Preparation And Property-studies Of Sepia Nano Ink And Its Application In Bread

In this paper,Sepia pharaonis ink sac was used as raw material,and nano-ink was prepared by enzymatic hydrolysis technology an dynamic high pressure microfluidization(DHPM)technology.The effect of DHPM on the physical properties such as particle size and solubility of the main component of melanin in the ink was studied.And the microstructure was characterized by infrared spectra(IR)and scanning electron microscope(SEM).The modification conditions for optimizing the physical properties of the ink were screened,and then combine high-quality ink bread with common wheat flour and explore the changes in quality and flavor during aging.The main research conclusions obtained in this paper are as follows:(1)In order to obtain high quality Sepia pharaonis ink,Pretreatment by enzymatic hydrolysis and study the best process of enzymatic hydrolysis of it.Using hydrolysis degree of Sepia ink as an indicator,the best enzymes were screened from acid protease,alkaline protease,neutral protease,papain and pepsin.On the basis of single factor experiment,the effects of enzymatic hydrolysis temperature,enzyme dosage and enzymatic hydrolysis time on the hydrolysis degree of the Sepia ink were investigated by response surface test.The results showed that enzymatic hydrolysis of sepia ink with alkaline protease and the optimal enzymatic hydrolysis conditions were as follows:the ratio of material to liquid was 2%,the enzymatic hydrolysis temperature was 51?,the pH was 10.0,the enzyme dosage was 4260 U/g,and the enzymatic hydrolysis time was 4.5 h,the maximum degree of hydrolysis was(21.27±0.05)%.At the same time,the UV-visible spectrophotometric verification test showed that the absorbance of the enzymatic hydrolysate increased significantly,further indicating that the alkaline protease has the best enzymatic hydrolysis effect on sepia ink.(2)Nano-ink was prepared by using sepia enzymatic hydrolysate as raw material,and the effect of DHPM on physical properties of ink melanin under different homogenization conditions(0?40?80?120?160?200 MPa)was studied.And its microstructure was analyzed by infrared spectroscopy(IR)and scanning electron microscopy(SEM).The results indicated that DHPM led to the depolymerization of Sepia melanin aggregates,thus increased turbidity,reduced average particle size and made the particle size distribution more concentrated and subtler,while improving its solubility in deionized water and physiological saline.Apparent viscosity and spatial chromaticity values were increased after DHPM treatment,which improved and maintained the rheological properties and color of Sepia melanin solution.The DSC method determined that DHPM had a certain influence on its thermal stability.It was found that the thermal denaturation temperature was 90.70? and the enthalpy change value(?H)was 0.45 J/g at 120 MPa and the Sepia melanin has good storage stability under this pressure.Infrared spectroscopy showed that DHPM treatment formed strong hydrogen bonds between molecules in the range of 3500?3300 cm-1,1700?1500 cm-1 and 1450?750 cm-1.Scanning electron microscopy showed that the sample particles became smaller as the pressure increased and aggregation occurred after more than 120 MPa,and the particle size became slightly larger.(3)The nano ink prepared by 120 MPa DHPM was vacuum-dried,and the obtained ink powder and bread wheat flour were used as main raw materials to produce high-quality ink bread.Using hardness and sensory scores as indicators,screening the best addition amount of ink powder and optimizing the optimal preparation formula and processing technology of ink bread by single factor test and orthogonal test.The results showed that when the amount of ink powder was 5%,the amount of yeast added was 1.5%,the amount of white sugar added was 20%,the amount of water added was 45%,the fermentation time was 90 min,the stirring time was 20 min,and the baking temperature was 185?.When the baking time is 15 min,the hardness of the ink bread is the smallest(2.01 N)and the sensory score is the largest(94 points),which is higher than the results of all combinations in the orthogonal test.(4)The quality and flavor of the ink bread aging process were studied by differential scanning calorimetry and electronic nose.The results show that compared with ordinary bread,ink bread always has a higher moisture content and specific volume,lower water activity,better water retention and the ink powder has a significant effect on the chromaticity changes of the crust and the core with the increase of storage time.Through the texture measurement,it was found that the addition of the ink powder can keep the bread taste for a long time.In addition,the swelling degree of the ink bread during the aging is lower than that of the ordinar bread,and less slag.The results of the electronic nose showed that the volatile component of the ink bread which had a great influence on its odor was an oxynitride and a high component.And the samples during different aging can be distinguished,which proves that the electronic nose technology can clearly distinguish the odor changes of ink bread and ordinary bread in different shelf life.