Change of the frozen storage quality of concentrated Mongolian milk curd under the synergistic action of ultra-high pressure and electric field

Based on the response surface method, the curd was frozen with a low voltage electrostatic field (LVEF) at −40 °C for 30 days after being treated by 286 MPa for 19 min. Compared with natural frozen samples, LVEF can effectively reduce freezing time and thawing loss of curd by 19.1 and 5.2%, respectively. LVEF reduced the size and rounded edges of ice crystals, maintaining color and hardness. The ultra-high-pressure-assisted (HPP) not only greatly accelerates the freezing rate and reduces thawing loss, but also delays proteolysis, and reduces loss of aroma. Also, HPP increases the β-fold and decreases random curl, leading stable secondary structure of the protein. However, the HPP yellowed the curd and increased its viscoelasticity. Both HPP and LVEF greatly decreased the Total Viable Count and Lactic Acid Bacteria count in curd. The HPP-LVEF-treated curd showed 50% decrease in freezing time, and a similar microstructure to fresh curd, suggesting that HPP before freezing and a combination of LVEF during freezing could improve the quality of frozen curd. •Curd was treated with ultra-high-pressure-assisted (HPP) at 286 MPa for 19 min.•HPP treated curd was frozen with low voltage electrostatic field (LVEF) at −40 °C.•HPP accelerate the freezing rate and delay proteolysis of curd during storage.•LVEF reduce size and round edge of ice crystal, keeping color and hardness of curd.•HPP-LVEF cut freezing time half, maintaining similar microstructure to fresh curd.