In this study, the effects of three peeling methods: mechanical peeling, soaking in still water and soaking in flowing water on physical and chemical indicators of white pepper such as whiteness value, black fruit percentage, broken fruit percentage, bulk density, moisture content, piperine content, and essential oil content were investigated. The composition and content of volatile compounds in the essential oils of white pepper were qualitatively and quantitatively analyzed by gas chromatography-time-of-flight mass spectrometry (GC-TOF-MS). The quality of peeled white pepper was evaluated by weighted analysis. Our results showed that there was no significant difference in the whiteness value between mechanically peeled white pepper and that peeled by flowing water soaking, but their whiteness values were higher than that of white pepper peeled by still water soaking. Mechanical peeling resulted in lower black fruit percentage and piperine content, but higher essential oil content, broken fruit percentage and bulk density compared with water soaking. A total of 33 volatile compounds were identified from the essential oils obtained by the three peeling methods, 21 compounds of which were common to all the oils, the predominant ones being 3-carene (41.96, 37.77 and 39.16 mg/mL, respectively), β-caryophyllene (36.43, 41.57 and 41.02 mg/mL, respectively), and limonene (29.38, 23.38 and 39.38 mg/mL, respectively). The electronic nose data showed that the flavor of the three white pepper samples was significantly different. The sensory evaluation showed that mechanically peeled white pepper had a stronger aroma and no odor. Furthermore, the weighted score of mechanically peeled white pepper was higher than that of white pepper peeled by water soaking. Therefore, the comprehensive quality of mechanically peeled white pepper is good, and it is suitable for large-scale production. The experimental results can provide a theoretical basis for pepper quality evaluation and industrial production.

The aim of this study is to explore the yield and flavor characteristics of essential oils extracted from black pepper, white pepper, green pepper, and fresh pepper fruit. The essential oils were extracted by steam distillation, and the extraction yields of different pepper essential oils were compared. The flavor characteristics of different pepper essential oils were analyzed by gas chromatography-mass spectrometry (GC-MS), electronic nose and quantitative descriptive sensory analysis. The results showed that the extraction yield of essential oil from fresh pepper fruit was 3.229 mL/100 g, which was significantly higher than that from white pepper, black pepper, and green pepper (1.718, 1.867, and 1.487 mL/100 g, respectively). A total of 48 volatile substances were identified from the four pepper essential oils, the main ones being β-caryophyllene, 3-carene, D-limonene, β-pinene, δ-elemene, and β-myrcene. The electronic nose data confirmed that discriminant function analysis (DFA) distinguished different pepper essential oils better than principal component analysis (PCA). The sensory evaluation showed that the pepper-like aroma of the essential oil of fresh pepper fruit was stronger than the other three essential oils and had higher acceptance. The results of partial least squares regression (PLSR) analysisshowed that the aromatic plant-like, herbal, and pepper-like aroma properties were positively correlated with (+)-α-pinene components. The experimental results provide a reference for the development and upgrading of pepper essential oil products.