破碎和均细化处理方式对胡萝卜汁中类胡萝卜素释放的影响

摘要

为研究不同破碎和均细化处理对胡萝卜汁中类胡萝卜素释放途径的影响,采用打浆﹑胶体磨和高压均质3种破碎和均细化方式处理胡萝卜汁.应用分光光度法对处理后不同植物组织(大细胞聚集体﹑小细胞聚集体和有色体)中类胡萝卜素含量,游离类胡萝卜素含量,总类胡萝卜素含量,油脂可萃取类胡萝卜素含量进行测定.应用激光共聚焦扫描显微镜观察不同处理后类胡萝卜素的分布情况.利用高效液相色谱法对油脂可萃取类胡萝卜素单体含量进行测定.通过显著性分析确定不同均细化处理对以上3种植物组织中类胡萝卜素含量﹑游离类胡萝卜素含量﹑总类胡萝卜素释放率和油脂可萃取总类胡萝卜素含量及单体含量的影响.结果表明破碎和均细化处理后,大细胞聚集体中类胡萝卜素所占比例减小(从36.18％减小至15.28％),小细胞聚集体(从11.11％增加至15.73％)和有色体部分(8.36％增加至30.56％)中类胡萝卜素所占比例增大,类胡萝卜素释放在对其释放阻碍程度低的组织部分中.经过均细化处理后,激光共聚焦显微镜下可见的类胡萝卜素颗粒减少,处理越均细,可见的类胡萝卜素颗粒越少.对胡萝卜汁处理越均细,胡萝卜汁中类胡萝卜素释放率越高,其中胶体磨和高压均质联合处理胡萝卜汁后类胡萝卜素的释放率为50.91％.对胡萝卜汁处理越均细,胡萝卜汁中油脂可萃取总类胡萝卜素﹑β-胡萝卜素和 α-胡萝卜素含量越少.研究结果对后续分析如何提高胡萝卜汁中类胡萝卜素生物利用率提供依据.%Carotenoids have received special attention owing to their health-related characteristics, including pro-vitamin A activity, antioxidant properties and prevention organisms against certain types of cancer. In carrot, the existence of chromoplast substructure and cell wall limit the release of carotenoids, thus adopting appropriate mechanical processing to destroy the cell wall and decrease the particle size is an effective way to improve carotenoid bioaccessibility. As the first step of digestion, the release of carotenoids from raw materials plays a crucial role in determining carotenoid bioaccessibility. The objective of this study was to investigate the effects of different crushing and refining treatments on release pathway of carotenoids in carrot juice. Pulping, colloid mill, and high pressure homogenization with different homogenization pressures, homogenization cycles and inlet temperatures were applied as crushing and refining treatments. After different crushing and refining treatments, carotenoid content in different organizational states (large cell clusters, small cell clusters and chromoplast fraction), free carotenoid content, micrograph of carotenoid distribution, release rate of carotenoids, as well as contents of oil-extracted carotenoids, β-carotene and α-carotene were investigated, respectively. Total carotenoid content was determined spectrophotometrically. β-carotene and α-carotene content were measured by HPLC. Micrograph of carotenoid distribution was observed by confocal laser scanning microscopy. The results demonstrated that after crushing treatment, carotenoid content of above-mentioned four fractions was in a decreasing order: free carotenoid, large cell clusters, small cell clusters and chromoplast fraction. After homogenization, there was almost no difference in free carotenoid content, however, there were about fourfold increase in carotenoid content for chromoplast fraction, twofold increase in carotenoid content for small cell clusters, and twofold decrease for large cell clusters. The proportion of carotenoid content decreased from 36.18％ 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. As the homogenization pressure increased up to 100 MPa and 150 MPa, confocal micrographs showed that visible carotenoid particles became smaller than the ones treated by other homogenization pressures. When the pressure reached 180 MPa, carotenoid tended to aggregate. The visible particle became smaller with the increase of homogenization cycle. Increasing inlet temperature contributed to aggregation of carotenoid particles. The value of carotenoid release rate was 50.91％ for joint processing of colloid mill and high pressure homogenization. However, different levels of homogenization pressure had no significant (p >0.05) effect on carotenoid release rate. Higher carotenoid release rate could be observed with an increment of homogenization cycle and inlet temperature. Therefore, suitable refining treatment can be found and applied to damage the cell wall and effectively promote the release of carotenoids in carrot juice. As lipophilic pigment, carotenoid must first be released from the food matrix, solubilized in the lipid phase followed by transferring into mixed micelles in the small intestine before the uptake by intestinal epithelium. Therefore, oil-extracted carotenoid content reflects the available dose that may be absorbed by human body. The highest oil-extracted carotenoid content in carrot juice was 34.79 μg/g treated by pulping. When the pressure increased from 10 MPa to 180 MPa, the content of oil-extracted carotenoids decreased at first and then increased. The value of oil-extracted carotenoid content reached 31.93 μg/g for 100 MPa and 31.5 μg/g for 150 MPa, respectively. Contrarily, the value was 27.07 μg/g for homogenization at 180 MPa. The highest contents of oil-extractedβ-carotene and α-carotene were 32.61 μg/g and 6.64 μg/g, respectively. Under the different conditions of homogenization, the content of β-carotene and α-carotene changed differently due to structural differentiation. This study has significance on subsequent analysis about how to improve carotenoid bioaccessibility in carrot juice. After refining treatment, polysaccharides such as pectin may be released from the cell wall, wrap around the carotenoid and affect the release of the carotenoid. Therefore, further research is needed to study the interaction between carotenoid and endogenous pectin in carrot juice after high homogenization.