Effects Of Wall-disruption On Nutrients Releases And Digestion Of Bee Pollen

Bee pollen contains approximately 250 substances and has anti-bacterial,anti-oxidant,anti-radiation,and anti-inflammatory properties.It has long been considered a natural highly healthy product.However,the digestibility and absorbility of bee pollen are always comparatively low due to the complex pollen wall structure.Therefore,wall-disrupted is particularly important for improving the digestibility and absorbility of bee pollen.In this paper,rape bee pollen,lotus bee pollen,camellia bee pollen,wuweizi bee pollen and apricot bee pollen were selected to treat with a combination of ultrasonication and high shear technique.To determine the effect of wall-disrupted on bee pollen in vitro and in vivo,the untreated and treated bee pollen were-subjected to static in vitro digestion,dynamic in vitro digestion and in vivo digestion in mice,respectively.The changes of bee pollen before and after wall-disrupted were evaluated on observations of scanning electron microscopy and transmission electron microscopy,particle size,the content of crude protein,amino acid,crude fat,reducing sugar,total phenol and total flavonoids.The results showed: the untreated bee pollen had the intact pollen grain while much fragments were presented in wall-disrupted bee pollen.The particle size is obviously reduced after wall-disrupted,and indicated that structures of pollen grains were destroyed.Moreover,the content of nutrient in wall-disrupted bee pollen was higher than the untreated samples.Contents of the total phenolic in camellia bee pollen increased most obviously,which increased up to 7.5-fold.The static and dynamic in vitro simulated digestion tests of five untreated and treated bee pollen showed that the pollen grains were still intact before and after in vitro digestion,and the changes of particle size were inconspicuous for untreated bee pollen.The changes of morphology and particle size were also not significant in treated bee pollen.After dynamic digestion,the digestibility of crude protein and crude fat in treated bee pollen was significantly higher than that of unbroken bee pollen.Among them,the digestibility of crude protein and crude fat in wall-disrupted camellia bee pollen was 38.53% and 24.15% higher than that of the untreated samples,respectively.On the other hand,the release of amino acids,reducing sugars,total phenols and total flavonoids from wall-disrupted bee pollen was also significantly higher than that of untreated bee pollen.For example,the release rate of total phenol and total flavonoids after the dynamic digestion of treated camellia bee pollen were 3 and 1.5 times than that of the untreated samples,respectively.The results of the in vivo digestion of mice showed that the treated bee pollen was easier to empty from the stomach and to enter the intestine.After 24 h,all of bee pollen was almost completely excreted.Bee pollen grains of 2 h and 12 h digestion was observed with fluorescence microscopy.We found that the treated bee pollen also had no significant change compared with the fragments before digestion;and the untreated bee pollen grains were still intact and had a clear outline after in vivo digestion.It is further proved that the in vivo digestion of mice cannot disrupt the bee pollen wall.In summary,the wall-disruption of bee pollen is beneficial to the release nutrients,contributing to the digestion and absorption of nutrients in the bee pollen.Therefore,it is recommended that bee pollen should be disrupted.