Evaluation of the impact of different drying methods on the phenolic compounds, antioxidant activity, and in vitro digestion of green coffee beans

Abstract

We investigated the effects of different drying methods (room temperature drying, heat pump drying, freeze drying, microwave vacuum drying [MVD], and combined microwave power vacuum drying) on the active ingredients of green coffee beans. We specifically focused on eleven phenolic acids, total phenolic content (TPC), total flavonoid content, antioxidant activity, polyphenol oxidase (PPO), the inhibition of linoleic acid peroxidation (LPO), and enzyme activity, and the bio‐accessibility in vitro and bioavailability of phenolics and antioxidant activities were also evaluated. MVD‐treated beans had the lowest PPO activity and the highest contents of 5‐caffeoylquinic acid (1.39 g/100 g DW), 3‐feruloylquinic acid (0.25 g/100 g DW), 4‐feruloylquinic acid (0.25 g/100 g DW), 5‐feruloylquinic acid (1.52 g/100 g DW), and TPC (5.98 g GAE/100 g DW), and the highest antioxidant activity. MVD was the least time‐consuming (0.63 hr/kg) and energy‐consuming (1.88 kwh/kg) method. Moreover, the strongest inhibition of LPO and α‐glucosidase was observed in MVD‐treated beans. Thus, MVD is suggested to be the most suitable drying technique for the preservation of phenolic compounds and bioactivities of green coffee beans.

Comprehensive evaluation of physicochemical properties and antioxidant activity of B. subtilis‐fermented polished adlay subjected to different drying methods

“…And the highest flavonoid content was found in IRD samples, approximately 1.60 times higher than that of FVD. It was supported by Cheng et al (2019), who also found that FVD resulted in less phenolic and flavonoid contents of green coffee beans compared with MVD and HAD, which was consistent with our results. Heating created more destruction of the tissue, which in turn led to the thermal degradation or transformation into simpler phenolic compounds, and polymerization or oxidation of phenolic and flavonoid compounds (Si et al, 2016).…”

Impact of different drying methods on the drying time, energy, and quality of green peas

“…The comparison of means between different treatments is shown in Also, following the FD method, the TFC in the HA-MW dryer was higher than other dryers (HA-IR, MW, IR, HA, and SD), because the moderate heat (resulting from the MW power and air temperature at the same time) leads to the swelling of raw materials, softening and acceleration of the rupture of plant tissue, decomposition of cellular components and thus, facilitating the extraction of flavonoids (Cheng et al, 2019;Kubra et al, 2015). This result is consistent with the results of and Li et al (2019).…”

Freeze-Drying of Plant-Based Foods

“…The use of FD is not limited to fruits and vegetables; it has been used to produce dried specialty foods from plant sources such as coffee, tea, and spices [4,7,8,11,[58][59][60][61][62][63][64][65].…”

“…Kraujalyte et al [62] found that instant tea produced by FD had high concentration of volatile compounds (318.65 ng/g), which was comparatively two to five times higher than those produced by other drying methods (68.60 to 143.33 ng/g). In the case of coffee, the content of phenolic acids in coffee beans after FD was reported to increase by 41% more than in fresh green coffee beans [59]. A FD process for coffee has been recently designed using mathematical modeling to optimize energy efficiency and preserve the important flavors and nutrients [9].…”