Study On Technology Of Mackerel Protein Recovery By Ammonia-water System

As aquatic products processing techonolgies in China were behind developedcountries, in the thesis, a new isoelectric solubilization/precipatation （ISP technology）system was established using ammonia as alkalization. Firstly, effect of ammoniasystem on protein safety and nutritional was studied with BSA as a model. Secondly,mackerel fish protein solubility in ammonia system was studied. Finally, processconditions and water-saving potential of ammonia system was explored with mackerelfish byproducts. Conclusions were as follows:1) Cross-linking of lysinoalanine （LAL） rose quickly at high temperature and pH.And NH₃inhibited the reaction to some extend from pH9.5to12.0at50℃,especially at the beginning of reaction. In addition, the ammonia system could protectsome kinds of amino acids better than NaOH system. In sum, the protein extracted byammonia system had greater security and better nutrition stability than proteinextracted by NaOH system.2) Mackerel fish protein solubility in alkali solution was better than that in acidsolution. And the regulation of protein solubility in ammonia system was almost thesame as that in NaOH system. The differences between ammonia and NaOH systemwere as follows: firstly, protein solubility decreased in ammonia system when the pHvalue of fish homogenate exceed11.0. Secondly, protein dissolution rate at solid-lipid1:7was close to that at solid-lipid1:10, so ammonia system could save30%watercompared with NaOH system. In sum, the new ISP technology was feasible andwater-saving.3) The maximum value of mackerel byproducts protein solubility in ammoniaand NaOH system was both around pH11.0at4℃. And protein solubility increased quickly as temperature increased appropriately, this could increase the operating rangeof pH. In addition, solid-lipid could be reduced to1:2.0by the new ISP technology,and twice extraction could further save three-fourths of water.4) pH value of fish homogenate could be adjusted to12.24at0.2MPa by fillingammonia, pH operation range of protein extraction could be achieved at lowerpressure than0.2MPa. And the pH value of homogenate was unchanged whenpressure was released after adjusting pH, this would bring convenience to subsequentoperations.In summary, besides the ability of extracting protein, ammonia system had manyadvantages compared with NaOH system, such as higher product safety, protectioncapacity of nutritional value, significantly water-saving and better operatingcontrollability. The new ISP technology had an important significance to innovationsof aquatic products processing technology in future.