Quality Aspects of Pre-Treated Potato Tubers (Solanum tuberosum L.) After Boiling and Warm-Holding

The preparation of steam-cooked potatoes in large-scale food service systems is challenging since it requires high flexibility and handling large volumes. To increase efficiency, potato tubers are industrially pre-treated, which includes peeling and chemical pre-treatments to avoid enzymatic browning. In large-scale food service systems, potatoes are often warm-held before serving. Industrial pre-treatment and Warm-Holding (WH) might, however, contribute to reduced eating quality in terms of subsurface hardening. This study investigates the impact of chemical pre-treatment (dipping in water (Ref sample), Organic Acid (OA), sodium metabisulfite (SMS), and OA+SMS) and varying Relative Humidity (RH) during WH. The textural evaluation revealed that hardness increased for WH with decreased RH due to evaporation as well as chemical pre-treatment, with a significant impact from OA+SMS. A visual evaluation showed a distinct layer on the surface of those samples treated with SMS and OA+SMS, while Light Microscopy (LM) images showed changes in cellular structure, with the formation of bricklike cells at the surface occurring to a greater extent in samples treated with OA or OA+SMS. The results showed that reduced eating quality due to subsurface hardening can be caused by these three different mechanisms.