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BACKGROUND: Jiuzao is the residue after Bajiu distillation which is usually used as forage for livestock. However, it is not fully utilized yet considering the content of protein remained. The present study aimed to isolate antioxidant peptides from Jiuzao protein hydrolysates, then add these peptides into Baijiu product to enhance the healthy value of Baiju. Meanwhile environmental pollution caused by massive Jiuzao can be mitigated indirectly. RESULTS: Four peptides Ala-Tyr-Ile(Leu) (AYI(L)) andAsp-Arg-Glu-Ile(Leu) (DREI(L)) were identified from Jiuzao protein hydrolysates, the extraction contents of AYI + AYL and DREI + DREL were 896.10 and 110.51 mg kg −1 Jiuzao, respectively. On the one hand, antioxidant activities of these peptides were investigated. For in vitro antioxidant assays, AYI, AYL and DREI exhibited strong capacities in oxygen radical absorbance capacity (ORAC) assay. Furthermore, three levels of four peptides were assessed by 2,2'-azobis(2-methylpropanimidamidine) (AAPH)-induced HepG2 cells model. The results showed that these peptides exerted a degree of antioxidant activities in cells. Meanwhile, selected peptides concentrations according to cell assays remined at effective doses after in vitro digestion. On the other hand, the influence of these four peptides on the characteristic aroma compounds in Baijiu was studied. Most characteristic aroma compounds releases were increased with the addition of peptides.CONCLUSION: In the study, antioxidant activities of peptides were evaluated, the feasibility of utilizing Jiuzao protein hydrolysates to obtain beneficial peptides was also proved. Healthy effect of Baijiu or other food can be increased by adding these functional substances. The findings might contribute to food application and Baijiu industries.

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To characterize potent odor-active compounds in preserved egg yolk (PEY), volatile compounds were isolated by headspace solid-phase microextraction and solvent-assisted flavor evaporation. Gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS) analyses identified a total of 53 odor-active compounds by comparing the odor characteristics, MS data, and retention indices with those of reference compounds. Twenty-seven odorants were detected in at least five isolates that were extracted and analyzed by the same method, and their flavor dilution (FD) factors, ranging from 1 to 2048, were measured by aroma extract dilution analysis (AEDA). To further determine their contribution to the overall aroma profile of PEY, 22 odorants with FD factors ≥16 and GC-MS responses were quantitated, and their odor activity values (OAVs) were calculated. According to the OAV results, 19 odorants with OAVs ≥ 1 are the potent odorants that greatly contribute to the characteristic aroma of PEY. Nine compounds were identified for the first time: (E,Z)-2,6-nonadienal, (E)-2-nonenal, 2-methylbutanal, dimethyl disulfide, trimethylamine, methional, dimethyl trisulfide, diisopropyl disulfide, and diethyl disulfide.

The key odorants of tartary buckwheat (TB) were researched by a sensory-directed flavor analysis approach for the first time. After the volatiles of TB were isolated by solvent-assisted flavor evaporation (SAFE), 49 aroma-active components with flavor dilution (FD) factors in the range of 1−2187 were identified using gas chromatography−olfactometry−mass spectrometry (GC-O-MS) combined with aroma extract dilution analysis (AEDA). Geranylacetone, phenethyl alcohol, and β-damascone showed the highest FD factors of 2187. All 49 odorants were further quantitated by the internal standard curve method, and their odor activity values (OAVs) were obtained. The overall aroma of TB was successfully simulated (similarity > 98.16%) by mixing 16 odorants (OAV ≥ 1) with their natural concentrations. The omission tests revealed that geosmin, α-isomethylionone, αmethylionone, β-ionone, linalool, β-damascone, geranylacetone, guaiacol, ethyl hexanoate, geraniol, vanillin, tetrahydrolinalool, and 2,5-dimethyl-4-hydroxy-3-(2H)-furanone were the key odorants of TB. Chiral analysis showed that tetrahydrolinalool and linalool existed as racemics in the commercial TB. The relative content of R-enantiomers of α-isomethylionone and α-methylionone was slightly higher than that of their S-enantiomers. The odor thresholds of R-and S-enantiomer of tetrahydrolinalool were first detected as 0.029 and 3.8 μg/L in air, respectively.