Browning Prevention and Sensory Evaluation of Frozen Yam Slices (Dioscorea cayenensis-rotundata Cv Kponan) of Côte D’Ivoire

Aim: To prevent enzymatic browning during the freezing of yam slices of the Kponan variety (Dioscorea cayenensis-rotundata).

Study Design: The experimental set-up was of a completely randomized design.

Place and Duration of Study: Department of Food Science and Technology, Food Biochemistry and Tropical Products Technology Laboratory (BATPTL), University of Nangui Abrogoua, Abidjan, Côte d’Ivoire, between August and December 2018.

Methodology: For this purpose, yam slices were either pretreated with a natural agent (lemon juice solution at different pH) or pretreated and blanched (85 °C for 2 min) and then packed in plastic bags and kept in the freezer at -18°C over a period of 4 weeks. Polyphenoloxidase and Peroxidase activities, Dry matter, rate of browning and sensory attributes of yam slices were determined.

Results: The results showed a decrease in polyphenoloxidase and peroxidase activities regardless of the treatment. The largest decreases in activity were observed in yam slices that were both pretreated and blanched compared to the control (about 53.49% decrease in the specific activity of the PPOs and 51.46% of POD). The combination of pretreatment and blanching also resulted in lower dry matter yam slices compared to pretreated slices only. After 1 month of storage in the freezer, the lower rates of loss (browning) were recorded for the slices of yams that were both pretreated and blanched compared to the other methods which had very high losses. The pretreated and blanched slices had high dry matter content. The sensory profile of slices processed by the combined technique after one month of freezing had a good appreciation for all sensory characteristics of yam.

Conclusion: In order to have a good product, the combined method is recommended for better freezer storage of yam slices.