# Processing Fresh-Cut Potatoes Using Non-Thermal Technologies and Edible Coatings
## 5 Emerging Processing Technologies: Operating Principles and Examined Parameters
### High-Pressure Processing (HPP)
A variation of HPP, called high-pressure low-temperature (HPLT) processing, involves pressure shift freezing (PSF), storage at \(-20\)\({}^{\circ}\)C for 3 days, and pressure-induced thawing (PIT); it has been applied to both potato cylinders [126] and entire, unpeeled tubers after vacuum-packaging in PE plastic films [138]. The pressurization fluid was a mixture of water and ethanol at a ratio of \(50/50\)\(w/w\). The mechanism of this process is based on the \begin{table}
\begin{tabular}{c c c c c} \hline
**Treatment** & **Processing Conditions** & **Pressurization Fluid** & **Storage Conditions** & **Reference** \\ \hline \multirow{4}{*}{HPP + UV-C irradiation} & (i) Immersion of slices in sodium & & & \\  & ascorbate (2\% \(m/v\)) for 3 min, & & & \\  & (ii) vacuum-packed in PA/PE bags, & Propylene & & \\  & (iii) UV-C irradiation: 2.70 kJ/m\({}^{2}\) & glycol/water (1:1) & 15 d, 6 \({}^{\circ}\)C & [11] \\  & for 5 min, (iv) HPP at 400 MPa for & & & \\  & 3 min, fluid temperature: 25 \({}^{\circ}\)C & & & \\ \hline \multirow{4}{*}{HP, high temperature} & (i) Potato cylinders packed in & & & \\  & LDPE bags, (ii) HPP at 600 MPa for & Propylene glycol & \(-40\)\({}^{\circ}\)C & [137] \\  & 1 min, final temperature: 117 \({}^{\circ}\)C & & & \\ \hline \multirow{4}{*}{HP, low temperature} & (i) Raw tubers were & & & \\  & vacuum-packed in PE films, & & & \\  & (ii) pressure-shift freezing at & & & \\  & 280 MPa and \(-28\)\({}^{\circ}\)C, (iii) storage & Water/ethanol (1:1) & 7 d, \(-22\)\({}^{\circ}\)C & [126] \\  & at \(-22\)\({}^{\circ}\)C for 7 d, & & & \\  & (iv) pressure-induced thawing at & & & \\  & 290 MPa and \(-28\)\({}^{\circ}\)C & & & \\ \hline \multirow{4}{*}{HP, low temperature} & (i) Raw tubers were & & & \\  & vacuum-packed in PE films, & & & \\  & (ii) pressure shift freezing at & & & \\  & 240 MPa and \(-22\)\({}^{\circ}\)C, (iii) storage & Water/ethanol (1:1) & 3 d, \(-22\)\({}^{\circ}\)C & [138] \\  & at \(-22\)\({}^{\circ}\)C for 3 d, & & & \\  & (iv) pressure-induced thawing at & & & \\  & 290 MPa and \(-22\)\({}^{\circ}\)C & & & \\ \hline \multirow{4}{*}{HP + citric acid 1%} & (i) Immersion of potato cubes in & & & \\  & 1% citric acid, (ii) vacuum & & & \\  & packaging in plastic bags, & & & \\  & (iii) HPP: 400 MPa for 15 min, & & & \\ \hline \multirow{4}{*}{HP shift freezing + HP-assisted thawing} & (i) Freezing and thawing at & & & \\  & 200 MPa, thawing process started & Water + ethanol (1:1) & - & [140] \\ \cline{1-1}  & at \(-22\)\({}^{\circ}\)C & & & \\ \hline \end{tabular}  
*PE: polyethylene; PA/PE: polyamide/polyethylene; LDPE: low density polyethylene; US: Ultrasound.  
\end{table} 
Table 4: _Cont._impact of pressure on ice water transitions, where HP improves the kinetics of freezing and thawing, as well as crystal characteristics [126]. Precisely, ice nucleation during freezing and crystal growth during storing and thawing can result in undesired cell damage and extraction of enzymes from the potato cells, enhancing PPO activity [126].