Combined effect of sonication and equilibrium-modified atmosphere packaging to improve storage stability of "Angelino" plums during extended storage

Abstract

This work focuses on the combined effects of ultrasound treatment (100, 200, and 300 W for 5 min) and equilibrium-modified atmosphere packaging (EMAP) to enhance the storage stability based on pH, aw, gas compositions in headspace, color changes (L*, a*, b*), organic acids, and texture profile of fresh “Angelino” plums for 120 days at 4°C. The results were expressed that pH values were increased (3.19-initial to 3.69/300 W–3.86/control) and Brix values were decreased (16.9-initial to 14.70/control–15.3/100 W) during storage. At the end of the storage, except the control group, O2 in the headspace decreased from 20.9%-initial to 16%/300 W–18.5%/200 W and CO2 was accumulated from 0.03%-initial to 4.9/%200 W–6.5%/300 W. Hardness (from 11,677, 6124 gf), gumminess (from 4344 g to 4335–6715 g), and chewiness (from 3831 and 2326–2638 g) consistently decreased as a function of storage. The hardness of “Angelino” plums had been maintained after the sonication combined with EMAP compared with the control during storage. The 100 W and 200 W sonication could significantly delay the degradation of malic (from 8957 to 4227–4236 mg/L) and tartaric (1796 to 1703–1722 mg/L) acid in flesh plums, but not citric acid and malonic acid over the storage period. The sonication (200 W) combined with EMAP enhanced the storage stability. Practical Applications: This research demonstrates that packaging fresh Angelino plums with micro-perforated lid films and subjecting them to sonication can enhance their storage stability, allowing for longer distribution via sea freight at a considerably reduced cost compared with air freight. This can potentially expand the producer's reach in international markets. Sonication had great potentials in stabilizing cell wall and maintaining hardness in the plums during storage. Moreover, the application of sonication, especially 200-W for enhancing storage stability without any detrimental effects on physicochemical properties and natural main organic acids (malic acid) of “Angelino” plums during the storage.