Effect of rice bran rancidity on the emulsion stability of rice bran protein and structural characteristics of interface protein

In the context of the increasing interest in natural food ingredients, the emulsifying and emulsion-stabilizing properties of three rhamnogalacturonan-rich apple pectin-derived samples were assessed by evaluating a range of physicochemical properties. An apple pectin (AP74) was structurally modified by a β-eliminative reaction to obtain a RG-I-rich pectin sample (AP-RG). Subsequent acid hydrolysis of AP-RG led to the generation of pectin material with partially removed side chains (in particular arabinose depleted) (AP-RG-hydrolyzed), thus exhibiting differences in rhamnose, arabinose, and galactose in comparison to AP-RG. All samples exhibited surface activity to some extent, especially under acidic conditions (pH 2.5). Furthermore, the viscosity of the samples was assessed in relation to their emulsion-stabilizing properties. In a stability study, it was observed that the non-degraded AP74 sample at pH 2.5 exhibited the best performance among all the apple pectin-derived samples evaluated. This emulsion presented relatively small oil droplets upon emulsion production and was less prone to creaming than the emulsions stabilized by the (lower molecular weight) RG-I-rich materials. The AP-RG and AP-RG-hydrolyzed samples presented a slightly better emulsion stability at pH 6.0 than at pH 2.5. Yet, neither pectin sample was considered having good emulsifying and emulsion-stabilizing properties, indicated by the presence of coalesced and flocculated oil droplets.

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Effects of ultrasound extraction on the physicochemical and emulsifying properties of rice bran protein

International Journal of Food Engineering ◽

10.1515/ijfe-2019-0115 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Li-Hui Sun ◽

Feng Yu ◽

Yu-Ying Wang ◽

Shi-Wen Lv ◽

Lei-Yu He

Keyword(s):

Rice Bran ◽

Protein Solubility ◽

Surface Hydrophobicity ◽

Absorption Capacity ◽

Emulsifying Properties ◽

Ultrasound Assisted Extraction ◽

Suitable Alternative ◽

Rice Bran Protein ◽

Assisted Extraction ◽

Ultrasound Assisted

Abstract In this study, rice bran protein was prepared by ultrasound-assisted extraction, and its physicochemical and emulsifying properties were also evaluated. Results demonstrated that a significant increase in protein yield was observed when ultrasound-assisted method was employed for extracting protein. Noticeably, obtained rice bran protein possessed excellent physicochemical properties, such as oil absorption capacity, protein solubility and foaming property. More hydrophobic groups were exposed in the process of ultrasound-assisted extraction, which led to the increase of surface hydrophobicity. More importantly, the ultrasound-assisted extraction could improve emulsifying properties of rice bran protein, and the emulsions prepared using protein samples exhibited the great stability. Besides, it was also found that emulsifying properties of protein samples presented a decrease trend with increasing ultrasound power and time. All in all, ultrasound-assisted extraction is a suitable alternative process for preparing rice bran protein.

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