| 【Objective】 The objective was to study the effect of different extraction methods on the oil quality
of soy sauce residue. 【Method】Oil from soy sauce residue were extracted by hydraulic pressing, screw pressing, lowtemperature
continuous phase transition extraction and solvent extraction, respectively. The color, odor, moisture and volatile
content, extraction rate, acid value, peroxide value, saponification value and fatty acid composition of soy sauce residue were
analyzed. 【Result】 The color of soy sauce residue oil obtained by two pressing methods was black-brown, and the sensory
perception was poor. Compared with the other three oil extraction methods, the yield and extraction rates of low-temperature continuous phase transition extraction method were the highest, which were 31.2 (±0.6%) and 97.0 (±1.7%), respectively.
And the acid value, peroxide value and saponification value of the oil obtained by this method were the lowest, which were
96.4 (±0.1) mg/g, 0.13 (±0.01) mmol/kg and 209.4 (±0.3) mg/g, respectively. According to GC-MS detection, the main fatty
acid compositions of soy sauce residue oil obtained by four extraction methods were the same, which were palmitic acid, ethyl
palmitate, stearic acid, oleic acid, oleic acid, ethyl oleate, linoleic acid, ethyl linoleate and linolenic acid, among which the
linoleic acid content was the highest, and the contents of linoleic acid obtained by four methods were 52.03%, 42.81%, 46.94%
and 52.82%, respectively. Compared with the main fatty acid compositions of soybean oil, soy sauce residue oil has more ethyl
palmitate, ethyl oleate and ethyl linoleate. 【Conclusion】 Compared with hydraulic pressing, screw pressing and solvent
extraction, low-temperature continuous phase transition extraction is an efficient way to extract soy sauce residue. Except for
the deep color of soy sauce residue oil caused by pressing methods, there is no obvious difference among the soy sauce residue
oil obtained by different extraction methods. The soy sauce residue oil obtained by four extraction methods has different degrees
of acid deterioration, which is not suitable for eating and can be processed for feeding or biodiesel, etc. |
