Flavor Enhancing Technology For Low Temperature-pressed Peanut Oil

Low temperature-pressed peanut oil is rich in nutrition,but the flavor is not good enough.Peanut by-products containing a lot of sugars and proteins,can be used as flavor precursors.The preparation of flavor substances by peanut by-products can be used to enhance the flavor of the low temperature-pressed peanut oil.In this study,HS-SPME-GC-MS was used to detect the volatiles in both high temperature-pressed peanut oil and low temperature-pressed peanut oil to determine the key volatiles in peanut oils.Taking the relative contents of key volatiles as the evaluation indexes,the raw materials,pretreatment condition,and extraction conditions were used to determine the optimum parameters,and the flavor concentrate with aroma of high temperature pressed peanut oil was prepared.The concentrate was added to the low temperature-pressed peanut oil,and the flavored low temperature-pressed peanut oil was generated,which flavor could simulate the high temperature-pressed peanut oil.The qualities of flavored low temperature-pressed peanut oil were characterized using accelerated oxidation experiment.This study provided a theoretical reference for the improvement the flavor of low temperature-pressed peanut oil,so as to improve the sensory quality of low temperature-pressed peanut oil.The main research results were as follows:According to the volatiles in high temperature-pressed peanut oil and low temperature-pressed peanut oil,it could be determined the key volatiles to produce rich flavor in high temperature-pressed peanut oil.The contents of aldehydes,alcohols and carboxylic acids in low temperature-pressed peanut oil were higher than that in high temperature-pressed peanut oil,while pyrazine,pyrrole and ketone were higher in high temperature-pressed peanut oil.HS-SPME-GC-MS and electronic nose combinding PCA results indicated that 2-ethyl-5-methylpyrazine,2,3-dimethyl-5-ethylpyrazine,2-acetyl-3-methylpyrazine,2-ethyl-3,5-dimethylpyrazine,2-methyl-5-propenyl pyrazine,and 2-acetylpyrrole made greater contribution to high temperature-pressed peanut oil.While(Z)-2-heptenal,nonylaldehyde and(E)-2-octenal made great contribution to the flavor of low temperature-pressed peanut oil,which were the key volatiles of low temperature-pressed peanut oil.Taking the relative contents of the key volatiles in high temperature-pressed peanut oil as the evaluation indexes,the raw materials,pretreatment condition and the extraction condition were used to determine the optimum parameters of the flavor concentrate.The main volatiles in the baking flavor of four kinds of peanut cake were pyrazines and pyrroles,and the main volatiles in baking peanut shell were aldehydes / ketones and furans.The best pretreatment was that the low temperature pressed peanut cake was baked at 180 ? for 15 min.Subcritical fluid extraction and supercritical CO2 extraction were the best for the extraction of flavor concentrate,followed by solvent extraction.The optimum process of subcritical fluid extraction was extraction with butane as solvent and 40 minutes at 40 ? for 3 times.The optimum conditions of solvent extraction were as follows: extraction with dichloromethane as solvent and extraction at 35 ? for 3 h.The flavor of low temperature-pressed peanut oil was enhanced and the quality was characterized using accelerated oxidation experiment.The best ratio of the flavor concentrate to enhance the flavor of low temperature-pressed peanut oil was 16: 1,where the peanut oil had a roastty and nutty note similar to that of the high temperature-pressed peanut oil and the burning,grass,sweetty note and the overall flavor were strong.The sensory quality of peanut oil in the low temperature-pressed peanut oil changed significantly during accelerated oxidation process.And the roastty,nutty and the burning note were weakened at the later stage of accelerated oxidation,and the oil and rancidity of the oil were oxidized.At the same time,the red value(a*)indicated an increasing trend,and the yellow value(b*)and brightness(L*)indicated a decreasing trend.The quality of flavored low temperature-pressed peanut oil was better than that of high temperature-pressed peanut oil and low temperature-pressed peanut oil.Acid value was 0.56 mg/g and the peroxide value was 3.40 mmol/kg after the flavored low temperature-pressed peanut oil accelerated oxidation at 100 ? for 5 h.And the oxidation stability was significantly higher than that of high temperature-pressed peanut oil and low temperature-pressed peanut oil.The shelf life of the flavored low temperature-pressed peanut oil was 3.20 years,which was significantly higher than that of low temperature pressed peanut oil 1.64 years and high temperature pressed peanut oil 1.16 years.The flavor enhancement process was conducive to extending the shelf life of low-temperature pressed peanut oil.