百香果贮藏过程中香气成分及其相关酶活性的变化特征

为阐明采后百香果香气品质的变化特征,本研究采用顶空-固相微萃取(HS-SPME)结合气相色谱-质谱联用技术(GC-MS),研究了常温(25℃)、低温(6℃)贮藏期间百香果香气物质主要成分及其含量,酯类化合物代谢关键酶脂氧合酶(LOX)、醇酰基转移酶(AAT)、乙醇脱氢酶(ADH)和氢过氧化物裂解酶(HPL)活性的变化规...

Variation Characteristics of Aroma Components and Related Enzyme Activities During Storage of Passion Fruit (Passiflora caerulea L.)

To clarify the variation characteristics of aroma quality in postharvest passion fruit, headspace-solid phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) was used to determine the main components and the contents in the fruit volatiles during storage at ambient temperature (25 ℃) and low tem-perature (6 ℃). The present study further analyzed the activity variation rule of key enzymes in ester metabolism pathway, such as lipoxygenase (LOX), alcohol acyltransferase (AAT), alcohol dehydrogenase (ADH) and hydroperoxide lyase (HPL). The results showed that the main aroma components in passion fruit juice were esters during storage at ambient and low temperatures, and their relative contents accounted for 40.00%-60.32% and 54.95%-69.27%, followed by alcohols and ketones. Furthermore, the main ester components with high relative contents were identified as ethyl butanoate, ethyl n-hexanoate, hexyl butyrate, ethyl acetate and hexyl hexanoate. During storage at ambient temperature, the relative content of esters in passion fruit peaked on 4^th day (60.32%) and decreased to 40.00% on 12^th day. However, this relative content peak appeared on 20^th day (69.27%) and remained 54.62%-69.27% within the whole storage period at low temperature. Above results indicated that high relative content of esters could be maintained by low temperature storage. The analyses on key enzymatic activities in ester metabolism pathway showed that little variation of LOX, AAT and HPL activities appeared in passion fruit juice during early storage period (0-10 d) at low temperature. The enzymes were active during late storage period. The activity peaks appeared later than those at ambient temperature storage, indicating that low temperature could effectively inhibit the activities of key enzymes in ester metabolism pathway. In addition, the relative contents of ester components were strongly correlated with the activities of LOX, AAT, ADH and HPL. This study would provide reference for quality maintenance and postharvest preservation of passion fruit.