The purpose of this study was to identify the changes in flavor and taste characteristics of black pepper treated by nonthermal sterilization. The sterilization method was intense pulsed light (IPL), ultraviolet (UV), cold plasma (CP), and combining sterilization. Also, the sensorial and instrumental evaluation were analyzed to evaluate the quality of black pepper before and after nonthermal sterilization. Afterward, the correlation between the sensory evaluation results and instrumental evaluation was analyzed to confirm the flavor changes of black pepper before and after sterilization. In addition, the difference in the pepper flavor before and after sterilization was evaluated to confirm of application in cooking.
The color value showed that after sterilization treatment, the color turned dark brown due to the decrease of the L value and the hue angle value. The chromaticity difference (ΔE) was 1.14 and 1.73, after UV treatment, CP treatment and IPL treatment respectively. The chromaticity difference (ΔE) after the combining sterilization was 6.11, which was greater than the IPL.
As a result of piperine content analysis, the piperine content of the samples before individual and combining sterilization were 10.7±0.53 mg/g and 28.4±0.25 mg/g, respectively. And the piperine content of all samples after nonthermal sterilization was decreased. The piperine content decrease was the highest after IPL treatment and the lowest after the UV treatment.
As a result of the electronic nose analysis, principal component 1 (PC1) was clearly divided into black pepper before and after individual sterilization. In addition, the PC1 and PC2 were divided into three groups, and it was confirmed that they were classified according to the intensity of the volatile components of the black pepper through the flavor pattern of the electronic nose analysis.
According to the intensity test, the color of the sample was dark after sterilization and showed a similar tendency to the result of the color measurement. After sterilization, the sample flavor was evaluated as weak, and an evaluation was conducted to distinguish the flavor of the samples before and after the sterilization treatment. This tends to be similar to the results of electronic nose analysis. The tastes were distinguished before and after sterilization in response to the weak sample after sterilization in the case of individual sterilization, but not in the case of combining sterilization.
Quantitative descriptive analysis (QDA) developed sensory languages of 13. In the case of individual sterilization, all flavor items except pine tree, dried pine needles, and green tea astringent taste and perilla seed nutty taste were evaluated as weak after sterilization treatment. In the case of the combining sterilization, the cool flavor of the pine needle toothpaste, peppermint, and red sichuan pepper were evaluated to be weak after sterilization. The perilla seed nutty taste was evaluated as strong after the combining sterilization. The correlation between the flavor profile and the developed sensory language was evaluated by principal component analysis (PCA). In the case of individual sterilization, all flavor items except the perilla seed nutty taste had a positive correlation with the sample before sterilization by factor 1 (F1), and the cool flavor had the largest correlation. In the case of combining sterilization, all flavor items except the perilla seed nutty taste and dried pine needles showed a positive correlation with the sample before sterilization by F1.
As a result of confirming the correlation between the results of the electronic nose and the description analysis, it was possible to confirm the sensory characteristics that each peak of the electronic nose analysis indicated. In particular, the cool flavor of green sichuan pepper and most peaks showed a high correlation in addition to the cool and grass flavor of peppermint, which also showed a high correlation.
Black pepper before and after sterilization was applied to beef radish soup, cream soup, and beef bone soup to confirm the flavor difference. Samples applied to individual sterilized black pepper, could be distinguished flavor in cream soup. In the case of beef radish soup and beef bone soup could be distinguished both flavor and taste. Samples applied to combining sterilized black pepper, the flavor and taste could not be distinguished in the cream soup but could be distinguished in the beef radish soup. In the case of beef bone soup, the flavor was distinguished but not the taste.
The flavor change of the black pepper was confirmed according to the sterilization method. It seems difficult to assess the strength of the black pepper flavor through the analysis of the piperine content as it differs from sensory evaluation. It is judged that the results of the electronic nose analysis and sensory evaluation tend to be similar and can be used as important data for evaluating the quality of the electronic nose analysis. Also showed a higher efficiency microbial reduction effect after combining sterilization than in the individual sterilization treatment. The overall quality characteristic analysis result showed the possibility of industrial application as the quality change after the combining sterilization treatment.