Establishment of Lower Hygroscopicity and Adhesion Strategy for Infrared-Freeze-Dried Blueberries Based on Pretreatments Using CO2 Laser in Combination with Ultrasound

Improvement of the drying quality of blueberries by catalytic infrared blanching combined with ultrasound pretreatment

This paper investigated the effect of catalytic infrared blanching combined with ultrasound pretreatment on quality and waxy structure of blueberries. Different blueberry samples were prepared, including control (untreated) and samples treated by hot water blanching (HB), catalytic infrared blanching (CIB), ultrasound-catalytic infrared blanching (US-CIB), and catalytic infrared blanching-ultrasound (CIB-US). The effect of different pretreatments on the microstructure of blueberry epidermis was studied. The drying time of blueberries after HB, US-CIB, and CIB-US was decreased by 11.61%, 17.54%, and 17.27%, respectively, compared with control (33.75 h), and drying efficiency was significantly improved. Blueberries after pretreatments had higher content of polyphenol and anthocyanin, with an increase of 29.51-44.21% in phenol and 8.81-20.80% in anthocyanin, the antioxidant capacity of blueberries was also better than control and CIB enhanced the antioxidant capacity of blueberries. CIB-US can be used as an efficient pretreatment method for blueberry drying.

Potential of CO2 laser for food processing: Applications and challenges

Laser food processing has the breath-taking potential to revolutionize the industry in many aspects. Among the different laser configurations, CO₂ laser has received special attention due to its relative high efficiency in power generation, its high-power output and its laser beam wavelength, infrared, which is strongly absorbed by water, the main component of food materials. Over the last 50 years, different uses of CO₂ laser for processing foods have been proposed so far, including cooking, broiling and browning, selective laser sintering, marking, microperforation for improving downstream mass transfer operations (e.g. infusion, diffusion, marinating, salting, drying, extraction), cutting and peeling, and microbial surface decontamination. The present work is a review of the state of the art of the use of CO₂ laser for food processing that covers the main characteristics and mechanisms of this technology, as well as the most important published results regarding its applications in the agri-food sector, highlighting the main challenges to bring out its full potential in the coming years.

Inhibition of nitrite in prepared dish of Brassica chinensis L. during storage via non-extractable phenols in hawthorn pomace: A comparison of different extraction methods

The objective of this study was to investigate whether non-extractable phenols (NEP) prepared by acid, enzymatic and alkaline hydrolysis in hawthorn pomace could reduce the nitrite content in prepared vegetable dishes (PVDs), analyzed through ultraviolet spectrophotometry and high performance liquid chromatography. The results showed that on the seventh day of storage, compared with the control group, the nitrite content of the samples added with acid, enzymatic and alkaline hydrolyzed NEP decreased by 40%, 28% and 19%, respectively, depending on different contents and chemical compositions of the recovered NEP. The nitrite reduction caused by NEP was mainly attributed to the growth inhibition of microorganisms producing nitrite (e.g., Escherichia coli and Pseudomonas aeruginosa) and the direct scavenging effect on nitrite, rather than affecting the activities of nitrate reductases and nitrite reductases in plant tissues. Use of hawthorn pomace is potentially a promising option to reduce nitrite in PVDs.

Effects of chitosan coating on freeze-drying of blueberry enhanced by ultrasound pre-treatment in sodium bicarbonate medium

Sodium bicarbonate medium ultrasound pre-treatment can enhance the freeze-drying process of blueberries, but the quality of dried products cannot meet the actual production needs. To yield higher quality products, chitosan coating was applied in blueberry sodium bicarbonate medium ultrasound pre-treatment enhanced freeze-drying process. The improvement effect of different chitosan coating methodologies on the procedure of blueberry freeze-drying, enhanced by ultrasound pre-treatment in sodium bicarbonate medium, was investigated. These include: chitosan solution soaking alone (CH-A), chitosan medium ultrasound treatment (US-CH), first sodium bicarbonate medium ultrasound treatment then chitosan solution soaking (US-NaHCO₃ + CH) and first sodium bicarbonate soaking followed by chitosan medium ultrasound treatment (NaHCO₃ + US-CH). While the treatments that presoaking in sodium bicarbonate solution (NaHCO₃-A), water medium ultrasound treatment (US-W) and sodium bicarbonate medium ultrasound treatment (US-NaHCO₃) were used as the control groups. Results demonstrated that ultrasound treatment and sodium bicarbonate soaking have positive effect on improving the freeze-drying characteristics of blueberries, while chitosan coating has a negative effect. Chitosan coating has a significant effect on strengthening limit effect of blueberry skin on juice overflow and weakening moisture absorption capacity of dried blueberry. US-NaHCO₃ + CH pretreatment yielded the best results for blueberry freeze-drying.