With increasing environmental awareness and consumer demand for high-quality food products, industries are strongly required for technical innovations. The use of various emerging techniques in food processing indeed brings many economic and environmental benefits compared to conventional processes. However, lipid oxidation induced by some “innovative” processes is often “an inconvenient truth”, which is scarcely mentioned in most studies but should not be ignored for the further improvement and optimization of existing processes. Lipid oxidation poses a risk to consumer health, as a result of the possible ingestion of secondary oxidation products. From this point of view, this review summarizes the advance of lipid oxidation mechanism studies and mainly discloses the shade of innovative food processing concerning lipid degradation. Sections involving a revisit of classic three-stage chain reaction, the advances of polar paradox and cut-off theories, and potential lipid oxidation factors from emerging techniques are described, which might help in developing more robust guidelines to ensure a good practice of these innovative food processing techniques in future.

The potential of using the bio-based solvent 2-methyloxolane, also known as 2-methyltetrahydrofuran or 2-MeTHF, as an alternative to petroleum solvents such as hexane, was investigated for the extraction of volatile compounds from hop cones (Humulus lupulus L.). Lab scale extractions were coupled with in silico prediction of solutes solubility to assess the technical potential of this bio-based solvent. The predictive approach was performed using the simulation software COSMO-RS (conductor like screening model for real solvants) and showed that the 2-methyloxolane is as good as or better than hexane to solubilize the majority of aromas from hop cones. The experimental results indicated that the highest aroma yield was obtained with 2-methyloxolane with 20.2% while n-hexane was only able to extract 17.9%. The characterization of aromas extracted by the two solvents showed a similar composition, where lupulone was the main component followed by humulone. No selectivity of the solvents was observed for any of the major analytes. Finally, a sensory analysis was performed on the extracts, showing that both concretes using 2-methyloxolane and hexane have similar olfactory profiles. The results indicate that 2-methyloxolane could be a promising bio-based extraction solvent for hexane substitution.

This study attempts to shed light on the efficacy of the solvent 2-methyloxolane (2-MeOx) as an alternative for hexane in defatting spent coffee grounds (SCG). Higher lipid yields were obtained with the bio-based solvent dry 2-MeOx (13.67%) and water-saturated 2-MeOx (15.84%) compared to hexane oil yield, which is of petroleum origin and is a known neurotoxin. Palmitic acid and linoleic acid were the principal fatty acids identified. The fatty acid profile of coffee oils obtained with hexane, dry 2-MeOx and aqueous 2-MeOx were similar. Lipid hydrolysis was observed in oils extracted with 2-MeOx, which warrants further investigation. The residual caffeine content in the defatted SCG was highest when hexane was used highlighting better solubility of methylxanthine compounds in the solvent 2-MeOx.

Coffee silverskin is a byproduct of the coffee industry, appearing in large quantities during the roasting step. In this work, a sober and simple water process is proposed, using extractions cycles, to produce valuable products including (a) an extract rich in caffeine, (b) possibly pure caffeine, and (c) insoluble fibers. The hypothetical number of necessary cycles was calculated and compared to the number of cycles used experimentally. Two types of cycles, with and without water compensation, were compared for their water consumption and the amount of caffeine extracted. The use of cycles, with the resulting product from a previous extraction as a solvent for fresh biomass, drove a significant rise in the content of caffeine determined by a UV–visible detector with a spectrophotometer and ultra-performance liquid chromatography (UPLC). After 11 extraction cycles with water compensation, we obtained an extract 4.5 times more concentrated in caffeine (4.25 mg/mL) than after a single extraction (1.03 mg/mL).

This work presents an innovative microwave-assisted subcritical water extraction (MA-SWE) approach for the simultaneous recovery of proteins and phenolic compounds from hemp seeds (HS). The extraction temperature (100–180 °C), time (5–60 min), and solid-to-liquid ratio (1:5–1:30 w/v) were optimized via Box–Behnken design. The effects of whole, crushed and defatted HS were investigated, with defatted HS exhibiting higher selectivity for proteins and polyphenols. Two optimization strategies were explored: one maximizing protein and polyphenol yields and another minimizing solvent and energy consumption, while maintaining competitive yields. The maximized conditions (MAPPY) were 180 °C, 57 min, and a ratio of 1:28, providing a protein selectivity of 48.91 g/100 g of dry extract (DE) and a total phenolic content of 7.24 g gallic acid equivalent/100 g DE. Regarding functional properties, both strategies yielded extracts with similar performance; however, the maximization strategy resulted in higher emulsifying capacities. These results support the industrial valorization of defatted HS by MA-SWE under optimized conditions to produce antioxidant- and protein-rich ingredients.