## 2 Thermal Technologies in Food Processing
According to [PERSON] [34] (1973), \"Whether the term sterilization or pasteurization is used to label a heat treatment designed to reduce the microbial population of a food, the basic purpose of the heat treatment is the same--that is, to free the food of microorganisms that may endanger the health of food consumers or cause economically important spoilage of the food in storage and distribution.\"  
Steam has been used in the pasteurization of low-moisture foods processes (Table 1) versus irradiation and gaseous pasteurization using ethylene oxide (EtO) or propylene oxide (PPO). Ethylene oxide (EtO) and propylene oxide (PPO) are fumigants effective in achieving significant reductions of microbial populations on low-moisture foods. EtO is used to treat spices, but it is known to cause loss of volatile compounds [35; 36; 37]. PPO is used to treat a variety of low moisture foods including nuts, spices, cocoa beans, and dried fruits [38; 39]. Table 1 presents the effect of pasteurization treatments on different microorganisms in human food. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Process** & **Food** & **Experimental Parameters** & **Target Organism** & \begin{tabular}{c} **Microbial** \\ **Inactivation** \\ **or Reduction** \\ \end{tabular} & **Reference** \\ \hline \multirow{2}{*}{Steam} & \multirow{2}{*}{Paprika} & \multirow{2}{*}{130–170 \({}^{\circ}\)C, 4–6 s} & Indicators & \multirow{2}{*}{3–4 log reduction} & \multirow{2}{*}{[40]} \\  & & & (e.g., Enterobacteriaceae, \\  & & & coliforms, yeast, mold) & \\ \hline Steam & Pistachios & 88 \({}^{\circ}\)C, 4 min & _Enterococcus faecium_ & 4 log reduction & [41] \\ \hline Steam & \begin{tabular}{c} Seeds, black \\ pepperons \\ \end{tabular} & 85 \({}^{\circ}\)C, 1 min & \begin{tabular}{c} _Salmonella enterica_, \\ _Escherichia coli_ O157:H7 \\ \end{tabular} & \(>\)5 log reduction in \\ \hline Steam & Almonds, pistachios & 200 \({}^{\circ}\)C, 15–30 s & \begin{tabular}{c} _S. enterica_, _E. coli_ O157:H7, \\ _Listeria monocytogenes_ \\ \end{tabular} & \(>\)5 log reduction in \\ \hline Steam & \
\begin{tabular}{c} Black peppercorn, \\ cumin seeds \\ \end{tabular} & 85 \({}^{\circ}\)C, 1–2 min &
\begin{tabular}{c} _S. enterica_ \\ _S. enterica_ \\ \end{tabular} & 5 log reduction & [37] \\ \hline Steam & Almonds & 95 \({}^{\circ}\)C, 25 s & _Salmonella Enteritidis_ PT 30 & 5 log reduction & [44] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Effect of pasteurization treatments on different microorganisms in human food. Adapted from [15]. The development of several commercially available systems that utilize controlled condensation steam (CCS) processes to pasteurize low-moisture foods has been demonstrated. CSS processes may operate at elevated pressure, at atmospheric pressure, or under vacuum. However, CCS processes maintain temperature near the saturation temperature to control condensation on the product. Pressurized processes (e.g., Ventilex) utilize high temperature (130-170 \({}^{\circ}\)C) and short time (4-6 s; HTST), whereas vacuum processes (e.g., Napasol, Steripure, Log5) reduce the saturation vapor pressure and can operate at temperatures below 100 \({}^{\circ}\)C and still maintain saturated steam conditions [29]. In Revtech, Safesteril, and Steristep systems, adding sensible heat to the product along with steam is controlled condensation and maintains the dry saturated condition of steam. Therefore, these CCS processes are named dry steam processes due to the very minimal condensation on the food product. Another type of dry steam is superheated steam (SHS), where the temperature exceeds that of saturated steam at the same pressure. In order to reach much higher temperatures than the saturation point, SHS is also produced by adding heat to saturated steam using an electric resistance heater [30].