Complex Fermentation Of Mackerel Processing Waste By Lactobbacillus Phan And Candida Utilis

Mackerel processing wastes,including fish head,viscera,tail and bones were produced as byproducts of aquatic food.These wastes contain abundant nutrients and some beneficial ingredients.Ineffective utilization of these processing wastes will cause the waste of nutritious resources and seriously environmental pollution.Microbial and chemical changes were investigated during the fermentation process of mackerel processing waste in this thesis.The main results and conclusions are as follows:(1)The basic composition and the scanning electron microscope of the mackerel processing waste before and after pasteurization were analyzed.The influences of the addition of different amounts of glucose(control,3%,6% and 9%)on pH,sugar content and biomass changes of Lactobbacillus Phan were studied during the whole fermentation process.Effects of different ratio of material to water(control,1:1,3:1 and 5:1)and different stiring speeds(control,60 r/min,120 r/min and 180 r/min)on pH and biomass changes of Lactobbacillus Phan were also investigated.The results revealed that the content of crude protein,crude fat,ash,salt content,total sugar and reduced sugar of mackerel processing wastes was 14.42%,6.2%,5.9%,0.2%,0.74% and 0.41% respectively.The results of scanning electron microscopy of mackerel processing waste after pasteurization showed that myofibrils had more clear folds and texture.In addition,the fermentation process under the combined conditions of 9% of glucose addition,3:1 of the ratio of material to water and 120 r/min of stiring speed can maintain the acidic environment,safety of fermentation process,and less energy cost.(2)The microbial and chemical changes of the mackerel processing waste in different temperature(25 ?,30 ? and 35 ?)were studied during complex fermentation process(0~48 h)by Lactobbacillus Phan and Candida utilis.The results showed that the biomass of Lactobbacillus Phan in different fermentation temperatures had no significant difference(p> 0.05),but 35 ? was not suitable to the growth of Candida utilis.Under the three fermentation temperatures,the content of water-soluble protein decreased,the content of non-protein nitrogen and amino nitrogen increased simultaneously,pH and total volatile base nitrogen increased after initial decreasing,and the changes of total acid was negatively correlated with that of pH.Based on productive growth of Lactobbacillus Phan and Candida utilis,decreasing of pH and increasing of amino nitrogen,complex strains fermentation could enhance the concentration of single-cell protein,inhibit the growth of spoilage bacteria,and thus improve the nutritional value of the fermentation matrix.(3)The microbial and chemical changes of the mackerel processing waste during complex fermentation(0~72 h)by Lactobbacillus Phan and Candida utilis in different amounts of papain(control,0.02%,0.1% and 0.2%,on the basis of the mackerel processing waste mass)were studied.The results showed that addition of papain had improved the biomass of Lactobbacillus Phan and Candida utilis.The pH value and TVB-N of fermented mackerel processing waste with the addition of the papain were lower than that of control sample.The content of total titratable acid and amino nitrogen was higher than that of control sample,while the content of true protein among the four samples was similar.The fermentation process with papain not only maintained the safety of the fermented environment,but also further optimized the nutritional value of mackerel processing waste.(4)The biogenic amines(putrescine,histamine,cadaverine and tyramine)changes of the mackerel processing waste during fermentation(0~48 h)were studied.The results showed that the composite strains could inhibit the fornation of cadaverine while could not inhibit the content of putrescine and tyramine.The composite strains could inhibit the content of histamine only in 24 h and 36 h.At the end of fermentation,the histamine content of the experimental group was 15.26 mg/kg,in line with histamine standards of the GB/T 19164-2003,and the fermentation environment was safe and feasible.(5)The moisture content,color and amino nitrogen content changes of fermented product in different drying temperatures(50 ?,60 ?,70 ? and 80 ?)were studied.The total amino acid content of fermented product after drying and the scanning electron microscope of fermented product before and after drying were also analyzed.The results showed that the higher drying temperature could have less drying time while there were no significant difference(p>0.05)in color change of four different drying temperatures.In the four different drying temperatures,there was the lowest amino nitrogen content in the 70 ? dried fermented product,and there were no significant difference(p>0.05)in the content of amino nitrogen among dried fermented product at 50 ?,60 ? and 80 ?.On the basis of the fermentation time and the survival perspective of Lactobbacillus Phan and Candida utilis,the optimum drying temperature was 60 ?.Dried fermented product had higher content of amino acid,than the mackerel processing waste.The myofibrillar structure of the dried fermented product made the tissue folder and texture more prominent.