This study investigated the effectiveness of novel and innovative pretreatments (NIP) using thermoultrasound and microwave-mediated freeze-thaw (TSFT, MWFT) for improving the mid-infrared drying of dragon fruit, as compared with recent pretreatment methods using cold plasma (CP), ultrasound (US), edible coating (EC), microwave and infrared blanching (MWB, IRB). Except for EC, all selected pretreatment methods induced ultrastructural changes, resulting in accelerated moisture removal and reduced drying time. In addition, all the pretreatments also induced modifications in colour, structure, and texture, with NIP demonstrating superior outcomes for colour, rehydration, shrinkage, and hardness properties. Blanching pretreatments (MWB and IRB) improved phytochemical and antioxidant properties, including total phenolics, betacyanin, betaxanthin, CUPRAC, hydroxyl radical scavenging, and ABTS, except for ascorbic acid, which was better preserved by TSFT. The study underscores the time-saving and quality enhancement advantage of NIP, over other recent methods for improving mid-infrared drying.
Red dragon fruit peel is a pectin-rich fruit waste that is a potential source of prebiotics and whose different sources and structures will influence its prebiotic function. Thus, we compared the effects of three extraction methods on the structure and prebiotic function of red dragon fruit pectin, the results showed that the citric acid extracted pectin produced a high Rhamnogalacturonan-I (RG-I) region (66.59 mol%) and more side-chains of Rhamnogalacturonan-I ((Ara + Gal)/Rha = 1.25), which can promote bacterial proliferation significantly. The side-chains of Rhamnogalacturonan-I may be an important factor in that pectin can promote the proliferation of B. animalis. Our results provide a theoretical basis for the prebiotic application of red dragon fruit peel.
Yanhong Liu,Xiwang Mu,Hui Wang,Mingyue Wang,Lingling Zhang,Guangrao Chen,Shuo Wang
Perishable food poses significant food safety hazards and threatens public health. Consequently, pH indicator films have garnered considerable interest due to their potential for early detection of food spoilage. This research used red-fleshed pitaya peel powder as raw material, and betalaines were extracted using DES composed of choline chloride and citric acid as hydrogen bond donors and acceptors, respectively. The extraction conditions were optimized by response surface experiment, and the content of betalaine (BT) extracted in the verification experiment was 4.39 mg/g. The film was prepared using the solvent casting technique. The above DES/BT solution (DES/BT) was added into sodium alginate (SA) and sodium carboxymethyl cellulose (CMC) pH indicator films, and the effects of DES/BT on the physicochemical, optical and surface properties of the films were studied. The results showed that the film with 0.7 mL (1.4 %, v/v) DES/BT had the best tensile strength(23.14 MPa), water solubility(16.02 %), and water vapor permeability (7.64×10 −5 g*m*m −2 *Pa*h −1 ). The addition of DES and DES/BT made the film surface texture uniform and wrinkle-free and the UV transmittance decreased from 73.27 % to 61.83 %. Experiments on the film in different pH solutions showed that the film had a colorimetric response. Overall, the incorporation of DES/BT into the films presents significant potential for monitoring food freshness.
危险品化学品经营许可证（带存储）