Impact of Hydrocolloids on Production, Quality Attributes and Nutritional Values of Egyptian Black Mulberry Fruits (Morus nigra L.) Leathers

Black mulberry (Morus nigra L.) is a popular, nutritional and palatable fruit in Egypt. In this research, trials were carried out to assess the quality of fruit leathers produced from black mulberry fruits under the application of different hydrocolloids (pectin, carboxy methyl cellulose CMC and Xanthan) for improving textural, functional and sensorial characteristics of the obtained leathers. Preliminary experiments proved that use of 1.25% pectin as binding agent produced superior fruit leather regarding rheological, textural, color and organoleptic quality compared with those produced using CMC or Xanthan as thickening agents. Based on these results, experiments were further continued to assess the impact of deseeding black mulberry fruit pulp and application of sun (solar) or oven drying on kinetics of drying process and quality attributes of the obtained leathers. Results showed that most of the drying pattern was in the falling rate drying phase and drying required 13 h and 18 h in oven (55 °C) and solar drying, respectively, Henderson and Pabis as well as Wang - Singh equations were the most suitable model to represent the drying pattern. SEM examination of leather surfaces showed a homogeneous structure and use of 1.25% pectin enhanced the integrity of the leather matrix through gelation and structure binding. Presence of seeds in the leather led to some crakes in the surface structure of the obtained leathers. It could be concluded that black mulberry fruits could be successfully used to produce good quality and nutritional leathers, when using pectin at the level of 1.25%.