VOR has a significantly lower OHC than MR. Although the MR has higher oil content it shows higher capacity to bind oil compared to VOR. According to Fernando et al. (2005) grapefruit fibre showed 1.20–1.52 g oil/g of substrate, lemon fibre showed 1.30–1.48 g oil/g of substrate, orange fibre 1.81 g oil/g of substrate and apple fibre showed 0.60–1.45 g oil/g of substrates of oil holding capacity. These values are very low compared to the oil holding capacities of CCWPs (Table 3). However, Oil holding capacities of MR and VOR are comparable with the values reported by Fernando et al. (2005).
Oil holding capacity is an important feature of polysaccharides. OHC relates to the adsorption of organic compounds to the surface of the substrates. This could also relate to the high cellulose content in the sample (Betancur-ancona et al., 2004). Oil holding is in part related to the chemical composition, but it is more of the porosity of the fibre structure rather than the affinity of the fibre molecule to oil (Biswas, Kumar, Bhosle, Sahoo, & Chatli, 2009). The structure of CCWPs is more porous as most of the non-cellular low molecular weight components are removed during isolation. Therefore adsorption of oil is easier in CCWPs compared to MR and VOR. Therefore higher oil holding capacity of CCWPs compared to MR and VOR is as expected.
VOR is a compact structure having protein, sugar, fat, mineral compared to MR. Therefore these non-cell wall fractions reduce oil holding capacity of VOR. MR is having higher fat but less of other components compared to VOR. Therefore MR can attract more oil compared to less fatty structure of VOR.