College of Food Science , Southwest University , Chongqing 400715 , People's Republic of China.
Chongqing Sweet Potato Research Centre , Chongqing 400715 , People's Republic of China.
J Agric Food Chem. 2018 May 2;66(17):4541-4550. doi: 10.1021/acs.jafc.7b05507. Epub 2018 Apr 23.
The granules of sweet potato starch were size fractionated into three portions with significantly different median diameters ( D) of 6.67 (small-sized), 11.54 (medium-sized), and 16.96 μm (large-sized), respectively. Each portion was hydrophobized at the mass-based degrees of substitution (DS) of approximately 0.0095 (low), 0.0160 (medium), and 0.0230 (high). The Pickering emulsion-stabilizing capacities of modified granules were tested, and the resultant emulsions were characterized. The joint effects of granule size and DS on emulsifying capacity (EC) were investigated by response surface methodology. For small-, medium-, and large-sized fractions, their highest emulsifying capacities are comparable but, respectively, encountered at high (0.0225), medium (0.0158), and low (0.0095) DS levels. The emulsion droplet size increased with granule size, and the number of freely scattered granules in emulsions decreased with DS. In addition, the term of surface density of the octenyl succinic group (SD) was first proposed for modified starch granules, and it was proved better than DS in interpreting the emulsifying capacities of starch granules with varying sizes. The present results implied that, as the particulate stabilizers, the optimal DS of modified starch granules is size specific.
将甘薯淀粉颗粒按粒径分成三部分，其中值直径（D）分别为 6.67μm（小粒径）、11.54μm（中粒径）和 16.96μm（大粒径），差异显著。各部分均按质量取代度（DS）进行疏水处理，分别约为 0.0095（低）、0.0160（中）和 0.0230（高）。测试了改性颗粒的 Pickering 乳液稳定能力，并对所得乳液进行了表征。采用响应面法研究了颗粒粒径和 DS 对乳化能力（EC）的联合影响。对于小、中、大粒径部分，其最高乳化能力相当，但分别在高（0.0225）、中（0.0158）和低（0.0095）DS 水平时达到最高。乳液液滴粒径随颗粒粒径增大而增大，乳液中自由分散颗粒数随 DS 增大而减少。此外，首次提出了辛烯基琥珀酸基团的表面密度（SD）术语，该术语比 DS 更能解释具有不同粒径的改性淀粉颗粒的乳化能力。本研究结果表明，作为颗粒稳定剂，改性淀粉颗粒的最佳 DS 具有粒径特异性。
