Effects Of Low Storage Temperature On The Nutritional Quality And Carotenoid Metabolism Of Wolfberry Fruit

Wolfberry(Lycium barbarum)is a traditional Chinese medicine which can be used both as food and medicine for its high nutritional value and outstanding pharmacological effects,especially for its abundant reserve of zeaxanthin dipalmitate,which is of great potential for developing new drugs.Wolfberry fruit is mainly used as a dried product.The nutritional components in wolfberry could be seriously damaged and the fruit may be polluted during processing.Its nutritive value can be preserved to the greatest extent by direct consumption of the fruit.Nevertherless,wolfberry fruit is very perishable as its skin is thin and tender,the preservation and storage of wolfberry fruit is still a key problem limiting its transportation and circulation.In the present study,“Zhongkelvchuan” and “Ningqi No.9” wolfberry fruits were stored under 4?and-4?,physiological characteristics and nutritional quality of them were investigated.The aim of the study is to improve the quality of the wolfberry fruit in supply chain.Moreover,the changes of main carotenoid components in Ningqi No.9wolfberry fruit and the transcription of carotenoid metabolism related genes were analyzed in order to understand the synthesis,accumulation and decomposition of carotenoids during storage of wolfberry fruit.The main results are as follows:1.Peaks of respiratory rate and ethylene productive rate was detected in both cultivars of “Zhongkelvchuan” and “Ningqi No.9” during postharvest storage,which suggested that wolfberry fruit belongs to climacteric fruits.Respiratory rate and ethylene productive rate were significantly decreased in-4 ? stored fruit than that in 4 ? stored fruit in accordance with delayed senescence in the former.2.The decrease of marketable fruit rate,fruit firmness,and the contents of TSS,TA,free amino acids and hydrolyzed amino acids was delayed in-4 ? stored fruit than that in 4? stored fruit in both cultivars.In addition,-4? storage increased the accumulation of polysaccharides thus maintained the nutritional quality of wolfberry fruit.3.The contents of zeaxanthin and ?-carotene in the two wolfberry fruits wererelatively low.The content of zeaxanthin dipalmitate in wolfberry fruit was abundant and was 75%-85% of the total carotenoid contents.The accumulation of total carotenoids and zeaxanthin dipalmitate in “Ningqi No.9” wolfberry fruits was significantly increased at the end of storage under-4 ? storage,but the“Zhongkelvchuan” was significantly increased the accumulation of total carotenoids and zeaxanthin dipalmitate under 4? storage.4.4? storage increased significantly the transcription of carotenoid synthesis related gene DXS2 and CRTISO,-4? storage increased significantly the transcription of carotenoid sink related gene CHRC,Or1 and Or2 at the end of storage.While 4 ?storage significantly increased the expression of CCD4 and other degradation related genes.To sum up,-4? storage effectively maintained the nutritional components of“Zhongkelvchuan” and “Ningqi No.9” wolfberry fruits and delayed the senescence of the two wolfberry fruits.Storage temperatures can increase the expression of carotenoid metabolism related genes.4 ? storage significantly up-regulated the expression of carotenoid degradation related gene CCD4 in “Ningqi No.9” wolfberry fruit.