids were slightly changed and FTIR spectra showed minor variation in peak intensities of oils from different MW roasted flaxseeds. MW roasting (540 W for 10 min) is recommended for improving quality and stability characteristics of FSO.

Impact of infrared and dry air roasting on the oxidative stability, fatty acid composition, Maillard reaction products and other chemical properties of black cumin (Nigella sativa L.) seed oil.

Black cumin seed (BCS) is a novel oil source with potential health benefits. This study investigates the influence of infrared (IR) and dry air (DA) roasting (140, 160 and 180 °C for 5 and 10 min) on BCS oil quality characteristics. Results revealed that the oxidative stability index (OSI), Maillard reaction products (MRPs), chlorophyll and carotenoid contents were increased while acid value (AV), peroxide value (PV) and color values were decreased in DA roasted (180°C for 10 min) BCS oil compared to other DA and IR treatments. DA and IR roasting slightly influenced the fatty acid composition (FAC) of BCS oils. FTIR spectra showed minor changes in peak intensities (at 2854, 2929 and 3008 cm-1) of DA and IR roasted BCS oils. DA roasting proved more effective than IR roasting. The oil from the DA roasted BCS at 180°C for 10 min had significantly higher oil quality and oxidative stability.