Drying sea buckthorn berries (Hippophae rhamnoides L.): Effects of different drying methods on drying kinetics, physicochemical properties, and microstructure

Abstract

Sea buckthorn berries are important ingredients in Chinese medicine and food processing; however, their high moisture content can reduce their shelf life. Effective drying is crucial for extending their shelf life. In the present study, we investigated the effects of hot-air drying (HAD), infrared drying (IRD), infrared-assisted hot-air drying (IR-HAD), pulsed-vacuum drying (PVD), and vacuum freeze-drying (VFD) on the drying kinetics, microstructure, physicochemical properties (color, non-enzyme browning index, and rehydration ratio), and total phenol, total flavonoid, and ascorbic acid contents of sea buckthorn berries. The results showed that the IR-HAD time was the shortest, followed by the HAD, IRD, and PVD times, whereas the VFD time was the longest. The value of the color parameter L* decreased from 53.44 in fresh sea buckthorn berries to 44.18 (VFD), 42.60 (PVD), 37.58 (IRD), 36.39 (HAD), and 36.00 (IR-HAD) in dried berries. The browning index also showed the same trend as the color change. Vacuum freeze-dried berries had the lowest browning index (0.24 Abs/g d.m.) followed by that of pulsed-vacuum–(0.28 Abs/g d.m.), infrared- (0.35 Abs/g d.m.), hot-air–(0.42 Abs/g d.m.), and infrared-assisted hot-air–dried berries (0.59 Abs/g d.m.). The ascorbic acid content of sea buckthorn berries decreased by 45.39, 53.81, 74.23, 77.09, and 79.93% after VFD, PVD, IRD, IR-HAD, and HAD, respectively. The vacuum freeze-dried and pulsed-vacuum–dried sea buckthorn berries had better physicochemical properties than those dried by HAD, IRD, and IR-HAD. Overall, VFD and PVD had the highest ascorbic acid and total phenolic contents, good rehydration ability, and bright color. Nonetheless, considering the high cost of VFD, we suggest that PVD is an optimal drying technology for sea buckthorn berries, with the potential for industrial application.

Cryogenic Pretreatment Enhances Drying Rates in Whole Berries

“…For the vacuum-and air-dried berries, color changes were similar and higher than for the freeze-dried berries, attributed to the reduction in brightness due to the Maillard reaction owing to higher temperatures, longer drying times and oxidation. Similar color results were found for seabuckthorn berries by [59].…”

Effect of Refractance Window™ and oven drying on physicochemical and sensory properties of peach (Prunus persica L.) surplus

“…All drying treatments, overall, exhibited distinctions from the control group and it shows a possible degradation or oxidation of carotenoids, which affected the natural yellow color of peach fruit and causes the arising of brown color as described in RWD production of mango powder ( 70 ) and hot air drying of sea buckthorn berries ( Hippophae rhamnoides L.) ( 37 ).…”

“…Color plays an important role in the sensory acceptance of dried products because it involves good drying processes and has a strong influence on consumer purchase decisions and product value ( 37 ). Visual recognition of a material and its subsequent assessment are part of a global appearance described by the color, and this is the first quality judgment made by a customer ( 38 ); for this reason, color is the most important appearance attribute ( 39 ).…”

Optimization of the pulsed vacuum drying process of green walnut husk through temperature adaptive regulation

“…These values were ∼10% higher than those obtained from other variable temperature drying processes. This increase in active substances can be attributed to the rupture in the cellular structure of GWH caused by the PVD drying process, reducing the activity of polyphenol oxidase and peroxidase, allowing more compounds to be released (Geng et al., 2023). This finding aligns with the SEM microstructure study, where alternating cycles of pressure and varying high‐temperature maintenance times resulted in varying degrees of damage to the cell structure of GWH.…”