High-density steam flash-explosion (HDSF) was first employed to extract flavonoids from pine needles. The HDSF treatment was performed at a steam pressure of 0.5–2.0 MPa for 20–120 s. Scanning electron microscopy and high-performance liquid chromatography combined with photodiode-array detection and electrospray ionization mass spectrometry (HPLC-DAD-ESI-MS) were used to characterize the morphological changes and analyze flavonoids of pine needles before and after HDSF treatment. Our results indicated that, after steam explosion at 1.5 MPa for 60 s, the flavonoids extracted reached 50.8 rutin equivalents mg/g dry weight, which was 2.54-fold as that of the untreated sample. HDSF pretreatment caused the formation of large micropores on the pine needles and production of particles, as well as the removal of wax layers. Compared to microwave-assisted, ultrasound-assisted, and solvent extraction, HDSF pretreatment took only 30 min to reach a maximum yield of 47.0 rutin equivalents mg/g flavonoids extract after pine needles were treated at 1.5 MPa for 80 s. In addition, after HDSF treatment, the aglycones were 3.17 times higher than that of untreated pine needles, while glycosides were lower by 57% (in HPLC-DAD individuals’ sum) due to hydrolysis of flavonoids glycosides. It can be concluded that HDSF is a practical pretreatment for extraction of flavonoids and conversion in the healthy food and pharmaceutical industries.

Currently, great attention is being paid to the utilization of biomass, such as feather keratins. It is imperative to extract and dissolve keratins from animal keratinous materials for exploitation of innovative biopolymers. However, most of the current processes are based on strong acid and alkali hydrolysis, chemical cleavage and other violent reactions, which are not eco-friendly and/or result in severe degradation and destruction of feather keratins. In this study, high density steam flash-explosion (HDSF) as an innovative pretreatment of biomass was firstly employed to treat feather waste. In HDSF treatment, steam with a powerful seepage force first penetrates into fibrous tissues and cells of feathers, and then quickly expands and breaks free of the structure upon an explosive decompression at supersonic speed (within 0.0875 s). HDSF effectively destabilized β-sheet crystals and intermolecular disulfide bonds without causing substantial damage to the keratin protein chain, dramatically increasing the extraction and dissolubility of feather keratins in polar solvents like water, salt solution and weak bases, as well as enzymatic accessibility. HDSF treatment could be a sustainable and practical pretreatment for extraction of feather keratin for exploitation of biomaterials and conversion of feathers to nutrient animal feed instead of the current chemical hydrolysis and hydrothermal treatment.

Pulsed electric fields (PEF) processing is a promising nonthermal food preservation technology, which is ongoing from laboratory and pilot plant scale levels to the industrial level. Currently, greater attention has been paid to side effects occurring during PEF treatment and the influences on food qualities and food components. The present study investigated the electrochemical reaction and oxidation of lecithin under PEF processing. Results showed that electrochemical reaction of NaCl solutions at different pH values occurred during PEF processing. Active chlorine, reactive oxygen, and free radicals were detected, which were related to the PEF parameters and pH values of the solution. Lecithin extracted from yolk was further selected to investigate the oxidation of food lipids under PEF processing, confirming the occurrence of oxidation of lecithin under PEF treatment. The oxidative agents induced by PEF might be responsible for the oxidation of extracted yolk lecithin. Moreover, this study found that vitamin C as a natural antioxidant could effectively quench free radicals and inhibit the oxidation of lipid in NaCl and lecithin solutions as model systems under PEF processing, representing a way to minimize the impact of PEF treatment on food qualities.

•Single cream was found as a good inducer for esterase to catalyze short and medium—a novel esterase from a psychrotolerant strain of glacier No.1 was purified and characterized.•Chain fat.•An improved zymography method was developed, which is simpler and faster.•It was proved EstTB11 had potential application in flavor development of dairy products.The production, purification, characterization and application of a novel cold active esterase by Pseudomonas sp. TB11 are described herein. A new finding regarding the production of extracellular esterase activity depending upon single cream as an inducer used for growth was investigated in this study. The crude esterase was subjected to a three-step enzyme purification, which resulted in a 15.21-fold purification and the specific activity of the final purified esterase increased to 1526.2 U/mg protein and purified EstTB11 had a molecular mass of 65 kDa. The N-terminal sequence of ten amino acids were: GVYDYKNLTT. Peptide mass finger printing revealed that some peptides showed homologues sequences (29%) to polyurethanase of Pseudomonas sp. FH4. Furthermore, the enzyme displayed the optimum pH of 8.5 and optimum temperature of 25 °C and significantly high stability at 15–35 °C for 72 h. The enzyme was incubated with different metal ions at concentrations of 5 and 10 mM, the activity of esterase was increased in the presence of K+, Na+ and Mg2+ and decreased with Ca2+, Al3+, Mn2+, and Fe3+. Experiments indicated that EstTB11 could hydrolyze milk fat to produce short and medium-chain fatty acid and this result layed the foundation for the application in increased aroma of milk products.Download full-size image