Optimization of pectin extract from pomace waste using response-surface methodology

Pectin is a heteropolysaccharide which is widely used as a gelling and stabilizing agent in the food industry. The study aimed to optimize and evaluate the quantity and quality of pectin extraction from apple pomace by acid hydrolysis at high temperatures as a traditional method of the main wastes of the apple juice industries. Extraction efficiency was optimized in the pH from 1.5 to 2, 60 to 90 minutes and 75 to 90 °C by response-surface method (RSM) with using the central composite design. In addition, the esterification degree, amount of galacturonic acid, equivalent weight, methoxyl content, emulsion activity, stability of emulsifier and water/oil holding capacity of pectin were determined under optimal conditions. The results showed that the maximum extraction efficiency (8.83%) was achived at pH 1.5, 90 °C and 90 minutes. The extracted pectin with a degree of esterification of 54% and galacturonic acid 68 mg/g was obtained at optimal conditions. Equivalent weight, methoxyl content, emulsifying activity and water holding capacity of extracted apple pectin were 916, 8.9%, 55.8% and 4, respectively. In overall, it can be possible to obtain different pectin with varying physicochemoical properties with chaning the extraction conditions. Furthermore, the extracted pectin had proper emulsion activity and stability which can be ultilized  in different emulsion based products.