Effect of Radio Frequency Assisted Thermal Processing on Quality and Functional Properties of Egg White Powder

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Abstract. Traditionally, egg white powder (EWP) is stored in a hot room maintained at 58°C to 60°C for 10 to 14 days for pasteurization and to improve functional properties. This long and energy-intensive process limits plant production capacity. In this study, radio frequency (RF) assisted thermal processing was evaluated for pasteurization of EWP with the objective of reducing the storage period in a hot room, thereby reducing the energy requirement, while minimizing loss of functional properties. Spray-dried EWP (pH ~9.5) was RF heated to 60°C, 70°C, 80°C, or 90°C and maintained at the same temperature for different storage periods ranging from 1 h at 90°C to 3 days at 60°C in a hot air oven. The quality and functional properties of the RF-treated EWP, including color, foaming capacity (overrun), foam stability, solubility, gel firmness, and gel elasticity, were evaluated. RF pretreatment of EWP at 90°C followed by holding in a hot air oven for 8 to 24 h provided optimal functional properties. RF-assisted thermal treatment at all levels did not significantly reduce the color lightness (L* values), solubility (Haenni value), and moisture content when compared to traditionally processed EWP. However, RF-pretreated EWP had a significantly lower foaming capacity (overrun) when compared to traditionally processed EWP. It was found that RF pretreatment at 90°C and holding in a hot air oven for 8 h or longer resulted in similar foam stability, water holding capacity, gel firmness, and gel elasticity. Therefore, we recommend RF heating of EWP to 90°C followed by holding in a hot air oven for 8 h or longer to produce similar or better functional properties compared to traditionally processed EWP. This treatment process is estimated to achieve ≥7-log reduction of Salmonella spp. Thus, RF-assisted thermal treatment can be used to reduce the pasteurization duration from the current 10 to 14 days to less than 24 h. We demonstrated the feasibility of designing a high-temperature short-time (HTST) pasteurization process for EWP using RF-assisted thermal processing.