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Procyanidins (PC) from Vitis amurensis seeds was extracted using high-intensity pulsed electric field (PEF). The process parameters including pulse number, electric field strength, ratio of material to liquid and ethanol concentration were studied using response surface methodology, and extraction yield of the extracts were determined. Antioxidant activity of the extracts by PEF, ultrasonic-assisted extraction (UAE), microwave-assisted extraction (MAE) and ethanol extraction (EAE) were compared based on total antioxidant capacity, DPPH radical scavenging capacity and ferrous ion chelating activity. The results revealed that the optimization of conditions of PEF are: pulse number 10; electric field strength 25 kV/cm; ratio of material to liquid 1:21 g/mL; ethanol concentration 63% (v/v), and the PC yields reached 8.23% under this condition. The PEF resulted in a highest extraction yield of PC among the four extraction methods. There was no significant difference in total antioxidant capacity of PC obtained by four methods, the DPPH radical scavenging capacity and ferrous ion chelating activity of PC extracted by PEF were close to that of UAE and MAE, which were superior to EAE. These showed that PEF was an effective method for extracting PC.

Mussel meat is rich in amino acids and is a good source of flavor enhancers. To find a high‐efficiency and suitable method for the Maillard reaction (MR) of enzymatic hydrolysate derived from mussel meat, we studied the changes of Maillard reaction between enzymatic hydrolysate and glucose/xylose under ultrasonic treatment (UsT), heat treatment (HT) and ultrasonic‐assisted heat treatment (Us‐HT). It was found the Us‐HT displayed the highest Maillard reaction rate and a significant increase in intermediate products and melanoidins compared to HT and UsT. The Maillard reaction products (MRPs) derived from the three treatments showed higher antioxidant activity, while the MRPs from Us‐HT had the highest antioxidant activity and ideal sensory properties. Therefore, Us‐HT is a potential method to prepare the Maillard flavor enhancer from mussel meat. PRACTICAL APPLICATIONS: The ultrasonic technology was applied as a novel food processing technique and can effectively promote the interaction of certain ingredients. Compared with single ultrasonic or heat treatment, ultrasonic‐assisted heat treatment can accelerate the reaction and improve sensory properties and antioxidant activities of MRPs derived from mussel meat hydrolysate. The ultrasonic‐assisted heat treatment is a potential technology for preparing the Maillard flavor enhancer. This efficient method supports the utilization of mussel meat and the development of flavoring essence and functional foods in the future.

This study investigated the application of ultrasonic pretreatment (UP) to assist with enzymatic extraction of chicken bone protein. Relevant parameters of UP including ultrasonic power, duration of treatment and temperature were studied. The effect of ultrasound was evaluated by examining the protein structure changes (i.e. surface hydrophobicity, secondary and tertiary structures, molecular weight distribution) and their functionalities (i.e. solubility, oil holding capacity, foaming and emulsifying properties). Higher protein extraction yield and surface hydrophobicity were evident after UP, along with the changes in the secondary and tertiary structure of the protein. UP alone effects the proteins having molecule weight at about 100 kDa. Results also reveal UP was capable of enhancing the protein functionalities. Therefore, UP could be applied as a suitable technology to improve the yield and quality of the protein extracted from chicken bone by enzymatic method, and as such, facilitating the potential utilization of waste byproduct from poultry industry.