Orange (Citrus sinensis) and grapefruit (Citrus paradise) peels were used as a source of pectin, which was extracted under different conditions. The peels are used under two states: fresh and residual (after essential oil extraction). Organic acid (citric acid) and mineral acid (sulfuric acid) were used in the pectin extraction. The aim of this study is the evaluation the effect of extraction conditions on pectin yield, degree of esterification “DE” and on molecular weight “Mw”. Results showed that the pectin yield was higher using the residual peels. Moreover, both peels allow the obtainment of a high methoxyl pectin with DE >50%. The molecular weight was calculated using Mark-Houwink-Sakurada equation which describes its relationship with intrinsic viscosity. This later was determined using four equations; Huggins equation, kramer, Schulz-Blaschke and Martin equation. The molecular weight varied from 1.538 x1005 to 2.47x1005 g/mol for grapefruit pectin and from 1.639 x1005 to 2.471 x1005 g/mol for orange pectin.

ABSTRACT:Moroccan Orange peels are a promising commercial source of pectin. Their massive industrialization generates a huge amount of solid waste. This work aims to develop a new valorizing reuse way of this solid waste by developing the extraction process of value-added products such as pectin from orange peels, which is the waste of orange juice processing industry. In this context, we evaluated the yield of pectin according to the state of the substrate and the acids used. Results obtained show that the peels which have undergone a Steam Distillation (SD) gives the highest yield of pectin (40% using sulfuric acid) compared to Fresh Peels (FP) (25.71% using citric acid).One part of the (SD) peels was dried outdoors and Non-Conditioned (SDNC), while the other was Conditioned (SDC) at 4°C. The highest yield of pectin for each one was respectively 40% using sulfuric acid and 34.81% using hydrochloric acid. The citric acid gives a satisfying yield in each peels stats, 38.52% using on (SDC), 31.88% (SDNC) and the lowest yield was 25.71% (FPC).The result of this work has emphasized that sweet orange peels are a good source of orange essential oil and pectin and has the potential to become an important raw material for food processing industries.