| Starch noodles are traditionally processed agricultural products that are popular in China and Southeast Asia.They play an important role in the value-added conversion of grain and potato.Because of inexpensive and great improvement of the alum on the processing performance and food quality of starch noodles,it would be added to traditional starch noodles production in China.However,the aluminum would be deposited in the body,and had chronic side effects,which can lead to osteoporosis,anemia,Alzheimer's disease and other diseases.In 2015,the State Health and Family Planning Commission issued“Announcement on Approval of?-galactosidase as a New Variety of Food Additives”?short as“Announcement”below?,which explicitly allowed the use of alum in the starch noodles and the aluminum limit is set to 200mg/kg,than the latest implementation of GB 2760-2014 prescribed the limit of 100mg/kg doubled.In addition,in order to replace or reduce the use of alum,KGM was added to overcome the shortcomings of easy to break.However,there is no relevant study on the effect of the deposition of Al3+in the body by using KGM.This paper focuse on the impact of alum and KGM on the properties and qualities of sweet potato starch after the publication of the"Announcement",and explored the interaction mechanism between aluminum and sweet potato starch.In addition,an in vitro digestion method was used to analysis the release of aluminum in the gastrointestinal tract of starch noodles with alum and KGM.Animal experiments were conducted to study the content of aluminum into the blood and those important digestive organs,and the accumulation of aluminum in brain tissues after the starch noodles were digested and absorbed.The main research contents are as follows:?1?The effect of alum and KGM on the gelatinization and retrogradation of sweet potato starch:when the alum increased from 1.75‰(100 mg/kg Al3+)to 3.511‰(200mg/kg Al3+),The peak viscosity of the mixed increased significantly,the disintegration value increased significantly,the setback value decreased significantly,the transparency of the starch paste decreased significantly,the retrogradation decreased,and the freeze-thaw stability of the starch gel decreased,the hardness,cohesiveness,and chewiness gradually increased.The rheological properties indicated that the alum increased from 1.736‰to 3.511‰can significantly increase G'and G"and increase the gel strength of sweet potato starch.Compared adding 3.511‰alum+3‰KGM with adding 3.511‰alum only,significantly increased the peak viscosity,disintegration value and final viscosity of the mixed system,but has no significant effect on the retrogradation value of the system,which improved the freeze-thaw stability of the starch gel,inhibited the long-term aging of the sweet potato starch,and reduced the hardness and chewing,and improved the viscosity of the gel.?2?The effect of alum and KGM on the quality of sweet potato noodles:with the increase of alum,the broken rate decreased from 55%to 5%,which significantly reduced the degree of swelling and cooking loss,increased the whiteness of noodles and the hardness,chewiness,cohesiveness and shearing strength,reduced the stickiness of the noodles.Adding KGM can reduce the hardness and chewiness of the noodles to a certain extent,improve the elasticity and viscosity,and reduce the shear strength of the noodles.Based on the correlation analysis,the broken rate and cooking loss were significantly correlated with the hardness,cohesion,chewiness and shearing force,and the quality of the noodles can be expressed by measuring the four indexes.Through the determination of mechanical indexes and sensory evaluation,it was showed that the addition of alum at 3.511‰and 2.633‰had no significant effect on the quality of sweet potato starch noodles.Therefore,we can chose the low dose of alum?2.633‰?in practice to reduce the content of Al3+in the starch noodles.?3?The mechanism of the interaction between alum and sweet potato starch:the infrared spectrum showed that the alum had obvious influence on the absorption peak of-OH at 3435 cm-1 of sweet potato starch noodles,and slightly moves toward 3445cm-1,indicating that the hydrogen bonding force does not play a major role,the main force is the ionic bond in this system.Thermodynamic properties showed that alum had no significant effect on the To,TP and TC of sweet potato starch,but significantly increased the enthalpy of starch.There was only one glass transition temperature of sweet potato starch noodles,indicating that the blend system of alum and sweet potato starch is compatible,and the addition of alum significantly improved the glass transition temperature of sweet potato starch noodles.Because alum and sweet potato starch are coprecipitated in a solid phase agglomerate form and form a gel and crosslinked together,the addition of alum maked the sweet potato starch noodles shown a strong anti-cooking performance.?4?Simulated stomach and intestine digestion test and animal experiments:With the increase of alum,the amount of Al3+released from the noodles increased,and the dissolution rate of Al3+in the stomach and intestine was about 50%and 10%,respectively.It indicated that the dissolution of Al3+in the starch noodles occurs mainly in the stomach.In addition,the addition of KGM to the starch noodles significantly reduced the dissolution of Al3+in the stomach.During the 12-week animal experiment,the appearance and behavior of the mice were observed.It was found that the mice fed with the alum starch noodles appeared irritable and abnormally active and had no obvious changes in body weight compared with other groups.Analysis of the organ-to-body ratio of mice in each group showed that long-term fed with alum starch noodles had no significant effect on the heart-to-body ratio,liver-to-body ratio and kidney-to-body ratio,but significantly increased the brain-to-ratio.Compared with the control group,the content of Al3+in the blood,heart,kidney,liver and brain of mice fed with low dose and high dose of alum increased significantly,and as the intake of alum increased,the content of aluminum also increased in mice.Compared with the KGM group,the content of Al3+in KGM group was lower than the high dose group. |
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