Influence of sweeping frequency ultrasonic pretreatment on pulsed vacuum drying characteristics and microstructure of okra based on real‐time monitoring

Study of okra pectin prepared by sweeping frequency ultrasound/freeze-thaw pretreatment on corrosion inhibition of ANSI 304 stainless steel in acidic environment

Green and efficient metal corrosion inhibitors are very essential, and natural okra pectin (OP) can fulfill this need with rational use of resources. OP was prepared by water-alcohol extraction method after freeze-thaw pretreatment (FTP)/sweeping frequency ultrasound pretreatment (SFUP), and used for corrosion inhibition of ANSI 304 stainless steel (304 SS) in 1 M hydrochloric acid (HCl). The molecular weight, hydrodynamic diameter and monosaccharide composition of OP were analyzed to determine the factors on the corrosion inhibition of 304 SS. During SFUP of okra, the time-domain variation of ultrasound field was monitored by piezoelectric film sensor, its frequency-domain variation was monitored by a hydrophone, and analyzed respectively by oscilloscope and spectrum analyzer. Static weight-loss method, electrochemical and microscopic analyses were used to evaluate the corrosion inhibition efficiency of OP at temperatures (25, 30, 40, 50 °C) and concentrations (0, 0.2, 0.5, 1, 2 g·L-1) to optimize corrosion inhibition performance. It was found that OP by FTP and SFUP had higher corrosion inhibition efficiency on metals in acidic environment. According to static weight-loss method, the corrosion inhibition efficiency of OP with concentration of 2 g·L-1 (25 °C) was improved to 90.27 % in the FTP group and 93.53 % in the SFUP group, which 5.14 % and 8.93 % higher than Control (without pretreatment). Meanwhile, the corrosion inhibition efficiency decreased gradually as the temperature increased. OP corrosion inhibition performance fit Langmuir adsorption isothermal model as a mixed adsorption based on physical adsorption. It was a mixed inhibitor to protect 304 SS from corrosion.

Role of dehydration technologies in processing for advanced ready-to-eat foods: A comprehensive review

Advanced ready-to-eat foods, which can be consumed directly or only need simple processed before consumption, refer to the products that processing with cutting-edge food science and technology and have better quality attribute. Cold chain and chemical addition are commonly used options to ensure microbial safety of high moisture advanced ready-to-eat foods. However, this requires freezing/thawing processing at high cost or has undesirable residue. Dehydration treatment has the potential to compensate those shortcomings. This article reviewed the positive effects of dehydration on advanced ready-to-eat foods, current application status of dehydration technologies, novel dehydration related technologies and the pathogenic bacteria control of products. It is observed that dehydration treatment is receiving increasing attention for ready-to-eat foods including space foods, 3 D-printed personalized foods and formula foods for special medical purposes. Recently developed drying technologies such as pulsed spouted microwave freeze-drying and infrared freeze-drying have attracted much interest due to their excellent drying characteristics. Finally, intelligent drying, dehydration-nano-hybridization and dehydration-induced multi-dimensional modification technology are some of the emerging R and D areas in this field.