Innovative Pulsed Vacuum Drying (PVD) Technique for a Safe and Sustainable Food Industry- Our Practice on Goji Berry Drying

Drying is one of the most common methods used for preserving and extending the shelf life of wolfberry, also called Goji berry. Drying of wolfberry is more difficult than some other biological materials, as a thin-layer of wax covers on its surface peel which hinders moisture transfer from inside to outside. Currently chemical pre-treatments are frequently employed to dissolve the wax layer and enhance drying rate. However, the chemical additives residue in products may trigger food safety problems and how to deal with larger quantities of corrosive chemicals is another serious problem. Therefore, it is imperative to develop alternative drying technology for wolfberry to enhance the drying process and quality attributes of the dried product. Pulsed vacuum drying (PVD) is a relatively new drying technique with advantages such as low oxygen environment processing which can prevent the adverse biochemical reactions and lower energy consumption compared to vacuum drying. The effects of drying temperature and pulsed vacuum ratio defined as the vacuum pressure duration versus atmosphere pressure duration on pulsed vacuum drying (PVD) characteristics and quality attributes of wolfberry in terms of polysaccharide content, color parameters (L^*, a^*, b^*, ΔE, and C), rehydration ratio and microstructure were investigated.

The findings of current work indicates that pulsed vacuum drying is a promising technology for wolfberry, which can not only reduce drying time significantly, but also enhance the product quality attributes in terms of the total polysaccharide content, color parameters and rehydration ratio.