Effect of berry size and sodium hydroxide pretreatment on the drying characteristics of blueberries under infrared radiation heating

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.

Modeling of drying and ameliorative effects of relative humidity (RH) against β-carotene degradation and color of carrot (Daucus carota var.) slices

Drying and β-carotenes retention kinetics were predicted using models in relative humidity (RH) drying condition. This was achieved by drying carrot slices using RH-convective hot-air dryer at 60, 70 and 80 °C under RH (10% 20% and 30%) conditions at 2.0 m/s air velocity. Three mathematical models describing thin layer were compared to their goodness of fit in terms of coefficient of correlation (R²), root mean square error (RMSE) and reduced Chi square ( χ 2 ). The Wang and Singh model could satisfactorily describe RH-convective drying of carrot slices with R², RMSE and χ 2 in the ranges of 0.996-0.999, 5.4 × 10^-4-9.4 × 10^-4 and 0.0150-0.03353 respectively. The results reveal that a range of 3.61-8.2% retention of β-carotene was observed for every 10% increase in RH in various drying air temperature. In summary, higher temperatures were mainly responsible for β-carotenes degradation however this can be mitigated when drying is conducted under higher RH.

Bioactive Compounds of Blueberries: Post-Harvest Factors Influencing the Nutritional Value of Products

Blueberries, besides having commonly-recognized taste properties, are also a valuable source of health-promoting bioactive compounds. For several decades, blueberries have gained in popularity all over the world, and recent years have seen not only an increase in fresh consumption, but also in the importance of blueberries for the processing industry. Blueberry processing mostly consists of freezing and juicing. Recently, more attention has been drawn to dewatering and drying, which are promising areas for developing novel blueberry products. Processing affects each biologically-active compound in a different way, and it is still unknown what changes those compounds undergo at the molecular level after the application of different processing technologies. This work presents the most recent state of knowledge about the pre-treatment and processing methods applied to blueberries and their influence on the content of biologically-active compounds. The presentation of methods is preceded by a brief overview of the characteristics of the blueberry species, a description of the chemical composition of the fruit and a short note about the main growing areas, production volumes and the management of fruit crops.

Sun drying of seedless and seeded grapes

In this study, sun drying behaviour of seedless and seeded grapes was investigated. The drying study showed that the times taken for drying of seedless and seeded grapes of berry size of 1.72 cm and 2.20 cm thicknesses from the initial moisture contents of 78.2% and 79.5% (w.b.) to final moisture content of around 22% (w.b.) were 176 and 228 h in open sun drying, respectively. The drying data were fitted to 12 thin-layer drying models. The performance of these models were compared using the determination of coefficient (R(2)), mean relative percent error (P), reduced chi-square (χ (2)) and root mean square error (RMSE) between the observed and predicted moisture ratios. The results showed that Midilli et al. model was found to satisfactorily describe the sun drying curves of seedless and seeded grapes. The effective moisture diffusivity values were estimated from Fick's diffusion model by 1.02 × 10(-11) and 1.66 × 10(-11) m(2)/s for seeded and seedless grapes.