Study On Changes Of Carotenoids Content In Peppers During The Drying Proeess

Peppers(Capsicum annuum. L.), the fruits of Solanaceae, have been cultivated for morethan300years in China and now widely planted in south and north with dozens of varieties.Pepper red pigment is a natural pigmet extracted from mature red pepper fruits, which hasconjugate structure and is one of carotenoids. Nowadays, there is a little research on thechanges of carotenoids biosynthesis during the drying process after the peppers harvest. Afterpeppers have been harvested at commercial maturity, carotenoids biosynthesis alwayscountine during the drying process and the process is affected by temperature and ray.Carotenoids biosynthesis would be interrupted when the water content dreased to a certainvalue. At the same time dehydrated processing method will affect the content of pepperpigment. Temperature, ray and water content of fruits are the main factors of carotenoidsbiosynthesis. Cultivar “Hangjiao” harvested at commercial maturity was used as materials forstudying effects of different temperatures, ray and water content on total carotenoids content.We had found out optimal adjustment measures promoting the pepper pigment generation byexploring the correlative relationship between total carotenoids, capsanthin, β-carotenoid andtemperatures, ray, water content, and provided a basic guidance for establishment reasonablepepper processing technology.(1)Separation and preparation of β-cryptoxanthin and capsanthin from the red pigmentThe red pepper power was extracted by acetone with ultrasonic extraction, saponificatedand separated by silica gel column chromatography. Thereafter, preparative high performanceliquid chromatography was used to refine and purify β-cryptoxanthin and capsanthin. Thestructure of β-cryptoxanthin and capsanthin was identified by UV, ESI-MS,1H-NMR and13C-NMR and the purity was determined by analytical HPLC. The results indicated that underthe conditions of chili pigment extracts and isopropanol with the ratio of1:9(g/ml), the qualityratio of chili pigment extracts and KOH was4:1,20%KOH methanol solution as extractingsolution, chili pigment extracts could be saponified completely with saponification reactiontime24h, room temperature. Petroleum ether and acetone were used as elution solvent ofsilica gel column chromatography for rough separation. β-cryptoxanthin and capsanthin couldbe better enriched when the petroleum ether and acetone volume ratio were10:1,4:1respectively. Under the conditions of acetone and water (95:5, v/v)(85:15, v/v) and velocity of5ml/min, β-cryptoxanthin and capsanthin monomer were obtained by preparative high performance liquid chromatography and the purity were99.0%、99.3%respectively. Themethod is simple, rapid, and reproductive, which was suitable for preparation ofβ-cryptoxanthin and capsanthin with high purity.(2) Study on changes of carotenoids content in peppers during the drying processChanges of carotenoids content in pepper (Capscum. Annuum.L) treated in differenttemperatures and light/dark conditions during the drying process were studied in this part.Cultivar “Hangjiao” harvested at commercial maturity was used as materials for studyingeffects of different temperatures (25℃,30℃and35℃) and ray (light or darkness) oncarotenoids biosynthesis during the drying process. The change curves and modeling of totalcarotenoids and water content were fitted. The results showed that total carotenoids contentwas5.49mg/g at30℃, which was1.067times,2.34times and2.12times compared with theother groups at25℃,35℃and30℃with darkness, respectively.Carotenoids content increased fastest along with the water content decresing from80%to50%. Content of capsanthin and β-carotene showed the same trend with the totalcarotenoids which were determined by HPLC. The equations could better describe thechanges of total carotenoids and water content in peppers during the drying process.Therefore, treatment at30℃with illumination maybe the best condition for the biosynthesisof carotenoids, which provided a basic guidance for the pepper dehydrated process.