Influence of Pre-drying Treatments on Quality and Safety of Sun-dried Tomatoes. Part I: Use of Steam Blanching, Boiling Brine Blanching, and Dips in Salt or Sodium Metabisulfite
The effect of various pre-drying treatments on the subsequent quality of sun-dried tomatoes was evaluated by determining moisture, color, rehydration ratio, mold, yeast, sulfur dioxide, and/or salt content. The 4 pre-drying treatments under investigation were (1) steam blanching or (2) boiling brine blanching, followed by gas sulfuring and (3) dipping in either salt (0%, 10%, 15%, 20%) or (4) sodium metabisulfite (0%, 4%, 6%, 8%) for 0, 2.5, 5.0, and 7.5 min. Neither blanching pretreatment improved the quality of the dried product. Salt dipping resulted in significant differences in rehydration ratio, yeast, and salt. The most effective salt pretreatment conditions were a 10% or 15% salt dip for 5 min. Sodium metabisulfite dipping caused significant differences in rehydration ratio, yeast, color, and sulfur dioxide. Dipping tomatoes in 6% or 8% sodium metabisulfite for 5 min before drying established the best color. The 9 pretreatments studied were also evaluated for storage stability at 25 °C and 30% to 34% relative humidity for 3 mo.