Study On The Effects Of Superfine Grinding On Physicochemical Properties And Nutrients Release Efficiency Of Natural Edible Plant Tissues

Plant foods such as fruits,vegetables,and large edible fungi are important components in human diet.They can provide consumers with a variety of essential nutrients and natural phytochemicals,which could enhance the nutrition,regulate the human body's functions,and reduce the risk of chronic some diseases.Due to the strong cell wall structure of plants and large fungi,the above food matrials are not easy to be destroyed,which often lead to the low release efficiency of nutrients and functional ingredients within them.Superfine grinding is a common method that can destroy the structure of plant food materials,improving the release efficiency of nutrients.At present,the research on superfine pulverization of plant food materials mainly focuses on submicron powders(1-10 ?m)and larger particles(> 40 ?m).The difference in physical and chemical properties between the above two powders lead to the obvious conclusion that the properties of superfine powders are generally superior,while the effects of superfine pulverization degree(characterized by average particle size)for different types of fruits,vegetables,and edible fungi on the physicochemical properties such as solubility,dispersibility,adsorption,chemical reactivity,fluidity,the stability,and release efficiency of phytochemical components at different molecular scales are still lack of research.In this paper,we studied the relationship between particle size and raw material properties by studying the convenient changes of powder properties,physicochemical properties and functional properties of several edible plant tissues during superfine pulverization.After systematic analysis of some food materials with different sources,the specific mechanism which affecting the bioavailability of raw materials was revealed from the perspective of the relationship between particle size and characteristic nutrient release and physical and chemical properties.Such kind of mechanism was verified by animal experiments in further.The main research conclusions were summarized as follows:1.The superfine grinding treatment of broccoli and the release efficiency of characteristic small molecule nutrients such as sulforaphane were studied.Firstly,the sulforaphane content was used as the evaluation index to determine the optimal blanching conditions of fresh broccoli,which was 58�C for 13 min.Under these conditions,broccoli was blanched,dried.After that,a series of broccoli powders with different particle size were prepared.In terms of powder properties,as the particle size decreased,the specific surface area of broccoli powder increased gradually;L* and b* values increased but a* and ?E* values decreased;the bulk densities increased,the angles of repose and the sliding decreased;the WSI increased gradually while the WHC and SC both increased at first and then decreased,and broccoli powder of 34.38 ?m held the highest WHC and SC values.The DPPH and ABTS radicals scavenging abilities of broccoli powder extracts increased gradually with the decrease of particle size.The extracts of finer broccoli powders showed stronger free radical scavenging abilities.Broccoli powders of 27.32 ?m or less showed strongest free radicals scavenging abilities with no significant differences.The dissolution of characteristic small molecule nutrients in broccoli powder in simulated gastric juice and intestinal juice increased significantly with time.With the same dissolution time,as the particle size decrease,the characteristic nutrient components dissolutions were significantly improved.Considering the effect of superfine grinding on the hydration proprities,antioxidant properties,and the dissolution of small molecular nutrients,the suitable pulverization size of broccoli powder was around 30 ?m.2.The superfine grinding treatment of D.officinale and the release efficiency of characteristic macromolecular nutrients such as D.officinale polysaccharides were studied.Firstly,the polysaccharides content was used as the evaluation index to determine the optimal drying conditions of D.officinale,which was air-drying at 60�C.The D.officinale was dehydrated under optimum drying condition and pulverized to prepare a series of powders with different particle size.As the particle size decreased,the specific surface area of D.officinale powder increased,but the surface-number and volume-surface means decreased,significantly.Powder with smaller particle size usually present better physicochemical properties than coarse ones,but not always.The extraction rates and antioxidant activities of antioxidant components from D.officinale powder gradually increased with the particle size decrease.When the particle size was 29.6 ?m or less,the polyphenols extraction rate was the highest with no significant difference.The antioxidant activities were significantly correlated with TPC and TFC contents.Fine powder of 29.6 ?m or less showed the highest DPPH free radical scavenging and total antioxidant activities,21.3 ?m for ABTS free radical scavenging activity,and 12.1 ?m for hydroxyl radical scavenging ability.The dissolution rates of protein,polysaccharides,and WSS had higher dissolution efficiency