Effect of high pressure homogenization on water-soluble pectin characteristics and bioaccessibility of carotenoids in mixed juice.

The effect of high pressure homogenization (HPH) compared with simple blending and milling on mixed juice properties, including water-soluble pectin (WSP) characteristics and total carotenoid bioaccessibility (TCB) was investigated. Overall, HPH treatments, which comprised of varied pressures, passes and inlet temperature (IT) affected WSP characteristics. Increased pressure showed decreased molecular weight (Mw), galacturonic acid (GalA) content and branching, and enhanced degree of methylesterification (DM) and chain linearity, suggesting degradation of RG-I fragments. Two passes at 140 MPa enhanced GalA content, nevertheless it reduced DM, implying rearrangement of depolymerized fractions. Besides, elevated IT combined with high pressure increased GalA content and DM signifying thermo-solubilization of certain HG-rich pectin. Notably, the TCB was enhanced by higher pressure and elevated temperature, which had positive relationship with DM and chain linearity of WSP and negative correlations with GalA content and Mw. Results highlighted the potential of HPH to improve WSP characteristics to enhance TCB.

Effect of high pressure homogenization on mixed juice stability, rheology, physicochemical properties and microorganism reduction.

Cloud instability and loss of fresh-like appearance are important quality defects of cloudy mixed juices determining consumer acceptability. Therefore, the aim of this study was to investigate the feasibility of high pressure homogenization (HPH) for improving cloud stability, flow behavior and physicochemical characteristics as well as reducing spoilage microorganisms in a cloudy mixed juice, consisting of carrot, apple and peaches. HPH treatments included pressure of 25 MPa, 100 MPa, 140 MPa and 180 MPa, pass of 1 and 2 and inlet temperature of 25 °C and 40 °C, respectively. Results indicated that increasing pressure and pass improved cloud stability, while increasing temperature had negative effect. Herschel Bulkey model could be well fitted to viscosity related data. Compared with control (non-homogenized, NH) sample, HPH at 140 MPa and 25 °C for 1 pass resulted in three times higher flow behavior index. Increasing inlet temperature also resulted in enhancing flow behavior. Besides, total soluble solids content was not affected by HPH, even though pH and color showed slight changes. Compared with NH sample, HPH at 140 MPa resulted in 4 log10 and 3 log10 reductions in total plate count and yeasts and molds count respectively. Thus, HPH at 140 MPa could effectively be used for enhancing cloud stability, improving flow behavior and reducing microorganisms in cloudy mixed juices.

Effects of high pressure homogenization and addition of oil on the carotenoid bioaccessibility of carrot juice.

Food processing and dietary lipids are considered as important factors for carotenoid bioaccessibility. The effects of high pressure homogenization (HPH) combined with oil or emulsion on carotenoid retention and bioaccessibility during digestion were investigated. The results illustrated that HPH decreased the area-based diameter (D[3,2]), and negative correlations were found between the total carotenoid bioaccessibility (TCB) and D[3,2] of carrot juice. The bioaccessibility of total carotenoids, ß-carotene and α-carotene of the homogenized samples was below 6%, while the addition of 2% oil, 10% oil or emulsion increased the carotenoid bioaccessibility (up to 14.08% for α-carotene). The carotenoid retention rate (CRR) of the homogenized samples was higher than that of the homogenized samples with oil or emulsion in each digestion phase. The CRR in the small intestine phase had a significant negative correlation with TCB, and therefore, a high TCB could be achieved despite a low CRR in the small intestine. Oil added as an emulsion had a slightly higher volume of free fatty acids released compared with oil added as such.

Effects of high pressure homogenization on pectin structural characteristics and carotenoid bioaccessibility of carrot juice.

Effects of high pressure homogenization (HPH) on stability, water-soluble pectin (WSP) and total carotenoid bioaccessiblity (TCB) of carrot juice were investigated to reveal the feasibility of applying HPH for improving TCB and the relationships between WSP and TCB induced by HPH. Results illustrated that HPH improved the juice stability and TCB. HPH increased the uronic acid content (UAC), and decreased the degree of methoxylation (DM) and acetylation (DAc) of WSP compared to non-homogenization. However, pressure and pass showed no significant effect on UAC, DM and DAc. HPH decreased the weight-average molar mass of WSP, signifying the degradation, which was enhanced by the increasing pressure. Emulsifying activity (EA) decreased with the increasing pass and inlet temperature. Functional relationships were found between TCB and WSP characteristics (DM and EA). Lower DM and EA contributed to higher TCB. Moreover, statistical correlations were found between TCB and indicators of WSP (UAC and DAc).