关键词: 聚乳酸；薄荷精油；樱桃；保鲜；低场核磁共振

Abstract: Three biodegradable packaging films were prepared by a casting method using polylactic acid/poly-3-hydroxybut-yrate-co-4-hydroxybutyrate (PLA/P34HB) as the substrate and diatomite loaded with peppermint essential oil as the sustained release antibacterial, namely PLA/P34HB, peppermint essential oil-PLA/P34HB, and peppermint essential oil-diatomite-PLA/P34HB films, and their performance was tested. Furthermore, their efficiency in preserving the quality of ‘Meizao’ sweet cherries was explored by measuring gas composition inside the packages and mass loss percentage during storage at (4 ± 1) ℃ as well as analyzing the water status of sweet cherries using low-field nuclear magnetic resonance (LF-NMR). Unpackaged samples were used as control for comparison. The results showed that the oxygen transmission rate (OTR) of the film with diatomite loaded with peppermint essential oil was 290.45 cm3/(m2·d·0.1 MPa), higher than that of PLA/P34HB film, 250.37 cm3/(m2·d·0.1 MPa). The improvement in OTR was beneficial to maintain the quality of cherries. LF-NMR analysis showed that the peppermint essential oil-diatomite-PLA/P34HB film maintained the water activity of cherries well. On day 12 of storage, the peak area percentage of bound water was about 2 times as high as that of the control group, which indicates delaying fruit spoilage and prolonging shelf life.

Key words: polylactic acid; peppermint essential oil; cherry; preservation; low-field nuclear magnetic resonance