Effects of high pressure nitrogen treatments on the quality of fresh-cut pears at cold storage

• Pressurized nitrogen treatment was beneficial to preserve quality of fresh-cut pears.
• HP nitrogen treatments forms clathrate hydrates to restricted water mobility and enzymatic reactions.
• The treatment inhibits microbial growth during storage at 4 °C.
• Dipping into chemical solution could reduce the changes in the color and firmness of pear samples during HP operation.

When fresh-cut fruit and vegetables are subjected to HP nitrogen treatments, the nitrogen gas dissolves into water and forms clathrate hydrates to restricted water mobility and enzymatic reactions. In this study, effects of HP (120 MPa) nitrogen treatments on preserving fresh-cut pears were studied at 4 °C for 14 days. Water mobility in fresh-cut pears was significantly reduced by the HP (120 MPa) nitrogen treatment. The activities of catalase (CAT) and peroxidase (POD) were restricted by the HP (120 MPa) nitrogen treatment. Respiration rate and ethylene production of fresh-cut pears treated by the HP (120 MPa) nitrogen for 10 min were lower significantly in comparison with control and treated by flushing with nitrogen and the HP air for 10 min. The treatment also delayed proliferation of spoilage microorganisms of fresh-cut pears, because the populations of both mesophiles and psychrotrophs did not exceed 6.0 log cfu/g, and those for molds and yeasts did not exceed 3.0 log cfu/g after 14 day storage. HP nitrogen treatment did barely affect the content of titrated acidity and soluble solids, and significantly reduced the total phenolics decrease in fresh-cut pears (p < 0.05). Dipping into chemical solution, such as 0.3% ascorbic acid, and 0.5% calcium chloride for 3 min, could decrease the changes in the color and firmness of pear samples during HP (120 MPa) operation, and the combined HP nitrogen with dipping treatment maintained good sensory quality of fresh-cut pears during storage. These results suggested the fresh-cut pears treated by HP nitrogen at 120 MPa for 10 min could be kept in a fresh-like condition for 14 days at 4 °C.Industrial relevanceThrough this study, HP nitrogen (120 MPa) methods reduced the water mobility, antioxidative enzyme (CAT, POD) activities, respiration rate, and ethylene production of fresh-cut fruit and vegetables, and restrained the growth of microorganisms within 14 days at cold storage. This could be a promising approach to preserve fresh-cut pears. It was demonstrated that pressurized nitrogen is a suitable means of preserving fresh-cut pears. However, HP operation has a negative effect on the color and firmness to some degree. The combination treatment between HP nitrogen and dipping in solutions (0.3% AA, 0.5% CC) showed a better means of extending the shelf-life of fresh-cut fruit and vegetables.