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To research the antioxidant activity and amino acid composition of antioxidant peptides from Macadamia integrifolia, the Macadamia integrifolia polypeptides were prepared by complex protease enzymatic hydrolysis, the constituents with optimal antioxidant activity (molecular weight less than 1000 Da) were obtained by macroporous resin and dialysis technology. The polypeptides were separated by Sephadex G-15 gel, and the scavenging and reducing ability of 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl and 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonate) radicals (ABTS+) of each component were evaluated. The optimal antioxidant components were separated and identified and analyzed by liquid chromatography and tandem mass spectrometry (LC-MS/MS). The results showed that, the G1, G2 and G3 were isolated by dextran gel column chromatography, G3 had the strongest antioxidant activity, its scavenging and reducing capacity of hydroxyl radicals was superior to glutathione with half maximal inhibitory concentration (IC50) of 6.18 mg/mL and 2.19 mg/mL, respectively. The half maximal inhibitory concentration (IC50) of scavenging capacity of DPPH and ABTS+ was 0.50 and 0.02 mg/mL, respectively. G3 was identified by liquid chromatography tandem mass spectrometry to contain 46 peptides, the length of each peptide was less than 10 amino acids. The molecular weights of the 9 peptides with matching scores more than 200 were 631~920 Da, and with no toxicity. The screened peptides with high antioxidant activity were HLLPK, KEFFP and KEFFPA, the molecular weights of them were 606.84, 666.83 and 737.92 Da, respectively. This research preliminarily revealed the antioxidant peptides composition of macadamia nut, deepened the research of antioxidant peptide of Macadamia integrifolia, and would provide a theoretical reference for the development and utilization of antioxidant peptide of Macadamia integrifolia.

Vacuum-fried products were prepared with macadamia kernels as raw material. Single factor experiment and response surface Box-Behnken test were used to optimize the vacuum frying process of macadamia kernels. Oil content, acid value, peroxidation value, color difference and sensory quality of vacuum-fried kernel were determined by comparing with raw kernel. The results showed that the effects of freezing temperature, vacuum frying temperature, vacuum frying time and vacuum degree on taste and flavor quality of macadamia kernels were significantly different (P

Foodborne pathogens are the main factors affecting food quality and safety. Timely and accurate strain typing data enable rapid detection of outbreak clusters, informing ongoing infection control and public health responses, which are important for preventing the outbreak of foodborne disease. In recent years, great progress has been made in various bacterial typing methods. This paper reviews typing techniques against foodborn bacterial pathogens, including serotyping, phage typing, pulsed-field gel electrophoresis, denaturing gradient gel electrophoresis, Repetitive-element PCR (Rep-PCR), infrequent restriction site PCR (IRS-PCR), amplified fragment length polymorphism (AFLP), restriction fragment length polymorphism (RFLP), multilocus sequence typing (MLST), core-genome multilocus sequence typing (cgMLST), single nucleotide polymorphism, and matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS). The principles of the different techniques are described with the condition in which they are applicable, and a comparative analysis of the traceability typing ability is discussed to provide epidemiological surveillance programmers for foodborne pathogens.