Optimization of alkaline extraction for dietary fiber of coffee silver skin and its effect on the quality and shelf life of Iranian Barbari bread

There is substantial evidence showing that consumption of unsuitable diets، typically containing high-energy compounds، is the cause of many diseases in man. Substitution of dietary fiber for these high-energy compounds in widely consumed food items such as bread can help promote health of communities. Dietary fiber was extracted from coffee silver skin with different particle sizes (4to 150microns)، using alkaline hydrogen peroxide at a concentrations of 1% to 5%، and an extraction time of 1-12 hours. The effects of these different extraction conditions on the physical characteristics of the coffee fiber produced and bread prepared from it were investigated. The findings showed that particle size of coffee fiber، extraction time and ratio of solution to powder had statistically significant effects on the physical properties of fiber and the quality and shelf-life characteristics of bread prepared from it. A longer extraction time led to a less dark color of the coffee fiber and higher water-holding capacity of the fiber. Based on the findings، it can be concluded that a longer alkaline hydrogen peroxide extraction time and a higher ratio of solution to coffee powder improves physical characteristics of the powder. In addition، reduction of particle size results in a decrease in firmness، improvements in organoleptic properties and a longer shelf-life، of bread made from it.