Microwave assisted fluidized bed drying of bitter gourd: Modelling and optimization of process conditions based on bioactive components

Drying and Bioactive Compounds Extraction of Ripe and Unripe Yerba-Mate Fruits

Yerba-mate fruits (Ilex paraguariensis St. Hil), are a source of phytochemicals, but currently have low economic value. This investigation aims to study the changes during the physiological development of the fruits, the mass transfer in the drying process, and the composition of dried fruits and seed oil to upcycle and enhance their economic value and explore new product applications. The drying process was evaluated under: 60, 80 and 110 °C. The development of yerba-mate fruits was monitored over 90 days, showing increases in diameter, mass, and density, along with darkening and color shifts from green to blueish/reddish. Drying times decreased with increasing temperatures, unripe fruits exhibited higher drying rates, and diffusivity coefficient was primarily influenced by temperature. Phytochemical analysis revealed higher saponin levels in unripe fruits and higher anthocyanin content in ripe fruits, with drying temperatures affecting these compounds. Yerba-mate fruit development, drying conditions, and ripening stages impacted their phytochemical profiles and color, providing insights for optimized processing and use.

Effect of microwave heating on the phenolic and carotenoid composition and antioxidant properties of Momordica charantia

Momordica charantia L. (MC) is a widely consumed vegetable known for its nutritional benefits, as it is a rich source of carotenoids and phenolic compounds. Various cooking methods are use in domestic settings, including microwave cooking. Therefore, it is crucial to investigate the impact of microwave cooking on the bioactive composition of MC. MC fruits were subjected to microwave heat for 5-, 10-, and 15-min. High performance liquid chromatography was used to identify of carotenoids and phenolic compounds, and total bioactive composition and antioxidant assays were conducted using spectroscopic techniques. There were 17 carotenoids and chlorophylls identified in MC fruit, including lutein, violaxanthin, antheraxanthin, pheophytin a, and all-E-β-carotene. The levels of these compounds significantly increased upon exposure to microwave heating. Similarly, 16 phenolic compounds were identified, and their amounts increased during the treatments, except for 3-hydroxyphloretin-6'-hexoside, quercetin-3-(6″-acetyl)-glucoside, petunidin-3-(6″-acetyl)-glucoside and petunidin-3-(6″-acetyl)-glucoside. The sample subjected to microwave treatment for 15 min exhibited the highest concentration of total phenolic compounds (TPC) at 754.5 mg/100g. The total flavonoid content (TFC) reached 94.6 mg/100g after 10 min of treatment. Additionally, the maximum total anthocyanin content, reported as 54.8 mg/L, was observed in the sample exposed to microwave heating for 15 min.

Non-covalent complexes of lutein/zeaxanthin and whey protein isolate formed at different pH levels: Binding interactions, storage stabilities, and bioaccessibilities

Lutein (Lut) and zeaxanthin (Zx) are promising healthy food ingredients; however, the low solubilities, stabilities, and bioavailabilities limit their applications in the food and beverage industries. A protein-based complex represents an efficient protective carrier for hydrophobic ligands, and its ligand-binding properties are influenced by the formulation conditions, particularly the pH level. This study explored the effects of various pH values (2.5-9.5) on the characteristics of whey protein isolate (WPI)-Lut/Zx complexes using multiple spectroscopic techniques, including ultraviolet-visible (UV-Vis), fluorescence, and Fourier transform infrared (FTIR) spectroscopies and dynamic light scattering (DLS). UV-Vis and DLS spectra revealed that Lut/Zx were present as H-aggregates in aqueous solutions, whereas WPI occurred as nanoparticles. The produced WPI-Lut/Zx complexes exhibited binding constants of 104-105 M-1, which gradually increased with increasing pH from 2.5 to 9.5. FTIR spectra demonstrated that pH variations and Lut/Zx addition caused detectable changes in the secondary WPI structure. Moreover, the WPI-Lut/Zx complexes effectively improved the physicochemical stabilities and antioxidant activities of Lut/Zx aggregates during long-term storage and achieved bioaccessibilities above 70% in a simulated gastrointestinal digestion process. The comprehensive data obtained in this study offer a basis for formulating strategies that can be potentially used in developing commercially available WPI complex-based xanthophyll-rich foods.

Quality and Process Optimization of Infrared Combined Hot Air Drying of Yam Slices Based on BP Neural Network and Gray Wolf Algorithm

In this paper, the effects on drying time (Y1), the color difference (Y2), unit energy consumption (Y3), polysaccharide content (Y4), rehydration ratio (Y5), and allantoin content (Y6) of yam slices were investigated under different drying temperatures (50-70 °C), slice thicknesses (2-10 mm), and radiation distances (80-160 mm). The optimal drying conditions were determined by applying the BP neural network wolf algorithm (GWO) model based on response surface methodology (RMS). All the above indices were significantly affected by drying conditions (p < 0.05). The drying rate and effective water diffusion coefficient of yam slices accelerated with increasing temperature and decreasing slice thickness and radiation distance. The selection of lower temperature and slice thickness helped reduce the energy consumption and color difference. The polysaccharide content increased and then decreased with drying temperature, slice thickness, and radiation distance, and it was highest at 60 °C, 6 mm, and 120 mm. At 60 °C, lower slice thickness and radiation distance favored the retention of allantoin content. Under the given constraints (minimization of drying time, unit energy consumption, color difference, and maximization of rehydration ratio, polysaccharide content, and allantoin content), BP-GWO was found to have higher coefficients of determination (R2 = 0.9919 to 0.9983) and lower RMSEs (reduced by 61.34% to 80.03%) than RMS. Multi-objective optimization of BP-GWO was carried out to obtain the optimal drying conditions, as follows: temperature 63.57 °C, slice thickness 4.27 mm, radiation distance 91.39 mm, corresponding to the optimal indices, as follows: Y1 = 133.71 min, Y2 = 7.26, Y3 = 8.54 kJ·h·kg-1, Y4 = 20.73 mg/g, Y5 = 2.84 kg/kg, and Y6 = 3.69 μg/g. In the experimental verification of the prediction results, the relative error between the actual and predicted values was less than 5%, proving the model's reliability for other materials in the drying technology process research to provide a reference.