Effects Of High Pressure Homogenization On Physico-chemical Properties And Carotenoid Bioaccessibility Of Carrot Juice

Effects of high pressure homogenization?HPH?on physico-chemical properties of carrot juice,and whole digestion process including the release of carotenoids from the raw material,processing method and in vitro digestion were included to investigate the carotenoid bioaccessibility.Different refining and homogenizing methods were applied to process carrot juice.The objective is to study whether HPH processing can be used as a new processing method to improve carotenoid bioaccessibility and provide theoretical basis on how to improve the stability of carrot juice and the bioaccessibility of carotenoids.The main conclusions are as follows:After refining treatments,the proportion of carotenoid content decreased from36.18%to 15.28%in large cell clusters,increased from 8.36%to 30.56%in chromoplast fraction and increased from 11.11%to 15.73%in small cell clusters.Therefore an enhancement of carotenoid content could be observed with the decreasing level of bio-encapsulation.After refining treatments,the visible carotenoid particles under laser scanning confocal microscopy decreased in size.The visible particle became smaller with the increase of refining degree.The intenser refining treatments contributed to higher release rate of carotenoids.The carotenoid release rate was 50.91%for joint processing of colloid mill and HPH.The intenser refining treatments contributed to the lower concentrations of total oil-extracted carotenoid,and oil-extracted?-carotene and?-carotene.With the increment of homogenization pressure and cycle,the peak of particle size distribution moved to the left.Compared with the non-homogenization treatment,median particle diameter(D₅₀),volume-based diameter?D[4,3]?and area-based diameter?D[3,2]?decreased by 52.41%,41.46%and 49.48%at the pressure of 20MPa,respectively.Compared with the treatment at 20 MPa,D₅₀,D[4,3]and D[3,2]decreased by 87.21%,82.9%and 84.49%at the pressure of 180MPa,respectively.HPH processing could effectively reduce the particle size in carrot juice and improve the suspension stability of carrot juice.The rheological data showed that the rheological curve of carrot juice conformed to the Herschel-Bulkley model.Carrot juice was considered as pseudo-plastic fluid?0<flow behavior index?n?<1?and had a gel-like behavior?storage modulus G?>loss modulus G??.With the increment of homogenization pressure?20 MPa¹80 MPa?and homogenization cycle?1 pass³passes?,apparent viscosity,G?and G?of carrot juice decreased.HPH did not reduce the carotenoid content in carrot juice and even promote the release of carotenoids from the raw material tissue to carrot juice.When the homogenization pressure was60 MPa,the homogenization cycle was 3 passes and the inlet temperature was 25?,?-carotene and?-carotene reached the maximum level at 44.86?g?mL^-1 and 22.39?g?mL^-1,respectively.HPH could alter the characteristics of water-soluble pectin?WSP?.HPH increased the galacturonic acid?GalA?content,and decreased the degree of methoxylation?DM?and acetylation?DAc?compared to non-homogenization treatment.However,pressure and pass showed no significant effect on GalA contents,DM and DAc.HPH induced the degradation of WSP,which was enhanced by the increasing pressure.When the pressure elevated to 180 MPa,WSP linearity increased significantly compared with control.The contribution of rhamngalacturonan?RG?to the WSP after different pressure and pass showed no significant difference.The values of emulsifying activity?EA?decreased with the increment of pass and inlet temperature.Total carotenoid bioaccessibility?TCB?was enhanced by HPH,and HPH combined with moderate inlet temperature could be applied to enhance the total carotenoid bioaccessibility of carrot juice.Significant correlations were found between TCB and indicators of WSP?DM,EA,GalA content and DAc?.What's more,functional relationships were found between TCB and certain indicators of WSP?DM and EA?,TCB could be increased by decreasing the DM and EA.