The effects of Perilla frutescens leaf extract (PLE) on the quality of surimi fish balls were investigated in the present study. Firstly, the extract was prepared by solvent extraction using 95% ethanol. Then, the phenolics in the extract were analyzed by instrumental analysis. The total phenolic content in the PLE was found to be 14.51 mg gallic acid equivalent (GAE)/g dry weight (DW). The amount of caffeic acid, ferulic acid, rosmarinic acid, quercetin, and apigenin, determined by high‐performance liquid chromatography (HPLC), was 4.80, 5.10, 2.95, 6.46, and 3.93 mg/g DW, respectively. Furthermore, the PLE was found to show high free radical scavenging activity toward DPPH and ABTS radicals with IC 50 values of 12.15 and 7.26 μg/ml, respectively. When PLE was fortified into surimi fish balls at 0.03% and stored at 4°C, it was found to slow down lipid and protein oxidation during storage of surimi fish balls as evidenced by the significant reduction in TBARS values and protein carbonyl contents ( p < 0.05). PLE (0.03%) also decreased the formation of total volatile basic nitrogen (TVB‐N) and inhibited the growth of E . coli compared with the control group ( p < 0.05). In addition, the overall acceptability of PLE‐added (0.03%) samples was higher than control samples during the storage process ( p < 0.05) by sensory analysis. Overall, PLE have the potential to be used as a natural food additive to improve the shelf life and sensorial qualities of surimi fish ball.

In the present study, Perilla leaf essential oil (PLEO) was extracted by steam distillation and analyzed using SPME-GC-MS. We further discovered that PLEO could inhibit the growth of Escherichia coli, Salmonella and Staphylococcus aureus. Then, we evaluated the impact of the addition of PLEO (0.01 and 0.03%) on the quality changes of a surimi-based food. We found that during 4 weeks of cold storage, the addition of the PLEO had minimum impact on food color and texture based on instrumental analysis and sensory panel evaluation. However, the addition of PLEO could significantly retard lipid oxidation and protein carbonylation and lower the formation of total volatile basic nitrogen. In addition, the addition of PLEO showed good antibacterial effect in this cooked surimi-based food, with the inhibitory effect of 0.03% volatile oils on the total plate count and E. coli as the best. Practical applicationsSurimi-based food is a kind of nutrient-rich and low cholesterol food, at the same time with the characteristics of tender meat, low fat, high protein and delicious taste. However, lipid and protein oxidation and microbial growth will make surimi product corrupt, affecting its shelf-life during storage period. Although synthetic antioxidants and preservatives have the advantages of low cost and high efficiency, people are worrying about synthetic food additives for their potential health risks and toxicity. The significance of this study is that Perilla leaf essential oil may be used as a natural and effective ingredient to replace the synthetic additives for the processing of healthy surimi-based foods, meanwhile develop a kind of surimi products with Perilla flavor.

Nomex honeycomb composites are used extensively in aerospace, automotive, and other industries due to their superior material properties. However, the tool wear during their machining can compromise the processing accuracy and the stability of the whole machining process, thus studies on the tool wear and strengthening method are urgently needed. This study presents a radial difference calculation method (RDC) to evaluate the tool wear of the disc cutter quantitatively in both conventional cutting and ultrasonic assisted cutting. The morphology of the tool wear process and its characteristics were analyzed. Two different heat treatments (salt bath quenching and vacuum quenching) were carried out to strengthen the tool performance. The research results demonstrated that ultrasonic vibration could significantly reduce the tool wear of the disc cutter, by up to 36%, after the same machining time. Salt bath quenching and vacuum quenching can both strengthen the tool performance. Particularly, after vacuum quenching treatment, the disc cutter’s metallographic grains were refined, and the tool wear could be reduced by 64%, compared to the as-received disc cutter. The findings in this study could be instructive to obtain further understanding of the machining mechanism and to improve methods in ultrasonic assisted cutting of Nomex honeycomb composites.