Chemical Composition Of Physalis Fruit And In Vitro Digestive Properties Of Its Carotenoid Esters

The physiochemical properties and nutritional characteristics of red(Physalis alkekengi L.)and yellow(Physalis pubescens L.)Physalis fruits were evaluated.A series of targeted research on the characteristic carotenoids were carried out,regarding the identification,changes during maturation,in vitro digestion,and functional product development.The main conclusions are as follows.(1)The yellow Physalis fruits showed high sugar contents but significantly low levels of organic acids,while the red ones had extremely lower levels of sugars but higher contents of organic acids,which rendered them distinctive tastes.The hydroxycinnamoyl glycosides prevailed in aqueous methanolic extracts of Physalis fruits,and the yellow Physalis fruits had values higher than the other fruits reported in literature.Additionally,two 4-hydroxyl-2,5-dimethyl-3(2H)-furanone(HDMF)glycosides,i.e.HDMF hexoside and HDMF malonyl hexoside,were tentatively identified for the first time in yellow Physalis fruits.(2)Zeaxanthin esters with various fatty acids were found to be the most abundant carotenoids in red Physalis,accounting for 51-63%of total carotenoids,followed by ?-cryptoxanthin esters(16-24%).In yellow Physalis,mainly free carotenoids such as lutein and ?-carotene were found.Total carotenoid contents were 19.8-21.6 mg/100 g for fresh red Physalis fruits and 1.28-1.38 mg/100 g for fresh yellow Physalis fruits,demonstrating that Physalis fruits are rich sources of dietary carotenoids.Yellow Physalis calyces contained only 153-306 ?g carotenoids/g dry weight,while red Physalis calyces had substantially higher amounts(14.6-17.6 mg/g dry weight),thus possibly exhibiting great potential as a natural source for commercial zeaxanthin extraction.(3)With increasing maturity,the content of lutein decreased,while ?-carotene in yellow Physalis fruits or carotenoid esters in red Physalis fruits increased,resulting in increment in total carotenoid contents.Carotenoids accumulated earlier in peel than in pulp in both fruits,and the contents in peel were ca.5-21 times of that in pulp.Chromoplasts in red and yellow Physalis fruits were both developed from chloroplasts,while different deposition forms of carotenoids were observed.Carotenoids deposited mainly as submicroscopic crystals in chromoplasts of red Physalis fruits and together with some tubules and globules,while mainly as typical crystals in chromoplasts of yellow Physalis fruits and some globules as well.(4)As hydrolysis of carotenoid esters is believed to be highly efficient in vivo,their insufficient hydrolysis in in vitro-digestion models,particularly,regarding zeaxanthin diesters,the mian carotenoids in red Physalis fruits,is a current issue.In this study,we found bile and lipids selection was crucial for in vitro digestion of carotenoid esters.The combined use of coffee creamer,pancreatin,carboxyl ester lipase,and bovine bile led to the highest hydrolysis efficiency of 29.5%.(5)Aiming at the utilization of zeaxanthin dipalmitate(ZDP,the carotenoid with highest content in red Physalis fruits)as a natural colorant or nutraceutical food,the ZDP nanoemulsion was developed.The optimized formation parameters for ZDP nanoemulsion were using PGE18(0.8%,w/w)as emulsifier,medium chain triacylglycerin as carrier oil,preparing by high pressure homogenization at 60 MPa with three passes.The optimized ZDP emulsion had droplet size smaller than 200 nm,and remained ca.90%of the original ZDP after 28 days' storage at 4?.