To evaluate the contributions of 3-methylbutanal, 2-methylbutanal, 2-methylpropanal, and benzaldehyde in cheddar cheese models, the threshold values, optimal concentration ranges, and perceptual actions of these compounds were determined at various concentrations. The thresholds for 3-methylbutanal, 2-methylbutanal, 2-methylpropanal, and benzaldehyde in the cheese matrix were 150.31, 175.39, 150.66, and 500.21 μg/kg, respectively, which were significantly higher than the corresponding values in water. The optimal concentration ranges of these aldehydes were determined as 150–300, 175–325, 150–350, and 500–1500 μg/kg, respectively. Based on the results of the threshold method and Feller’s model, five binary mixtures were found to have synergistic effects, and only the pair of 2-methylpropanal and benzaldehyde was determined to have a masking effect. In addition, the synergistic olfactory effects between the four ternary mixtures and the quaternary mixture of these aldehydes were also assesSsed using Feller’s model. In a σ-τ plot analysis, synergism was usually observed when these odor pairs were at their threshold levels. In summary, the results suggested that perceptual interactions among these aldehydes exist in a cheese model variably with different concentrations and threshold ratios. This study will be helpful to a further understanding of the nutty aroma and improving the aroma quality of cheddar cheese.

In this study, an artificial starter culture was prepared using the core microbial species of JIUYAO to produce Chinese rice wine (CRW). The fermentation activity and flavor profiles of CRW samples fermented with traditional JIUYAO, a commercial starter culture, and our artificial starter culture were compared. The optimal protectant combination for lyophilization of the artificial starter was established as 15.09% skim milk, 4.45% polyethylene glycol, 1.96% sodium glutamate, and 11.81% maltodextrin. A comparative analysis revealed that the ethanol content of the three CRW samples was similar. The total acid content of the CRW sample fermented with the artificial starter (7.10 g/L) was close to that of the sample fermented with JIUYAO (7.35 g/L), but higher than that of the sample fermented with the commercial starter (5.40 g/L). An electronic nose analysis revealed that the olfactory fingerprints of the CRW samples fermented with JIUYAO and the artificial starter resembled each other. For both above mentioned samples, the flavor profiles determined by gas chromatography–mass spectrometry indicated some differences in the variety and content of the aroma compounds, but the key odorants (odor activity values ≥1), such as isoamyl acetate, ethyl acetate, phenyl alcohol, and isoamyl alcohol, were similar.

A nutty flavor is desirable in Cheddar cheese and is easily accepted by most Chinese consumers. Although compounds responsible for nutty flavor in cheeses have been documented, no final conclusions have been reached. In this study, nine samples of top‐selling Cheddar cheeses in the Chinese market were selected, and the odor‐active compounds responsible for the nutty flavor in these samples were studied by gas chromatography‐mass spectrometry (GC‐MS), gas chromatography‐olfactometry (GC‐O), sensory evaluation, and aroma addition experiment. Forty‐nine volatile flavor compounds were identified by GC‐MS via headspace‐solid‐phase microextraction, and 14 odor‐active compounds were identified by GC‐O. It was determined that 2‐methylbutanal, 3‐methylbutanal, and benzaldehyde contributed to the nutty flavor of Cheddar cheese, according to Chinese tastes. The addition of suitable concentrations of these compounds to a model of Cheddar cheese without nutty flavor resulted in the perception of nutty aroma by sensory analysis. These results indicate that 2‐methylbutanal, 3‐methylbutanal, and benzaldehyde are the key aroma‐active compounds, which could make positive contributions to the nutty flavor of Cheddar cheese and favored by Chinese consumers within a certain concentration range.

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