Chemical Composition, Bioactive Compounds and Organoleptic Characteristics of Osmotic-Air Dried Apple (Cubes and Slices)

Abstract

The effect of osmotic-air dried treatments on the chemical composition, minerals, Vitamin C, pectin, polyphenoliccompounds, antioxidants, colour and sensory properties of apple (slices and cubes) were determined comparing with fresh apples. The results indicated that, the moisture content of osmotic-air dried samples ranged from 2.07 to 2.67% compared to 85.48% for fresh apples. Osmotic-air drying process caused a reduction in crude protein, crude ether extract, crude fiber and vitamin C, while the nitrogen free extract (NFE) increased. In addition, increasing the concentration of the soaking sucrose solution to 50% led to more reduction in the previous mentioned nutrients. Also, nutrient contents of apple slices were lower than those of apple cubes. All osmotic-air dried apples had significantly higher content of sugars and acidity with lower pectin content than those of the fresh apples. In addition, increasing the sucrose solution concentration caused a significant increase in the sugar content. It is obvious generally that mineral contents (phosphorous, calcium, iron and sodium) of all the osmotic-air dried apples were lower than those of the fresh ones. Apple samples soaked in 40% sucrose solution had higher mineral contents than those soaked in 50% sucrose solution. Also, apple cubes had higher mineral contents than apple slices. Osmotic-air drying process reduced the total phenolic contents and antioxidant activity. The reduction was higher in apples soaked in 50% sucrose solution than those soaked in 40% sucrose solution and for apple slices comparing to apple cubes. The correlation coefficient reveals a positive relationship between antioxidant activity and total phenolic compounds. Also, osmotic-air dried apples had slightly lower colour lightness values than the fresh ones. The results also showed that apple soaked in 50% sucrose solution were higher in overall acceptability values than those of apples soaked in 40% sucrose solution. Generally apple slices had higher values than cube ones.