The Effect Of Fat Crystal Structure On The Digestibility Of Fat Crystalline Emulsion And Its Mechanism

Fat is one of the three essential nutrients for the human body and plays an important role in maintaining human health.However,fat is the densest and its poor satiety effect always leads to overconsumption,which is often considered as a leading cause of obesity,cardiovascular and cancer.The fat digestibility within the gastrointestinal tract?GIT?directly determines their absorption and bioavailability,the modulation of fat digestibility will be an effective way to reduce fat absorption under the trend of higher ingestion.And the physical state and fat crystal structures are closely related to to their digestibility,understanding the digestion behaviors could guide to produce healthy fat-contained foods.Therefore,the crystalline O/W emulsions with different solid fat content?SFC?and fat crystal structure were constructed,and the effects of“quality”?fat crystal size and polymorphic form?and“quantity”?SFC?on the digestibility and fermentation behavior were investigated,the digestion mechanism was also investigated.The results would further provide theoretical and technical support for the production of healthy fat-conntained foods.The main contents and results are as follows:?1?The digestibility of crystalline O/W emulsions with different SFC and fat crystal structures?fat crystal size and polymorphic forms?The constant-temperature storage?4?,25?,37??was used to construct crystalline O/W emulsions with different SFC and fat crystal structures?fat crystal size and polymorphic forms?,and the fat crystal characteristics and in vitro simulated digestive behaviors were studied.The results of DSC,p-NMR,XRD and PLM showed that the SFC decreased as storage temperature increased;the emulsion stored at 4? only contained?'form,while the?form of emulsions stored at 25? and 37? were 6.25%and 97.8%,respectively;the size of fat particles decreased as storage temperature decreased.After oral and gastric digestion,all of the emulsions underwent complete coalescence and flocculation,the d_4,3values increased significantly?p<0.05?.After gastric digesion,the d_4,3values decreased in the order of constant temperature?4??,?25??,?37???p<0.05?,and the Zeta potentials of emulsions showed no significant difference?p<0.05?.The FFA-released assay results during intestinal digestion indicated that the lipid digestion extent of emulsions decreased in the order of constant temperature?4??,?25??,?37??.?2?The digestibility of the crystalline O/W emulsions with same SFC and different fat crystal structures?fat crystal size and polymorphic forms?The constant-temperature storage?4??and fluctuating-temperature storage?37?-4??were used to construct crystalline O/W emulsions with same SFC and different fat crystal structures?fat crystal size and polymorphic forms?,the fat crystal characteristics and in vitro simulated digestive behaviors were studied.The results of DSC,p-NMR,XRD and PLM showed that the two emulsons had same SFC;the emulsion with constant-temperature storage?4??only contained 1.88%of?form,while the emusion with fluctuating-temperature storage?37?-4??had 14.54%of?form;the sizes of fat crystal in the emulsion with fluctuating-temperature storage?37?-4??were larger than the emulsion with constant-temperature storage?4??.After oral and gastric digestion,all of the emulsions underwent complete coalescence and flocculation,the d_4,3values increased significantly?p<0.05?.The d_4,3values and the the Zeta potentials of emulsions after gastric digestion showed no significant difference?p<0.05?.The FFA-released assay results during intestinal digestion indicated that the lipid digestion extent of emulson with constant-temperature storage?4??was higher than the emulson with fluctuating-temperature storage?37?-4??.?3?Study on the fatty acid release characteristics of the crystalline emulsions during the small intestine digestionThe FFA release profiles of four crystalline emulsions during intestinal digestion were investigated,which followed a similar trend:a rapid release in the early stage and then followed by a gentle release.After 2 h of intestine digestion,the FFA release extent of the emulsions with constant-temperature storage?4?,25?,37??,and fluctuating-temperature storage?37?-4??were 78.447%,72.220%,70.243%and 64.631%,respectively.The release percentage of C14:0 during intestinal digestion was the highest,while the release percentage of C18:0 and C16:0 was lowest.For the crystalline emulsion systems with different SFC and fat crystal structures,the digestion extent decreased as SFC decreased and?crystal content increased.For the crystalline emulsion systems with the same SFC and different fat crystal structures,the digestion extent decreased with the increase of?crystal content.?4?Study on the digestive mechanism of the crystalline O/W emulsionThe variation of four crystalline emulsions during the GIT was similar.In the oral stage,the interface membrane remained intact,and the flocculation mechanism was depletion flocculation;in the gastric stage,obvious aggregation and partial coalescence occurred,while no obvious coalescence occurred;in the small intestine stage,a small amout of fat crystals was observed,and no lipid droplets were found.No significant correlation between the Zeta potential,viscosity,interface protein adsorption,interface protein concentration after gastric digestion and digestion extent were found.For emulsion systems with different SFC and fat crystal structures,the SFC,?crystal content and the d_4,3 after gastric digestion were the determinants of fat digestion in the small intestine.While for the same SFC and different fat crystal crystalline emulsion systems,the fat crystal size and polymorphic form were the determinants of fat hydrolysis.?5?Study on the in vitro fermentation of the crystalline O/W emulsionThe four O/W crystalline emulsions had similar flora composition after in vitro fermentation for 24 h,and also had their unique flora composition.The F/B values of crystalline O/W emulsions were significantly lower than those of the blank group?p<0.05?,together with the abundance of Prevotella?p<0.05?,indicating that the crystalline emulsions could potentially reduce the risks of host obesity and diabetes.Moreover,emulsions with fluctuating-temperature?37?-4??had the greatest effects on intestinal flora communities,the F/B value of the emulsion with fluctuating-temperature?37?-4??is the lowest,and the relative abundance of Prevotella was the highest,indicating most beneficial to host health.