Development of Fermented Peach–Apricot Mixed Juice and Study of Its Storage Stability

To address the challenge of postharvest spoilage in flat peaches and white apricots, we developed fermented peach–apricot mixed juice (PAMJ) using these fruits as raw materials through multi-strain synergistic fermentation. Its fermentation processes were optimised through uniform design and single-factor experiments. The flavour characteristics of PAMJ were analysed using an electronic nose, an electronic tongue, gas chromatography–mass spectrometry (GC-MS) and sensory evaluation indices. PAMJ demonstrated optimal performance in terms of peach–apricot flavour profile, sweetness-sourness balance, and overall acceptability, achieving the highest sensory scores. Additionally, GC-MS analysis identified 116 volatile organic compounds, with PAMJ exhibiting the highest contents of terpenes and ketones. PAMJ was identified as the optimal fermentation matrix. Subsequently, response surface methodology was used to optimise its fermentation parameters. PAMJ represented a post-mixing fermentation system wherein peaches and apricots were initially mixed and subsequently fermented with a bacterial consortium comprising Limosilactobacillus fermentum (15%), Lactobacillus acidophilus (10%), Levilactobacillus brevis (34%), Lacticaseibacillus paracasei subsp. Tolerans (13%), Lactiplantibacillus plantarum subsp. plantarum (13%) and Limosilactobacillus reuteri (15%). After fermentation with an initial inoculum concentration of 5.2 × 10⁶ CFU/mL at 37 °C for 20 h, the initial soluble solid content of PAMJ increased from 16 to 16.5 °Brix, superoxide dismutase (SOD) activity increased from 250 to 295 U/mL and the number of volatile compounds (NVC) increased from 60 to 66. Furthermore, the storage stability of pasteurised PAMJ was evaluated by monitoring SOD and NVC at 5-day intervals. The data were analysed using kinetic and Arrhenius equations. The shelf life of PAMJ at 4 °C, 25 °C and 37 °C was 69, 48 and 39 days when NVC was used as the index and 99, 63 and 49 days when SOD activity was used as the index, respectively. These findings indicate that fermentation with lactic acid bacteria exerts positive effects on the quality of mixed juices, providing a novel strategy for processing speciality fruits in Xinjiang.