| Star anise(Illicium verum Hook.f.)is also known as Chinese anise,anise,or Da Liao,belonging to the Illiciaceae(illicium)family.The dried fruit of illicium verum plants(also known as star anise)is one of the traditional spices,which is widely used in Chinese catering industry.Meanwhile,the star anise can not only give the dishes unique flavor,but can also effectively reduces the fishy and mutton smells.Fresh star anise has green color,high moisture content,and is difficult to store and transport.Therefore,the star anises used in daily seasoning are mainly dried fruits,which are brown-red or brown-yellow.At present,the drying treatment of postharvest star anise mainly depends on traditional sun-drying or simple mechanical drying,but it has a great influence on the quality of the star anise.Besides,the storage of dried anise is an important part of its production and sales.At the same time,the storage time of dried anise is long.Therefore,unreasonable packaging and storage conditions will lead to a serious decline in commodity quality and edible quality.However,the recent research on star anise mainly focuses on its volatile oil(flavor substance)and biological activity but rarely on different drying methods,packaging methods,and quality formation mechanism of it.Therefore,this study mainly explored the effects of different drying treatments and packaging storage methods on the quality of star anise.Meanwhile,we further explored the changes in pigments before and after drying to provide theoretical basis and technical support for the processing and storage of star anise,and to provide some theoretical references for the future research of star anise pigments.The main results are as follows:1.Effects of different drying methods on the quality of star anise.In this part,the effects of five drying methods(hot air drying(HAD),heat pump drying(HPD),far infrared radiation drying(FIRD),microwave drying(MD),and sun drying(SD))and blanching treatment on the drying characteristics,sensory evaluation,color,volatile oil content,trans-anethole in volatile oil content,and shikimic acid content of star anise were studied.Meantime,the volatile compounds in star anise were analyzed by gas chromatography-mass spectrometry(GC-MS)and principal component analysis(PCA).The results showed that the blanching treatment could significantly increase the drying rate,and the drying time of MD was the shortest.From the perspective of sensory and color,the samples dried by SD-B were the best,followed by MD-B and HPD-B.For the HPD,the retention effect of volatile oil and trans-anethole in the sample was the best,with retention rates of 84.58%and 79.40%.At the same time,in the blanching treatment group,HPD-B was also superior to other drying methods,and the comprehensive score of volatile substances contained in the star anise was the highest.2.The study on the changes of star anise pigment before and after drying.Ultra-performance liquid chromatography(UPLC)and Ultra-performance liquid chromatography of quadrupole time of flight-tandem mass spectrometry(UPLC-Q-TPF-MS-MS)were used to analyze the composition of fat-soluble pigments and alcohol-soluble pigments of star anise before and after drying.The results showed that 10 substances including chlorophyll b,pheophorbide a,pheophytin b,pheophytin a,13~2-hydroxy-pheophorbide a、pyro-pheophorbide a,pheophorbide b,chlorophyll a,lutein andβ-carotene were identified from the fat-soluble pigment extract,and most of them were yellowish-brown.12 substances including shikimic acid,proanthocyanidin B1,catechin,cyanidin-3-O-glucoside,rutin,isoquercitrin,isorhamnetin-3-O-rutinoside,isorhamnetin-3-O-glucoside,naringin-7-O-glucoside,hyperoside,quercetin and kaempferol were identified from 80%methanol pigment crude extract,and most of them were flavonoids.In addition,the quantitative analysis results suggested that the degradation rates of chlorophyll a and chlorophyll b after drying were both close to 100%,and the degradation rates of lutein andβ-carotene were 67.7%and 49.0%,while the content of chlorophyll derivatives was significantly increased.Moreover,there was no significant difference in the content of total flavonoids(P>0.05)between before and after drying,while the contents of total polyphenols and catechins were decreased significantly(P<0.05).3.Effect of packaging methods on the quality of dried star anise during storage.The dried star anise was packaged by four different ways including woven bag(W-BP),transparent plastic bag(TP-BP),transparent sealing bag(TS-BP),and black lightproof sealing bag(LS-BP),and was stored at room temperature for 1 year and regular sampled.The changes of the sensory score,moisture content,volatile oil and its main substances(trans-anethole),shikimic acid and main volatile substances were analyzed.The results showed that the storage time and packaging methods had significant effects on the quality of star anise(P<0.05).By comparing the four packaging methods,we found that the effect of two sealed packaging methods(TS-BP and LS-BP)on preventing moisture absorption of the sample was better than other two methods.The color and sensory score of star anise packaged by TS-BP was the best,but LS-BP could effectively reduce the loss of shikimic acid,volatile oil and its trans-anethole.According to the GC-MS and PCA analysis,it was found that the score of volatile substances contained in the LS-BP sample was the highest,followed by TS-BP,TP-BP and W-BP.Considering the above results,LS-BP was more suitable for the storage of dried star anise at room temperature.In summary,HPD was the most suitable mechanical drying method for fresh star anise processing,and the blanching treatment before HPD could significantly enhance the drying rate,improve the color of the sample,and increase the content of volatile substances.Furthermore,the pigments identified from star anise were 8 kinds of chlorophylls,2 kinds of carotenoids,2kinds of anthocyanins,and 9 kinds of flavonoids.Meantime,the contents of chlorophyll,2kinds of carotenoids,total polyphenols and catechins decreased,while the contents of chlorophyll derivatives increased after star anise drying.However,there was no significant difference in total flavonoids content before and after star anise drying.Finally,through the study on the changes of storage quality of dried star anise under different packaging methods,it was found that LS-BP was the best way for star anise storage. |