in the initial stage and gradually reached equilibrium with the increase of time.As decrease in particle size,the time for reaching equilibrium was significantly reduced.Powder of 29.6 ?m or less showned no significant difference in protein dissolution efficiency,while 21.3 ?m for polysaccharides.The maximum WSS for powders of 29.6 ?m or less was about 45% with no significant difference.The dissolution rate of characteristic nutrients in D.officinale,antioxidant contents,and antioxidant activities increased gradually with the particle size decrease,and then reached equilibrium.Considering the above results,the suitable pulverization particle size for D.officinale was around 20 ?m.3.Effects of superfine grinding on the physicochemical properties of asparagus fiber were studied.With the decrease of the particle size of asparagus fiber,the specific surface area and WSS significantly increased;WHC,OHC,and SC increased at first and then decreased,and reached the highest WHC,OHC,and SC values at 32.7 ?m.Similarly,the fluidity of asparagus fiber increased first and then decreased as the particle size decrease.The apparent viscosity of asparagus fiber decreased significantly as the particle size decreased.After superfine greading treatment,the TDF and IDF contents of asparagus fiber decreased,while the SDF content increased,significantly.What's more,the free and bound polyphenols and flavonoids contents and NIAC ability increased significantly with the partilce size decrease.The NIAC ability between powders of 9.97 ?m and 3.18 ?m showed no significant difference.As the particle size decreased,the glucose content in the dialysate gradually decreased at the same time point.Samples of 9.97 ?m and 3.18 ?m exhibited the greatest glucose adsorption ability and the smallest maximum glucose diffusion rate.Considering the effect of superfine grinding on the powder characteristics,antioxidant components,fiber composition,and adsorption abilities,the suitable pulverization size for asparagus fiber was around 10 ?m.4.Effects of asparagus fiber of different particle size on intestinal function and health were studied.Animal experiments proved that the all the three asparagus fiber samples had certain laxative effect.Compared with the model group,all the three samples could significantly improve the constipation and increase the intestinal propulsion rate.There was no significant difference in intestinal propulsion rate between SG0.03 and SG0.01 groups.In the defecation experiment,the difference between the first black stool time and the total defecation amounts with 6 h were significantly different from that in the model group.But there was no difference between SG0.03 group and SG0.01 group.The asparagus fiber with different particle size could significantly reduce the concentration of ammonia in the cecum.Compared with the SG0.08 group,the effects of the SG0.03 and SG0.01 groups were better,but the differences of the two groups were nonsignificant.All the three samples could significantly affect the dry weight of the feces in mice,but the difference in SG0.03 and SG0.01 groups was not significant.Asparagus fiber with smaller particle size was more effective in inhibiting fecal bacterial enzyme activity than the blank group.The difference between SG0.03 and SG0.01 groups was not significant,either.Combining the hydration properities of asparagus fiber with different particle size,it could be concluded that the particle size distribution of SG0.03(~30 ?m)could meet the requirements in improving intestinal health.5.Effects of superfine broccoli powder on the physicochemical properties of dough were studied.Superfine broccoli powder of 30 ?m could increase the gelatinization temperature of wheat flour.The peak,trough,final,and setback viscosities of wheat flour decreased significantly as the superfine broccoli powder content increase.Wheat gluten dilution by superfine broccoli powder resulted in weakening of the dough strength.However,the interaction between superfine broccoli powder and starch molecules compensated for the reduced strength due to dilution of the gluten protein.Adding superfine broccoli powder could increase the elastic modulus(G')and viscous modulus(G'')of the dough.However,the intrinsic rheology of the dough did not change,which still was the same G' > G'' trend(tan ? < 1).A proper proportion of superfine broccoli powder was very important for the volume of the bread.Higher superfine broccoli powder may cause the dough to be too soft to hold the gas well,thus reducing the bread volume.The specific volumes of breads with superfine broccoli powder added from 3% to 9% were not significantly different from that of the blank group.When the proportion of superfine broccoli powder were increased to 12% and 15%,the specific volumes of the breads were significantly reduced.As the proportion of superfine broccoli powder increased,the recovery and cohesiveness of the bread decreased significantly,while the chewiness and adhesion increased significantly,indicating that the addition of superfine broccoli powder increased the hardness of the bread as well as sticky but lack of elasticity.According to the sensory evaluation,it could be concluded that when the amount of superfine broccoli powder was 9% or less,the bread was acceptable.