In order to predict the moisture ratio of in-shell peanut during infrared-assisted spouted bed drying, the effects of drying temperature (55, 60, 65 and 70 ℃), inlet airflow rate (16, 17, 18 and 19 m/s) and the amount of glidant (1.0, 1.5, 2.0 and 2.5 kg) on the drying time and drying rate were investigated. A BP neural network model whose topological structure was “4-11-1” was established using drying temperature, inlet airflow rate, the amount of glidant and drying time as the input layers, and the moisture ratio of peanut as the output layer. The number of nodes in the hidden layer of the established network was 11. The results showed that drying temperature and inlet airflow rate were the main factors affecting the moisture ratio of fresh in-shelled peanut. Increasing the inlet airflow rate or drying temperature could effectively shorten the drying time and improve drying efficiency. Using the Levenberg-Marquardt (LM) algorithm and tansig-purelin as the training function and the network transfer function, respectively, the BP neural network model was obtained after finite training. The determination coefficient (R²) between the predicted value and the experimental value was 0.99, and the mean square error was 0.02. Compared with the traditional classical model, the BP neural network model allowed rapid and accurate prediction of the moisture ratio. This model can provide a theoretical basis and technical support for on-line prediction of moisture ratio of fresh in-shell peanut during infrared-assisted spouted bed drying.

In order to study the effect of ultrasonic pretreatment on the structure of peanut protein isolate microgel particles (PPIMP) and the characteristics of Pickering emulsion stabilized by it, the structural changes of PPIMP after ultrasonic treatment at a 500 W power for 10, 20, 30 and 40 min were evaluated in terms of its particle size, zeta potential, surface hydrophobicity, infrared spectrum, and emulsifying properties and the particle size distribution, stability index and rheological properties of the Pickering emulsion were systematically investigated. The results showed PPIMP pretreated by ultrasonic for 20 min had the smallest particle size, and the largest surface hydrophobicity, emulsifying capacity and emulsion stability. Meanwhile, the relative content of α-helix in PPIMP increased, the relative content of β-sheet decreased, the hydrogen bonds between protein molecules were destroyed, and the protein molecules were unfolded. In addition, Pickering emulsions with oil phase volume fractions of 65%, 70%, 75%, and 80% stabilized by PPIMP exhibited a typical non-Newtonian pseudoplastic behavior, and the Pickering emulsion with 80% phase oil presented the best stability among all prepared Pickering emulsions. The results of this study confirmed that PPIMP can be used as an effective Pickering emulsion stabilizer, which is helpful for the preparation of PPIMP-based Pickering emulsion with high stability and its application in the food industry.

This experiment investigated the effects of soaking treatment (for 45 min) with different color fixatives (0.1 g/100 mL citric acid, 0.2 g/100 mL citric acid, 0.2 g/100 mL sodium bicarbonate, and 1.0 g/100 mL sodium chloride solution) after blanching for two minutes on the browning inhibition and drying characteristics of daylily buds during hot air drying. The color, nutrient composition and microstructure of dried products were characterized, and the chemical structure was analyzed by Fourier transform infrared (FTIR) spectroscopy. The pretreatment conditions for dried daylily buds with improved commodity value were determined using principal component analysis (PCA). Results showed that the browning inhibitory effect of steam blanching was better than that of hot water blanching. The decreasing order of the browning inhibitory effects of color fixatives was 0.2 g/100 mL citric acid solution > 0.1 g/100 mL citric acid solution > 1.0 g/100 mL sodium chloride solution > 0.2 g/100 mL sodium bicarbonate solution. Daylily buds pretreated with 0.2 g/100 mL citric acid solution showed the highest drying rate, and the dried product had high rehydration ratio. Collectively, the dried product prepared by steaming followed by soaking with 0.2 g/100 mL citric acid solution had good quality with respect to color, flavonoid and polyphenol contents and microstructure. PCA indicated that the contents of polyphenols and 5-hydroxymethylhydrate were highly correlated with color and browning degree, and chewiness had the highest correlation with hardness. Out of the eight principal components, two (the first one included polyphenol content, browning degree and color difference, and the second one included hardness and 5-hydroxymethylfurfural content) were extracted, which could well reflect the comprehensive information on the quality of dried daylily buds. This study can provide theoretical and technical references for the deep processing of daylily buds.

In this study, a composite hydrogel system was constructed by cross-linking of primary network hydrogels of gelatin (GE) and sodium hexametaphosphate (SHMP) by transglutaminase (TGase) after addition of Lactobacillus plantarum in order to improve its viability and bioavailability. The experimental results showed that the modification by SHMP and TGase changed the gel strength, water distribution state, and gel network structure of gelatin, and reduced the gelation rate, so that the three-dimensional network structure of the gel was more stable, and the intermolecular forces of the composite hydrogel was stronger, contributing to the resistance of the encapsulated L. plantarum to adverse environments. The presence of L. plantarum was found to slightly disrupt the ordered structure of the hydrogel by scanning electron microscopy (SEM). Endogenous fluorescence spectroscopy analysis showed that addition of L. plantarum resulted in the exposure of the extended region containing tryptophan within the GE molecule to a more polar environment. The steric effect occurred during the gelling process, delaying the formation of covalent crosslinks and physical interactions between the biopolymer molecules, which led to changes in their microstructure. Simulated gastrointestinal digestion tests and storage tests showed that L. plantarum encapsulated in GE/SHMP/TGase gels had better survival rates and gastrointestinal release properties compared to single GE-based hydrogels. It was confirmed that GE/SHMP/TGase hydrogels had a better protective effect on L. plantarum. In conclusion, this study has explored a new method for preparing GE-based hydrogels as a delivery system for probiotics, which will provide a theoretical basis for the development of probiotic functional foods.