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. 2022 Jan 24;11(3):318.
doi: 10.3390/foods11030318.

Pulsed Vacuum Drying of Pepper (Capsicum annuum L.): Effect of High-Humidity Hot Air Impingement Blanching Pretreatment on Drying Kinetics and Quality Attributes

Zhihua Geng  1 , Xiao Huang  1 , Jun Wang  1   2 , Hongwei Xiao  1   3 , Xuhai Yang  1 , Lichun Zhu  1 , Xiaochen Qi  1 , Qian Zhang  1 , Bin Hu  4
Affiliations

Pulsed Vacuum Drying of Pepper (Capsicum annuum L.): Effect of High-Humidity Hot Air Impingement Blanching Pretreatment on Drying Kinetics and Quality Attributes

Zhihua Geng et al. Foods. .

Abstract

With a high moisture content, fresh peppers are perishable and rot easily. Drying is essential for shelf-life extension. The natural thin wax layer on the pepper surface hinders moisture transfer. Traditionally, chemical dipping or mechanical pricking is used to remove this wax layer. However, in chemical dipping, chemical residues can trigger food-safety issues, while the low efficiency of mechanical pricking hinders its industrial application. Feasible pretreatment methods are advantageous for industrial use. Here, an emerging pretreatment technique (high-humidity hot-air impingement blanching, HHAIB) was used for peppers before drying and its effects on drying characteristics, microstructure, and polyphenol oxidase (PPO) activity were explored. The impact of drying temperature on color parameters and red pigment content of pulsed-vacuum-dried peppers was also evaluated. PPO activity was reduced to less than 20% after blanching at 110 °C for 60 s. HHAIB reduced drying time and PPO activity and promoted chemical-substance release. Effective water diffusivity was highest (5.01 × 10-10 m2/s) after blanching at 110 °C for 90 s, and the brightness value and red pigment content were highest (9.94 g/kg) at 70 °C. HHAIB and pulsed vacuum drying are promising pretreatment and drying methods for enhancing the drying rate and quality of red peppers.

Keywords: drying characteristics; high-humidity hot-air impingement blanching (HHAIB); kinetic modeling; polyphenol oxidase activity; pulsed vacuum drying (PVD); transmission electron microscopy (TEM).

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Schematic overview of the experimental setup.
Figure 2
Figure 2
Schematic diagram of equipment used for high-humidity air impingement blanching.
Figure 3
Figure 3
Schematic diagram of the device used for drying.
Figure 4
Figure 4
Effects of HHAIB (high-humidity hot-air impingement blanching) on residual activity of PPO (polyphenol oxidase). Notes: different letters in the figure reveal significant differences (p < 0.05) according to the Duncan test.
Figure 5
Figure 5
Drying kinetics curve of pepper at different blanching temperatures. Notes: different letters in the figure reveal significant differences (p < 0.05) according to the Duncan test.
Figure 6
Figure 6
Drying kinetics curve of pigment pepper at different blanching times. Notes: different letters in the figure reveal significant differences (p < 0.05) according to the Duncan test.
Figure 7
Figure 7
Transmission electron microscope (TEM) images of red pepper samples under different HHAIB treatment times. CK—control group; CW—cell wall; Pt—plastid; M—mitochondria.
See this image and copyright information in PMC

References

    1. Wang H., Zhang Q., Mujumdar A.S., Fang X.M., Wang J., Pei Y.P., Wu W., Zielinska M., Xiao H.W. High-Humidity Hot Air Impingement Blanching (HHAIB) Efficiently Inactivates Enzymes, Enhances Extraction of Phytochemicals and Mitigates Brown Actions of Chili Pepper. Food Control. 2020;111:107050. doi: 10.1016/j.foodcont.2019.107050. - DOI
    1. Food and Agriculture Organiszation (FAO) Fao Stat Database. [(accessed on 3 February 2021)]. Available online: http://www.fao.org/faostat/en/#data/QC.
    1. Morm E., Ma K., Horn S., Debaste F., Haut B., In S. Experimental Characterization of the Drying of Kampot Red Pepper (Piper nigrum L.) Foods. 2020;9:1532. doi: 10.3390/foods9111532. - DOI - PMC - PubMed
    1. Wang J., Yang X.H., Mujumdar A.S., Wang D., Zhao J.H., Fang X.M., Zhang Q., Xie L., Gao Z.J., Xiao H.W. Effects of Various Blanching Methods on Weight Loss, Enzymes Inactivation, Phytochemical Contents, Antioxidant Capacity, Ultrastructure and Drying Kinetics of Red Bell Pepper (Capsicum annuum L.) LWT Food Sci. Technol. 2017;77:337–347. doi: 10.1016/j.lwt.2016.11.070. - DOI
    1. Xiao H.W., Bai J.W., Sun D.W., Gao Z.J. The Application of Superheated Steam Impingement Blanching (SSIB) in Agricultural Products Processing-a Review. J. Food Eng. 2014;132:39–47. doi: 10.1016/j.jfoodeng.2014.01.032. - DOI

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