Hot Water Treatment and Pre-processing Storage Reduce Browning Development in Fresh-cut Potato Slices

Abstract

<jats:p>Enzymatic browning is a serious quality limitation for fresh-cut potato (<jats:italic>Solanum tuberosum</jats:italic> L.) that has been successfully controlled by heat treatment in other commodities. The use of brief heat treatments with 55 °C water (HW) applied to ‘Russet Burbank’ tubers for 10, 20, 30, or 40 min before cutting was evaluated for potential implementation to control tissue browning. After heat treatment, tubers were held at 20 °C for 0 or 1 day before peeling and slicing. Control tubers were not previously immersed in hot water. All slices were placed in perforated plastic bags and stored at 5 °C for 6 days. Exposure to HW for 30 or 40 min caused severe heat injury. Browning developed in all treatments as indicated by color measurements and discoloration scores (index of extent of discolored area on the slice surface) during storage. Hot water treatment for 10 min best reduced browning, but only when treated tubers were stored intact for 1 day at 20 °C before cutting, as indicated by discoloration scores and changes in <jats:italic>L*</jats:italic>, <jats:italic>a*</jats:italic>, and <jats:italic>H<jats:sup>o</jats:sup></jats:italic> values, which were significantly different from either the control or the other HW treatments. Generally, the severe browning that developed in control slices during storage was associated with significant increases of 25% and 71% in phenolic content and antioxidant capacity, respectively. On the other hand, phenolic synthesis increased by only 6.25% to 13.2% in HW-treated slices during storage and polyphenoloxidase (PPO) activity was 24% to 31% lower compared with the activity before storage. Immersing potato tubers in 55 °C water for 10 to 20 min followed by storage at 20 °C for 1 day before processing reduced but did not prevent browning of peeled slices in terms of color changes and discoloration score. There was no significant correlation between browning and phenolic content or PPO activity.</jats:p>

Inhibition of Enzymatic Browning of Fresh-Cut Potato by Immersion in Citric Acid is Not Solely Due to pH Reduction of the Solution

“…A good correlation between all color parameters and discoloration score was reported earlier by Tsouvaltzis et al . (), contrary to Thybo et al . () who found a good correlation only between L * and a * for peeled potatoes and Rocha and Morais () who reported that browning intensity correlated better with a * than L * values of fresh‐cut apples.…”

“…Browning severity was similar in untreated ‘Russet Burbank’ potato slices stored for 6 days at 5C in an earlier study (Tsouvaltzis et al . ). Further acidification of the 0.5% citric acid solution slightly reduced the discoloration score (Table ).…”

“…Total phenolics content of potato pieces before storage was 0.197 mg GAE kg −1 FW and had not increased in control samples after 6 days of storage at 5C (0.202 mg GAE kg −1 FW) (Table ), contrary to an earlier report (Tsouvaltzis et al . ) for the same cultivar and storage conditions. Probably, the difference is due to the different storage conditions to which the tubers were subjected before their arrival at the local market.…”

“…; Tsouvaltzis et al . ). The resulting tissue slurries were used for the determination of PPO activity, total phenolics, and ascorbic acid contents, as well as pH and antioxidant capacity.…”

Fresh-Cut Produce Quality

“…The former treatment is currently the most common in the fresh-cut industry. Several studies have investigated the application of heat treatments by dipping for quality retention and safety control to replace the use of chemical treatments in fresh-cut carrot (Alegria et al, 2012), melon , broccoli florets (Moreira et al, 2011), potato (Tsouvaltzis et al, 2011), mango (Djioua et al, 2010), peach (Steiner et al, 2006;Koukounaras et al, 2008) and kiwifruit (Beirão-da-Costa et al, 2008). In general, temperatures used for hot water dips on different fresh-cut products can range from 40 to 60 C, while dipping duration ranges from a few seconds to many minutes (up to 70 min).…”